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EF 50MM F/1.8 STM LENS

peterl
Contributor

Considering purchasing this lens to start a Prime collection, it seems very cheap, what will all the ramifications of using this lens on my 70D EF-s camera be?

15 REPLIES 15

I think of focal length and aperture, though it does appear that others use focal ratio.

"That's low *aperture ratio*, not focal ratio."

 

The 'speed' of a lens is found by dividing the focal length by the aperture. This 'aperture ratio' is normally refered to as focal rario.

EB
EOS 1DX and 1D Mk IV and less lenses then before!

I wouldn't say "normally". it seems to be more of an astronomy term. It seems pretty rare in photography literature.

"I wouldn't say "normally"."

 

Must be the circles we run in.  I bet I haven't heard aperture ratio used in describing the f-ratio of a lens twice. Smiley Happy

EB
EOS 1DX and 1D Mk IV and less lenses then before!


@ebiggs1wrote:

"I wouldn't say "normally"."

 

Must be the circles we run in.  I bet I haven't heard aperture ratio used in describing the f-ratio of a lens twice. Smiley Happy


Maybe just a regional difference in terminology. Where I grew up, we called a creek a "bayou". Here we call it a "brook".

Bob
Philadelphia, Pennsylvania USA

TCampbell
Elite
Elite

The "ratio" being discussed is the "focal length" to "aperture" ratio.  

 

Usually I hear this called the "focal ratio" and only occasionally do I hear someone say "aperture ratio" (it really is both ... if you wanted to be really specific then you'd use the term "focal length to apeture ratio" and that would eliminate all ambiguitity.   But people like to shorten things.

 

Either term is correct (or at least correct enough that everyone else should know what you mean.)

 

 

Tim Campbell
5D III, 5D IV, 60Da
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