Coma Corrector

[mick pinner]

does a coma corrector ( non magnifying type ) alter the focusing distance to any substancial degree ( in/out ) when using a DSLR, and does the F/L have a bearing? thanks.

[Gama]

The Baeder MPCC moves focus out by only 10mm, so do yourself a favour read bout this item.
Does not alter the f ratio, and is big enough to use in a DSLR or other large size sensors.


Theo.

[mick pinner]

thank you very much Theo, will do.

[Gama]

Just a little more info, you need to make sure the distance is 55mm from the face of the sensor to the face of the last lens in the corrector, if not you will get coma in the outer filed of view..

I use this on my 20D and also on my QHY8. The corrector works on my 22 f4.5 Newt with no probs, so you should have no probs with it.

[bojan]

Sorry Gama, I noticed this thread too late and when I tried to remove my post/thread, I could not :-(

What kind of threads are used on the corrector? I have seen on Baader website they say it is 48mm diameter (camera side), but they do not specify the pitch. That means we will need an adaptor (to Canon or whatever).
Also it seems the other side has different thread, 2"x? again no pitch specified, but perhaps this one is easier since they say it is a "standard", used for 2" focusers?

Also, I remember some time ago I saw something for half the price of Baader... If I find it again I will post the link here..

[bojan]

Those guys have Vixen at better price (see link below)
http://www.telescopes.com/site_search/index.php?cat=&keywords=coma&t=1

Probably it is the same thing....

[Gama]

The coma corrector has T threads on one side and T thread and also 2"filter type thread on the other.

You connect the camera side with a T mount and the correct spacing (55mm) T thread spacer, and either thread it into a T thread to 2" nose piece or straight into a T thread adapter

Theo.