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Amazing lens, incredible sharpness

Started Aug 20, 2013 | User reviews thread
Great Bustard Forum Pro • Posts: 45,641
Re: Um...

Moti wrote:

c_henry wrote:

No my question was simple, *you've* somehow made it about numbers out of context, light falling on sensors, efficiency, noise etc. I for the life of me can't understand why you're trying to make it so difficult.

You asked a simple question and the simple answer is YES, for the purpose of exposure, f/1.8 remains f/1.8 no matter on which body the lens is mounted. The rest is academic.

What is "the rest" and how is it "academic"?  If, by "the rest", you mean that 4x (2 stops more) light will fall on a FF sensor than an mFT sensor for the same exposure (resulting in half -- one stop less -- noise for equally efficient sensors) and that the DOF will be half as much, then, yes, it is "academic".

Of course, this means that 150mm f/1.8 on FF results in a rather different photo than 75mm f/1.8 on mFT, and 150mm f/3.6 on FF results in a rather similar photo.  So why would we shoot 150mm f/1.8 on FF unless it resulted in a better photo than 75mm f/1.8 on mFT?  And why would we then say 75mm f/1.8 on mFT is "the same as" 150mm f/1.8 on FF?

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