SimonIRE

8 hours ago, ONIKKINEN said:

Saturated stars are not useful for FWHM measurements, and of course in did not use them so the exposure is perfectly valid. Round stars are easy to get and thats not the point of guiding at all, the point is a round and small star. Equal errors in both RA and DEC at the same time result in a round star, yours are so big there must have been a sizeable error or terrible seeing, possibly both.

Again, it feels like looking for things to say. To say that round stars isn’t the point of guiding isn’t right. To say that round stars are easy to achieve (in this case, without active guiding) isn’t true (and feels tone deaf). Look at all the posts here and on CNs by people struggling with trailing stars and having difficulties with guiding. 
 

And to have equal guiding errors in both RA and dec such that the stars are basically perfectly round, also seems overblown. The unguided performance of this mount….which I am now using, is phenomenal. My point, relates to this mount and 10 Micron mounts. And, I was merely trying to provide some data. 

1 hour ago, DaveS said:

Fabulous kit, not envious at all. Yeah, right 🤣. Actually the first time I've seen an actual real photo of the DDM100, as distinct from renders.

I'm still holding on to my two DDMs by the way!

It was some your posts that helped me make a move from 10 Micron to ASA. That said, the 10 Microns are easier to use (I think…I’m an ASA newbie)

57 minutes ago, ONIKKINEN said:

Have no say in the mount matter, couldn't afford any of the mounts discussed in this thread 😬 but obviously want one one day.

But on the fits file, are you sure its a good idea to not guide with the mount? Looks like you have somewhere in the range of 3-4'' (or even more, depending on software used to measure) FWHM stars, which is unexpected with a high spec instrument such as this and wouldn't believe for a seconds its optical quality related. Honestly this is what i get with an 8'' newtonian on an AZ-EQ6 on an average-a bit worse than average seeing night guided at 0.6-0.8'' RMS, so either you really do want to guide or the seeing was horrendous this night. My 2 cents anyway.

Stars do look round but just too large to believe its doing a great job without guiding.

The image is over exposed and I agree the stars are large. The guiding on this mount is the best I’ve seen among the mounts I’ve used. I’m not sure how you attribute the FWHM to guiding issues when other parameters indicate arguably as close to visually perfect star roundness as you could ask for. I can post some other images. 
 

The main point I was trying to make was that the 10 Micron mounts, in my experience, guide really well but do need to be guided. 

9 hours ago, DaveS said:

If you want 0.25" or better then find yourself a S/H ASA DDM. But finding hens' teeth might be easier.

Unless you can afford a DDM100 at in excess of £25k

I have a GM4000 and recently have been testing my DDM100 in Spain. The GM4000 guides beautifully with a hybrid guide-model approach. 10-15 sec pulses get it to guide at 0.15-0.20". But the DDM100, with its predictive tracking, truly doesn't need guiding. I have attached a FITs file of M45, 10 minutes unguided at 0.33"/px (QHY600) using an iDK14.5 (AG Optical). The image is nothing much, other than a demonstration of star quality at this FL with small pixels. I was really happy with this; it's an unforgiving imaging train. 

M45-Ha-0001.fits

On 01/08/2022 at 15:08, tonyowens_uk said:

Hi newbie! I dont think its meaningful to speak of the quality of a motor or any other technical component in the abstract. A 200 step/rev hybrid stepper motor cant be compared to a brushed DC servomotor without looking at the context. If that is running an axis of a telescope mount, we are looking at torque vs speed characteristics, electrical efficiency, noise emission, 'cogging' behaviour, spindle positioning elasticity (drive stiffness), robustness, wear life, ease of packaging, ease of commissioning and reliability. And in this application no meaningful comparison is possible without also including the motor drive electronics, cabling, connectors and firmware. On one side we have Maxon/Scitech and industrial sealed connectors and screened cabling. On the other, we might have a Chinese generic 400 step/rev NEMA17 hybrid stepper driven by a Trinamics TMC2209 driver and commanded by Onstep running on a modern ESP32 embedded controller, with unshielded and unsealed motor wiring. Or it might be a similar controller board operating a Clearpath SDSK stepper-servo with 6400 tic embedded encoder via Onstep's step/direction interface, and wired with silicone-sheathed shielded cable and metal IP65-rated M12 multipole connectors.

In terms of measured following error during tracking (motion quality), the difference between these three solutions may well be negligible. Autoguiding compensates perfectly for the lack of a high-resolution axis encoder on all of these solutions. The torque capacity superiority of the stepper solutions is irrelevant as input torque capacity of Mesu's friction drive will limit how much motor torque can be delivered. The speed advantages of the servo are irrelevant as the steppers can 'pull' higher overall transmission gearing if necessary. As the friction transmission is (as I understand) backdriveable, the efficiency of the stepper-based drivetrain may be more efficient if the mount spends significant periods held stationary. Or not, as the case may be. There will be no difference in noise emission when tracking between these mounts except for the servo's faint 20 kHz commutation whine. None of these systems will exhibit cogging behavior visible in images (provided the servo is properly tuned with a small 'deadband' of about +/- 2 encoder counts and provided the Trinamics driver running the simple stepper has plenty of drive current available).

One big difference between the simple stepper system and the other two (servo and servo-stepper) might be drive (motor rotor) positioning stiffness. Whether far superior rotor stiffness of the latter solutions provides any benefit will depend on the amount of friction in the Mesu's transmission. As this is far lower than worm drive mounts, for example, it may well be that there is no perceptible difference. But in a worm drive mount, especially of the antibacklash type where drag friction is significant, a difference is likely to be apparent in rms guiding error.

 Another difference emerges when looking at ease of commissioning. The Scitech servo system needs careful tuning to obtain stability without micro-oscillation at tracking speed or sluggish response to positioning moves, which makes building the systems more involved. None of these systems (so far as i'm aware?) employ speed reduction gearheads so all should be equally reliable. The only one that is environmentally-sealed to normal industrial standards for outdoor use (advisable for remote-controlled observatories for example) would be the servo-stepper one I mentioned with waterproof connectors.

So there you have it. There is a very big difference between the cost of these three systems, the Scitech one being most costly by far. This is easily explained by:

1. the manufacturing economics of the relevant component suppliers
2. the avoidance of the need to recoup very substantial R&D costs on the Onstep system which is a GPL development that is designed to run on COTS hardware
3. the fact that there are multiple parties involved in the supply chain for Scitech which leads to greater margin-taking

For many end-users, performance differences between these systems will not be apparent, meaning that there is no perceptible diffrence in 'quality'. For a minority of users who need the greater simplicity of repairs and maintenance of the stepper system e.g. remote controlled imagers, that might be a better choice for them. For another minority who are interested in remote satellite tracking and orbital parameter calculations and need high dynamics, a servo-stepper system might be their choice. And perhaps a few (like me) admire the form and finish and heritage of historical highly-engineered assets - for us, the existing Maxon/Scitech solution is also appealing.

 

Tony Owens

This is really interesting, thanks

2 hours ago, Deadlake said:

How does colour/contrast compare between your LZOS and TOA?

This isn’t easy to answer. On planets, the LZOS definitely wins both on colour and resolution (obviously) but the TOA is incredibly good. Colour correction to my eye on the TOA is slightly better. As an astrograph with the 67 flattener it produces and perfectly flat field across a IMX455 chip - something you might expect but I have failed to achieve in my FSQ106 for example (I am a pixel peeper to the nth degree). I’m going to change the focuser though - I have a FT arriving next week. My LZOS is now in Spain for imaging only. 

Although weight is perhaps a negative, the TOA130 is the best corrected refractor you can buy in my opinion. The only comparable scope that I haven't looked through is the AP130GTX which I expect is very very good too. 

Although Talon is expensive, it integrates very well with image capture programmes so if you’re monitoring weather, for example using a Cloudwatcher, you can stop imaging and close the roof if it rains. Integration with ASCOM is the difficulty people  have trying to roll their own solution. Talon is also used by several remote hosting observatories such as E-Eye. Like I said, it’s pricey, but it’s allowed me to image with confidence on those nights where the weather is unpredictable. 

I've been reading this thread with interest. I recently sold my TSA120mm - awesome scope by any measure. I noticed some of the posters here have got the More Blue rings. There really is (IMHO) a lack of stylish/high quality ring alternatives to the Tak cradles and I too, bought these rings for my TOA. However after experimenting with them I found that they were a source of flexure in my set up. I also have experience with Moonlite Rings (get them from Ron at Moonlite, I also think Rupert sells them at Astrograph) on my FSQ106 and have found them to be really really solid and look great. The FSQ106 version fit the TSA 120mm. I eventually bought some for my TOA and used the More Blue rings to mount accessories on the sides. Now its rock solid.

I also had some problems with some More Blue risers that I bought so overall, I think I have had bad luck with this brand. I should add though that I emailed Steve at FLO about it and I seem to be in the minority. 

Anyway, if you are wondering about really good rings for either an FSQ85, 106, TSA120 or TOA 130, Moonlite do very nice ones. Just FYI. See images below. 

Hi Ossi,

The ring holes are M6 - I am pretty sure of this. 

My advise regarding the Imperial plate is based on the reviewers; several have Esprit scopes and following discussion with FLO, were advised to get the Imperial plates. If you have any doubt, just email FLO - they will answer the same day. 

Simon

Very sad to hear people are threatening court action against HOUK. 

Ossi - 

You need the imperial version of the ADM Losmandy plates. I would suggest avoiding the Skywatcher plates. If you go here, you will see that a number of reviewers pretty much had this exact question. The rings on the Esprit, like pretty much all rings, are M6. When in doubt - go here to get screws. I keep M6 and M8 screws of various lengths because they are always needed. 

Not to disagree with Carole above - but I would also advise a Losmandy over a Vixen dovetail for the Esprit (assuming weight isn't a major issue)

Hope this helps. 

Best

Simon

Stu,

Don’t worry,  some would consider your purchases relatively restrained. This hobby is dangerously addictive. Your gentle “isn’t it?” at the end of your post is a clear sign that you are beginning the feel the effects. 😄
 

I spent 25 years doing visual with a single pair of binoculars. I started AP a few years ago. Now I have an observatory at home and another one in Spain…😳

13 minutes ago, vlaiv said:

What is actually your concern about resolution?

If you can afford and mount large telescope - I'd say go for it regardless of the fact that you'll be seeing limited.

Just make sure you pick up sensible working resolution for your conditions. I'd say with such a large scope - target somewhere around 1.2-1.4"/px. That will be good sampling rate for most time. There will be few nights a year where it will be too high and few nights a year where it will be too low (provided your mount is good enough).

Even if you can't utilize resolution - you can utilize light gathering. Large aperture gathers more light and will offer faster imaging at given resolution.

My mount is good - its a 10 Micron 4000 HPSII and can pretty much carry anything. Thank you very much for this practical guidance. 

Thanks Steve - 

It would be great to hear from some of those RC and ODK owners too. 

Your experience resonates within mine alright!

Simon

Hi All, 

I am new to SGL but active over on CN's (I have moved back to the UK after years working in the US). I am contemplating purchasing a Planewave CDK - probably the 12.5" (F8) but possibly the 14" (F6.7). I may use the x0.66 reducer if I get the 12.5" although its back focus requirements are incredibly tight and probably prevent using an OAG. I am interested to hear from any other imagers in the UK using a CDK or similar design large aperture scope. I have some doubts/uncertainty whether the seeing where I am (Kent - in a Bortle 5/6) will support this aperture. I

I would be grateful for opinions on this! Thanks.

Best, 

Simon

This thread makes sad reading. HOUK built my observatory right at the end of 2019 and completed it the first week of January 2020. Gareth and Nathan were nothing but gentlemen and did a really excellent job. Electronic communications were definitely an obstacle for them though. I fully understand the frustrations expressed here as well as the concern about losses. I doubt there is anything shady going on - it sounds like they are simply having a very tough time. I hope things start to improve for them. 

I have to add, I had HOUK set up my observatory and they were fantastic. There is no doubt that they are a little challenged by modern communication systems. On Whatsapp, Nathan would take many days to respond to a text and it would clearly show that he hadn't looked at it in days. Email is a little better. However, their product is superb and worth the wait - they are true craftsmen. 

I am far more active over on CN's and Backyard Observatories in the US are exactly the same - long periods of going "dark" and preternaturally long waiting lists. I am not saying that this is good (perhaps its not even acceptable) but these folk run their timelines they way they run their timelines; its just the way it is. Makes your observatory that much sweeter when it's built. 

Simon

Really useful. Many thanks!

Graham, 

I sent you a PM. 

Simon

Hi All, 

I am looking for a programmable network power switch (with multiple power outlets) for my observatory. I looked at the Digital Loggers kit and this seems to fit the bill but is there a UK solution to this? The specific Digital Loggers product I am interested in (here) is out of stock and I'd prefer to buy locally. 

Any suggestions on this?

Many thanks, 

Best, 

I have the TSA 120mm which I use for lunar and solar imaging. I got it about 6 months ago. Last night, I looked through it for the first time (yes - sacrilege to have left it so long). I was blown away. Super sharp, perfect colour correction - really very very good. I also have an LZOS 152mm which is a great scope, but boy, is the TSA120mm something special. 

For imaging I would go with an FSQ106 if you are aiming for a "forever" scope.  I also have this and it's a joy to use. 

Hi All, 

I am new to this forum (I am active on CN - I used to live in the US but I am back home in the UK now). 

I have recently moved from a QSI683-FSQ106 combo which is very forgiving to a QHY600-FSQ106 set up and I am having some difficulties. The summary is that, as perhaps I should have expected, my field does not appear to be as flat as I had hoped (as measured in CCD inspector). 

I just read this thread with great interest

I am having great difficulty taming the outer 30% of the image. The combination of small pixels and large sensor are proving to be a significant challenge. Added to this, I think I have some tilt. 

In the interest of having an easy life (particularly given that experimenting with equipment is very difficult when so few nights are clear), I am seriously considering downsizing to a smaller sensor. The next clear night I am going to try 2x2 binning and see if that helps. 

I am very interested to hear people's experiences with the IMX455 sensor, specifically in relation to achieving a flat field. Some of my colleagues have suggested that if visual inspection of the images looks good, then who cares but I am pretty sure I can see eggy stars in the corners. 

Thanks for reading, 

Best, 

Simon

Just one more; tonight's shift. 

I got rid of the Edge and replaced it with an FSQ106. 

Sorry about the messy observatory - and the pink Dyson hoover :)

I've been blessed - 152 LZOS and a TSA 120mm. To be honest, and I say this cautiously because a lot of folk love SCTs, I barely use the Edge. I am hoping to replace it (with another refractor). A Tak 128mm is on my wish list but they are very difficult to get hold of. The one in the posts above mine is a beauty.