mikeonnet

Is this any help using PIPP? https://sites.google.com/site/astropipp/example-uasge/example-4

So.... Although I don't own either of those two telescopes you mentioned and neither the AVX mount, but I do have the Celestron Advanced GT mount with an Evostar 80 ED refactor and find it more than adequate for AP, just make sure the mount is polar aligned or you will run into guiding issues. I think the mount you have will be more than capable with a 80mm scope. One the subject of refractors, have you considered 2nd hand? There is a Explore Scientific ED 80mm on ebay at the moment (Mint Condition is says) and although you haven't mentioned about camera's for imaging & guiding but maybe the pennies saved can assist with the additional kit for AP as auto guiding is a must.

Yes, it's a ZWO camera and as others have suggested, it is probably a spacing issue. I will try and experiment when it's next clear. I have attached one of the Luminance subs on M27 (saved as a jpg to upload onto here). This was taken on the same night after the bahtinov mask picture above. Like I say, I will try different spacing from the camera to reducer and update if I have resolved the issue.

Thanks for all the replies. It sounds as though it is a spacing issue then and I will give it another go when it gets dark & clear. I will try with the 1.25 nose piece adapter that I can then slide in / out from the filter wheel and test again because at the moment the camera is screwed on to the filter wheel with a M48 adapter, then the wheel has a 16.5mm extension tube that screws to the reducer so I'll try the nose piece connections for now and make subtle adjustments while in live view mode to see what happens. Attached is the full image of the 'curved' bahtinov mask image. I will update when I get a chance to try with the nose piece fittings instead. Thanks again all.

This was just a snapshot from Firecapture, so roughly 1/8th of a second and yes, it wasn't properly polar aligned as I just took the scope out to try it again. It was last weekend that I tried the camera / filter wheel for the first time and properly PA the mount but had the same 'curved' spikes then (using APT software)., hence I thought I would quickly try it tonight but with the same effect. I will try it without the focal reducer and just connect the camera + wheel onto the scope (providing I have enough back focus) and see what happens. I can only think of the spacing between sensor and focal reducer isn't quite right. Just seems strange that the lines are curved and not straight, yet my dslr attached to the reducer was perfect.

Hi all, I'm looking for some advice on the 'curved banana' shaped spikes I have. Having used a DSLR connected to a 0.85 focal reducer & Skywatcher 80 refractor, the bahtinov diffraction spikes were perfecly straight including the diaganal lines. However, I am now using a ZWO mono 290 and a filter wheel with the adapters (55mm from the sensor to reducer) but now the lines are curved - see image. I know it's a noisy image but this was just a quick snapshot but my main concern is what is causing the curvature of the spikes. Is this an issue of the camera not being the correct distance to the reducer? I have only had a quick imaging session of M27 the other day and too be honest, it seemed OK but I just wonder if this 'wobble' will be impacted on all the light frames I will be taking. Any advice please... I