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Esteemed Contributor
Posts: 2,607
Registered: ‎02-17-2016

Re: EF 50MM F/1.8 STM LENS

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

VIP
Posts: 9,796
Registered: ‎12-07-2012

Re: EF 50MM F/1.8 STM LENS

"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.

EOS 1DX and 1D Mk IV, along with, a lot of other stuff.
Esteemed Contributor
Posts: 2,607
Registered: ‎02-17-2016

Re: EF 50MM F/1.8 STM LENS

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

VIP
Posts: 9,796
Registered: ‎12-07-2012

Re: EF 50MM F/1.8 STM LENS

[ Edited ]

"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

EOS 1DX and 1D Mk IV, along with, a lot of other stuff.
Highlighted
Esteemed Contributor
Posts: 4,590
Registered: ‎06-25-2014

Re: EF 50MM F/1.8 STM LENS


@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
Boston, Massachusetts USA
Esteemed Contributor
Posts: 3,628
Registered: ‎06-11-2013

Re: EF 50MM F/1.8 STM LENS

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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