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Re: [APML] Framing shots - was New North American Nebula
Hi Alan,
I don't have a goto mount, or digital setting circles either.
The way to frame nebulae that you can't see is with the star patterns
around it.
I Xeroxx a copy of Uranometria, and I have an overlay I place on the chart
that frames the object at the exact field of whatever focal length I am
going to use. I mark the frame on the copy of the chart at the orientation
I want. I then cut the copy of the chart down to 4 x 5 inches.
In the field, I use a small 4 x 5 battery powered light box with a lot of
red cellophane over it, so that it is very dim. I have a clear sheet of
acetate over the top of the light box that is taped down on two sides. This
allows me to slip the chart under it which protects it from dew, and allows
it to be removed and changed for the next object I wish to photograph.
I use a Nikon F3 with a DW-4 6x magnifier on the camera that is extremely
helpful in framing objects that I can't see.
Since the view in the DW-4 is reversed, I simply flip the chart over upside
down in the lightbox.
I either star hop to the object, or dial it in with the manual setting
circles for the really faint stuff.
Once I'm there, I double check the framing in the camera with the DW-4 and
the light box.
I'm farsighted, but I need reading glasses to see the chart. So I have a
pair of those half-glasses. I slide them down on my nose, and by careful
arrangement of the light box near the eyepiece of the DW-4, I can look
through the DW-4 and simply shift my gaze to the light box to compare star
patterns without even having to move my head.
Keeping the light box as dim as possible, but still able to see the stars,
is important to keep your dark adaption and see the faintest stars on the
ground glass through the DW-4.
This method works down to about 300mm focal length. Anything shorter than
that is too large for the chart to fit in the lightbox.
Also, with my AP 130 EDT refractor and 300/2.8, the visual limiting
magnitude of the stars in the scope on the ground glass is almost exactly
the same as the limiting magnitude of the stars in Uranometria.
Anyway, the secret is to match the star patterns.
Jerry
At 09:28 AM 9/9/2002 -0400, you wrote:
>Hi Rob and all,
>
>Not having a goto mount, nor digital setting circles, I find that framing
>objects I can't see to be somewhat of a gamble. I pull the camera off of
>the scope and stick a 26mm eye-peice inside of a tube I rigged up to be
>parfocal with the camera to frame shots. The problem is that when I try to
>match up the field of view with the little squiggly lines showing a nebula
>on my sky charts, I don't always get it right.
>
>If any one has suggestions on better ways to frame shots I would like to
>hear of them.
>
>Thanks,
>Alan
>
>Original Message:
>-----------------
>From: Robert Gendler robgendler@worldnet.att.net
>Date: Sun, 8 Sep 2002 10:42:08 -0400
>To: astro-photo@seds.org
>Subject: Re: [APML] New North American Nebula
>
>
>Hi Alan,
>I like the rich, deep color and the overall processing.
>Its a very pleasing image. My only comment would be
>the composition. The field would look more symmetric
>shifted slightly to the left. All in all a nice image.
>Rob Gendler
>Email: robgendler@att.net
>Web site: http://www.robgendlerastropics.com/
>----- Original Message -----
>From: "Alan Brent Jordan" <aljordan@gwi.net>
>To: <astro-photo@seds.org>
>Sent: Friday, September 07, 2001 5:11 PM
>Subject: [APML] New North American Nebula
>
>
> > Hello,
> >
> > While this one won't break any resolution records, I put up a new photo
> > of the North American and Pelican nebulae that I took this past Thursday
> > night. The shot is a single 90 minute exposure on Kodak Supra 400 taken
> > with a Takahashi FS-102 at F6. This is the first nebula shot I have
> > taken using a Hutech IDAS LPS filter. I was happy to see that the
> > Hutech filter helped reduce the aparent graininess of the 400 speed film
> > quite a bit and allowed for a much denser image on the negative. Curves
> > were adjusted using photoshop.
> >
> > http://home.gwi.net/~aljordan/astro/naNeb.html
> >
> > Comments and criticisms are welcome.
> >
> > Alan
> >
> > --
> > Alan Jordan
> > aljordan@gwi.net
> > http://www.gwi.net/~aljordan/astro
> >
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