Re: [APML] Hybrid approach: First light results Pentax 6x7 Lens useonCCD camera with filter wheel/focuser

["Richard Crisp" <rdcrisp@earthlink.net>]

Actually for the Veil, I like Ha, [OIII] AND [SII}

here are a few examples:

http://www.narrowbandimaging.com/pickering1_page.htm

http://www.narrowbandimaging.com/veil_nebula_region_page.htm

http://www.narrowbandimaging.com/ngc6992_network_nebula_in_ha_page.htm


I do have a 90mm f/2.8 lens but I am going to hold off using it until I work
out the bugs with the 150mm. If I get good results with them both, I may buy
another lens, perhaps a 200mm or so.

I was planning to put the push-pull screws into the mounting flange last
night but I was simply exhausted from too many sleep deprived nights in a
row. Ahh, the joys of mixing astro and a regular day-job :-)



----- Original Message ----- 
From: "George Anderson" <georgea@cam.org>
To: "Richard Crisp" <rdcrisp@earthlink.net>; "Discussion of Film
Astrophotography" <astro-photo@seds.org>
Sent: Thursday, August 05, 2004 8:47 PM
Subject: Re: [APML] Hybrid approach: First light results Pentax 6x7 Lens use
onCCD camera with filter wheel/focuser


> Very nice and interesting results.
> I am envious of what you are able to capture in 10 minutes with HA
> filtering.
> How long before you put an 80mm or wider lens on the camera?
> I was under the impression that the veil was best with an OIII filter as
> opposed to HA. You should (if I am correct) get a stunning shot of the
> veil with the OIII.
>
> George Anderson
> Montreal Canada
>
> Clear skies and good health
>
> > Richard Crisp wrote:
> >
> > I have been experimenting with a homemade adaptor to permit Medium
> > Format
> > (6x7) Pentax camera lenses to be used with my Astronomical CCD
> > cameras. The
> > adaptor also features support for a color filter wheel and digital
> > focuser.
> >
> > One of the interesting properties of the medium format lenses is their
> > long
> > back focus. That permits me to easily add a color filter wheel and an
> > inline
> > digital focuser. If I were to use a lens for a 35mm camera I would
> > have
> > significantly less back focus and would probably be unable to use the
> > focuser.
> >
> > The other interesting thing about the medium format sized lenses is
> > that I
> > am using only a small part of the "sweet spot" in the center of the
> > FOV. I
> > am thinking that may permit me to still take good images without
> > having the
> > world's most expensive optics etc.....
> >
> > I completed the initial configuration of the adaptor late Sunday
> > evening,
> > Aug 1. Of course as luck would have it I was clouded out at home. The
> > next
> > two nights also featured significant cloud cover. Last night, however,
> > I had
> > a break in the clouds long enough to permit me to take a few test
> > exposures with the
> > 150mm Takumar f/2.8 lens I initially used.
> >
> > Initial results show elongated stars in the lower right corner of each
> > image. Furthermore there is some defocusing in that part of the image.
> > This
> > all points to a tilt of the lens axis relative to the optical axis. My
> > next
> > move will be to add a tilt adjustment (push pull screws) to
> > hopefully permit that to be "tuned out".
> >
> > In interest of documenting what I have done, I have prepared a web
> > page that
> > shows pictures of the adaptor in action, as well as test images. Some
> > are
> > terrestrial (the first ones) and the ones from last night. For indoor
> > shooting under normal room lighting, I was using an [OIII] filter with
> > 30
> > second exposures. The indoor images are not dark subtracted or flat
> > fielded.
> > The astro images were dark subtracted but not flat fielded.
> >
> > Comments welcome.
> >
> > http://www.narrowbandimaging.com/pentax_6x7_lens_adaptor_page.htm
> >
> >     ---------------------------------------------------------------
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> > Astro-Photo@seds.org
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