RE: [APML] Focusing OM-1 - but what about the Nikon F2?

["Richard Klappal" <klappal@xnet.com>]

An appropriate magnifier is good since there is little movement when close
to focus, but I don't have one.

The eye's ability to focus on the star is reduced/eliminated when using the
clear screen. Even out-of-focus stars will appear as points. Stability
relative to the cross-hairs is the same as being focused on the plane of a
'knife-edge'.

-----Original Message-----
From: astro-photo-bounces@seds.org
[mailto:astro-photo-bounces@seds.org]On Behalf Of Stuart Heggie
Sent: Sunday, 28 November, 2004 05:58
To: Discussion of Film Astrophotography
Subject: Re: [APML] Focusing OM-1 - but what about the Nikon F2?


Richard, thanks! I have the B screen for the F2 which has the cross-hairs.
I've tried it on the
moon and it has done a good job. I still think that it must be more prone to
doubt due to my eye's
participation but your results speak volumes.
Stuart
----- Original Message -----
From: "Richard Klappal" <klappal@xnet.com>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Saturday, November 27, 2004 11:24 PM
Subject: RE: [APML] Focusing OM-1 - but what about the Nikon F2?


> Find, if they're still available, the F2's
astrophotography/microphotography
> focusing screen. My systems are Canon, which use a double crosshair on a
> clear glass field surrounded by a fine matte; Nikon had one that was very
> similar or the same.
>
> Using knife-edge technique, focus on a bright star. (Align star with
> cross-hairs; move your eye back-and-forth across the field of view.  If
the
> star moves in relation to the cross-hair, adjust focus. Repeat until star
is
> stable relative to cross-hair. The star's image is then focused in the
same
> plane as the cross-hairs.)
>
> -----Original Message-----
> From: astro-photo-bounces@seds.org
> [mailto:astro-photo-bounces@seds.org]On Behalf Of Stuart Heggie
> Sent: Saturday, 27 November, 2004 21:45
> To: Discussion of Film Astrophotography
> Subject: Re: [APML] Focusing OM-1 - but what about the Nikon F2?
>
>
> Duncan, I have read all of Jerry's writings on this topic (and most on
other
> topics). I am left
> with the impression that for my camera lenses I can use the Hartmann Mask
> approach with a
> winter/summer calibration which I have done. For my scope, I want
something
> real-time and
> repeatable and he seems to be firmly in the KEF camp. Thanks!
> Stuart
> ----- Original Message -----
> From: "Duncan Munro" <dmunro@sfu.ca>
> To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
> Sent: Saturday, November 27, 2004 2:13 PM
> Subject: Re: [APML] Focusing OM-1 - but what about the Nikon F2?
>
>
> > Hi. It turns out that Jerry Lodriguss has a whole series of articles
> > discussing different methods of focusing:
> >
> > http://www.astropix.com/HTML/I_ASTROP/TOC_AP.HTM
> >
> >
> > makes for good reading.
> >
> >
> > cheers
> >
> > Duncan
> >
> > Stuart Heggie wrote:
> >
> > >Hey everyone - I want to say THANKS for the dialogue and the friendly
> banter too. The focus
> > >challenge of a system seems to rise exponentially as f-ratio goes down.
> My f/4 newtonian and my
> > >f3.5 long lens are really tough to get focused well.
> > >
> > >I am going to go with a KEF. If this list serves no other purpose
(beyond
> the pure pleasure of
> so
> > >many great images) it would be in getting to skip a lot of hassle and
> jump to a reliable answer
> > >fast.
> > >
> > >Thanks!!!
> > >Stuart
> > >
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> > >
> > >
> > >
> > >
> > >
> >
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