Re: [APML]: varimagnifier/FOCUSING

["Bobby Middleton" <bobbym@webwide.net>]

Bobby said:
> 
> > Yes, that is why the B&K focuser and the verimagnifyer are so helpful
for
> > the Olympus camera lines. But a bright screen in a camera
> > without a removable prism is still prone to mis-focusing, same as it is
for
> > a camera with the prism out. Unless you know for sure you are
projecting on
> > the bottom of the screen,  then you can mis-judge the focus. That is
where
> > the tape trick might be of some value.


Philip said:

> > This works very well with the Beattie Intenscreen. I think you
mentioned 
> that you use a clear screen. Does this mean that it is *completely*
clear? 
> If so, I don't understand how it can be used for focusing - I imagine
that
> there must some degree of frosting on the base to allow the focus point
to 
> be reached?


I'm using a small square of frosted scoth tape on the bottom of that
*completely* clear M screen. Without it, it 
is impossible to judge focus. With the tape, I have a small central portion
of the screen that I
put a star onto for critical focusing with a 12x magnifying EP. 
The reason I prefer the M screen is for its much higher brightness. I frame
& compose with a 8x
loupe I altered to fit down onto the screen. This setup gives views as
bright as an eyepiece. Much brighter than a D screen.
 So  I have the advantages of a bright clear screen (except for the small
center piece of tape) and still 
have a way to project an image onto the correct focal plane.       

Bobby Middleton


astropics at: http://www.webwide.net/~bobbym/astro1.htm