big help please!

[blink138 (Pat)]

hello members
has someone got a similar image train to this one and will it work?
i only have a slight grasp of "back focus" at this stage
here will be the image train:

c11 > moonlite with reducer incorporated > OAG (length?) need help with this > lodestar > dslr

i have read so many uncouraging results about not obtaining focus etc...... but no going back and too much money invested
will it work?
thanks guys and please help me!
pat

[blink138 (Pat)]

bump

[Shiraz (Ray)]

I have no experience of the c11, but since no-one else replied... A few posts on another forum suggest that you will not have a problem at all. apparently extending the focal plane outwards (maybe even to as far as 300mm) increases the SA, but not disastrously.
http://www.cloudynights.com/ubbthrea.../o/all/fpart/1

[blink138 (Pat)]

thanks very much ray
what is SA?
pat

BTW i contacted hutech because i was interested in their OAG, i gave them my desired image train...... but for some reason said it would not work!
this has caused me sleepless nights
i will check that link thanks ray

[blink138 (Pat)]

ahh.... it has just clicked what SA indicates!
pat

[blink138 (Pat)]

ray that link explained things much better than anything else i have read and i have been researching it for about 2 months
pat

[Shiraz (Ray)]

hope it goes well Pat. did Hutech say why they thought it would not work?

A modest amount of spherical aberration should not have a major detrimental effect for DSO imaging, since the resolution you get from that size aperture will largely be determined by atmospheric seeing, not the scope.

[blink138 (Pat)]

yes he said if i am using reducer - t ring - dslr.... it is too short for OAG!
pat

[Shiraz (Ray)]

You will certainly not fit it all into the nominal spacing of 110mm. However, the Celestron site implies that the reducer will work from 50mm out to a spacing of 225mm, which is plenty.
http://www.celestron.com/c3/support3...articleid=2243

Understand your anxiety - no definitive data anywhere. If you still have options, maybe get the focuser/reducer and try it out with eyepieces to see what it does at various spacings. Also might consider the narrow OAG, look for a camera with small flange-focal plane distance and get a short draw tube for the focuser if possible - all will help you get closer to the nominal 110mm spacing if that turns out to be important.

[blink138 (Pat)]

yes ray when i first bought the moonlite i wanted it for visual too but it does not come to focus with reducer / diagonal / eyepiece
it does come to focus fine with prime focus imaging though
so i dont know if the moonlite sticks out too far from the actual visual back of the c11 or i need an extension tube (probably the former) which would signify getting a very slim OAG which the hutech was (13mm)
i may ask any of our members on another thread if anybody has a spare OAG to try out
thanks again ray
pat

[Shiraz (Ray)]

or just put in a 13mm spacer where the OAG would normally go to see if it will still focus?

[blink138 (Pat)]

oh ray that is an excellent idea..... thinking outside the box..... i like!!!
pat