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Is this sensor tilt or something else?

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4 replies to this topic

#1 mr1337

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Posted 21 June 2021 - 03:25 PM

Trying to start using my 70mm Meade Quad with the ASI2600 and noticed the stars are a bit wonky in the corners... I'm familiar with having an out of collimation SCT or backfocus issues but I didn't think the petzval design would be inlcined to have the same backfocus problems.

 

ngc7538_lion_70mm_01_sho_mosaic.jpg

 

Should I be adjusting tilt to help correct?

 

Thanks!

Mathew



#2 ew22

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Posted 21 June 2021 - 03:30 PM

I am not an expert and recently am suspecting i have a tilt issue, but i would try adjust spacing first in your case.  



#3 Gert

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Posted 21 June 2021 - 03:38 PM

Hi Mathew,

 

I've seen similar with ASI2600MC and the canon 200mm F2.8 lens.

 

Antares_Nebel_v4_corners.jpg

 

The following helped me

  • Carefully removing the tilt plate from the camera and inspecting if it was attached properly. I found a small spec of debris that was caught between camera body and the tilt plate and removed it.
  • Carefully feeling the tapped holes in the camera body for any rims or burrs. I thought I felt some and covered the camera opening with tape and used a small flat key file to remove the burrs. Same for the tilt plate.
  • Taking test exposures and adjusting the tilt plate.

 

Cheers,

Gert



#4 mr1337

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Posted 22 June 2021 - 11:04 AM

Thanks all - will give it a shot and report back.



#5 rgsalinger

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Posted 22 June 2021 - 11:29 AM

With the Petzval design there is NO spacing requirement. I have two Petzval scopes and all that you do or need to do is to focus them. So, in this case, either the scope is terrible or there's a combination of tilt, focusing and poor correction going on. If the spec says that is can cover an APS-C chip and it's a new scope, I'd be sending it back after doing a bit of further checking. Don't hold onto it beyond the time when it can be returned. 




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