seems to me that aligning a glass flat parallel to a sensor would be child's play via a spacer. I think that this technique would be good in a rangefinder camera but not in a SLR because in order to get the dust out of the focal plane it would need to be too far away from the sensor and would interfere with the mirror travel. JCO
This has already been made by Sigma in their SD-9 and SD-10 DSLRs. And according to their users, it works well to keep dust away from the sensor.
Carlos
