Imaging through a right angle mirror

BlackWidow (Mardy) · #1 07-04-2013, 02:34 PM

I have been imaging for a while on my LX200 using a QHY8. I have now added a 6.3 focal reducer after the electric focuser and am currently spaced at 85mm from the back of the reducer to the CCD face. This gives me around F7.5 .. However I have been reading that to get F 6.3 I should be spaced at around 125mm and this is a problem due to limits of my fork mount.

I have a good crystal right angle mirror that could help with the clearance of the fork mount. Is this a good idea? And should the reducer be before the right angle or after? And if before do I include the right angle in the spacing calculations? My thought suggest to me that the reducer should be after the mirror and the spacing be done the same as without it.

I know some will say the the reducer should be at the visual back, however this causes vignetting real bad once you add the elec focus as the spacing to the CCD gets too great. I am happy that my spacings seem to work, it's just getting very long to target southern targets.... The normal v
Challenges of this scope..

Interested to get others opinions

Mardy

multiweb (Marc) · #2 07-04-2013, 02:37 PM

Quote:

Originally Posted by BlackWidow

have a good crystal right angle mirror that could help with the clearance of the fork mount. Is this a good idea? And should the reducer be before the right angle or after? And if before do I include the right angle in the spacing calculations?

If your diagonal doesn't have any chromatic aberrations then go for it. I should be taken into consideration with your reducer spacing as you'll have to factor for the extra length in the light path if you place the reducer before.