6 replies to this topic

[cmanley134]

Hello all - I have been chasing what I believe to be a tilt issue in my optical train for a little while now and want to get some outside opinions before I start trying to adjust anything. I'm using a SpaceCat 51 and 294MC Pro with no other elements - just the required spacers to reach 55mm of back focus. I see some elongation of the stars towards one of the corners and not in other parts of the image. The location moves when I use the SpaceCat's field rotator so based on my understanding that means it is optical and not related to the camera sensor.

 

I've analyzed the images in ASTAP and oddly enough it's not indicating that there is significant tilt in either the stack or individual frames. I'm linking to an Imgur album which I believe has all of the necessary info to evaluate the issue, including ASTAP screenshots. Please look through all of the images and written comments before requesting anything additional. Would love to hear some thoughts from folks more experienced than I. Thanks so much!

 

https://imgur.com/a/Me4karU

Edited by cmanley134, 30 June 2022 - 01:07 PM.

[Borodog]

That's a fantastic image. My suggestion is to stop pixel peeping. :O)

[cmanley134]

That's a fantastic image. My suggestion is to stop pixel peeping. :O)

Thank you so much! I am really quite pleased with it, can't wait to add some additional data to bring out more of the background details. This is definitely a small issue but it's something I would like to get to the bottom of if possible. 

Edited by cmanley134, 30 June 2022 - 01:16 PM.

[ChrisWhite]

Most likely it is a lens collination issue. Those petzval designs are problematic for collimation and can get screwed up in shipping, etc. It's a very common problem for the redcat scopes.

[cmanley134]

Most likely it is a lens collination issue. Those petzval designs are problematic for collimation and can get screwed up in shipping, etc. It's a very common problem for the redcat scopes.

Is it possible something like this could happen during regular use? I do carry my tripod out to my usual shooting location each night so it's possible that I've set it down a bit too roughly on occasion - it's never been dropped though. I didn't notice the issue on the first few targets that I shot with it. At first I thought it was a tracking/guiding problem but ruled that out after observing the uneven effect. 

 

In any case I hope it's not anything too serious - I'm not the original purchaser of the scope so I am not sure what if any warranty protection I have access to. 

Edited by cmanley134, 30 June 2022 - 02:37 PM.

[ChrisWhite]

I'm not sure how much of a force could cause a lens to go out on these. It is a common problem inherent to the petzval scopes though. Even the fsq106 has this happen.

You can get a collimation eyepiece and check it.

[cmanley134]

Just a brief update, during my session last night I watched the first few frames come in and... no issue. I have no idea what was different but the problematic corner was mostly if not fully normal again. Just goes to show that these little quirks are a normal part of the hobby!