Telescope flip mirror assembly

Hi!

Does anyone have any expereince with those telescope flip mirror assemblies? This is the type where you mount it to the back of a telescope, have a mirror or prism assembly that directs the view to an eyepeice for finding and focusing, and then you flip the mirror or prism down to send the image to the camera.

My concern is, how accurate is the focus on them? If I were to use one for nature photography and flip it to the camera would I still have precise focus?

Thanks!

eb

If you have an slr it would be easy to check. Otherwise mount your camera and check with a ground glass set on the film plane. Obviously the accuracy is going to depend on how well the camera adaptor is mounted and how good your eyepiece matches the setup.

I assume you mean that you would use the eyepiece for high-power focusing, but that you would still use the camera viewfinder to compose the image? I can't answer your question specifically, but what about getting one of those viewfinder magnifiers that attach to the camera to help you focus? Although most of them seem to be limited to about 2X magnification.

With my Nikon F3, I can remove the prism and then put a loupe directly on the focusing screen to magnify it. I have a Peak 8X with a rectangular base; I had to machine a little off each side at the bottom, but now it will fit into the F3 where the prism would go, with enough friction to hold it in place. If you are shooting in daylight I suppose you would need to put the finder back on before taking the shot, or else drape something opaque over the top to block extraneous light.