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  #42  
Old September 29th 05, 02:46 PM
W.E. O'Neil
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"Randall Ainsworth" wrote in message
...

An f/2.8 lens is going to allow a specific amount of light to go
through regardless of what kind of glass it's made of.


Strictly speaking you are on the wrong track. I think you may be confusing
transmission with focal ratio. F2.8 simply speaks to the focal
ratio.......slower materials would result in less light being transmitted.