----- Original Message -----
From: "J. C. O'Connell"
Subject: RE: Full Frame - What's the problem?
I don't think the size of the lens mount matters at all, it's
the size of the len's image circle that matters with regards
to sensor size, not the diameter of the lens mount.
The conventional theory (and i don't know if there is anything to it or not)
is that the very oblique angle the light has to take when it exits the lens
towards the edge of the full frame sensor causes a sort of vignetting,
caused by the actual sensor being somewhat below the surface of the chip.
The idea then, is to make the exit angle less extreme by increasing the
diameter of the rear lens element.
A larger lens mount facilitates this.
Image circle size really doesn't enter into it, as long as there is enough
to cover the sensor.
William Robb
