4 replies to this topic

[paulgreeny83]

Setting up in Malibu mountains in a yurt for my first night of DSO AP. Added my new Celestron 6.3 reducer with the Sony A7 iii camera. Test image shows terrible vignetting. I was expecting the outer rings due to the sensor size but there’s also inner rings that make any wide DSOs such as Orion Nebula impossible to properly capture. I can crop but I’ll lose too much FOV. 
 

Any ideas or thoughts much appreciated. 

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[maadscientist]

What scope? The C8's and the non Edge 9.25s have a restricted back end that will mechanically vignette a full frame camera.

 

Make sure you take flats!

 

BTW if you have one of those, alternatively you can remove the reducer. Don't worry about being at F10, bump the ISO up to at least 800. I have successfully imaged at ISO 12,800 on the Sony A7III. But you image scale will narrow, and like you said you wanted it wider. Take those flats!

Edited by maadscientist, 08 May 2024 - 09:08 PM.

[paulgreeny83]

Evo C8. I’ve seen others use it with a 6.3 reducer and Sony A7 iii though?

[maadscientist]

It's just the full frame camera won't fully illuminated because of the choke on the back of the scope. You can still salvage by using flats. Take them at sunset, get your histogram over from one third to one half. maybe take two sets , one at a third and one at a half. Cover the scope and take a handfull of darks at each exposure length. If you can't do that, you can do it in the morning, or transport the scope back with the camera attached in the same position you imaged in and take flats when you get home. On that type of vignetting, you will be surprised at the good results with the flats calibration.

[paulgreeny83]

Ok, Thank you!