resolving power

Started 3 months ago | Discussions thread
fferreres Veteran Member • Posts: 4,146
Re: resolving power
2

thayes15 wrote:

Hi all

I admit I know nothing about the `resolving power' of a lens. But if it's true that some old lenses have the `resolving power' for a 24 mpix sensor but not a 45 mpix sensor, for instance, has anyone tested this theory?

Has anyone tried an old lens on a smaller and larger mpix sensor and noticed any difference? E.g. the same old lens on a Nikon D850 and a Nikon D610 or the same old lens on a Sony A7 4 and a Sony A7 2?

It's a bit more complex than that. First, the "resolving power" varies by f-stop, as the more curved outer part of the lens starts to not get used when you stop down. The other is that the "resolving power" is almost invariable much higher in the center than in the corners. This means that in parts of the image, it's resolving much finer detail. Combine both, and it's not clear if it has/doesn't have "resolving power"  at certain resolution, but rather a continuum of gray area responses.

Also, it's a bit hard to define exactly if something is good enough for 24MP or 42 or 60MP sensor. However, it is very true, than one can observe how camera resolves detail in a scene in sensors of increasing resolution. To some extend, this is akin to reading an MTF chart...which varies by f-stop and by distance to the axis. But since we don't have this for most old lenses, we are left with tests.

I too, would like to know how many lenses do under a 60MP sensor. But I won't pay $3500 for such sensor, and may have to wait a few years until price goes significantly down.

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