Re: ATM precision of secondary mirrors

[Bruce Swayze <swayze@europa.com>]

On Sat, 13 Sep 1997, Ken Lowther wrote:

>> It is indeed possible to have the best of both worlds.  You can enjoy an
>> all-around instrument that will give you the best planetary views as well
>> as the deep sky splendors and richer field views.  Man!  Is this hobby
>> getting good or what?  
>> 
>
>When using these high powers on sort focal ratio scopes, are you using
>coma correctors, or is the image still far enough from the edge that off
>axis coma isn't a factor?
>
>Ken Lowther  

Some of the people were using Televue's Paracorr, but I don't have one yet.
 But I like Nagler eyepieces because they are already corrected for use in
fast focal ratio instruments while still working just as well in longer
ones.  And they give such incredibly good contrast, too.  So I find that
even when you use them in a barlow in a short focus instrument, the views
are excellent.  

At higher powers, you are only examining a very small portion of the image
produced by the primary mirror, and it's right in the middle of the field.
So you are indeed far enough from the edge, nearly on-axis.  

Best regards,


"*-.,_,.-*"`"*-.,_,.-*"`"*-.,_,.-*"`"*-.,_,.-*"`"*-.,_,.-*"`"*-.,_,.-*"`"*-
Bruce Swayze
swayze@europa.com
http://www.europa.com/~swayze    Swayze Optical Home Page 
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