Thread: Orion Wide Field
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Old 19-03-2010, 11:36 AM
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Octane (Humayun)
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Join Date: Dec 2005
Location: Canberra
Posts: 11,159
Bojan,

Is the idea of the external mask (like Hartmann mask with one hole) to prevent diffraction spikes due to the diaphragm when stopping down?

I ask as I will be purchasing the 400mm f/5.6L USM shortly to use on the STL-11000M.

H
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