Well of late i have been slowly transforming my 10" dobsonian tuned for the visual user into a tuned for the astro photographer.
Motives for doing this.
- 100% illumination of the imaging plane standard = 8mm... BAD
- Primary mirror cell = pitiful
- focuser while it'll do for now = sub standard
Things that I have done so far.
- Increased the 100% illumination of the imaging plane from 8 --> 24mm
- Pulled the primary mirror cell apart and made some adaptions so that the mirror is held in place around the bottom of the mirror. Ive had heart destroying problems for over 6 months trying to figure out what the hell was wrong! Problem here was the mirror cell for the actual mirror is flimsy when i locked the collimation off it would warp the cell, now i thought that using a tissue to make sure that the mirror clips where JUSToff the mirror surface was fine. but once the cell twisted it pushed the mirror into the mirror clips thus causing ASTIGMATISM....... The fix for this was to remove 2 of the felt pads and insert a thin piece of rubber just on the inside of the cell, under the mirrors own weight it should just fall in (maybe a bit of lubricant on the rubber so it doesn't stick), replace the shotty collimation springs and your done! reliable collimation, a mirror cell that doesn't pinch the optics.!
-focuser is still to come! i need some more time in the prototyping lab!
If anybody has done something like this then shout up
The next thing i would like to do is run some baffling down the inside of the OTA, has anybody got any good ideas?