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What's causing these issues with Hyperstar


Geordie mc

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Hello everyone. Ive had issues with my Hyperstar setup on my Edge 8 for sonme time. Ive tried collimating it numerous times and the back focus should be correct as I'm using the adapter for my as11600 mm cool that was supplied by Starizona. Im thinking it could be camera tilt or sensor not quite perpendicular to the focal plane as the issue is really with the left hand side of the image. The further left you go the worse it gets. The image is a single 2 miunute SII sub taken through a Baader 2 inch F2 filter mounted inside the Hyperstar's camera adapter.  Any insights or advice on this would be much appreciated. Thanks you.

Light_NGC896_120.0s_Bin1_20211213-220034_-10.0C_0002.png

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  • Cornelius Varley changed the title to What's causing these issues with Hyperstar

I have to say that this looks a bit like both tilt and wrong offset.  What camera are you using (ie. what size frame) ?

The filter, of course, does have an impact on the spacing, typically quoted as requiring 1/3 of the filter thickness added to the back focus.  Have you checked things without the filter?

For comparison, here is a 10 minute stretched stack of the corners from my Hyperstar 9.25" with a small, uncooled, camera (Ultrastar) with 11.2mm diagonal.  This is, undoubtedly, smaller than yours (I/m guessing an ASI 1600, 22mm diam, judging from the pixel count?) but shows the quality that you should be able to get if everything is (nearly) right.  I think I do still have a small amount of tilt in the camera chip itself.

Tony

 

Pal2_corners.jpg.f7dde64df13c795b4427de4f3166f7b9.jpg

 

Edited by AKB
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Hi Tony. Thanks for help. Im indeed using a asi1600 cmos camera with a 2/3rds chip. Good point regarding checking without the filter. Ill try that tonight if it stays clear. If there's a bit of tilt too - which i think there is - have you any idea how i can adjust for that? Im presuming we are talking tiny alterations on the camera itself or do i adjust using the Hyperstar collimation screws? I'd certainly be happy enough if my stars looked like those in your image. 

Thanks again

John

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3 minutes ago, Geordie mc said:

If there's a bit of tilt too - which i think there is - have you any idea how i can adjust for that?

Several threads on this recently… bigger cameras highlight the issue!

Try this for a start – I’d always (usually!) believe the way @ollypenrice approaches things…

 

In terms of actually correcting it, aside from an separate tilt adjuster, a very thin shim on the offending side, under the thread, should do it.  You can buy such things, but the tag on this one, suggested by @gorann might be too large for a Hyperstar:

 


HTH

Tony

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Thanks for that info Tony. Olly does know his stuff so ill look into his methods.

I tried without a filter last night but could only take very short exposures due to the Moon. Couldn't really see a difference, but it was great seeing so I tried to collimate again using the usual defocus method and it looked slightly off. A bit of adjustment led to an improvement. I was using the ASIair pro and forgot to save the images though. I think I'll retry using APT as it has the collimation aid. Its really hard to judge by eye if you've got things dead centre so this might help. Might try an artificial star too. It was tough adjusting the Hyperstar in sub-zero temperatures! It also means i can do it regardless of the weather - no clear nights for the next 10 days sadly. 

Hoping that with a very careful collimation I might not need to do anything else but ill certainly look into the tilt as well. Thanks very much for the support on this. I'll post again when Ive hopefully made good progress. Have a great Christmas and best wishes for 2022.

Regards,

John

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