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Old Apr 7, 2009, 12:03 PM   #1
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In the Olympus E-520 manual on page 123 the following is stated:

"A Four Thirds system lens with f2.0 brightness, for example, is equivalent to f4.0 when converted to the aperture of a 35-mm camera."

Does this mean that the fastest Zuiko lens is actually f4.0?
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Old Apr 7, 2009, 3:04 PM   #2
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garys17 wrote:
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In the Olympus E-520 manual on page 123 the following is stated:

"A Four Thirds system lens with f2.0 brightness, for example, is equivalent to f4.0 when converted to the aperture of a 35-mm camera."

Does this mean that the fastest Zuiko lens is actually f4.0?



No, because it is an f2 lens used within the 4/3rd's format series of cameras, which are the only camerasthat a Digital Zuiko lenswill work with. Why worry with how it would perform on, say, a Canon 5D or Nikon D3?

I don't even really understand whyOlympusmakes statements like that in printed material. It is IRRELEVANT what theaperture would be on acamera that uses a sensor the size of a 35mm piece of film because a Digital Zuiko willnever be used on that type camera andonly helps muddy the waters even further for many who really don't understand.

Think of it this way....using the same logic, you could also saythe new35mm f1.8 DX Nikkoron an aps-c camerawith a 1.5 crop factor (Nikon cameras such as the D90)is only equivalent to something like f3.3 converted to an aperture fora 35mm camera, butthey (Nikon)don't post stuff like thateven though that is the case, so don't go reading more into that statement than you need to.

Tokina makes a fantastic 12-24 f4 lens in the DX format for Nikon aps-c cameras, so using the 1.5x factor, if you put that lens on a full-frame DSLR, it becomes an f6.3 zoom, but that lens is not designed for, and would never be used on a full-frame DSLR, so making that type statement makes no sense because it will never be used that way.


The only type camera where an f2 lens is *really* f2, interms ofa 35mm film-sized sensor,is if you are usingan f2lens designed to cover the image circle ofa 35mm piece of film, and only ifyou are using itona full-frameDSLR.





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Old Apr 7, 2009, 7:51 PM   #3
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garys17 wrote:
Quote:
In the Olympus E-520 manual on page 123 the following is stated:

"A Four Thirds system lens with f2.0 brightness, for example, is equivalent to f4.0 when converted to the aperture of a 35-mm camera."

Does this mean that the fastest Zuiko lens is actually f4.0?
You will notice the title of the paragraph is "Depth of Field" and that statement is correct. The DOF of my 35-100 f2 is the exact same as a 70-200 f4 lens being used on a full 35mm sensored camera.

If you are trying to gain additional DOF, of course, this is no problem at all. If you are looking to restrict DOF (make it narrower) then the big sensored high dollar camera will have an advantage.

Everyone has different needs. I shoot alot of telephoto and the shorter focal lengths the 4/3 sensor uses is a huge benefit to me. The 50-200 is nicer to carry than a 100-400 lens, and sharper to boot. Because the lens is shorter to get an equivalent field of view, the DOF is deeper, and that is something I generally like for shooting long. I normally want additional light so I can stop down to gain even more.

In total, no its not a f4 lens. Its a f2 lens that is half the focal length. The AF system is operating on f2 light. The viewfinder is illuminated with f2 light. Its a f2 lens! Becaues shorter lenses have greater DOF, it shares that characteristic with a f4 lens in 35mm format that has twice the focal length.

Have I confused you more?

Greg
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Old Apr 7, 2009, 8:13 PM   #4
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Yes, Northern Greg is correct. The subject is on the equivalent depth of field, and the 4/3 lens has more depth of field for the same f-stop, etc.
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