Bob Andersson wrote:
If memory recalls the F ratio is lens diameter/sensor diameter...
Nearly right - it's the focal length divided by the effective lens diameter (taking account of the iris). But these sort of questions are easily answered by the OP doing his own research, an essential skill for a student and an engineer.
doesn't do it then, as long term members here know, a good reference site for the mechanics (as opposed to Gordon's DSLRTips
which concentrates more on the practicalities) is CambridgeInColour
thanks bob, and everyone who posted , well i always knew somthing about the topic i just need certain confirmation on those , as a fresh mechanical engineer , i just needed to study something like this it is an amazing thing to learn the mechanism , but thanks again i will ask only
those questions which are not available on sites after googling ,
and Mr.gordon sirs dslr tips also is very helpfull and also the site cambridgeincolour is a nice site to refer to