Telescopes and cameras?

[MrKickalot]

Has anyone ever attached their camera(DSLR) to a telescope? I was talking to the guy at Ritz camera and he all but wasted my time. He was telling me what it took to do it but of course he had nothing to actually show me. I really think that I would enjoy taking pictures of the stars and moon and stuff like that but I am a little iffy when it comes to actually buying everything needed without some sucess stories!! A picture or artical on attaching the camera to the telescope would be great!!

Thanks all!

Jason

[sparty314]

Jason,

I have firsthand experience only with Meade telescopes and my Canon film EOS cameras and also my 10D. Copying directly from Meade: (http://www.meade.com/catalog/etx/etx_accy.html)

The basic means of photography through any ETX Astro Telescope or Spotting Scope, the T-Adapter threads to the rear cell of the telescope, followed by a T-mount appropriate to the user's brand of 35mm camera. In this way the camera body is rigidly coupled to the telescope's optical system, which in effect becomes the camera's lens.

I purchased the T-Adapter and T-mount (from memory, about $40 total) and it all works just as promised. Realize, however, that the telescope is usually a *very* slow lens and you will (of course) have to manually (and sometimes with great difficulty) focus.

Someone can correct me if I'm wrong, but the method of photography described above is called prime focus photography--that is, the telescope itself functions as the camera's prime lens. Using that method, you will be able to capture great images of the Moon (and Sun with the correct filters!), and awesome terestial telephoto images. It is also possible to capture deep sky objects using that method. However, deep sky objects (nebula, galaxies, star clusters, etc.) are *much* fainter than the Moon or Sun, and so they require very long exposures--on the order of several minutes. So, the camera/telescope must be guided so you do not see the blurring (or star trails) caused my the sky's aparant motion (actually, the Earth's rotation). That is where it gets tricky! The telescope needs to be motorized and polar alligned or else it just won't work! (Actually, you can buy a field de-rotator to use on an altazimuthly mounted scope, but that introduces even more complexity!) So, in order to get great images of deep sky objects, you need a motorized telescope, a sturdy tripod for it, and some way of fine tuning the guiding of the telescope (usually off-axis guiders and retical eyepieces).

As you can see, taking pictures of the Moon and Sun is much easier and less expensive than taking quality pictures of stars and other deep sky objects.

Another alternative is to use a relatively wide angle lens on your camera, set it on a tripod and experiment taking several minute long bulb photos. You can really get so interesting star trail images that way, and it eliminates the need for a telescope.

Finally, I've not mentioned photographing planets yet. The reason is because even using a telescope and the prime focus method, the planets are just too small (angularly, at least) to be able to image in that way. For them, you need to insert an eyepiece inbetween the camera and the telescope. This method is called eyepiece project. Doing this requires another adapter and it causes the optical system to be ever slower (~f/120). This method requires a lot of patients, but can be very rewarding as well.

I know this is a Canon DSLR forum, but I must suggest that you investigate a current trend in amateur astrophotography--webcams. Basically, the idea is that you throw away the lens of the webcam and hook up the (now exposed CCD) directly to the telescope (prime focus). Since the webcam's CCD is really small you get a huge manification/crop factor (call it whatever you want), so eyepiece projection is really not necessary. You capture a minute long video that has several hundred (low quality frames). Then, back inside, you can use freeware to automatically sort, align, and stack all of the images to produce a final image that rivals some of the best amateur images from just a few years ago.

Actually, Meade now offers a product designed to take a lot of the fiddling out of this entire process. It is called the Lunar Planetary Imager (http://www.meade.com/autostar/lpi.html), and I recommend that you at least check it out.

[mattchase]

This is a question with a looooong answer. I don't have any pictures handy, can take some later on, but can at least tell you what you will need.

The first thing you need to decide is if you want a Refractor or a Cassegrain style telescope. Typically, refractors are better performers for astrophotography, having faster apertures and sharper optics, but they are also bigger in size and more expensive. Cassegrains are slower (as in apertures), but usually have longer focal lengths and are much smaller in size. In the end, you could spend just as much on either system.

So now you need a decent telescope on a good solid mount. The $200 special you see at Walmart that has a motor drive built in is not likely to work, as the tracking probably won't be smooth or accurate enough, and the mount may not even be able to support the weight of the camera. The tripod and mount / motor drive are actually more important than the telescope, and often will cost more than the telescope too. I spent about $650 on my setup, and while it works, it isn't the best. The motor drive tracks ok, but the controls aren't the most precise, and the scope isn't as sharp as could be. But given the price, I am pretty happy (the higher end alternatives were about $2500-$3500 for scope and mount). You could probably do this for about $450 if you went with a smaller scope than I did, and still get the same tripod / motor drive, but I wouldn't recommend any less of a drive than mine as it just won't give the results that you are going to want. Mine was purchased from Orion Telescopes, www.telescope.com . The scope is the SkyView Pro 120mm EQ.
- Sidenote: If I were to do it over again, I would probably get the SkyView Pro 120St or SkyView Pro 100mm EQ. This is because these two scopes are both shorter focal length with a faster aperture. When you are doing astrophotography, having the longest lens isn't always the best thing, and I have decided for my tastes a shorter focal length would have been better. The shorter length will show more of the sky, so for photographing constelations and star clusters in general, you will have better results. The faster aperture is a huge plus, because even just 1 fstop could mean the difference between a doing 15 minute instead of a 30 minute exposure (or 30 minutes instead of 60!). And those times are not uncommon. Another reason is both of these scopes are much smaller in both size and weight, meaning less to carry, and less to balance on the tripod / motor drive.

You will need a t-mount adapter for your camera. This is a 2 peice (sometimes 3) thing that has a standard Canon lens mount on one end, and an open hole in the other end. A 2nd peice screws into that hole and protrudes out, which then goes into the telescope eyepeice holder. There are a couple of different kinds, one is meant for only attaching your camera to the telescope, while another has extra room in it for you to place an eyepiece inside before attaching the camera to the telescope, which will give you more magnification. The prior of the two you should be able to find for $20-$30, the latter I am not sure what it costs.

You will need the cable release for your camera, unless you keep all your exposures to less than 30 seconds (based on the 10D specs). You can get a lot done in 30 seconds, but if you are lucky enough to be in an area where it still gets really dark, you are going to want to go for many minutes to capture all the constalations and galaxies and whatnot. Cable release is about $50 ($130 for the better timer version).

There are any number of accessories you might want, such as star charts, a hartmans mask, a dew sheild, etc. These things you will have to discover on your own. I would highly recommend making a hartmans mask, as it will help you focus, which is one of the most difficult things to do through a scope without some form of aid. See instructions here for making one http://www.weasner.com/etx/astrophotography/focus-aid.html .

And finally, here is what I recommend to anyone thinking about taking up astrophotography. If you don't already own a telescope, don't go buy one just yet. Go get this device http://www.telescope.com/shopping/product/detailmain.jsp?itemID=296&itemType=PRODUCT&iMainCat=6&iSubCat=24&iProductID=296 , which will give you a taste for doing this type of work without the expense. It is a compact EQ mount with a head on it for a camera to mount on, and will work with most medium sized lenses (my 70-200 2.8 lens is a tad heavy, but would probably work with some extra counterweights). Buy the EQ-1M motor drive as well, and for $100 you have a ready to go, fits in your backpack astrophotography platform. I keep this item in my car, so that I can pull it out at anytime, and for wide field work (17mm-50mm) it works great. One modification I made was to attach the EQ mount to my Bogen tripod, as the threads on the base of the EQ mount are the same size. This gives you a more stable tripod, and also gets you up off the ground (as the unit only comes with about 10" long "table top" lengs).

I will go take some pictures of my stuff later today, and post them in this thread. In parting, a shot of the Milky Way I did using my 10D and (I think) 17-35mm lens, piggybacked on my telesocope (piggyback = mounting the camera and lens on top of the scope, using it to track but not using the scope as the lens). http://www.matthewchase.com/astrophotos/2_22_03/img_4563.htm , tracking for about 8 minutes.

[ifurlong]

its easy! you just need the adapter that fits EF bodies, I bought one from telescope city and it works fine, its fun, you can use it as a really long tele and the usual night sky stuff

[iwatkins]

Great thread. Full of useful info.

I don't have a telescope but have always been interested myself in astrophotography.

Thanks Matt for the info. on the eq. mount. I may well try that. I love the idea of setting up the camera to track the sky and leave the shutter open for minutes without getting star trails.

Cheers

Ian

[sparty314]

Matt's suggestion about the equitorial mount is a good one. Let me offer another:

If you already have a motorized telescope, consider buying a piggyback mount/adapter for it. They basically are sort of like a hose clamp with a camera screw on it that you can use to have the scope guide your camera.

Many of the best astro-images I've taken have been done this way. Super-precise polar alignment was not necessary because I was using a 28mm lens as opposed to something like 1250mm. In fact, I usually just use my old (pre-computeried control) Meade ETX-90 with its clockdrive for this application.

[GenEOS]

I was sucked into the Mars excitement for purchasing a telescope with my wife, who is the astronomy buff. I believe we purchased the ETX-125 from the discovery store. I had high hopes of using it with my D60.

It is basically an 1800mm f16 lens. Do the math to get what the 10D equivelant is. I will list the encountered problems.

1.) The T-Adapter and build quality of the scope do not go well with the weight of a D-60, 10D etc. Even stripped down to camera body only. The threaded portion that is molded into the scope body moved and when I put the t-adapter on and used it a few times, the t-adapter would not unscrew off. Did this because of the weight and leverage the items added to the scope produced. I now have this piece permanantly attached to the scope.

2.) The weight of the camera requires a counter weight for the scopes motors to be able to move it. The scope, with camera attached needs to be balanced. I had to fabricate a counter weight from plans I saw on the net.

3.) Foccusing the scope is very difficult. I think this has to do with the build quality of the scope. It is a nice scope for the money. A comperable scope, built nicer would cost a whole lot more.

4.) What you are able to see in the scope is not anywhere near what you will see through the camera and the f-stop of the scope sucks.

I did hoever take a nice picture of 1/2 of a brick on my neighbors house across the street at a higher asa.

I found the focusing problem to be the biggest bummer of all. On the next scope we buy, I am going to do way more research on the focussing mechanism.

After toying around with mars shots, which I did get, but nothing like the pictures on the scopes box, I started asking questions to other scope photographers.

I found that most use a camera attachment that mounts to the eyepiece. Most use a small digital point-n-shoot and get pretty good results.

Another person did a little non standard rigging and put a 20x eyepice in the tube of the t-adapter. I found this worked, but focussing was still a big problem.

For the money we spent on the scope, eye pieces (we bought some very expensive Tele-View eyepieces) and cases to put it all in, I could have bought another L glass lens and gotten far better results with it.

It was truley a learning experience and we did get a darn nice scope. I am not slamming the Meade scope at all. It is a very nice piece of equipment and will do a lot of stuff we don't even now how to do yet. What I am saying, is it is not an excellent piece of photo equipment, but you will be able to do some things with it.

Do a lot of research before you drop the bucks. Ask yourself if the few shots you are going to get, are enough to justify the scope and costs. For us it was fun and we had the money to play with it. We came out of it with a nice scope for looking at stars and learned a lot.

That's my 2 cents worth...good luck.

[mattchase]

Here is a shot of the t-mount. The two parts in the lower half of the image are what you need, they are the Canon EOS compatible mount, and the telescope eyepiece adapter. The eyepiece adapter screws into the mount, and you then put the protruding end into the telescope where you would normally put an eyepiece.

http://www.matthewchase.com/digitaldingus/samplephotos/tmount.jpg

The larger item in the background is also an eyepiece adapter which also screws into the mount, but the extra barrel size will accept a normal telescope eyepiece, which lets you get higher magnifications. The tradeoff is sharpness and aperture, and it is a pretty big tradeoff (I never use this item).

[DaveG]

If you speak to an amateur astonomer you'll feel a bit like you are in the Twilight Zone when you discuss lenses. Photographer's will speak about focal lengths and then apertures. Astromomers will rarely mention the focal length of their telescope and then only as an after thought, since a lot of the relative magnification is done with various eyepieces of equally various powers.

But the main weirdness is when they talk about aperture. When we talk about aperture it's almost always in f-stops. The aperture of my 300 mm lens is f2.8. When astonomers talk about aperture they will talk about the width of the front element as in my 300 has an aperture of 120 mm.

It took me awhile to figure out WHAT they were talking about and it finally clicked when one of them proudly boasted that the aperture of his 300 mm Nikkor was 75 mm. I infered that he took two mm off of the filter size of his lens (77 mm) to get that number, so I (with joy in my heart) mentioned the 120 mm "aperture" of mine - as I too took off 2 mm for the filter. Yes as silly as this was, we took 'em out and measured them and I'm not talking about lenses.

In any case in astronomy aperture is critical since more aperture/speed the lens has, the more light will be gathered. Then after more light has been gathered, dim objects will show up in the photo for the given ISO and shutterspeed.

[GenEOS]

DaveG wrote:
If you speak to an amateur astonomer you'll feel a bit like you are in the Twilight Zone when you discuss lenses. Photographer's will speak about focal lengths and then apertures. Astromomers will rarely mention the focal length of their telescope and then only as an after thought, since a lot of the relative magnification is done with various eyepieces of equally various powers.


I am a true amateur when it comes to telescopes and the multitude of set-ups. I did learn to get the power of your set-up, you divide the focal length by the eye-piece size. Thus an 1800mm focal length scope with a 10mm eye piece yields a 180x power. Not a lot when you are looking at mars.....even at its closest.

I do howver like the fact that all the eye-pieces of various manufacturers are standardized sizes.

On another note, the t-adapter shown above in this post is one that mounts to the eyepiece hole of a scope, on the meade ETX scopes, this t-adapter mounts to the rear of the scope. You flip a knob to swap between it and the eye-piece.