40% isn't much large than the obstructions in Meade SCTs.

If you were to graph CO size against the damage it does to the image, the
curve would be flat (next to zero damage) until you get up to 15-20%
obstruction (depending on who is doing the evaluating). From there it
increases slightly to about 25%, starts to angle up and somewhere between
30-35% goes very steep. There is a very big increase in this area, but it is
even worse for the 35-40% CO.

Clear Skies

Chuck Taylor
Do you observe the moon?
Try http://groups.yahoo.com/group/lunar-observing/

Are you interested in understanding optics?
Try http://groups.yahoo.com/group/ATM_Optics_Software/

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