6.3 focal reducer and back spacing on a fork mount cpc

[Loki1978]

Hi All, 

I had a question about back spacing. I want to by a f6.3 reducer for my sct. I know I need 105mm back spacing to use this reducer but I'm already quite limited in lat with my cpc 800 on a wedge. I think with 105mm and an atik ccd I will hit the mount base quite early. 

Can I use a diagonal to use up back spacing the same as straight though extension tubes?

 

[michael8554]

Diagonals aren't usually recommended for imaging.

However, needs must.

I don't know the optical path length of a typical Diagonal off-hand, but if you're lucky it will fit between the FR and the camera and allow 105mm spacing.

If not that's going to be a long bendy train.

Maybe only use for high Dec targets ?

Michael

[Loki1978]

Michael, 

Thanks for the reply. Yeah I understand less optical obstacles in the imaging train is better. I think like you say I will try to use straight spacer adaptors unless the target is high. I actually bought the cpc800 before I started down the AP route, otherwise I would have bought an equatorial mount and tube. I don't actually have a decent diagonal, only the 1.25" diagonal that came with the scope. So I would need to buy a 2" diagonal as I've changed everything over to 2"

I will try the straight spacers first. I've got a Williams Optics z73 which I have no mount for. I think I might stop spending on the cpc800 and save up for the mount for the Z73 as I think this may be better for the imaging I'm doing.