Re: [APML] A Fresh Lens Recommendation Thread

["Mike Cook, AF9Y" <mwcook@concentric.net>]

You might be interested in this approach if you haven't already seen it:

http://www.galaxyimages.com/focus.html

Of course with a CCD, only the center FOV of the lens would be used so
the performance would be even more impressive.


Mike


>From:           	stephen pitt <lthuedk@pe.net>
> 
> > This might be an ideal lens for use with an ABG CCD like the ST-2000.  I wonder
> > if RoboFocus could be adapted to drive it.
> 
> I don't know.  The focus ring is ~2.5" in dia, located in the center of
> the lens, which is 9.5" long.  I too would like very much to attach a
> CCD camera to this optic.  You probably noticed slightly elongated stars
> at the top of the corner shots, but the degree is rediculously small.
> 
> While no correction in a camera lens can be perfect, this SD has very
> low chromatic aberration-about what one would expect in a very good ED.
> 
> I shoot at Joshua Tree, where the skies are fairly dark.  As I said
> elsewhere, the lens will vignette with other films of less contrast and
> broader value range, especially when clarity is down.  But its never
> objectionably bad.  On a bad night, I'm sure there would be some
> vignetting with the EII at f2.8.  Unfortunately, I made no notation to
> that effect on the sample night.  Clearly, it was a good night.
> 
> Stephen
> 
> 
> > 
> > Mike Cook
> > AF9Y
> > 
> > Date sent:              Tue, 17 Dec 2002 14:42:17 -0800
> > From:                   stephen pitt <lthuedk@pe.net>
> > To:                     astro-photo@seds.org
> > Subject:                Re: [APML] A Fresh Lens Recommendation Thread
> > Send reply to:          astro-photo@seds.org
> > 
> > > Hi Mike, sure:
> > >
> > > http://www.light-to-dark.com/corners
> > >
> > > >From the 2700 dpi image.  Stephen
> > >
> > > "Mike Cook, AF9Y" wrote:
> > > >
> > > > Stephen,
> > > >
> > > >     That looks quite impressive, especially if it was taken at F/2.8.
> > > > Could you show a 1:1 crop of  the corners to give us an idea of
> > > > how good it really is?
> > > >
> > > > Mike Cook
> > > > AF9Y
> > > >
> > > > Date sent:              Tue, 17 Dec 2002 10:26:13 -0800
> > > > From:                   Stephen Pitt <lthuedk@pe.net>
> > > > To:                     apml <astro-photo@seds.org>
> > > > Subject:                [APML] A Fresh Lens Recommendation Thread
> > > > Send reply to:          astro-photo@seds.org
> > > >
> > > > > In my previous post, I recommended the Tokina 2.8 SD.  Here is a
> > > > > positive taken with it:
> > > > >
> > > > > http://www.light-to-dark.com/EII
> > > > >
> > > > > When viewed over a lightbox, the stars are perfectly pin pointed.
> > > > >
> > > > > Stephen
> > > > >
> > > > >
> > > > > --  APML Archives at <http://astro.umsystem.edu/apml/>  ---
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> > > > >
> > > >
> > > > Mike Cook, AF9Y
> > > > http://www.af9y.com
> > > > mwcook@cris.com
> > > >
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> > 
> > Mike Cook, AF9Y
> > http://www.af9y.com
> > mwcook@cris.com
> > 
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> 


Mike Cook, AF9Y
http://www.af9y.com
mwcook@cris.com





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