symmetal

I mentioned above that high speed uses a lower bit resolution depth so is quicker to convert each pixel. Your camera is 12 bit as specified so high speed would probably be 10 bit. As you record at 8 bits, sampling at 10 bit has no effect on image quality. As you're stacking many 'noisy' frames you will recover up to 4 bits more sampling resolution anyway so your final stacked image will have effectively 12 bit resolution. Your camera spec didn't specify dual sampling rates so wasn't sure if it had a high speed mode but it seems to. 🙂

USB Traffic is setting the speed at which the capture program will send the data over USB. If set too high a bottleneck in the imaging recording process somewhere may cause data to be lost so the capture program can throttle the data speed with the USB Traffic setting. Setting it to 100% or 1 in your instance means no throttling. If your capture program doesn't flag any errors you should be OK at 1. Again I wasn't sure if it had any effect over USB2 but it seems to. 🙂

A shorter cable was a last resort so probably won't affect things if your speed has increased a lot without problems. Not sending the camera data via a USB hub should still benefit you though as far as speed is concerned.

Alan

I have had stars turning into seagulls when the spacing is too far away, rather than the classic sausage stars rotating around the centre. There is still a part of the star image pointing towards the centre too which may imply the FF is perhaps not compatible as it's showing too far and too near effects at the same time.

What did your unbinned images look like when the spacing was way under that recommended, as you posted previously when they looked good binned.

Alan

The seeing was bad last night so won't be able to see if it's better on the planets. However I took videos of a defocused and focused star. The focused star didn't show any useable diffraction rings as it was too chaotic although the dancing patterns were not evened out overall and were brighter top left. The defocused star showed this off centre doughnut consistantly which doesn't look good and confirms the focused star brightness spread.

The doughnuts were much better than this before I used the Hotech. 🙁 Reports from people who have used the Hotech swear by its accuracy so I'm a bit surprised. Maybe the return dots not being exactly opposite the corresponding laser may have something to do with it. These star videos were taken with an ADC still in the path but set to null. Anybody have any thoughts?

I've found that the ADC doesn't affect the bahtinov optimum focus spike position when it's adjusted from min to max which is good to know, though the coloured fringes do change. I thought the ADC moves more or less of the prisms thickness in the path as it's adjusted which I assumed would alter the optical path length but it doesn't seem to as far as focus is concerned.

I suppose an artificial star is the next to use and see what it shows.

Alan

7 hours ago, michael8554 said:

Given the amount of mirror flop in the average SCT, how consistent were the dot positions as you altered focus and then refocused ?

Michael

Good point. I tried it again today. I found that to see the horizontal crosshair positions correctly you have to position yourself below the scope looking up. From the side as yesterday you can't judge them precisely.

This time the corrector plate axial alignment looks spot on which is good. I found with focus you have to choose whether to collimate after focusing in or after focusing out. Continuously focusing in one direction doesn't change collimation but changing direction does. Also after repeatedly changing direction, the collimation consistantly swaps from one position to the other which is also good to know. So it's always to best to finally focus on your object in the same direction in which the scope was collimated. I found that anticlockwise turns on the focuser moves the mirror forward which should be more consistant, rather than the mirror possibly moving under gravity after clockwise turns.

Here's the results of  best collimation after focusing anticlockwise. Target looks similar to yesterday but the focuser mirror is more central. 🙂

here's the results after turning the focuser clockwise from the resul above. A noticeable change. Focusing to get the three dots coincident on the focuser mirror is not critical and has no effect on the collimation results as long as they are just roughly coincident.

Should be clear tonight so real images will hopefully tell. 😀

Alan

According to the specs it is a USB2 interface camera so the quoted frame rate of 640x480 @ 106fps is rather optomistic and may be quoted for the max theoretical usb2 transfer speeds which are usually never reached in real life. Is it sharing a hub with other equipment connected which will split the USB2 bandwidth available between the devices connected to the hub.

Also what's the length of the cable being used and is there a repeater in the cable if it's a long extension cable. These will significantly reduce the maximum data transfer speed. Use a separate USB port on the PC to connect the camera only and the shortest, good quality cable you can use is your best option.

The USB Traffic options usually refer to USB3 interfaces so may not be available or do much for USB2. High speed mode uses a lower bit depth for A to D conversion. The camera spec just specifies only 12 bit so this mode may not be available. As others have said these will be listed in the options if you click the 'More' button.  

Edit: 640x 480 @ 106fps is 32MB/s data rate just for the image data. There will be extra bandwidth required for all the other traffic needed to achieve the transfer. USB2 max theoretical data speed is 480 Mb/s which equates to 60MB/s. This is for the USB2 controller chip in the host PC and may be shared between 2 ports or more on the PC. Not all of the 480MB/s are available for data transfer as some will be used in managing the USB protocol data blocks and handshaking etc. The general concensus seems to be is that the maximum sustained data transfer you can achieve in practical terms on one port in ideal conditions is 40 to 45MB/s.

Alan

Only just remembered I bought a Hotech collimator not long after buying the scope over 20 years ago. 😁 I used the defocused doughnut method after recently putting it in the shed after 10 years without use, and it looked OK so left it. Viewing the Hotech YouTube video makes it easier to work out how to use it  than the written instructions. 

The lithium battery in the collimator package was still good. 🙂 I got the scope square on to the collimator by aligning the laser crosshairs, took about three interations of the alignment loop to do and was straightforward.. The Hotech video was done with a Celestron but I couldn't do the focuser tilt adjustment or the corrector plate alignment as the LX200 secondary isn't removeable and doesn't have the corrector plate collimation screws like the Celestron, and it would be a pain removing the corrector plate ring and inserting shims under the corrector and putting the ring back on to test. 😬 If the scope was looking straight up it would be easier to do this but I'm not going that far.

Looking at the inside tips of the laser crosshairs, which indicate the secondary cutoff the corrector plate looked very slightly off in the vertical direction but not enough to worry about I thought.

I turned on the three secondary collimation lasers and only saw one reflected on the target near the middle. 😲 Turning the focus to align the three dots on top of each other on the mirror inserted in the focuser, they were well off to one side rather than in the centre of the focuser. I adjusted the secondary collimation screws and got all three dots equidistant from the centre and the dot on the focuser mirror was a lot closer to the centre but not perfect.

Here's the final result. The three reflected dots are now equidistant but not on the radial lines opposite the lasers. If I put them on the radial lines they aren't equidistant. I suspect how I've got it is the preferred alignment. What does everybody think?

Looking at the photo again it looks like I could have got the vertical crosshairs a bit more equidistant from the centre so maybe it wasn't fully square on and the corrector plate actually isn't out like I thought. This may have brought the dots closer to the radial lines and the dot closer to the focuser center.

It's a lot better than the start though when all that was visible was the bottom dot on the 1 circle. 😁 It looks to be good for the next few days so will try it on the planets again and see if the adjustment gives actual better results. 🙂

Alan

Congratulations on your new purchase Steve. I use a 178MM with the Lunt60 and have no banding problems. Can you post an image to show what they're like. I'm sure you also know a mono camera would give a better result than a OSC for Solar too. 😊

Do you manage to fit the full disk using the DSLR in movie crop mode? My 700D would in theory, with just a few pixels to spare but I haven't tried it. 🙂

Alan

The stars do look good in the corners but being binned that will hide any issues to some degree. As to why it seems to work best at a spacing way below the recommended distance I can't say.

Your scope only has around 55mm of focus travel and as it was supplied with two 2" extension pieces implies they would need to be used in some situations to achieve focus. You've run out of focus as the 24mm reduction you made in the flattener spacing distance has to be made up by the focuser just to achieve focus.

Maybe the FF is not compatible with the scope, although it falls within its requirement specification range. Your scope being f7 is nearer the slower end of the range and I would have thought slower scopes would be less critical on spacing distance than faster scopes.

Take some test images unbinned and if they are still very good then you could just buy a longer 2" extension to replace one of yours to give some focus travel to spare. Maybe you could email AltairAstro to see what they say, or maybe someone on the forum can give an explanation as to why it works best at such a reduced spacing distance. 🤔

Alan

I keep the camera in the same orientation each time for testing after making spacing adjustments to try and minimize any tilt errors from confusing the results. Pointing towards the zenith for your test images also reduces any possible sideways focuser slop from causing an issue.

 Your corners look similar so hopefully tilt isn't a problem for you. When you get good results pointing straight up you can take test images pointing at low Dec, both sides of the Meridian and fingers crossed there is no change.

Good luck.

Alan

If you have a motor focuser then you don't need the focuser lock screw. Locking the focuser would stop the motor focuser from working, and the holding torque if using a continuously powered stepper motor would stop the focuser from slipping. In most cases the detent torque from an unpowered stepper motor is enough to hold the focuser in position.

Alan

Thanks. Very informative. Much like I do, though I run it through Registax wavelets again after Winjupos with the wavelet settings quite low just to tease a bit more out. 😀

Also the short duration video is important on any planets if you have an Alt/Az mount due to field rotation as well, especially if your pointing near the meridian where the field rotation is greatest, though Autostackert can correct for that too as long as it isn't too great. 🙂

Alan

The spec for your flattener does say 'approx 55mm' which is a more realistic figure. Those specified with close tolerances are probably those made to match a particular model of scope. The flattener distance is affected by the focal length so a flattener advertised as suitable for a range of scopes can only give an approximate spacing distance.

I've generally found that even allowing for the extra glass I invariably have to add extra spacing around 1 or 2 mm to get the best stars. I don't remember having had to reduce the distance from the calculated value. Perhaps the 1/3 glass thickness is too low a figure in reality.

I think you'll manage it in the end without having to impinge on your neighbour's property. 😁

Alan

OSC cameras generally have a UV/IR cut filter in the protection glass so another IR cut in the way would serve no purpose.

If the OSC camera had no UV/IR cut protection window, an added IR cut filter would improve image sharpness by blocking out of focus IR light hitting the sensor. Also, as the OSC bayer filters generally all pass IR to some extent, without the IR cut filter the colour balance would also be wrong, as Neil says.

With a mono camera you would normally use filters anyway for LRGB so an IR cut again wouldn't do anything. With no separate LRGB filters, so effectively wideband luminance, an IR cut would improve image sharpness as above.

For planetary an IR only pass filter can be useful on a mono camera as it blocks the shorter wavelength visible light and so the resultant image is less affected by the atmosphere so can yield a sharper image. However the camera IR sensitivity is not as high as in visible so the image is very dark and a longer exposure may be necessary which is then more affected by seeing.

Alan 

1 hour ago, 04Stefan07 said:

Yep I’ll give that a go. So how come the recommend 55mm (Flat) and 56mm (ZWO) is incorrect if I need to add more space?

I’m guessing there’s really no way of telling how much I need other than adding more spacers and seeing what happens. 

I'm not sure what the 56mm ZWO spacing is referring to, as the only critical distance is the one specified by the flattener data sheet, presumably the 55mm you mentioned. As I mentioned above, any extra glass in the way requires the spacing to be increased from that specified, in which case I would have thought your 56mm setting would have been closer to what's required.

All you can do is add more spacing, initially in larger amounts, until you see a definite change in the star shapes and go from there to find the optimum distance. It's not a quick process, especially if you don't have an adjustable flattener. At least you don't appear to have any significant tilt which is a bonus. 🙂

Alan

I was thinking you had an adjustable flattener in my earlier reply suggesting 1mm increments, but if you haven't it's a bit more hard work adding/removing extenders.

Your stars do indicate the flattener spacing is still too close as they are pointing towards the centre. I've found than when the spacing is too far, while some flatteners do produce elongated stars appearing to rotate around the centre as is often suggested, others can produce more coma like aberrations instead.

One point to note is that having filters, or any other glass, in the path between flattener and sensor requires you to increase the specified spacing distance by around 1/3 the thickness of all the glass in the way, to get the actual distance required. The specified flattener spacing distance is quoted for just air between the flattener and sensor. With say 1.5mm filters and 2mm camera protect glass, the distance you want to aim for is the specified distance + (1.5 + 2) / 3 or just over 1mm beyond the specified distance.

It's good to know whan too far a distance looks like, so if you can, add say a 5mm spacer and check you get stars other than pointing towards the centre and how bad they look. This gives an indication of where you should be heading regarding optimum distance. It's quite normal to find that to get the optimum stars you need to have the actual distance a little different from what you've calculated by sometimes a mm or so, so treat the calculated distance as a starting point rather than an absolute value.

Alan 

1 hour ago, blinky said:

And just to check, the finder screws are the ones that are not countersunk in the image above? The ones on the side

Yes that's right. Along with probably a similar pair on the other side. I assumed they are mainly used for attaching finder scopes which is why I called them that, but they can of course be used for mounting anything. 🙂

As they're open holes and the focuser tube is visible through them they are useful for helping reduce focuser flop. For that it would be better if they were placed at 90 degrees away from the countersunk main tension screws but using them saves having to drill a hole in the side of the scope. 😁

Alan 

I could convince myself that I could feel movement but it would be hard to measure. Best to check your finder mount holes are M4 before ordering. They are on my FLT98 and ZS61 so probably are on yours. The ZS61 threads were a bit looser than the FLT98 so a dab of thread lock on them may be needed. The finder holes on one side are above the engraved scale on the focuser so it's best to use the finder holes on the other side to avoid the screws catching on the scale.

Alan

The two recessed screws on top apply some downward friction push on the focuser to remove any up/down sloppyness. Just tighten them until there is some resistance. Not too tight.

However when the scope is pointing in the direction of the meridian these screws are now on the side of the scope and so are not so effective at preventing slop in the current up/down direction. I had this problem in my FLT98 where tilt was evident when the scope was on its side. Increasing the pressure on the two screws mentioned just jammed the focuser preventing autofocus.

My solution was to insert long enough nylon grub screws in the unused mounting holes for the finder mount either side of the top friction screws, until they touched the focus tube, applying some force in the up/down direction when the scope is on its side and it was enough to stop the sloppiness without causing too much friction to affect autofocus. I think I used 10mm M4 nylon grub screws though 8mm would be fine. The screws were a nice snug fit in the threads so don't move on their own once set. 🙂

Alan

Pretty good for first planetary. 🙂

Yes, focusing on a star with a bahtinov mask is a useful way to achieve focus and is what I do. Some use Jupiter's moons to focus with a mask but I haven't tried that.

Your background is heavily black clipped. you need to check the preview histogram on your capture software and increase the camera offset (sometimes labelled brightness) so the full background sky hump on the left is to the right of the left edge of the histogram so none of it is clipped. During wavelet sharpening and other processing you can end up clipping the data if it's close to the left, or right, edges of the histogram. The offset used is normally higher than you would use in DSO imaging.

Use high gain and set exposure to 5mS or so to help freeze the seeing variations. Don't worry about it looking very noisy in preview or underexposed in the histogram. Capture in 8 bit mode and also try high gain mode on the camera to increase the fps, and disable gamma during capture, or set it to 50 which turns it off anyway. Applying gamma takes processor time so lowers fps. Use ser format rather than avi for capture as it's more versatile and better supported. Use as small a region of interest  (ROI) to keep the planet in view during a capture, again to increase fps. Only ROI height affects fps, the width doesn't.

Here's the processing flow I followed when starting out which is useful. Registax wavelets is a bit of a dark art but this video helps. 

Imppg is also good for deconvolution sharpening, particularly on the sun and moon, but it only works on mono images so you'll need to split rgb to three mono channels if you want to use it for colour.

Good luck.😊

Alan

I don't think the flattener would be incompatible especially with the 1600 sensor size, which although larger than the 178 is not really a large sensor.

It looks like the OAG setup is introducing some tilt which isn't helping. For a refractor a separate guide scope is normally not an issue.

For flattener spacing adjustment you need to refocus each time you've altered the spacing and preferably at the centre of the image each time. Autofocus routines will often focus at an edge of the frame when there's tilt, which makes the opposite edges suddenly appear much worse so it may be worth using a bahtinov mask on a bright centre star each time for consistancy.

Start at flattener spacing like 5mm closer than the specified distance and all the corners should have elongated stars pointing towards the centre maybe some worse than others. Move the spacing out by 1mm, refocus and check star shapes again and whether one or more corners look better. Keep moving out by 1mm or so until you're say 5mm beyond the specified distance and all the corners are distorted again, probably in a different direction to when you started. You should find all four corners have given good stars at some point in your tests, but perhaps unfortunately not all corners at the same flattener spacing distance, due to tilt.

Hopefully you can find a distance where the corners aren't too bad overall and can live with that. If not you're in the realms of tilt adjustment which can be another can of worms in itself.

Alan

Star bloating with narrowband isn't really an issue compared to LRGB even with long exposures. Brighter stars will always be clipped unless you only expose for a few seconds.

With my ASI6200MM I expose for 10 mins for narrowband at gain 100, where the HGC kicks in. At this gain setting of 4 x unity I would need around an hour of Ha to swamp the read noise and significantly longer for SII and OIII. At this exposure the brighter stars are clipped on all the narrowband channels so always appear white in processing which doesn't look out of place. Adding real colour stars afterward tends to imply that the colours assigned to narrowband are also 'true colours' which they aren't if you apply the common NB colour palettes to give pleasing colourful images. 🙂

10 mins is a good compromise between allocating enough dynamic range to the NB data, and avoiding a lengthy ruined image due to guiding problems or a plane flying through. 😦

NB filters tend to give halos unless you pay huge amounts of money, my OIII gives smallish halos. Having strange colour halos around real colour stars looks more odd than strange colour halos around white stars. To try and hide the halos takes a lot more effort in processing. Starnet++ doesn't remove halos satisfactorily. 🙂

Alan 

7 hours ago, ollypenrice said:

It worked perfectly, Alan. 

By the way, since the time bug of a couple of years ago when the Meade GPS stopped working, I simply stopped using the GPS entirely rather than risk a patch. Everything works better without it. GoTo is more reliable and setup takes a fraction of the time.

Olly

Thanks Olly for confirming that. 🙂 I'll get one to to have a complete setup again though they are a bit pricey. If I realized they were PIC chips in the handset I'd have been a bit more careful. 😬

As you say, if the scope is only at one location then the GPS offers no benefits. I can confirm that Starpatch from StarGPS works fine if you want to update it. Using the trial version for the update means it's free too. 😀 Much quicker and reliable than Meade ASU. It worked fine indoors taking a couple of minutes to GPS lock, but the GPS just times out once I'd moved it to the shed. I had to move the scope over rough ground on a trolley as I was on my own so maybe something got dislodged concerning the GPS bit.

Alan

On 27/08/2020 at 13:40, ollypenrice said:

Yes, I saw that price difference. TS said it wouldn't work for mine but I think it will. I'll give it a go. Thanks.

Olly

Olly, did you get the Autostar II replacement handset from TS and if so can you confirm it does work with the LX200GPS despite what TS say?

I stupidly wired my handset with reverse polarity and it's now dead. 😢 Didn't think it had much in it apart from buttons and a display but it uses 2 PIC chips to scan the buttons and drive the display so looks like no chance of fixing it.

I'm using the handbox emulator in Autostar Suite which works fine, but it would be nice to have a real working handset.

Alan 

Thanks everyone. I expect the scope enjoys doing something useful again. 😊 You're right @skyhog, if it's in one location all the time the GPS is not all that useful, and it's quicker to enter by hand, as the location is already stored in the scope anyway.

Here's a few close ups of the setup. I fitted  the capture PC and the black box containing power distribution, focuser control, dew control based on Robert Brown's design on top the scope to keep the scope balanced along with the weights on the bottom. Sandwiching them between two sheets of perspex with threaded rods and butterfly nuts easily allows changes in PC etc without having to redesign the fixing method. The little module on top the perspex is the temp/humidity sensor. The little heat given off by the PC has  no significant effect. The remote temp sensor for the corrector plate is one of the two leasd from the main dew shield heater. Only two cables, blue and white on the floor, leave the scope for power and ethernet. The black box next to the scope control panel splits the incoming power between the scope and the power distribution on top. Scope RS232 via USB/RS232 converter on front of control panel.

I made the scope dolly from some scraps of wood. It's not very strong but the tripod legs sit over the wheels so the stress on the wood is small. The wooden block on top the dolly arms go under the height adjustment screw pads as I couldn't find long enough threaded screws with knobs. The two plywood sheets lie on the paving stones to bring the scope level with the shed floor, three thick aluminium plates bridging the gap. The aluminium plates glued to the floor are to spread the weight of the wheels when in the shed as the plastic floor was bending at those points.

On the shed shelf is a cheap mini PC to allow remote desktop to the imaging PC for initial setup and fine focusing with a bahtinov mask. There's also a UPS on the shelf powering the main 150W 12V PSU on the left side of the rear mounting board. The UPS is mainly to avoid the satellite receiver and data processing PCs falling victim to a mains blip or power cut up to 40 mins, as they are running 15 programs between them and it takes a while getting them all running again together.

The clock on the wall is to enable quick entry of time and date at scope start up and the paving stones in the shed rear corner are ther as the sleeve bolts holding the shed down failed to grip in that corner and I can't get the bolt out. Note the extractor fan in the shed roof, air in from bottom right, as it gets fairly hot inside on sunny days with all the satellite gear running and the shed closed. 40 deg C before I installed the fan.

I'll next try imaging with the ASI224MC and 2x Powermate to see if the pictures are any better than just the ASI178MC. I also found the ADC setup feature in Firecapture made it simple to correctly adjust the ADC. I was surprised to find the ADC didn't affect the focus, just shifted the image which is good to know.

Alan

Put the 10" LX200GPS in the shed I recently put up to house the new weather satellite receiving setup. It had sat indoors for years as I couldn't be bothered to cart it outside for one night since moving to Cornwall. It seemed a shame taking up space doing nothing. Indoors I checked it still worked though the autostar keys needed holding down tight to work. Cleaned all the rubber pads and contacts, including LED ribbon and dabbed some ACF50 on all the contacts. Good as new. 😀 Changed the battery on the main PCB which was dead and installed the latest 3rd party Autostar software which corrects the GPS week rollover problem on old GPS receivers and the GPS worked indoors after spending around 15 mins getting the complete data information from the satellites.

After putting in in the shed though the GPS no longer works timing out after about 20 mins. 🙁 Never mind, I'll just enter in using the Autostar. Found the Autostar coily cable didn't quite reach the shelf in the shed where the PC was, so having plenty of phone cable and RJ10 connectors, quickly made up a longer lead to use with the Autostar. Plugged it in. Nothing on Autostar. Put coily lead back. Still nothing. Checked pin wiring of coily lead. It's not 1 to 1 but a mirror image. Forgot phone handset cables are mirrored and likewise the Autostar. That'll teach me to be complacent and not check the wiring first.

Autostar got reverse power. I think it's just the display driver IC that's dead but need to get the scope out. There's only two surface mount ICs in the Autostar so not much to go wrong. Real shame after it was still working 20 years after purchase.

Need to get scope working without Autostar. 🤔 Install latest Autostar Suite from around 12 years ago. It runs on Win 10 if you select Win XP compatibility mode. It's got an Autostar Controller simulator too. And it works. Easier clicking the buttons on the simulator than using the actual box. 😀 Did a one-star align and bingo. Autostar Suite has a display like an old version of CdC so it's then easy to click on a planet and tell it to slew there. And it did, well within the FOV of the guide scope I'm using as a finder scope. I had also fitted a Steeltrack Diamond SC focuser with Lakeside motor to enable easy remote focusing.

Two nights ago although everywhere was soaking wet after a days rain I noticed Jupiter at around midnight so fired up the scope and got videos of Saturn, then Jupiter. My ASI224MC would need a 2x Powermate to get the optimum focal ratio so used an ASI178MC instead which with smaller pixels has an optimum focal ratio of f14 so didn't really need a Powermate.

LX200GPS with ZWO ADC and ASI178MC, 10 videos of 45 seconds at 95fps, 6ms exposure, stacked in Autostackert, processed with Registax, WinJuPos and PS.

Quite pleased with the result after all that. 🙂

Alan