Posted: 6/6/2004 10:35:55 PM EDT
| Anyone here know anything about telescopes? I've been trying to use mine to take pictures of the night sky. I have a T mount the conects my telescope to my Nikon. I get what I want to take a picture of in the center of the eyepeice. focus it. then rotate the mirror up so the light can go directly into the camera. But when I look through the camera all I see is black. I try focusing. I go all the way both ways and nothing. It's like no light is reaching the camera. But I know that light is reaching the camera because when I put it on a street tamp I can see that(blurry of course). I've been fidilng with it for a while now and can't seem to get it to work. |
|
I dont know much about telescopes, but here's an idea. Focus it on something big and bright, like a full moon. Try that to see if you can get it sorta focused, and work from there. I'll talk to some ppl at work tomorrow about it and see what they have to say. Someone might know since I work at a planetarium 
|
|
Is the T mount set up so that the film in the camera is the exact same distance from the mirror as the eyepiece? Then the focus should be OK. It could be that the camera viewfinder darkens things so much you just don't notice the image. (have you tested it on the moon?) Note that most SLR cameras cut off the viewfinder while the shutter is open. And of course you will need a long exposure time, as little vibration as possible, and good tracking for deep-space targets. I assume you've got that taken care of though :) (used to wanna-be an amateur astrophotographer) |
| the Tmount had 2 lengths short and long. I tried both. since the moon wasn't up before the clouds rolled in and it started raining I didn't get a chance at the moon. It's possible the view finder is just darkening to too much. the telescope automaticaly tracks objects. very cool. I need more eye peices for it. I'm still working on minimising vibration and the best way to have a long exposure. |
|
I suspect you’re really out of focus and the camera needs to be moved either forward or backward quite a bit. Suggest you first try a few daylight shots of distant objects (absolutely don’t accidentally point the telescope at the sun, though). Or you might try this. Remove the camera; point the telescope at the street lamp (or any other distant bright object); rotate the mirror up (I assume it’s in the telescope, not the camera); put a piece of white paper approximately where the film of the camera would be and then move it back and forth until you see an image (probably inverted) projected of whatever the telescope is looking at. The film in your camera needs to be in the same place that the paper is when the image is in focus. Ground glass (which I doubt you have) is even better for this than white paper since you can see through it. Waxed paper also works, though not terribly well. Hope this helps! Edited to add: if the mirror your talking about is in the camera then things are different – no offense, but I’m assuming you’re not just looking directly into the back of the camera with the camera back open. |
There's only a couple that don't, and they're fairly expensive. The Canon EOS RT is an example. This is your problem. You can't look through the camera viewfinder to check things, so you have to totally compose the image first and pray everything is in focus. |
Again, no offense!!  I just couldn’t figure out where the mirror was that were mentioning since your Nikon most likely also has one that swings out of the way. Also, it is in fact possible to open the camera back and focus from there (though not by simply looking into it). Ground glass is exactly that. It’s a flat piece of glass with one side that has been ground, i.e. frosted. It’s used for seeing optically projected images (among other things). If you’ve ever seen an old microfilm viewer, their screens are ground glass (or something very similar). And as mentioned above, your Nikon has ground glass in it. For your purposes a piece of waxed paper would probably be quite adequate since you’re just trying to get a ballpark idea of where the in-focus image from your telescope is falling. |
|
The mirror in question is in the telescope. it sends the light to the eye piece. I rotate it up so the light can get into the camera. Were it can then hit the mirror in the camera which directs it to the veiw finder. The mirror in the camera rotates up when you press the button to take a picture not before. Thanks for the help guys I'll be doing some daylight trouble shooting today. |