Astrophotography Piggy Back help

[diegodog]

Hello All,

I have been searching and cannot find which seems to be a simple thing so I am obviously not searching for the correct thing. I would like to hook my camera up to the eyepiece on my telescope but cannot find the part. I took some of my first shots with the camera hooked up to the scope (no eyepiece) and they came out soft. I would like to capture what i am seeing in my eyepiece.

Can some one show me the correct piece to hook up my camera to my eyepieces.

Thanks!

[Woolburr]

You should be able to find a Canon T-Mount adapter or telescope specific adapter here. http://www.bhphotovideo.com/c/shop/3408/Camera_Adapters_Mounts.html

[PhotosGuy]

mounting a s5 to a telescope. (http://photography-on-the.net/forum/showthread.php?t=535426)

[E-K]

What kind of camera and what kind of telescope are you using?

e-k

[Marnault]

Without knowing what camera and scope you have it will be hard to give specific advice.

But I will assume you are using a Canon DSLR.


Now first off Piggyback photography is when you mount your camera with a lens on top of your telescope, generally for wide field astrophotography.

Attaching you camera directly to the telescope, using the scope as a lens, is called Prime Focus photography.

And finally, using your camera with a normal lens, looking through your eyepiece that is attached to the scope is called afocal photography.


It's also important to note each of these 3 methods require different methods to mount your camera, and each have their own level of difficulty. Piggyback being the easiest, afocal being the hardest, prime focus being much more challenging than piggybacking, but somewhat easier than afocal.

The reasoning for this is because of the increased focal length between the three methods, piggyback is usually with a focal length between circular fisheye to short telephoto. With prime focus your focal lenght is totaly dependant on your telescope, but even the smallest scope usualy has a focal lenght of at least 400mm, most are around 800-1500 though, but some go as high as 4000mm (im sure there are some that go higher but thats beound the scope of this discussion)

Afocal is quite differant, since you are magnifing the image from your telescope, so the actual focal lenght is much greater than normal. For example if your scope has a focal lenght of 1000mm, and you have a 20mm eye peice in there you will have a 50x magnification (1000/20=50). Now using a camera with a 30mm lens, looking through the eyepeice would give you an efective focal lenght of 1500mm (30*50=1500).

Now for taking images of the moon using such a long focal lenght isn't a major problem since your shutter speed will be quick enough that you shouldn't need very precises tracking if any at all.

But for any other object you will need to do longer exposures to properly resolve any detail and this is where long focal lenghts start to be a major problem. Once you get above 1000mm you need a pretty high end mount for precise tracking.



Now you mentioned that when shooting in prime focus your images were soft, this is most likley a focus issue. How did you attempt to acheive focus?

If you have a smaller scope, 600mm for example and trying to photograph the moon a good option would be a 2x barlow. This is something you place between the telescope and the camera when shooting in prime focus, it will double your focal lenght thus making the moon take up more of the frame. You can find 1.6x, 2x, 3x, 4x, & 5x barlows on most astronomical online stores. I personaly find a focal lenght of 1400-1600mm to be ideal to fill the frame with the moon.

[diegodog]

Without knowing what camera and scope you have it will be hard to give specific advice.

But I will assume you are using a Canon DSLR.

Using a canon xsi (also have wifeys 40D) and a Celestron c11 Cassegrain Also have the 6.3 focal reducer on the way

Now first off Piggyback photography is when you mount your camera with a lens on top of your telescope, generally for wide field astrophotography.

Yeah just learned that today. Sorry for the noob coming out in me.

Attaching you camera directly to the telescope, using the scope as a lens, is called Prime Focus photography.

More Noob

And finally, using your camera with a normal lens, looking through your eyepiece that is attached to the scope is called afocal photography.

More Nooooob


It's also important to note each of these 3 methods require different methods to mount your camera, and each have their own level of difficulty. Piggyback being the easiest, afocal being the hardest, prime focus being much more challenging than piggybacking, but somewhat easier than afocal.

Oh no. Prime Focus did not go to well. Will get some images up tonight. They came out "good" actually as good as I have seen around the net but no where near the crispness I want. I want to capture what I am seeing in my eyepice.

The reasoning for this is because of the increased focal length between the three methods, piggyback is usually with a focal length between circular fisheye to short telephoto. With prime focus your focal lenght is totaly dependant on your telescope, but even the smallest scope usualy has a focal lenght of at least 400mm, most are around 800-1500 though, but some go as high as 4000mm (im sure there are some that go higher but thats beound the scope of this discussion)

Afocal is quite differant, since you are magnifing the image from your telescope, so the actual focal lenght is much greater than normal. For example if your scope has a focal lenght of 1000mm, and you have a 20mm eye peice in there you will have a 50x magnification (1000/20=50). Now using a camera with a 30mm lens, looking through the eyepeice would give you an efective focal lenght of 1500mm (30*50=1500).

Now for taking images of the moon using such a long focal lenght isn't a major problem since your shutter speed will be quick enough that you shouldn't need very precises tracking if any at all.

But for any other object you will need to do longer exposures to properly resolve any detail and this is where long focal lenghts start to be a major problem. Once you get above 1000mm you need a pretty high end mount for precise tracking.

I have the cg-5 I think as far as tracking goes.

Now you mentioned that when shooting in prime focus your images were soft, this is most likley a focus issue. How did you attempt to acheive focus?

I attempted focus using the focus knob on my scope. Why do I have a feeling that is wrong. LOL

If you have a smaller scope, 600mm for example and trying to photograph the moon a good option would be a 2x barlow. This is something you place between the telescope and the camera when shooting in prime focus, it will double your focal lenght thus making the moon take up more of the frame. You can find 1.6x, 2x, 3x, 4x, & 5x barlows on most astronomical online stores. I personaly find a focal lenght of 1400-1600mm to be ideal to fill the frame with the moon.

I think my focal length is 2800. I am not sure I have seen the entire moon through the scope

[diegodog]

Also I am thinking this is the piece I need to attatch the camera to the eyepiece.

http://www.celestron.com/c2/product.php?CatID=50&ProdID=367

[Marnault]

Also I am thinking this is the piece I need to attatch the camera to the eyepiece.

http://www.celestron.com/c2/product.php?CatID=50&ProdID=367

Yup that's the right piece you need, assuming you already have a t-ring for you camera.

Alright, so now that I know what gear you have, I can be a little more specific to your setup.

C-11 2800mm F10
CG-5 Mount
Canon XSi

So you have a great scope for imaging, adding the focal reducer will really help, you will have a 1700mm F6.3 using that. F10 is slow for imaging anything other than planets or the moon. But with the focal reducer you have a great scope for imaging galaxy's, planetary nebula's, globular clusters and planets.

The XSi is a great camera for DSLR imaging, using live view to achieve focus is a huge help and saves you about $150 since you should not need a knife edge focuser. Also the low noise at ISO 800 realy helps.

Now for the bad news, your mount, the CG5, is not really suited to imaging anything other than the moon or bright planets. You might be able to get a usable exposure up to 1min, but that's a lot of weight on a mount like that. Even with the focal reducer your well above 1500mm which is where things start to get tricky and expensive.

So if you want to do anything other than planets or the moon be prepared to upgrade your mount, and expect to spend at least $1200+ for a non-goto mount, and even more if you want goto.


I actualy have the exact same mount, except mine is made by Orion. But the design and build are nearly identical. It works great for doing some astrophotography with my 400mm lens, but I dont even bother trying to image with my 5" Mak-Cass which has a focal lenght of 1540mm. Even walking near the mount causes some pretty extreem wobble in the images. Ontop of that the tracking moters are quite rough, and tracking error will showup in your images on anything over 2min exposure at this focal lenght even with a little scope like mine.

[diegodog]

Hey Marnault,

Thanks for the reply.

Yeah i am slowly finding out that the gc-5 is not really what I need for pinpoint accuracy and smooth tracking with my scope for the really distant stuff. My main objective right now is to do the planets and the moon. I am not moving on till I get a spectacular, crisp image of the moon (prob will be able to afford a new mount by the time I get that accomplished somewhere around year 2034). Although my moon shots using prime focus were ok they were not earth shattering. I want to get that crisp "oh my god" view I see through the eyepiece onto my sd card. Once I get the moon I will move on to the other planets. Once I accomplish that I will try the piggyback (40 bucks for the mount). I saw some sweet shots of the milkyway and I think m31 using this method.

I bought my gear for astrophotography but am also dabbling in macro, landscapes, portraits, wildlife - just about every type of photography so it is coming along slowly.