A reminder for some memebers as to what the F stop is all about.

Started Jan 26, 2014 | Discussions thread
Great Bustard Forum Pro • Posts: 43,011
Re: If I am making any sense with this ..

Sergey_Green wrote:

Great Bustard wrote:


Again, it will depend on the particular pair of lenses you compare. Also, lenses for 4/3 have to be twice as sharp as lenses for FF to resolve as well for sensors with the same pixel count and AA filter,

Yes, but we can not say if the FF lenses will not resolve twice just as well, as they are always tested on cameras that have larger pixel sensors. And as time goes by and technology evolves I see that those same FF lenses (that were supposedly resolving only half of what FT lenses were) are only getting better and better with every wave of the new cameras.

Good indication of their real sharpness, I think, would be a comparison against the 3-rd part lenses that are (can be) used on both systems.. If the FT lenses are to be twice as good in resolution, then they would simply outclass and outshine anything else that is not done by Olympus. So far I have not see this happening.

You raise some good points, here. It would be interesting to see lenses tested on the same sensor, since this also takes care of the issue of the AA filter.

but FF sensors tend to have more pixels, so they have to be more than twice as sharp to resolve as well. So, let's say the 4/3 lens was 1.5x as sharp. That would help narrow the gap, but the gap would be there, nonetheless.

And the gap is always there. The only time it narrows is when the comparison is done around the same numeric apertures, like wide open against wide open, without and hint or point that wide open on FT is like half closed on FF.

For sure. But, as we both know, comparing, for example, f/2 on 4/3 to f/2 on FF would only make any sense if the scene were within the DOF since, by definition, the portions of the scene outside the DOF are going to have less and less resolution as you move from the focal plane.

I just don't believe they are (or need to be) twice as sharp as most of the FF lenses are. Not from what I see at least. And we were to test FF lenses on as packed sensors as what FT's are, then the lines per mm numbers would be likely similar as well.

Like I said, it would be interesting to test. However, the results would vary considerably, depending on the particular lenses being compared and where in the frame you are looking, even presuming the same DOF.

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