Since you have a reflector (I assume a newtonian telescope), the focal plane of the image is probably just 1 inch or so out of your fully racked-in focuser.
However, when you attach your camera though the T adapter-T ring combination, the CCD sensor in the camera is about 2 inches away from the top of the focuser.
Therefore, even when you rack your focuser all the way in, the image still forms fairly far from the CCD in you camera. So no focus.
With Newtonian reflectors is generaly hard to reach focus with a camera attached in prime focus, because you don't have enought in-focus range..
There are a few solutions, none straighforward. One would be to push the image "out" of the focuser by physicaly moving the primary cell 1 or 2 inches forward.. The other is to replace your focuser with one with VERY low profile. The third one is to use a relay lens placed inside the focuser to move the image out a little bit. But relay lenses are not the standard fare in astronomical gear, so you'll proably have a very hard time finding one..
The other solution is to not do it altogether. Buy a small refractor, their focusers have much larger ranges and they are generally designed for photography.
Well, there is another solution, do "projection" photography, and yes, you will need to buy another piece of equipment for that..
Using a Nikon D-70s with a telescope
in Nikon
Posted
There is a response from a friend of mine:
Since you have a reflector (I assume a newtonian telescope), the focal plane of the image is probably just 1 inch or so out of your fully racked-in focuser.
However, when you attach your camera though the T adapter-T ring combination, the CCD sensor in the camera is about 2 inches away from the top of the focuser.
Therefore, even when you rack your focuser all the way in, the image still forms fairly far from the CCD in you camera. So no focus.
With Newtonian reflectors is generaly hard to reach focus with a camera attached in prime focus, because you don't have enought in-focus range..
There are a few solutions, none straighforward. One would be to push the image "out" of the focuser by physicaly moving the primary cell 1 or 2 inches forward.. The other is to replace your focuser with one with VERY low profile. The third one is to use a relay lens placed inside the focuser to move the image out a little bit. But relay lenses are not the standard fare in astronomical gear, so you'll proably have a very hard time finding one..
The other solution is to not do it altogether. Buy a small refractor, their focusers have much larger ranges and they are generally designed for photography.
Well, there is another solution, do "projection" photography, and yes, you will need to buy another piece of equipment for that..