[codemonkey (Lee)]

Originally Posted by Eden

Lee --



This makes sense :-) I didn't realize that the image you supplied was a snippet from a full frame. I've had this problem in some of my images.

Field curvature and coma are to be expected in many telescope designs and refractors are not exempt from this, especially in products from the low end of the market (yours and mine). Refractors with a triplet lens design suffer from this problem to a lesser degree. A field flattener would help, but also double-check your focus because even a slight deviation from focus will amplify these off-axis aberrations.

Originally Posted by Asterix2020

Hi Lee,

I think you have field curvature which is present in ED80's. The only way to fix it is a field flattener/reducer.

Check out this pics for comparison.

My ED80 before field flattener:
http://www.astrobin.com/full/88107/0/

With flattener:
http://www.astrobin.com/full/93400/C/

I bought this flattener since it it designed for the ED80. I couldn't find it locally.
https://www.teleskop-express.de/shop...ED-80-600.html

You guys are legends, thanks muchly for your help :-)

I'll chuck that on the list of things to convince the wife to let me buy...