Relationship between lens speed and sensor size

Started Oct 8, 2012 | Discussions thread
fotowbert Senior Member • Posts: 2,506
I don't think so

sherwoodpete wrote:

fotowbert wrote:

The  OP's point is essentially that a sharper and faster lens on a smaller sensor may possibly "outperform" a larger sensor with the typical entry level lens.  His premise is all about lens quality, and requires the average entry level DSLR lens to be so optically inferior that it more than offsets its sensor size advantage.   

That may not be the point at all.

That's was my take on the OP's 2nd post where in his last sentence he sums up what he has been thinking out loud about.

I doubt the OP is relying on diffraction in making his assertion the small sensor "P&S under certain conditions and assuming an average consumer-level lens on a DSLR can outperform the DSLR due to a faster lens optimized to the particular camera".

In good light, and with the aperture set for reasonable depth of field (as in landscape shooting), the limitation is not necessarily about lens quality, but rather the fact that the image quality may be limited by diffraction in both the compact camera and the DSLR.


Lens quality is of primary importance in determining IQ regardless of the light level.

Diffraction is a secondary effect acting to soften the sharpness the lens is capable of producing.

When the image is somewhat soft to begin with then diffraction losses are likely to go unnoticed!  In this respect only shooters with sharp lenses need worry about small apertures.

I hadn't thought about this until now.  It good to know many of my lenses are immune to diffraction!

Thanks for your post.  John

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