Why do older camera lenses have faster F-stops?

Started Apr 14, 2013 | Discussions thread
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Joseph S Wisniewski Forum Pro • Posts: 34,130
Or Sigma, or dpReview...

Barrie Davis wrote:

Dave Luttmann wrote:

Dave Luttmann wrote:

EinsteinsGhost wrote:

Barrie Davis wrote:

EinsteinsGhost wrote:

Joseph S Wisniewski wrote:

Dave Luttmann wrote:

Joseph S Wisniewski wrote:

EinsteinsGhost wrote:

Joseph S Wisniewski wrote:

Yes, because it's micro four thirds, and the DOF and you need f0.9 to have the light gathering and DOF equivalent of the "plastic fantastic" $100 f1.8 lenses on FF. So, some old "cine" lenses get reincarnated.

DOF yes (at same FOV), exposure no.

Exposure yes.

Cut the sensor area into a quarter of what it was, and you have 1/4 of the photons in the picture, so you need to throw 4x the light at it to get the same results. Just like in the film days, when tri-x was probably my most shot film on the 4x5, while tech pan was one of my favorites on 35mm.

Physics is a bear.

Exposure...no.  I get the same shutter and aperture rating using a FF camera at iso 100 and f8 as I do on an m43 body.


Exposure... yes.

Come on Dave, you've shot many different film formats and different digital formats. Do you shoot the same ISO in all formats?

No, it doesn't. The f-stop equivalence applies to DOF, not to exposure.

Ahh... That is what you think, is it?  I'll bear your opinion in mind for the future.

"Observation" should trump "belief". Try it.

I did.  I set up my Fuji x10 at iso 100, f 5.6, 50mm equiv FOV and obtained the exact same shutter speed on my Nikon D700 with the same settings.  Pretty easy test....

You didn't do the IMPORTANT part of the test.

The part where you set everything to take an "equivalent" picture with equivalent DOF, noise, dynamic range, motion blur, the whole nine yards?

Some people don't like sauce for the goose, Baz.

Which simply proves Joseph and Barrie are mistaken.

Oh I can be mistaken; it happens all the time. But Joe? NEVER!


We need these guys to go off and tell Sigma and dpReview how "wrong" they are. Did you see the disgraceful news item this morning?


"Sigma has announced the 18-35mm F1.8 DC HSM Art lens for APS-C DSLRs - the world's first constant F1.8 zoom. The lens covers a 27-52.5mm equivalent range, and will be available in Canon, Nikon and Sigma mounts. As yet there is no announcement of a recommended price. The lens will offer the light-gathering and depth-of-field equivalent of a constant F2.7 on full-frame, which may under-cut the need for some photographers to change formats." (emphasis mine)

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Rahon Klavanian 1912-2008.
Armenian genocide survivor, amazing cook, scrabble master, and loving grandmother. You will be missed.
Ciao! Joseph

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