Gary Clayton

I ended up with mine Infront of the filter tray as I thought it best to keep the filters as close to the camera as possible.

If it's printed in PETG it should be fine outside, but if it's PLA not so much

That's the 3D model, just turn it of in the options tab and it will display the easier to view 2D version, it's showing that your back focus needs tweaking a bit, try to get the curvature radius number as large as possible.

Single unprocessed 5 minute sub on M13 using an APS-C sensor, no calibration frames or crop to test out the new SM 1:1 field flattener, I adjusted it to 23mm on the scale for my setup, it will need minor tweak's when time allows.

3 minutes ago, SAW said:

I don't have the tilt plate connected the camera is bolted directly to the filter wheel.

In that case try getting the back focus correct first, other things to check are your focuser tube and camera rotator make sure there both nice and tight with no play or movement at all.

5 minutes ago, SAW said:

I have some tilt shims which side do I need to put the raised part on ? How much should I reduce my spacing each time to notice any changes ?

It's impossible for me to say as I don't have access to your rig, it's going to be trial and error on your part. Does you camera have a tilt adapter ?, if so your need to work out which side is which as well as it's top and bottom, if your using a ZWO camera my understanding is that the bump in the camera's body is the top, have a look at these videos to get you started.  https://www.asgastronomy.com/collimation-tilt-and-backfocus/

51 minutes ago, Anthonyexmouth said:

What's the best bang for buck dual NB filter at the moment? preferably one with minimal halo issues. 

Difficult one this, I started off with the Optolong L-eXtreme and was mostly pleased with it apart from the halo issue which seemed particular bad so I ended buying the Antlia ALP-T "Gold" dual band 5nm filter and have not looked back, this was before the new L-Ultimate came out though. I am not sure that there is a cheap option if halo's are an issue for you.

With a lot of fiddling I managed to get mine down to this from around what you have

10 minutes ago, SAW said:

I loaded this frame into astap.

Light_Cygnus_300.0s_Bin1_H_20230624-012407_0031_a_REF.xisf 49.77 MB · 0 downloads

This quite clearly shows both your tilt (32%) and your Off-axis aberration (back focus error) as being high, try to get this in the 0.20 mark, I would start on the tilt first by shooting a starfield that has no nebula or clusters in it at around 30 second mark.

9 minutes ago, SAW said:

Would that cause the stars to look like crosses if it's too close ?

If your to close to the reducer you get radial shaped stars pointing to the centre of the image as per the top image and cross shaped/diagonal stars if your to far away from your reducer as per the lower image, so in your case you seem to be to far away from your reducer but also have some camera/focuser tilt.

1 minute ago, SAW said:

Thanks all. I'll check a single sub.

if you post a single sub, we can check it out in ASTAP.

8 minutes ago, Anthonyexmouth said:

Top stars look like they are doubled up. but nowhere else. 

I think  that it's just coma coming from the reducer as there seems to be both a combination of tilt and back focus errors going on, much worse at the bottom causing the small cross shaped stars

Hopefully this guide should help

42 minutes ago, SAW said:

I was using my 2600MM last night on the 90mm for the first time, normally use the 183MM without any problems. What is causing the really bad star shapes all along the bottom ? Can I fix it or do the optics need collimating ?

If you look at the bottom corners you have cross shaped stars indicating that your sensor is to far away from the reducer as well as having some tilt as the top ones are not as bad 

There is very little difference if any as far as picture quality goes and this is to be expected considering that they both use the same sensor, the AA 26C seems to be a bit more finicky regarding it's USB port preferring USB 3 over USB2 but apart from that you can't go wrong with either camera, it depends if your stuck with the ASIair ecosystem or not.

Mine has just arrived and I have fitted it to my SM90, it feels very well made and is very easy to adjust for the correct back focus, hopefully I will get to try it out this evening on something like M13.

I see that the1:1 field flattener is now available from FLO, I will let you know how I get on with it once it arrives

 https://www.firstlightoptics.com/stellamira-telescopes/stellalyra_adj_flat_90_125.html

Leo triplet taken last night, 60x5 minute subs using an IDAS D1 filter on my Altair Hypercam 26C and 0.8 reducer on the SM90, looking forward to the 1:1 flattener in time.

Sorry wrong thread

12 hours ago, tomato said:

Great image, may I suggest posting the un-annotated image so we can view the galaxies without the text intruding.

Thank you for the kind comments, un-annotated image as requested

Messier 81 and Messier 82 about 12 million light-years away in the constellation Ursa Major, taken over the last two nights from my back garden and hindered by the Moon!.
159 X 5 minute subs, so just over 13 hours total intergartion time
Stacked and drizzled in Astro Pixel Processor then finished in PixInsight
StellaMira 90 with 0.8 reducer/flattener
IDAS D1 Light Pollution Suppression Filter
Altair Astro Hypercam 26C Camera
Ioptron CEM40G equatorial mount

I have also just spent some time adjusting the tilt on my setup which comes from my camera, and it's a learning curve trying to figure out which origination the camera is in relation to the tilt adapter screws, but in the end I managed to get it reasonable low as not to be to objectionable once the image is cropped out.

Don't expect perfectly round stars in all the corners with an APS-C size sensor though.

1 hour ago, FLO said:

They are incoming.

Currently on the water, so will probably arrive at our warehouse mid-late April. 

HTH

Magic, I will have one when they arrive 

Question for FLO, do you have a 1:1 flattener that screws onto the M63 focuser?

I managed just 2 hours worth of imaging last night on the M81, M82 area before it clouded over yet again.