any tips for use- TOAG MPCC and DSLR

[graham.hobart]

Hello all, yesterday finally got around to putting my Orion thin off axis guider together with my MPCC (new version) and cooled 60Da. Now the clouds have come in I can't test it but anyone having a similar set up have any tips/pitfalls for this arrangement?
My calipers read approx. 55mm for sensor to thread distance on the corrector, And I am using a Star Shoot astroguider for now as it screws directly onto the OAG without any need for adaptors.
Anyone need spacers for the guider?
I have a lodestar which I will use down the track but that's in reserve on my guide scope for now just in case the OAG doesn't pan out.
Cheers
Graham.

[rustigsmed]

nice one graham,
how is your 60da cooled? was it a DIY?
I have a TSOAG9 which I assume is similar to the orion. what have you done about the bayonet? I had to buy a '0mm' one to make mine work.

cheers

[graham.hobart]

HI, its a cooled 60Da-done by CentralDs - a great job but makes the camera very back heavy. Usually gets a stable temp 10-15'c below ambient though and although I love my 5D mark II, it runs very hot which in Summer adds noise ++ to my shots.
The TOAG came with a T ring adaptor for bayonet fitting so I just plonked that on. I took the locking ring off the coma corrector although this didn't seem to make any difference to the assembly width.
Did you measure and space the distance between camera and OAg and guide cam and oag accurately?

[Amaranthus]

The main trick is to get the distance between the OAG pick-off prism and the two sensors (camera, autoguider) identical. Calipers and spacers help! You'll know when this is right, because your guidercam stars will be in focus when your camera is. It can be frustrating to get this right first time around, especially since the OTOAG hasn't got a helical focuser.

[rustigsmed]

sounds good graham, a cooling option is on the to do list for me - perhaps the cds-600d. as for the spacing I think mine is actually more like 57mm (it has been ages since I got it going) and that still works pretty well.

i'm actually about to move onto a RCCI (need space for filters) so am about to go through the whole spacing thing myself again too.

[graham.hobart]

Barry is that measured from the mid point of the prism or the front or back?

[Amaranthus]

Mid-point.

[graham.hobart]

Cheers ,
The positioning of the pick off prism- is it critical to be mid point when setting up or arbitrary?

[Amaranthus]

The pick-off prism should ideally be as close to the edge of the TOAG ring as possible, to avoid shading your camera chip - definitely not centre if you can avoid it.