Re: Telescope comming along...
- From: Tim Auton <tim.auton@xxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 22 Sep 2005 03:27:12 +0100
none <""gcain\"@(none)"> wrote:
[snip]
>I would like to be able to have the camera hooked up to the computer via
> a USB cable so I don't need to be anywhere near the telescope to use it.
>
>Most of the cameras Ive seen people use have been glorified WebCams. I
>can't see the image quality being anything above appalling from these
>though, am I wrong? 300K pixel resolution doesn't seem like it could
>give too good a picture when the image is so small and dark to start off
>with.
Webcams are the best thing for lunar/planetary imaging, where the
subject is bright and the limitation is generally seeing. The high
frame-rate of webcams lets you take hundreds or thousands of images
and select the best - the ones with minimal atmospheric distortion.
Stacking the 'cream of the crop' then removes the noise introduced by
the sensor. Webcams are poor for other targets though.
>Is it possible to hook a decent Digital SLR up to a telescope and is it
>worth while?
Yes and yes. The main limitation is the lack of IR sensitivity, even
far red like Ha is quite seriously attenuated by the filters (designed
for terrestrial photography) on the sensor. It's not a show-stopper
though, you can still take decent images with the filter in place.
Canon do a special version of the 20D (no internal IR filter and some
other tweaks) specifically for astro-imaging, the Canon 20Da.
Hutech sell pre-modified DSLRs and external filters to covert back to
terrestrial use:
http://www.sciencecenter.net/hutech/
You can remove the filter yourself (there are guides for various
models on the web), but I left the one in place on my 20D. I didn't
like the idea of taking my new £1100 camera to bits, at least not till
the guarantee has run out!
Tim
--
You are being watched. This gives you power.
.
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