Re: [ATM] Using Barlow to reduce Coma

["Mark" <marco.miglionico@btinternet.com>]

O.K., so if I were to pop in a 40mm plossl, then coma would look
as bad with and without the Barlow?

My common sense tells me that as I am only looking at half the field with 
the barlow in, so
it would be like looking at the centre area without the barlow -  which has 
less coma!

By that rationale, what I want to know is comarping the smaller field with 
the barlow in the F3.3 scope,
to say a scope with an F6.6 mirror --   what will the difference be? 
(Bearing in mind I know
that the Barlowed F3.3 is looking at the central part of the field which has 
inherently less coma.)

Help.

----- Original Message ----- 
From: "Mel Bartels" <mbartels@bbastrodesigns.com>
To: "'AMT LIST'" <atm@atmlist.net>
Sent: Wednesday, January 25, 2006 4:32 AM
Subject: Re: [ATM] Using Barlow to reduce Coma


>> What my question really is: will my F3.3 mirror have the same coma as
>> an F6.6 newt if I use a x2 Barlow?
>
> This isn't as easy to answer as one might think since the definition of
> 'same coma' is fuzzy.  But strictly speaking, no, a Barlow will not 
> decrease
> or increase coma.
>
> Mel Bartels
>
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/ 

_______________________________________________
ATM mailing list http://www.atmlist.net/