Guest Dave Wall Posted December 16, 2013 Share Posted December 16, 2013 Coma correctors are they necessary. Link to comment Share on other sites More sharing options...
Brantuk Posted December 16, 2013 Share Posted December 16, 2013 Usually when imaging with newtonians you need a coma corrector. There may be other occasions I'm not aware of but that's where it seems to be used most Link to comment Share on other sites More sharing options...
Daz Type-R Posted December 16, 2013 Share Posted December 16, 2013 The short answer is, depends on your scope. A Newtonian utilising a parabolic mirror is subject I believe to coma but only a F6 and below, the faster you go, the greater the coma (chromatic aberration or CA). Certain scopes are designed to reduce these affects or you can buy a coma corrector. I found wiki's page on coma correction to be nice and clear.... http://en.m.wikipedia.org/wiki/Coma_(optics) But wiki is open to human error, so I would see if anybody else on here has any more. Link to comment Share on other sites More sharing options...
Guest Dave Wall Posted December 16, 2013 Share Posted December 16, 2013 Hi Daz & Brantuk, Building up an astrophotography kit I have skywatcher 200p want to get the essential items first. Link to comment Share on other sites More sharing options...
Guest Kheldar Posted December 16, 2013 Share Posted December 16, 2013 Is it essential? No (Crop FTW) Would I buy one (and did I for the 200P?) Yes You will get coma at the outer FOV if you slap a DSLR on that ... however if you're using a webcam/small CCD you probably wouldn't even notice it ... Link to comment Share on other sites More sharing options...
Brantuk Posted December 16, 2013 Share Posted December 16, 2013 Ahh great - I've learned a bit more there to stow away in the "coma advice cells". Link to comment Share on other sites More sharing options...
andyboy1970 Posted December 17, 2013 Share Posted December 17, 2013 Yes for imaging and if like me you own cheap eyepieces... My ATIK is 1300x1000 ish pixels and I get coma at the edges and this is less than half the area a DSLR covers. If you read up about it you will see that you don't have to go far from the mirror sweet spot before coma starts to creap in. Link to comment Share on other sites More sharing options...
Guest Dave Wall Posted December 17, 2013 Share Posted December 17, 2013 (edited) Thanks guys. Edited December 17, 2013 by Dave Wall Link to comment Share on other sites More sharing options...
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