More backfocus please

I've run out of backfocus behind my AT8RC 8" RC scope to accommodate my imaging needs. What is the best way to add additional backfocus to the optical train?

Rich

Best solution would be an additional extension ring. You could can the distributor or put up an ad.

I don't think I quite understand--(I get confused easily and I cannot remember if Backfocus is intravel or outtravel):

As you are moving your focuser out, do you run out movement before your star comes to focus?

Alex

Richard,

Before you go adding optics, relay lenses, and all that--maybe you need to consider just what all you have in the train that is pushing the sensor so far back. These scopes are made with ten inches of backfocus. That is a lot. What all do you have back there? Could something be removed, or coud you substitute a thinner version of it?

Alex

Hi,
If your scope is a cassegrain then the backfocus is a function of the secondary mirror position.
If the secondary holder allows it, you can try to move the secondary a little closer
(just a few mm) to the primary. The backfocus will move a lot more than that
because of the mag factor.
I don't know what impact that would have on distortion and field curvature.
good luck