Re: [APML] need advice on camera mount

["Stuart Heggie" <Stuart.J.Heggie@sympatico.ca>]

Jerry, your last comment made me think of an idea. Wei-Hao, if you were to
use the set-up in your picture but find a way to use Losmandy's DCM2 which
has a lateral movement as well as up and down, you could swing the rear end
of the camera back and forth on the DCM2 maybe up to 15 degrees and
sometimes the objective would be straight through the ring and sometimes at
an angle but it might work fine. That way you can mount the dovetail on your
scope the traditional way (very strong) and still pivot the camera on top.

Stuart
----- Original Message ----- 
From: "Jerry Lodriguss" <lists3@astropix.com>
To: "Wei-Hao Wang" <whwang@gmail.com>; "Discussion of Film Astrophotography"
<astro-photo@seds.org>
Sent: Wednesday, March 23, 2005 11:19 PM
Subject: Re: [APML] need advice on camera mount


> Hi Wei-Hao,
>
> Personally, I believe in over-mounting everything.  It's hard to tell
about
> the Takahashi Guiding Mount TGM-2 because I can't get a sense of scale
from
> the picture.
>
> I use a lot of Gitzo stuff, and I think it's great, but I wouldn't ask it
> to do what you want to do... just my 2 cents.
>
> If you do end up going down this road, make sure you mount the
> camera/rings/plate to whatever you put it on, with more than one screw,
> because it will pivot with just one, probably during an exposure.
>
> Also, one screw at the bottom of the mount, whichever you choose, is
likely
> to pivot also.
>
> If you were going to shoot with a digital camera, and limit your exposures
> to 3 to 5 minutes, you might get away with this kind of rig. If you're
> going to shoot film and expose for 30 to 60 minutes, I would doubt it will
> be consistently successful. You may get away with it in certain
> orientations, but not in others.
>
> I don't have any personal experience with the Arca-Swiss monoball head,
but
> it's rated capacity is a lot more than the weight of what you want to put
> on it, so that would be in its favor. The problem is that these things are
> generally used in a studio and not for 30 to 60 minute exposures on a
scope
> tracking the stars. Even if the monoball head was rock solid, if you
> conventionally mount it with just one screw on the bottom and one on the
> top, I would be very afraid of something pivoting and moving during the
> exposure.
>
> When I shoot with a 300/2.8 and 400/2.8 on top of my 130EDT f/8 refractor,
> I have them mounted on a 3/8 inch thick aluminum plate that has one hole
at
> the back end, and a slot on the sky end. This gives me a couple of degrees
> of aiming flexibility in declination and I can lock it down rock solid,
but
> no where near the 15 degrees you seek.
>
> Jerry
>
>
> Photoshop for Astrophotographers
> http://www.astropix.com/PFA/PFA.HTM
>
>
>
>
>
>
>
>
>
>
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