Re: [APML]: varimagnifier/FOCUSING

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

I'll mention this because it works so well for me. With a bright screen,
put a small (1/2" long) square of frosted scotch 
tape on the BOTTOM of the focus screen. The image will project upon it.
Then you still have the framing and 
composition advantages of a bright screen, plus your eye wants to focus on
the correct part of the screen.
I'm using a M screen (completely clear) for my Nikon. The dim fuzzies are
just that behind the tape, but it's exactly what they
look like in the D screen which is considered the best for focusing astro
images. So I slew the image out from under the tape to get a good, bright
look at it and make sure it's the right little fuzzie. While I'm off-center
with the object, I'll find about a 3rd mag star and put it under the tape.
Then I'll put some magnification on it for critical focusing. Then I
re-center the object for the correct composition, and start my guidestar
search.
This works good for me, but I've still got good vision. Your milage may
vary.

Bobby Middleton




>From Mark:
 
> >I'm sorry, but I agree with Chris here.  One cannot get consistent
perfect 
> >focus with any system that lets your eye be part of the focusing
process. 
> >Your brain will always adjust your eye muscles to bring the view to
focus in 
> >your head, even if it is a little off on the film plane.

>From Chris:

I have to agree.  The problem is made worse, the brighter the view screen. 
>  I get excellent views through the finder with an Olympus 1-12 focus
screen, 
> but I can adjust for a wide range of focus with this screen using my
eyes.
>    The only way that I have been able to get good focus through the
finder is 
> by doing it during twilight.  For some reason, I am best able to focus my

> camera with only the viewscreen if I find a bright star during twilight, 
> focus on it and lock the scope at that point.  Whenever I have done this
and 
> checked the focus later with the Sure Sharp, my focus has been dead on.
>    Clear skies!
>                MK
> 
> http://www3.sympatico.ca/mark.kaye/