Re: [APML] A Fresh Lens Recommendation Thread

[stephen pitt <lthuedk@pe.net>]

"Mike Cook, AF9Y" wrote:
> 
> Wow!  I'm very impressed.  I've tried a Nikon 300 ED F/2.8 and never got close to
> that performance.  A few additional questions:
> 
> 1) How did you focus it?

With a 6x finder scope atop the DW4, all atop the F3, using a defocused
star method.
> 
> 2) Did you have any additional filtering in line (UV or Sky)?

No filter.
> 
> 3) What body did it mate to (Nikon or Cannon)?

Nikon F3
> 
> 4) How much?

$2200 new.
> 
> 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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