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Old 07-07-2021, 08:31 AM
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rustigsmed (Russell)
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Join Date: Mar 2012
Location: Mornington Peninsula, Australia
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Quote:
Originally Posted by gregbradley View Post
It looks to me as quite a bit off not just a bit. Perhaps 5-10mm.

This is a 130mm F5.53 or so isn't it? So its not that different to my AP130.

A 1mm spacer difference with that (the Quad TCC is very sensitive to spacing) made a noticeable improvement but it wasn't anywhere near as distorted in the corners as that.

Roland Christen has a procedure for setting spacing on flatteners.

You focus the central stars. Then you focus a corner star and note if you had to rack in the focuser or rack it out to focus it.

If you had to rack in you needed to decrease the spacing. If you needed to rack out you needed to increase the spacing.

Keep in mind reducers may not do corner stars well on a full frame sensor unless they are very high quality and at least 3 inches in diameter preferably 3.5+.

Even then some corner stars may not be perfect. That has been my experience with various reducers. Very few correct a full frame sensor and they are usually pricey.

Straight flatteners are way easier to get right and they are more forgiving and generally speaking do a better job.

Greg.

Greg.

thanks very much for the info Greg so i may be quite a distance off yet - i will definitely try that method out to double check there is too much spacing. that will then verify the diagrams linked from cloudy nights.

here is the link to the corrector https://www.teleskop-express.de/shop...ollformat.html - the telescope native is 130mm f7, it is meant to do full frame.

the thread on the corrector is raised a tad making it a bit confusing if the imaging system is meant to screw all the way down or not. the image linked it was screwed all the way down.

Cheers

Russell
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