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Toxophilus

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Posts posted by Toxophilus


  1. On 10/12/2019 at 08:45, steppenwolf said:

    Thank you, I look forward to seeing your result - it is a fascinating region of the nebula

    Unfortunately the cloud moved in and put a stop to things. My guiding was absolutely spot on with the mount behaving better than it ever has. Still it was an exploratory session to get a feel for my new scope with narrowband and how much exposure for each filter it would need. Looks like I'm going to have to wait for the skies to clear again.

    • Like 1

  2. Beautifully done! Strangely enough I have just started grabbing some data on almost exactly the same region tonight. Came on for a read on SGL whilst keeping an eye on the guiding and found this. I just hope I can get half as good a result.

    • Like 2

  3. 23 minutes ago, bob-c said:

    Hi Mark,

    Things are going quite well now with mine also since I installed the new firmware FW190718..It is a treat to use now and I am chuffed with it.  I still need to do some fine tuning though and hopefully I will get there in the end....once again a great review and it has helped me already..

    Bob.

    I'm glad its going well. There is a newer version of the firmware (190820) I tried it for a couple if images one of M34 and one of a the core of M33 (which I'm about to post on astrobin). @Jkulin found it OK but felt that it was not quite as good in RA. I found it not as good in both RA and Dec. It still produced a good image but the stars are not quite as tight for me when compared to 190718, so I reverted back to it.

    • Like 1

  4. 20 minutes ago, bob-c said:

    Thank you Mark for a great and in depth review. I hope all goes well for you in the future and you truly get those lovely images.

    Bob.

    Hi Bob, 

    Many thanks! I hope the review is helpful to someone and that you found it interesting. It is a bit long but there was a lot to cover and it was worthwhile doing it justice. I'm getting some great images now with the rig as I start to really fine tune things. We just need some clear skies now. Its been a frustrating year weather wise.

    I hope all is going well with your setup now.


  5. Scope and mount upgrade project - Part 3

    Having tried my AD250 with my Skywatcher AZ-EQ6 and found that it was struggling to handle the combination of focal length and weight to the precision that I wanted, I decided to upgrade the mount.

    My site does not have the room for a permanent observatory or pier, so whatever I went for needed to be ‘portable’ as I would have to set up from scratch whenever I wanted to use my rig. Also going from something that is transportable, could, in the future give me the opportunity to port the kit to a truly dark site if the opportunity arose.

    I had seen good results from the iOptron CEM60-EC and after some consideration of a variety of options that were available to me, I decided to go for an iOptron CEM120-EC mount on the iOptron 360 Tri-Pier.

    Overview

    I’m not going to detail all the technical specifications as they are easily available on the iOptron site. However, pertinent bits of specification are:

    ·         Right Ascension Periodic Error: ~±3.5 arcsec for the non-encoder version and <0.15 arcsec RMS for 4 min on the versions fitted with encoders.

    ·         Resolution: 0.07 arc seconds 

    ·         Slew speeds of 1,2,8,16,64,128,256, 512x sidereal and a maximum speed of 4°/sec.

    Encoder fitted mount come with a dedicated PEC graph that the encoders measured:

    image.png.81e3ee3ef1036b0157922b96cd79d1ca.png

    Payload

    The heaviest rig that I am running at the moment is just shy of 19kg so with the CEM120-EC rated at an imaging payload of 120lbs (54.4kg) I was well within the capability of the mount with plenty of room for expansion such as running multiple scopes, etc.

    image.png.74e9f6851dd7561dba642ae3a88b1583.png

    Weight

    A piece of kit capable of handling these kinds of masses accurately is not going to be lightweight, but just how heavy is all this kit?

    image.png.dcad742fdfee7faabab8d3eb3238f128.png

    Using my highly scientific and accurate bathroom scales:

    The mount itself came in at 26.8Kg
    The two 10Kg counterweights at 20.4Kg
    The counterweight rod at 4.7Kg
    and finally, the 360 Tri-Pier at 19.8Kg

    A grand total of 71.7Kg!

    So, no lightweight - but as individual parts nothing too difficult to lift and carry. The mount, being the heavy one, has plenty of places to get a good grip and is not too bad to carry a short distance (20 or 30m).

    Portable?

    So, would it be considered ‘portable’? That would depend a lot on your own opinion for the criteria, health, strength etc. But for my purposes and situation, it’s portable. I plan to only ever be setting it up in my garden so would only be carrying it 10m or so. If I were to take it to a dark site I would be loading it into the car to transport it and then carrying it no more than 30m or so - something that would not unduly phase me. It has all been transported to the Practical Astronomy Show earlier this year and set up with no trouble (although I did use a cart to move it as it was more like 300m to get it to the display).

    Connectivity

    The PC connectivity options built into the mount are quite simply astounding. There are so many options it is hard to know which to go for. Having tested the USB, LAN and Wireless options they all work as efficiently as each other, so it all boils down to personal preference.

    image.png.9871a745de6ea1d60c35dab55ec9e955.png

    Available to you are Serial connection via the Handbox, a dedicated RS232 connection, Direct USB, LAN or Wireless (with the supplied mini angled antenna). I use the wireless connection. It requires me to connect to the CEM120’s wireless network before starting the iOptron Commander software that is used to interface to it. This removes a cable from the rig and keeps things cleaner, and so is my prefered option. Once the Commander software is up and running, the ASCOM drivers for the mount then allow any compatible software to work with the mount.

    I use Sequence Generator Pro and have not had a problem with it. Cartes du Ciel has been used to control the mount on other occasions with no problems. So I can only assume that this will be the case for other ASCOM compliant software.

    The mount has a dedicated port for 12v to power it on its lower section (pictured above). When the mount is switched on, this also supplies power to the 3 x 1A 12v (5.5mm x 2.1mm) ports situated on the saddle (1 on the rear and 2 on the right hand side)

     image.png.1be1cb3cd2e78d40aebca33b70b4b6db.png  image.png.5e7a988421a0c988d52f779fa8bf84f1.png

    If you need more power up at the saddle, there is a dedicated 10A input mounted on the rear center section of the mount that pushes power to the 2 x 5A (both 5.5mm, one with a 2.5mm center and the other a 2.1mm) outputs on the left of the saddle. These are permantly powered and not controlled by the mount.

     image.png.101bb032a9b15a50108dc10e44e1c6f0.png  image.png.9951efea5ca2f75e528cf035b992c98b.png  

    The center section is key to your data services mounted on the saddle. It provides connetions to a access a 4 port USV 2.0 hub that is mounted on the saddle and a single USB 3.0 connection, also avaialble on the saddle and access to the polar scope (covered later).  It also provides an ‘Aux In’ port via a 4 pin connector that output on the saddle, This can be used for pretty much anything you want from low power to data, or something else. I contacted iOptron regarding the maximum power for this port as nothing is mentioned in the manual, they suggested no more than 5A. I have been running around 3-4A at 12v with no problems.

    The only two connectors left to mention that are mounted on the saddle are the ST4 Guide port and the iPort. Both of these feed directly into the main board at the bottom of the mount. So in the case of ST4 guiding you don’t have any trailing cables, just a short cable from the camera to the back of the saddle.

    The iPort is propriatary to iOptron and I have not had chance to use it yet. However it can be used to drive a variety of iOptron accessories such as electronic focusers.

    All the cables are neatly run through the center of the mount and having rotated the saddle and mount in mulultiple directions I was unable to detect any cables catching internally. All this means that you can keep your cabling as short and neat as possible and eliminating the fears of cable drag, with no more dangling cables to tempt the cat to play with in the last 5 sections of a 30 minute exposure.

    The last connection to mention is the GPS receiver. It’s just a standard mini coax screw type fitting and nothing to get excited about. iOptron do provide a GPS antenna with a straight fitting and a long (5 or 10m cable - I haven’t measured it). This is ideal for getting the antenna outside if the mount is installed in an observatory, but for my purposes it was too long - so I purchased an alternative with an angled connector for neatness and less damage risk when moving the mount, and shortened the cable to allow me to mount the antenna via some semi-permanant ‘glue dots’ on the side of the mount.

    image.png.56eb5e5acc31a42be16825930b9fd6a3.png

    Polar Scope

    I have a QHYCCD PoleMaster electronic polar scope mounted on my CEM120-EC. It is rather neatly hidden behind a screw on cover to keep it clean when not in use. The mounting kit provides a plate that the scope is attached to and a short USB lead that connects to the rear of the central input/output panel of the mount. The polar scope then slides in and is secured by 3 screws that have expanders on them to grip the inside of the mount, keeping the scope in place. It took me around 10 minutes to install. Access to the polar scope is then done via the polar scope connection on the rear centre panel of the mount. I then run a short cable from there to my Pegasus Ultimate Power box to access it via the computer whilst polar aligning. Once finished I simply remove the temporary cable, put the cover back on and return the mount to its zero position and I’m ready to go.

    image.png.8154b1cff917841c9bcfcc1f78bd749b.png  image.png.c006752077f57bc546924f17d10dba2d.png

    Adjusting the mount for polar alignment is a simple affair, altitude is done with a large dial at the front and azimuth is adjusted via two knobs on the rear that balance against each other, so you need to loosen one before adjusting the other. Both provide smooth operation and are well made. There is a lot of backlash in the altitude adjustment, but this is no major issue as if adjustments are needed to lower the mount. I always go too low and move up to the correct position, ensuring that the altitude adjustment is carrying the full load of the mount.

    image.png.571ebcbc15c22054f76c8666b6a75064.pngimage.png.de8e216ba46b6d2739ed157ba6b77d0a.png  

    The mount comes with rather nicely made knobs to secure it to the pier, which is fine for permanent setups. However, as I am constantly taking my rig apart. I found that the azimuth adjustment knobs could impinge on them when taking things apart, causing wear to the red anodizing. In the end I replaced them with simple M8 hex bolts which made things a lot easier.

     image.png.9583cfd2cd09d695496bff481dd934d5.png  image.png.67e6d4601853d8872240d192fb56b8bf.png 

    Mounting Your Scope

    The saddle on the mount only takes Losmandy style dovetails, so if you have Vixen rails you will either need to replace them or buy or make an adaptor (as I have done).

    The saddle is extremely long 435mm (17”) and uses a fixed dovetail that you slide a Losmandy rail into. You then lock everything in place via 3 chamfered 8mm brass pins adjusted via substantial knobs on the side. The pin system does offer more flexibility if you were to use this with multiple scopes, rather than a clamp style saddle system.

    image.png.13d424d106c38b387f14708e2608988f.png

    Some people have found the tolerance on this fixed dovetail too tight, and I believe that iOptron can swap it out if you find this to be the case. Personally, I have used several different Losmandy rails with this mount and they have all been a good fit. I have found that the pins lock the rail in place well and I have never had even the slightest movement of a scope. My AD250 was originally only held by 1 of these pins and I had no issues with it in doing so. However, for peace of mind I did put a longer rail onto the scope to allow me to use 2. The longer rail also made getting the scope on and off and balancing easier. As I don’t use the rear securing pin, I have wound that out to almost its full extent, so if grip were lost and the scope slipped backwards it could go no further than this pin anyway.

    The saddle itself is held on via 4 bolts and is designed to be removed, so that it can be rotated for dual scope setups etc. It also has 3 sets of mounting holes to allow you to fine tune balance with scope saddle position.

    A small word of warning

    When initially setting up the mount is placed in a horizontal position, so naturally you will need to wind it to its correct altitude setting. Be careful when doing this as the cables coming from the main board can move outwards as you do this, and there is a pinch point that can trap and damage the cables if you are a little over eager with the process. The manual does mention this issue but is easily missed.

    image.png.6faddccbc6fb490c643eff88ccaf5a8d.png

    No Clutch

    The mount does not use clutches, but instead implements a ‘switch’ type mechanism where-by you can lock and unlock each axel and engage or disengage the worm ring drive.

    image.png.c27f40ac5b0166a82ceb157d420d49d5.png  image.png.5f3e84c4211c93fc5289e5b817d15c54.png

    The manual comes with multiple warning and an explanation of how the system works, but it gave me concerns about getting it wrong and accidentally damaging the worm. I contacted iOptron for further clarification. They confirmed that, if the axel lock were left on with the drive engaged and an attempt to slew the mount was made, or if for some reason the mount/scope accidentally fouled on a pier or tripod or something else, that the stepper motors were designed to skip and prevent any accidental damage. It is not something that you want to do regularly, but occasionally will not cause a problem. This has happened to me and it makes an awful racket, so you soon get around to halting it anyway for fear of waking the neighbourhood at 3am.

    Balancing

    The bearings on the axels are extremely smooth, and balancing the scope is an easy task. Balancing is done via the 4.7Kg 38mm thick 540mm long stainless-steel counterweight bar and the supplied 10Kg counterweights. I received 2 with my mount but I believe that it usually comes with only 1.

    When installing the counterweight bar, I found that the dry stainless thread screwing into the aluminium socket was both stiff and very noisy, so a tiny dab of grease helped a lot there. I also found that the mass of the counterweight bar could easily catch you out if it had not caught the thread properly or when it comes free from the thread when removing it. So, I always put a piece of cloth under the counterweight bar to protect the mount from accidental chips to its paint work.

    The saddle also has 4 x M8 threaded holes, 2 on the front and 2 on the side, near the front that will allow you to add and adjust extra weight to fine tune balance or install accessories etc. The saddle can also be moved back and forwards a little by the extra mounting bolt holes provided to allow you to get the best position on the saddle for your scope when in balance.

    Once near balance just sub millimetre tweaks are needed and a perceivable difference at each position change can be noticed. But once balanced the scope move effortlessly. In my case, once the counterweights were set, the AD250 just balanced with only minor tweaks to its forward/backward position of the saddle. It makes my AD250 look like it is almost floating through the air once right.

    Slewing and Tracking

    Slewing the mount at maximum speed is accurate and usually puts my target somewhere near, plate solving then gets a target centred with usually only a final small tweak from the plate solving to get it perfect. Slewing at this speed is not particularly noisy and is on a par with most mounts. To me it’s a fraction louder than it was with my Skywatcher AZ-EQ6. Slower speed slews and adjustments are pretty much silent as you would expect.

    Whilst tracking there is an audible ‘ticking’ noise that comes from the mount but not anything that you would notice unless you had your head almost against it. When halted after long runs I have noticed a slight electronic buzz coming from the mount, but this seems perfectly normal and goes away once the mount is moving or tracking again.

    Hand Controller

    Although I have not used the hand controller much the menus are easy to navigate, and the display is very clear. The quality of the buttons means the it is easy to use even with relatively cold hands. There is a controller heater option that can be enabled, this is ensure that the LCD display is kept operational at very low temperatures and not for warming your hands on (although on some nights that would have been a nice feature). The menus are comprehensive, easily navigated and cover all the things that you would expect. I won’t go into any detail on this as it’s all available in the pdf manuals from the iOptron site.

    Firmware

    The various boards and the hand controller can all have their firmware updated and iOptron release regular updates to this via their web site. I have done this many times and the process is painless and quick, although when updating the boards you do need to re-calibrate the encoders if you have them fitted when you do so, via a simple procedure. I also tell the mount to search its zero position once I have done this as I have found that it will sometimes lose it, meaning initial slews after updating can be inaccurate if you don’t.

    360 Tri-Pier

    The 360 Tri-Pier is beautifully made. It collapses down smaller than many other tripods that I have used and is really a solid build quality, matching and setting off the CEM120 perfectly.

     image.png.5cc79b14e7e19e46e2f8f81788e5aeb0.png  image.png.092a91608e9168779ceb73e9443cd317.png

    Height adjustment is done via 4 pre-determined positions (from fully closed to fully open) that you simply screw the locking knobs into. This controls the height of the pier with some small differences in the spread of the substantial legs. I run mine on the last but one position but having tried all of them it is stable in all usable positions. When finished with and collapsed up it tucks neatly away in a corner without risk of falling over.

    The pier is quoted at being able to hold 165Kg, way above what I ever plan to mount on it. When fully closed it is around 81cm high, and at its highest position it goes up to around 101cm with a maximum leg spread of just over 106cm.

    The ring that is used to lock the height of the pier has a few millimetres of play in it to allow it to slide up and down easily as you adjust it. This is no issue, but If like me you have a pre-levelled spot that you put your scope each time you use it. When locking the height in place if you change to order or tension that you do the locking knobs up in, then you will find that you need to adjust the feet a little each time you use it to get it back to level. That said, you should be checking its level anyway.

    image.png.ed44f79a29d79ad4ea53f40c05473a26.png

    Levelling is done via simple threaded feet, and gives you around 51mm (2”) of adjustment so you don’t need super level ground get going out in the field. These feet are hinged to drop securely flat on the ground and work extremely well. They are only 80mm in diameter, so on soft ground having a larger hard surface to place them on to prevent it sinking or shifting is advisable.

    image.png.2c7b2e31d58164a4afa16a93cd8832b3.png

    The large flat pate at the top of the pier is designed to match the mounting surface of the CEM120 perfectly and the fact that there are no locating pins or azimuth adjustment pins to align makes life a lot easier when putting the mount onto the pier. You just need to drop it onto the top and slide into place and secure with the 4 locking bolts. A lot easier than many systems with locating pins etc.

    image.png.8e09f41ea3d42ce17499e956fa63135f.png

    The top plate can easily be removed for bespoke plates to be added if needed.

    Guiding

    The CEM120 is compatible with either ST4 guiding (via the ST4 port on the saddle) or pulse guiding. Both methods work fine with the mount. I run mine using pulse guiding over the wireless connection and it works perfectly and cuts down on the number of cables in use.

    Initially I did have a lot of issue with guiding and had some very disappointing results (more detail below). I believe that I have got them resolved now with the latest beta firmware update from iOptron, so my comments here are based on current results.

    The skies recently have not been good to say the least, however from my last endeavours with the CEM120-EC my guiding over the night was below 0.4” total RMS over both declination and right ascension, with it often being down at 0.3” for sustained periods. When guide adjustments were issues by PHD2 the response of the mount would almost always be precise and correct well without over correcting. Because of this I found tuning the guiding to the seeing was usually a relatively easy job and often was more a case of adjusting the exposure times more than anything else.

    The following is a screen grab from PHD2 from one of the last sessions that I did with the mount whilst imaging Melotte 15 in Hydrogen Alpha to give you an idea of how it is currently behaving.

    image.png.d43a64a5ee65a3047e89b956e3713406.png

    And this a heavily zoomed-in unprocessed (other than a stretch) part of a 10-minute single sub frame from the same session:

    image.png.e6ce8d5725d264459e8020c03fb61ef4.png

    I was more than happy with my star shape from this session.

    Build Quality

    Having seen inside the CEM120 and how well put together it is I was delighted with the build quality. My CEM120 was immaculate inside and not over greased or with stray bits of manufacturing swarf lying around inside. All the parts were well finished and the design simple, effective and maintainable.

    Where cables have been run their paths are clear, although one or two of the finer cables are run through tight spaces that, if not positioned correctly, could get pinched if you were not careful when taking parts of the mount apart. The electronics all uses commonly available connectors so if cables were accidentally damaged it should be easy enough to get replaced.

    Perhaps the only part in the build quality that I have found a little disappointing is that the anodising on the saddle and the azimuth adjustment knobs has started to wear. This is down the fact that I am constantly removing my scope and with the initial impingement issue with the mount securing knobs that I mentioned earlier. I have probably subjected these parts to more than 20x the wear that an observatory-based user would subject the mount to. Which could be considered acceptable and to be expected, but my old ADM saddle had similar if not more use with no noticeable wear to its anodising.

    Issues

    I can’t say the my CEM120-EC was perfect out of the box. Initially I had a lot of problems due to the firmware on the mount.

    The first issue I encountered was as the mount approached the meridian, rather than pausing or performing an automatic flip as was configured on the boards, it would simply halt and slew the scope in declination to point at the ground.

    The next was more frustrating and has frustrated a lot of people: Guiding.

    I initially found that guiding was just not responding and then responding if great lumps in declination only. I contacted Altair Astro and they were extremely helpful in working with me and iOptron to try to resolve the issue.

    At first it was believed that there were tension issues with the declination drive. iOptron sent me detailed instructions on how to adjust it but this did not work.

    Further trails led iOptron to believe that the issue may be further in the mechanisms and so again details instructions were sent on how to access the internals of the declination drive and make the adjustments. When I got to the part that was believed to be the root of the issue, I could not find any of the expected play and so put the mount back together. This did give me the opportunity to have a look inside and the mount, as mentioned earlier, is beautifully made.

    By now things were getting frustrating and with the combination of bad weather/skies delaying trying things out this only helped make things harder. At this point iOptron, Altair and I had reached the conclusion that the issue must be firmware. I was issued a beta version that I trialled, and this fixed the problems with declination but made things worse in right ascension and introduced some behaviour issues with the mount with respect to its automatic flip.

    Ultimately, I ended up obtaining around 6 different versions of the firmware from an iOptron users forum. I did an analysis of each version and how it guided and passed my finding on to iOptron. At the same time many other users of the CEM120 were doing similar things.

    At the start of August 2019 iOptron released a new version of the CEM120 firmware (FW190718). I had heard good things about it and so installed it onto my mount. The results were instantly better, and it looks like iOptron have finally got a good version of firmware for the CEM120.

    Certainly, I am happy with how the mount is currently behaving, although these issues were frustrating and infuriating. Credit needs to be given to Altair Astro, they were as helpful and as understanding as possible and they went out of their way to help me a lot and it must have been frustrating for them too. I spent a lot of time talking with Nick and Ian about the mount and the problems that I was encountering, and their support was invaluable.

    Summary

    I absolutely love the 360 Tri-Pier and CEM120-EC combination. It gives me the ‘portability’ that I require and looks a really neatly designed and finished package. My initial troubles with getting good guiding did generate a bit of a love-hate relationship with the mount and I has taken me a little while to begin to trust the mount as well as I trusted my Skywatcher QZ-EZ6. However the build quality is superb and way beyond anything I have ever used before.

    The mount is working well with Sequence Generator Pro and PHD2 and (when weather permits) I’m getting what I think are superb images for my location.

    iOptron seem to be getting the firmware behaving better with respect to guiding, and I am now happy with the results. I hope that iOptron may even be able to improve the firmware to provide even better guiding in the future. There are mounts capable of better, but as far as I have seen, there are few if any other options at the payloads and price point of the CEM-120EC.

    I still have a lot to learn with astrophotography and the mount, and I firmly believe with some further fine tuning I can get even better results.

    • Like 1

  6. Scope and mount upgrade project - Part 2

    The scope that I upgraded to after some consideration and a little bit of serendipity was an AD250 from www.656Imaging.co.uk. I am currently running this using:

    • FeatherTouch 3” 1.5” travel focuser
    • Celestron off axis guider
    • Starlight Express lodestar X2
    • Xagyl 2” 5 position filter wheel
    • Badder 2” filters
    • Atik 383L+ camera
    • Pegasus Astro Motor Focus
    • Pegasus Astro Ultimate Power Box

    Previously I had been running all this kit on my Meade LX90 (other than the focuser, motor focus and the lodestar). I think there are plenty of reviews of this kit on the internet and I reviewed the 1.25” Xagyl filter wheel some time ago. The 2” is very similar, in-fact slightly improved in their v2 of the wheel and so reviewing it again would not reveal anything new.

    Design

    The AD250 is a 10” Corrected Dall-Kirkham. The Dall-Kirkham design uses an elliptical primary and a spherical secondary and so requires a corrector to ensure a flat field - details on the design can be found at https://en.wikipedia.org/wiki/Modified_Dall–Kirkham_telescope. The AD250 uses a 3-element corrector to produce a 50mm flat field with a focal length of 1700mm and an f ratio of 6.8

    image.png.ebd49fc3c4f55af8c4c5cc3970140ca7.png

    The AD250 uses an oversized rear cell with a carbon fibre truss. The carbon trusses are deliberately over-engineered to ensure no movement of the front cell. Peter’s design tapers from the oversized cell at the rear to the smaller front cell to effectively form a cone/triangular structure to increase strength without adding any substantial weight. In use, this idea bears out with constant focus and star shapes wherever you point the scope in the sky. A side effect of the oversized rear cell is that it improves air flow, helping smooth currents and assist with cooling the primary and gives more room for maintenance etc. The mounting of the secondary is very solid and held in place by a strong spider. The secondary can be adjusted easily via 3 grub screws.

    image.png.7af3bfe4ad95c967d0231fe0f278eafd.png

    In use, I found that my focus did not substantially shift with temperature and star shapes were always consistent. I tend to re-focus with filter changes anyway so this may be a factor as I will only run for an hour or so on one filter at a time.

    The main supports are modular and so can be drilled and altered to fit any accessories that you may want. The top and bottom ones have a lot of pre-drilled and tapped holes making the fitting of alternative rails, cameras and in my case my Pegasus ultimate power box a relatively simple task.

    image.png.0769562ac99651274ce551f95cb705ab.png

    My AD250 came with a Losmandy style dovetail for mounting, but as these are treated as ‘mount adaptor plates’ any adaptor could be made for any mount. The plate that I originally had was 6” long and has held very securely by the ADM plate that I had on my Skywatcher AZ-EQ6. However, the CEM120 mounting plate only provides 3 ¼” pins to hold your scope. As the AD250 dovetail only provided the surface area to utilise one pin. Although it was held on securely enough and, in truth, it was perfectly safe as it was, I felt happier having invested so much with a bit more surface area to clamp on and so swapped this out for a longer Losmandy rail.

    The rear cell has an access port at the rear and can be modified to mount accessories if needed. It has 3 fans to provide air flow to smooth the air over the mirror, reduce the build-up of dew and get the mirror temperature down. These are powered via a 12v centre positive 3.5mm jack socket. I run this from a port on my Pegasus UPB so I can remotely control them.

    image.png.cf00c0cfe13448247abc471e0b90ccc1.png

    Dew Control

    The spider provides plenty of room to run a cable for a dew heater that can be wrapped around the secondary. The tapered nature of the secondary mount body means that unless you are using a very thick dew heater it is hidden behind it with respect to the primary. I have another dew heater around the housing that contains the corrector which fits very neatly, both dew heaters are powered and controlled via a Pegasus Ultimate Power Box. I also keep the fans running to help eliminate any currents and keep the air flowing over the primary to help stop dew forming. So far, I have not been troubled with any dew forming.

     image.png.c73cab199918057f52506953513727a5.png  image.png.d9cd430f2395a3f87822469da1f8c8e3.png

    Focusing and Optical Set-up

    The rear of the AD250 just has the corrector cell protruding slightly and there are 4 mounting screws to hold a focuser adaptor plate. This plate can be made to allow you to mount virtually any focuser of your choice. I chose the Starlight Instruments FeatherTouch 3”, driven with a Pegasus motor connected to a Pegasus Ultimate Power Box. This combination has worked well for me, and my ‘V’ curves have been consistent.

    image.png.688b71ba671d9420058abcfb355bde6f.png

    I am only hanging 2Kg or so of OAG, filter wheel and camera on the back, well within the limits for the FeatherTouch. More substantial imaging rigs may require something a bit stronger such as an Optec Focuser Gemini Focusing Rotator, etc. If that is the case, just let Peter know and he can get the correct adaptor made.

    The focuser adaptor plate can also be adjusted to allow you to align your camera sensor square to the optics and fine tune its position for optimum results.

    The back focus of the AD250 is 213mm from the back of the scope to the sensor (obviously extra glass such as filters, etc. will change this slightly). This gives plenty of room to get your imaging train in and with my rig I only need the move the focuser out around 6mm, keeping the imaging train as strong as possible.

    image.png.78141f4344b74fcabde44344f3823929.png

    The AD250 has a 50mm flat field and whilst I’m not using that kind of area currently it is producing excellent star shapes across the whole of the sensor on my Atik383L+. The following is the star test image that Peter provided me with when he setup the scope with my optical train:

     image.png.0b10805243d7d8f16cc205734c92c4d3.png

    Weight

    The quoted weight for the AD250 is 13.5Kg. With all my equipment mounted on it, it weighs in at 18.7Kg, which for me is easily manageable to get on and off the mount even in the dark. I am sure that the way the AD250 balances makes a big difference though.

    The design of the AD250 is such that the centre of balance is just forward of the primary mirror, meaning that once your camera, filter wheel etc. is mounted that the balance is placed near the primary making balancing on the mount easier and lifting and manoeuvring the scope on and off the mount easier, with no sudden changes in balance as the scope comes free of the mount.

    Cover

    Protecting your precious scope is always a top priority and Peter’s scope comes with a well-made custom fit cover the fits the scope perfectly. It is made using the same material as the shroud and flat cap and is secured by a pull cord at the rear.

    image.png.7396e15a9f9e890999af258b66daea08.png

    Shroud

    One advantage of the truss design is that it eliminates tube currents, however the local light pollution in my area means that I use a shroud to control this. Peter has, for each of the scopes in his AD range, a specifically designed high quality shroud. The shroud is enough to cut any stray light but provides enough air flow to still help control those pesky tube currents. Running the fans at the same time ensures that things are kept as stable as possible. Again, the cover it is secured by a pull cord at the rear.

    image.png.771df5b30e3ec75316f2af6d23dc7d62.png

    Flat Cap

    Bad flats can ruin a good image and good ones can save a poor one. Taking flats and ensuring that they are as even and smooth as possible is always a bit of a trial and people use several techniques to try to get them as good as possible. One of the common techniques is to use an old white tee-shirt for this purpose to act as a diffuser.

    Peter has taken this to another level with his ‘flat cap’. It is a custom-made cover that slips over the front of the scope and fits securely, providing a thick, smooth white diffuse surface to make getting good quality flats a lot easier.

    image.png.d8f40117598d4206c49622966e005169.png

    The material used in the cover, shroud and flat cap is the same and if necessary, washes extremely well. I accidentally dropped my flat cap and got it very dirty. A quick run in the washing machine on a gentle cool cycle and it was as good as new.

    Star Colour

    One thing that I have noticed over my old scope is that my star colour is vastly improved. When combining my colour frames, the alignment of the colour has always been extremely sharp.

    Photographic and Visual

    The AD250 is designed to be used both photographically and visually. I have only really used it for astrophotography and have been delighted with the results that I get from it. I have used it once for visual work just to have a quick look - but I was having to dig around in the dark to find adaptors to get my eye pieces to fit, When I did find a good combination it looked very promising and is something that I must try again properly. I have heard reports from visual users that it fulfils its visual capacity more than admirably.

    Summary

    In short, I absolutely love this scope. It has produced sharp stars with a consistent shape across the frame. The contrast (allowing for the high level of light pollution in my location) and above all the star colour is fantastic. The build quality is excellent and the support from Peter second to none. If you want the full technical specifications for the optics they are available on the www.656Imaging.co.uk site.

    I just can’t wait to get this scope out to a truly dark sky and really see what it is capable of.

    • Like 1

  7. Scope and mount upgrade project - Part 1

    This has been a long time in the writing mostly due to work/life pressure, weather and a whole series of other factors. Finally, I find myself in a position due to circumstances beyond my control to do something that I have been trying to get done for quite some time now. Anyway, down to business...

    I have split this into three posts, the first one some background and history of events on how this upgrade went, then the other posts with more technical and ‘in use’ information of the scope and the mount.

    Back in 2017, I had been looking to upgrade my main telescope (back then an old 8” Meade LX90). The decision was made when a good friend and fellow ‘Astronut’ invited me to go and see what was available at North West Astrofest. I was looking for something similar but with considerably better optics - the short list being another Schmidt Cassegrain, a Ritchey Chretien or a Dall-Kirkham (or similar type of scope). We went around the show and I got a good feel for what was out there, but nothing quite hit the mark for me at the show. We went outside to look at the H-alpha scopes and talk over options - and the only conclusion was to try another show later in the year.

    But as we were talking, we got discussing things with another astronomer and I mentioned my dilemma. We spent quite some time talking about it and other subjects. During the conversation he mentioned that he was in the process of designing and building a scope and showed us some photos of technical drawings and photographs of parts that had already been machined. It certainly looked an impressive piece of kit that he was planning, and he was certainly not messing about. We exchanged contact details, and over the following few months we kept in touch out of interest. When his scope was ready, we arranged to go and have a look. It was certainly everything that his drawing promised it to be and more! By then I was pretty much set on saving for a 10” Dall-Kirkham - which is exactly what he had built. I was so impressed with the build quality and the thought that had gone into the design that, whilst we were having a bite to eat in the local afterwards, I put it to him that his scope was exactly what I was after and would he consider building me one. The astronomer that I am talking about is Peter Shah.

    Peter is well known in the astro community had has been involved in the design of several telescopes and optical systems for Orion Optics, in the UK and is a well-respected astrophotographer. At that point in time he had just started setting up 656Imaging.co.uk to sell his range of scopes, and so agreed to build the first production version of his 10” Dall-Kirkham called the AD250 for me.

    The deposit was paid, and the build started. Peter kept me informed of the build progress all the way - these are not ‘off the shelf’ scopes and so, like any high-end equipment, take time to manufacture (particularly as I had ordered at a busy time of year). 3 months later it was built, and I arranged to go and collect it. Unfortunately, I had chosen to install a Starlight Instruments 3” feather-touch focuser. At that time Starlight had production challenges and that focuser was as rare as the proverbial hen’s teeth - so much so that I was faced with almost 7 months of waiting to get the focuser, despite ordering it at the same time as the scope!

    Peter’s original plan (and this is what he will do for anyone purchasing one of his scopes, if they want) was to put the scope together with my focuser, filter wheel, OAG, camera etc. and set it up perfectly for me with test frames. This would enable me to take the scope home, put it on the mount and be up and running with none of the usual new scope setup frustrations. However, as the focuser had not arrived and he couldn’t do this until it arrived, we agreed that we would re-visit this at some point in the future.

    Eventually the focuser arrived and, after a phone call with Peter, I was able to fit it and get it setup on the scope with relative ease. The first test frames showed that I was not perfect in my setup but very close - good enough to get going after such a long wait for the focuser and finally ‘have a play’. The mount that I was using at the time was a Skywatcher AZ-EQ6 which I absolutely loved, however it soon became apparent that, whilst it would slew accurately and handled the weight with no problem, for the quality of imaging that I was hoping to get its guiding accuracy was simply not up-to handling the longer exposure times that I wanted to use with the AD250. This was something that I had anticipated, knowing that I was at the limits of the recommended imaging weight for the mount.

    image.png.1e9a42a1f78d0779ff45df90c2120cbd.png

    I had looked at a variety of options, from ‘hyper-tuning’ to alternative mounts, and, after seeing the performance of the iOptron CEM60-EC, I eventually decided to invest and go with the iOptron CEM120-EC with the iOptron Tri-Pier 360.

    We were going to the IAS2018 show, and Altair-Astro were there with one on display - and so the order was placed. A few weeks later the new mount arrived, and everything was put together for the first test runs.

     image.png.8d2cac1d8e4373545dadce59fd3fde6e.png  image.png.9207d2628d06884c441e5d89c0d9aea0.png

    The CEM120-EC balanced beautifully and looked amazing, and the AD250 seemed to float when mounted on the iOptron. However, there were gremlins lurking within the firmware... This is always the risk that you take with any piece of newly released kit - that could be teething issues with it, and this was certainly the case with the mount. The first runs with the mount showed issues when passing the meridian, causing the mount to randomly slew and a few other niggles. The biggest and most important one was that the guiding was far worse than with my beloved AZ-EQ6 which I had now sold to a lucky new owner.

    I contacted Altair Astro about my concerns, and they were very understanding and helpful in addressing the issues with iOptron, passing on communications and keeping in touch as we worked through the problems. At first there were suspicions that the guiding errors were due to issues during assembly, and adjustment instructions were sent. This did give me the opportunity to have a look inside the mount and how it was put together. I have taken a few mounts apart in the past and you almost always find stray grease and the odd bit of swarf lurking in the casing - but my CEM120 was immaculate inside and not over greased. All the parts were well finished and the design simple, effective and maintainable. Seeing the inside of the mount, and how well put together it was, gave me more confidence in it despite the guiding being poor.

    After some frustrating times the conclusion that I, Altair, iOptron and the independent iOptron forums (that were reporting the same issues on other 120’s) came to was that it must be firmware.

    It was around this time that Peter had my scope back for a while, as it was frustrating him that he had not had the chance to get it set-up with my camera, etc. as originally promised. The weather was bad, so it was a great opportunity to get the optics setup perfectly.

    The design is such that Peter only needed to laser align it, then run a star shape test image when the skies briefly cleared to see if any very fine tuning with the camera mounted was required. This was the result with my Atik 383L+, guider and filter wheel:

    image.png.6820e601e1e70fe1967c3591f6dc5645.png

    We looked all over the image and could not see anywhere that it needed to be adjusted and if you did it would be so fine an adjustment it was simply not worth the effort.
    By then, I had managed to find a version of the firmware what was behaving reasonably well on the mount and so tried M106 with the freshly setup optics. This was the result:

    image.png.dbae116e613333d10dc8ba1939750b43.png

    Considerably better than I ever got from my old LX90:

    image.png.7c783ce7e565146f96617f19ba2eb483.png

    I was a happy bunny! 😊

    I was thwarted at this point by the British weather too as it did not allow for consistent or regular opportunities to test things. There was a period of 4 months where the skies were so bad that I could do nothing.

    Fortunately, iOptron (unsurprisingly) were working with other users around the world to refine their firmware and, in the middle of September, I managed to get hold of the latest version of their firmware and installed it on my mount. The first clear night I got, I setup to test it and was getting below 0.4” total RMS guiding with it often being down at 0.3” for sustained periods. There are mounts capable of better, but as far as I have seen there is nothing at the payloads that I am using and at the price point of the CEM-120EC.

    I did a single H alpha image from 12 10-minute subframes of Melotte 15, and made the stars white by using Straton to extract them and then drop them into the Green and Blue channels. This was the result:

    image.png.90823398ac767bb9998ac1bd58416715.png

    I have since done two more images, again with similar guiding results. The guiding for M29 was not quite as good, probably due to the breezy conditions that night, although I was still happy with the result.

     image.png.ccd507f487d209c3dfdba20692ca29cc.png  image.png.3df5a807a2e95f6165369b818c61eacc.png 

    Currently the mount appears to be working well with the latest firmware. Personally, I think its capable of even better and I’m hoping that iOptron will continue to keep refining the firmware. I certainly have a version of the firmware that is good enough for my current setup.

    In summary, my experience with this upgrade - whilst trying my patience considerably with the wait for the focuser and the problems with the mount - has overall been a good one.

    Altair were very helpful, spent a lot of time talking with me at shows and on the phone and also liaised with iOptron on my behalf.

    iOptron were responsive with direct emails, and did get there in the end with the firmware - I just hope that they can squeeze even more performance from the mount.

    Several months on, and lots of taking the scope on and off the mount (I pack everything away after each imaging session) plus the transporting of the scope once set up with my imaging rig to get it home, and the stars are still just as sharp and beautifully shaped. So, in terms of optical construction, the AD250 seems a very stable and robust scope.

    Dealing with Peter and 656 Imaging was a delight, I was kept up to date with the progress of the build, and Peter kept true to his promise and optimised the optical setup of my rig. I have spent a lot of time working with Peter on this project and he has helped me considerably with my frustrations with the mount, also helping me improve my imaging technique and processing.

    In return for all his hard effort in helping me, I helped him out by loaning him my mount and scope for the Practical Astronomy show where he launched 656 Imaging. Peter has an amazing passion for astronomy and astrophtography. He is extremely knowledgeable, professional, responsive and helpful and more than willing to help you improve – if you are willing to listen. He’s certainly been more than patient with me!

    All my imaging is done from a heavily light polluted site. Having the 360 Tri-Pier allows me to be ‘portable’ so I can’t wait to get out to a properly dark site to see what the AD250 it is truly capable of.

    If you want more detail on these images and more you can get it on my Astrobin account: https://www.astrobin.com/users/toxophilus/ or message me.

     

     

    • Like 3

  8. I have been battling condensation in the observatory/garden office for a while. It's not bad or serious, but I wanted to control it. So I decided to get a dehumidifier to solve the problem. I had a good dig on the internet and there are loads available. However I found https://www.dry-it-out.com/ and noticed that they were the only supplier that specifically mentioned observatories in its list of dehumidifiers (and yes there is are specific needs for observatories which I was surprised to discover). 

    I didn't know which one to go for and so decided to give them a call. I spoke with Roger Banks there. He was really friendly, helpful and knowledgeable. After a few questions on the environment that I had for my scope and how I used my observatory, he made a recommendation. He went in to detail explaining how it worked and why it was best suited for me. Satisfied I placed the order and my new dehumidifier arrived the next day with free delivery. The prices were comparable if not slightly cheaper than most other suppliers, but the advice invaluable.

    Switching it on for the first time, I was getting water pulled out of the air within a couple of minutes. It worked overtime for the following day and I emptied well over 2 litres of water out of it. I now have a wonderfully dry observatory and the dehumidifier just automatically kicks in occasionally to keep levels at what I require.

    I could not be happier with the service and results from Dry-It-Out.com

    • Like 5
    • Thanks 1

  9. OK as promised this is where everything that I was talking about is set.

    First go into your Equipment Profile Manager and select the profile you want to edit.

    Select the focus tab and ensure use auto focus is set and then click set to configure it

    Capture.JPG.690576a5730576cdb0de95bbbffeab33.JPG

    Setup auto focus on filter change and disable auto focus with filter and then click the 'For Filters' button

    Capture01.JPG.e8a2851a8c5cd14995554d77bdf2a050.JPG

    Configure the times that you want for the filters 

    Capture02.JPG.7b723480da43a4b204d66bd6ed44f07b.JPG

    The select the guiding tab and ensure pause guiding during auto focus is enabled

    Capture03.JPG.940241c22bf17e64b5b38e8915bfafe1.JPG

    That should fix your problem for focusing with an OAG using narrowband filters. alternatively you could use the technique that steppenwolf has suggested which is to focus with a clear filter and then use offsets to bring everything into focus for a specific filter. The downside to that is that you need to work out the offsets for each filters (the settings are all in the dialogs that I have added) and any temperature compensation you may need. The upside is that focusing between filters will be faster than using each specific filter for auto focusing. The advantage of using each specific filter is that it will take account of any changes in your kit as temperatures or conditions change with less 'up font' work, but it will take more time out of your active capturing time. 

    Hope this helps and Good luck, let us know you get on.

    Mark

    • Like 2

  10. 19 minutes ago, Jbro1985 said:

    If it sheds any light...

    I'm using the baader c7nm set for Ha OIII and SII and have guided through each filter previously without an issue though, including autofocus.  Weird there's an issue this time.  

    I didn't realise there was an option to not guide through autofocus - I'll have a look for that in SGP (or do you mean to manually do this?).

    I did reduce my PhD exposure setting to 3 seconds from 4 the other day.  Perhaps that is it.

    Thanks everyone

    When I get home I should be able to have a look at where the options are in SGP. But you can set focus duration for individual filters, if you are using on exposure setting for all filters then 3 seconds probably won't be enough for the autofocus mechanism to pick up sufficient star data. Yes there is an option to disable guiding whilst performing an autofocus in SGP, again I'll see if I can find where it is in the configuration. But have a poke around its all in the the equipment profiles somewhere, but a little buried in the dialogs. Let me know if you find them before I get chance. Good luck.

    • Like 1

  11. Hi, 

    I've not looked at the logs as I don't have the software to analyse them available to me at the moment. The big problem with OAG's is that as you adjust the focus it changes the focus on the guide scope too. So you could have a couple of problems going on here.

    If the filters are not particularly par-focal then the focus may be so far off that PHD2 is not able to select an appropriate guide star or it can but the seeing was pushing the star mass out too much or it was loosing it all together. This would be apparent for just viewing the screen and your stars would be obviously out of focus or really faint. 

    What I suspect is more likely is that as the SII filter is so strong it needs longer exposures to get sufficient data to calculate the focus on. If PHD fails to obtain focus on its initial run it pushes the focus even further to try to find focus at a different range of values. This can push the focus out sufficiently for PHD to give up as it has lost the star. With an OAG the best thing to do is (and I can't off the top of my head remember where the settings are) is to increase the exposure time for that filter and disable guiding whilst autofocus is in progress, this will avoid this issue. This does assume that your mount can hold sufficiently tight stars for say 10-15 seconds (or even more) which may be required for SII to get enough data to calculate the focus values.

    Hope this helps

    Mark

    • Like 1

  12. 10 hours ago, peter shah said:

    Nice work Mark Stars look pin

    Cheers Peter. I'm delighted with the end result. Some detail was lost in the finer parts of the galaxy due to the fine cloud getting in the way. but careful selection of the better sub-frames helped keep the damage to a minimum. The hardest part was getting rid of the gradients that were left from the combination of light pollution and the cloud 'enhancing' it.

    43 minutes ago, bob-c said:

    Lovely image Mark, well done.

                                                     Bob.

    Cheers Bob. I'm delighted with it.


  13. This was taken as a last run with my old mount before the new owner collected it and I wanted to be sure that it was running perfectly for them as my new on is on its way.
    The 5 nights that I gathered data on were all plagued with fine high altitude cloud and an almost full moon, I ended up throwing a lot of sub-frames away (16 in all, just over 2.5 hrs worth). However I was delighted the the guiding and the behaviour of the mount (having recently cleaned and tuned it) and, given the challenges the seeing presented, the final image. I ended up adding some Ha data in the end just to make this a little different to my other M33 images. If you want more information the astrobin link is: https://www.astrobin.com/373994

    M33 - Watermarked.png

    • Like 15

  14. This was taken over 4 nights between the 24th September and 6th October as I have a small windows to view objects in the south due to houses and a great big tree getting in the way.

    Messier 2, also known as NGC7089 is a globular cluster in the constellation of Aquarius. It is one of the largest know globular clusters and was discovered in 1746 by Giovanni Domenico Maraldi. It lies approximately 55000 ly away and is around 174 ly across.

    M2b - Watermarked.png

    • Like 6

  15. Nicely done, especially if you had a battle with the dew.

    I must agree this is one of my favourite targets. Like the great nebula its a target that's harder that you would think to image due to the high dynamic range.

    • Thanks 1
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