Chris

I agree with your assessment Vlaiv, expecially on an individual frame basis. I thought it would be interesting to see a 400% zoom crop of the stacked and processed image. I'm thinking the final image may be what counts for many and there is a difference, the elongation appears to be a little less obvious after stacking and processing.

Jpegs were to blame. 400% zoom on a RAW saved as png:

I'm not sure why mine looks different to yours in that case? I'll try zooming in even further.

Is that from the centre Vlaiv? I crop zoomed the centre of the image and the stars were round (well square because of compression) I'll show you when I've figured out how to upload a super cropped image that doesn't appear tiny

I've used CCD inspector to chart the FWHM over the course of the night. As you can see it gets pretty bad later on, but not using a dew strap could have caused this due to lens haze. Also, CCD inspector doesn't open the Fuji Raw files so this is based on Jpegs (I have the camera set to RAW plus jpeg) and I know you're supposed to use RAW for this. For reference the setup gives a pixel scale of 2.29"/pixel. The mean average FWHM was around 6" which isn't great. For what it's worth: Here is the actual real world difference between sub 6 (the best FWHM because sub 1 was me focusing on a star :D) and sub 23 (the worst) When I've recovered from the dreaded lurgy and have another clear night I will repeat the above (but on another target) and see how it compares.

I was using a stand alone Fuji XT1 so no PC hook up for FWHM info. I stacked 90% but all subs had round stars when I zoomed so I probably could have stacked 100%. The whole thing feels supernatural some how!

Ah right, I was thinking you meant the worm shaft was 0.6mm too short full stop, as in 0.6mm too short to be adjusted out. That's a bit less shocking but I realise it was still a pain to adjust. I guess the bearing will only need to come out again if it wears out, and If the bottom bracket bearing of my road bike can take 1000's of miles of abuse I think you should be good for years to come I think iOptron should feel more embarrassed for machining it oversized to begin with! I can only hope that doesn't happen too often!

It's one of our customer returns. Does that make a difference?

I probably should point out that I technically don't own the mount, it's on loan so please don't think I'm just hear rubbing in how good my mount is or anything like that, I was just genuinely surprised and wanted to know if others had a similar experience. I think we might have to agree to disagree regarding money as I wouldn't expect the same quality or results from a 1k mount compared to a 3k mount, just like I wouldn't expect the same handling speed performance from a Dacia Sandaro compared to er? an expensive car.....I can't think of one

Thanks for bringing up pixel scale as this needs to be taken into account when looking at tracking performance. Someone will of course have a much harder time trying to image at 1"/pixel compared to say 4"/pixel. I probably should have mentioned that my 5 minute subs were at a pixel scale of 2.3"/pixel. p.s. blimey well done for getting 20-25 hours imaging in the last 6 weeks!

Sad to hear but kudos for sorting it out, you're clearly tenacious! Did you shim the 0.6mm end clearance and wrap something around the bearing so it didn't move around? As someone who trained as a CNC machinist from school it's hard to relate to components being passed through inspection which are out of tolerance. The inspectors would be right up in your grill if you were 1/10th of a thou out! A different type of engineering world maybe ?

I think this is where the price thing may come into it to some extent? I am after all lucky enough to be using a 2.2k mount at the moment. It might be fairer to compare brands by price, for example how does say the SW HEQ5 compare to the iOptron CEM26 as they are about the same price. Is the QC and tracking better for one compared to the other?

I think I'd describe myself as someone who likes to try different things rather than someone who went through a dozen mounts looking for one without problems. I.e. I've chose to sell good mounts in the past just to free up money for something I wanted. As someone who has paid full second hand price for problem mounts on more than one occasion I've chose not to follow suit and just give the problem mounts away or sell them as spare or repair. My last mount went to the local high school to be used manually with a Vixen refractor.

Excellent report! I especially liked the 38 Lyncis plot twist

Hey, It would be interesting to have some empirical data for the PE curve but my next move will be to grin insanely at the mount as I attempt to go for even longer subs! That will have to wait though as I currently have the dreaded you know what 🤒

Hey Mark, I know it can be pot luck sometimes can't it. At least your GT5 sounded like a good one, better than the GT5 I had by the sounds of it. I'm sorry to hear your CEM26 broke after just one use and glad the retailor sorted it as they should do, I would always make the retailor your first port of call. You also kind of raise a good point about buying goto mounts second hand. It's one astro item I stopped buying on the second hand market as the poor examples naturally get moved on more than good examples, and there is so much to go wrong with a mount compared to say a telescope or eyepiece.

As a serial kit tester I've owned/used my fair share of mounts including a number of Sky-Watcher and Celestron mounts as well as an Explore Scientific, but I think I may be an iOptron convert after using a GEM45! Yes, you would expect a 2K iOptron to be better than a 1k Sky-Watcher for example, however, I'm just surprised by how easy the iOptron has made imaging and I'm having a real blast! I was looking to jump on the whole ASI Air thing as it does look like an amazing product, though I feel the GEM45 has made this less needed with such a quick and and accurate goto system plus the realisation that periodic error is so low that I don't need to guide! I was getting 5 minute unguided subs @432mm on the California nebula last week, and I'm sure I could have gone longer! I've never seen anything like it! I know iOptron is one company that states periodic error figures and the standard (Non EC Encoder) GEM45 is stated to have < 7 arc seconds. I suspect such a post will attract both very good and very bad stories, and perhaps not what's typical? so it may not be possible to see a true picture, I'm just wondering if others have found that they don't need to guide with their iOptrons? As always I documented my experience below:

The facepalm that must have happened when they realised the Hubble was myopic (all down to a spec of dust on calibration equipment I believe!) and against all odds they 'popped' back up with a pair of specs and sorted it, amazing! I basically have high hopes as long as the James Webb gets up there! Adrenaline wont be in short supply the day of the launch that's for sure!

These are superb so I think you'll only get good judgements

Used an Optolong L-Enhance filter with the StellaMire 90 this time round and barely norticed any vignetting when using the filter. It was like I had took flat frames (I didn't) : )

Yeeah! Managed to stack Fuji RAF files in DSS this time round! It must have just crashed last time. Image of the California Nebeula saved as 32bit. I also used an Optolong L-Enhance filter which seems to help quite a bit with the vignetting which is a real bonus! Processed using the same method as before.

Transparency looks good in Suffolk tonight, I'm not far from the most easterly point of East Anglia so I guess I'm right on the edge of that horrid looking Jetstream. Taking some 3 minute subs on the California Nebula with the StellaMira 90 EDT and they look magic on the screen of the Fuji XT1 at least. We'll see how things are when they appear larger on the PC!

Stumbled across this thought provoking audio visual experience and thought I'd share:

Looks very good to me, congratulations!

Well I certainly didn't make it easy for you with just light frames, Vlaiv, but I'm loving those stars Looking at the two renditions above I think I need to calm down with how much I stretch my data lol You two know when to stop and it looks cleaner as a result!