Quote:
Originally Posted by rustigsmed
thanks everyone for the input - looks like slightly too close - i much prefer that to too far away, hopefully will get another crack at it toward the end of the week.
thanks again - much obliged.
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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.