Thread: New COMA Killer
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Old 14-08-2019, 06:58 AM
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gregbradley
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Join Date: Feb 2006
Location: Sydney
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Quote:
Originally Posted by alocky View Post
For a 40mm lens it is a very very large chunk of glass. My Polarie handles it just fine, though and the results wide open are pretty tight - better than my Leitz 50mm Summicron in the corners.

Here's an hours worth on Crux with the Polarie, Sigma 40 and D810a
https://www.astrobin.com/420737/
Lovely shot Andrew. A bit of coma but that's about as good as it gets at F1.4.

The only other lens that may do better is the newish Sony 24 1.4 GM. Sony specifically stated that they were able to minimise corner aberrations for astro. But the supply of them seemed to stop for a while as a few quality control issues surfaced on the net. They are making them again now.

F1.4 though is perhaps not the best target for a lens as my Zeiss Loxia is pretty perfect at 21mm f2.8 and with a tracker you simply expose longer or do more subs to compensate for the slower F ratio.

I tarted my Polarie up. I got the counter weight from the Star Adventurer and the upgraded holder from Vixen so the polar scope can always see through the holder plus I put a wedge on it.

Greg.
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