should this reach focus?

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Hi all - been a while :)

I have a question regarding my Meade 12 inch ACF scope - Im using a Bintel crawford focuser:

http://www.bintel.com.au/Accessories/Focusers/Bintel-2--SCT-Crayford-Focuser-10-1/502/productview.aspx

With a mirror diagonal in place, I cannot reach focus with my DSLR. Is that normal? i would have thought that there would have been more than enough focus throw to get there...

Oh, Ive made sure that the mirror lock is not engaged :)

btw, it works without the diagonal installed, but it's a pain in the butt to use. :)

[gasman1]

This is probably normal for a DSLR in prime focus because of the added ~20mm mirror box depth. The diagonal is typically removed for a DSLR, but a 2X Barlow will probably make this work for you. Another solution is using a MIL camera like my Sony which adds ~20mm of back focus for you.
:)

[tlgerdes]

Remove the diagonal.

[gasman1]

Another advantage to the low profile MIL cameras over the SLR cameras is their substantially reduced weight. Also you can focus them without a viewfinder using the LCD screen and a magnifying loop or nothing if you eyes are that good. A DSLR on a CST without a diagonal could be really awkward to focus.

[tlgerdes]

As Gary says the camera focal plane is about 50mm further away than an eyepiece one you add a the 2" nose piece and Canon adapter, hence you need the camera 50mm closer to the scope. That is why you cant use the diagonal. You shouldnt need a barlow.

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Thanks guys - the reason I ask is that the guys from Bintel seemed to think that my Meade SCT should have more than enough focus travel to make it work, even with the diagonal. I was concerned that something might be wrong with the focusing mechanism, which appears a bit dodgy anyway.