Telescopes and Cameras

Night photography is difficult, from what I have read. So I would
imagine this is even more difficult, having a camera mounted on a
telescope and taking photo graphs that way. I would think that the
exposure times are too long to get useful photos of moving objects no?
Only planets and stars could be the subject right?

I was involved in a discussion somewhere else about this subject, and
thought I would check with people a little more knowledgable than
myself.

"R.Schenck" wrote in message
om...
Night photography is difficult, from what I have read. So I would
imagine this is even more difficult, having a camera mounted on a
telescope and taking photo graphs that way. I would think that the
exposure times are too long to get useful photos of moving objects no?
what sort of moving subject would you want to photograph at night with a
telescope?
Only planets and stars could be the subject right?
and the moon... you probably could do some landscape stuff at night.
Using a telescope isn't real hard - you will need a "T-Mount" adaptor for
your telescope and camera. In my case, I have a Pentax K Mount camera, so I
get a K-Mount-T-Mount adaptor then a T-Mount extension tube for the scope.
You don't use an eyepiece lens in the telescope, and there is no lens in the
camera. Basically the main lens/mirror of the telescope becomes a long
telephoto for your camera. The aperture is relatively small so exposures are
normally quite long. A common size of small reflector telescope has a 900mm
focal length and a 100mm diameter so it is equivalent to using a 900mm lens
at F9. Depending on your camera, you can probably use your camera's inbuilt
light meter for the moon, but it will probably be pretty useless for stars &
planets, so experiment with various shutter times. Use a low speed film -
100 or less iso - for the finer grain. Slide film is a good option. You will
probably be surprised at the colours that come up of things that look hazy
white to your eye.
Some precautions - if you are photographing anything less bright than the
moon (ie planets/stars), you will need an equatorial mount for the telescope
and a tracking motor. Otherwise the amount the subject will move due to
rotation of the earth will cause blurring or streaking. If you are going to
point your scope at the sun, there is a special filter material you can get
that blocks out the majority of the light - this filter material goes in
front of the telescope. If you don't use it you will cook your camera (or
eye if you are dumb enough to look down it). There are filters you can get
that go at the eyepiece end, but they get very hot and are prone to failure.
Finally make sure you have a reflector telescope. Cheap refractor telescopes
suffer terribly from chromatic abberations.
If you want to get out of it on the cheap, you can try using an eyepiece
lens in the scope and a standard lens (eg 50mm) on your camera and
hand-holding the camera over the eyepiece. This will work reasonably well
for bright subjects such as the moon and some planets.
You can also use a telescope in the daytime for photographing terrestial
subjects - my father has a scope with a focal length of about 2m - a few
years back I took a photo of a spider in a tree - from about 100 yards.

I was involved in a discussion somewhere else about this subject, and
thought I would check with people a little more knowledgable than
myself.

R.Schenck wrote:

Night photography is difficult, from what I have read. So I would
imagine this is even more difficult, having a camera mounted on a
telescope and taking photo graphs that way. I would think that the
exposure times are too long to get useful photos of moving objects no?
Only planets and stars could be the subject right?


Mostly stars. Galaxies, if you don't mind counting groups of stars. A
few neubla, here and there, but you probably need the Hubble Telescope
to get the best pictures of them.


Then, of course, there's the moon. Some people get some pretty fine
pictures of it.


http://www.pbase.com/bret/image/34152890


But if the moon and the stars don't intrest you as photographic
subjects, then focusing on earthly subjects would be a better idea.


E

R.Schenck wrote:

Night photography is difficult, from what I have read. So I would
imagine this is even more difficult, having a camera mounted on a
telescope and taking photo graphs that way. I would think that the
exposure times are too long to get useful photos of moving objects no?
Only planets and stars could be the subject right?


Mostly stars. Galaxies, if you don't mind counting groups of stars. A
few neubla, here and there, but you probably need the Hubble Telescope
to get the best pictures of them.


Then, of course, there's the moon. Some people get some pretty fine
pictures of it.


http://www.pbase.com/bret/image/34152890


But if the moon and the stars don't intrest you as photographic
subjects, then focusing on earthly subjects would be a better idea.


E

Eldritch wrote:

Mostly stars. Galaxies, if you don't mind counting groups of stars.
A
few neubla, here and there, but you probably need the Hubble
Telescope
to get the best pictures of them.


Not quite.

A high-end scope plus some cooled CCD will do.
http://www.telescopes.cc/nebulae.htm

Eldritch wrote:

Mostly stars. Galaxies, if you don't mind counting groups of stars.
A
few neubla, here and there, but you probably need the Hubble
Telescope
to get the best pictures of them.


Not quite.

A high-end scope plus some cooled CCD will do.
http://www.telescopes.cc/nebulae.htm

(R.Schenck) wrote in message . com...

I was involved in a discussion somewhere else about this subject, and
thought I would check with people a little more knowledgable than
myself.

The responses were informative, but i want to emphasize that the
object is moving. Ok, see, this is stupid but, I was on web forum,
and some joker there is claiming that when he points his backyard
telescope to the big dipper, he is seeing all sorts of activty,
flitting lights and such, and is saying that this is a 'ufo gateway'
or some such bull. I was like, take some photos, it'll be difficult,
but he's saying these things are there very often, that there are lots
of them, and that they've been 'active' there for decades. So, would
it even be possible, with an introductory camera and a not
particularly impressive telescope?

You'd think that they guy would be willing to purchase a really good
telescope and a specific camera for this, but, alas, ufo-ers tend to
not be particularly rational. Anyway, I had been saying that it
should be possible, very difficult but possible. However, from
reading the posts, it looks like its not possible right?

And, yes, I would've thought that -other- professional astronomers
would've seen this too. I now this has actually ventured into the
realm of the weird and off topic, but I figured I could get a pretty
definitive answer from the people here.