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Digital Rebel question

Started by plunkett, 02/09/2004 07:20PM
Posted 02/09/2004 07:20PM Opening Post
I finally had a chance to try out the DR with my 12.5" dob last night and was disappointed to find that I do not have enough in-focus in prime OR with projection. Are there any cures for this or do I just give up? I can get focus on my ETX-90 (using eyepiece projection), but the edges of my photos are blurry (not vignetted, blurry). Are all these problems due to the distance to the film plane?

Pat
Posted 02/10/2004 03:27PM #1
etx 90 problem is due to the mak's extremely curved focal plane. without a field flattener, any type of camera will show images this way. What you need for your dob is to move the primary forward towards the secondary or vice versa, or use a relay lens set. Many barlows function as relays as well, slipping your camera adapter into a barlow then into the focuser will really slow down your f/ratio, but it should come to focus at least.
Posted 02/10/2004 07:41PM #2
You could look into the Denkmeier Optical 2" OCS, which is normally used to increase backfocus for binoviewers but can also be used for photography:

http://www.AstroMart.com/messages.asp?message_id=52692&page=

Joplin