[troypiggo (Troy)]

Originally Posted by Dennis

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Here is a link to a review of the Canon EOS 5D Mark II which has a table listing the Diffraction Limited Aperture values for several Canon DSLRs.

http://www.the-digital-picture.com/R...ra-Review.aspx

Cheers

Dennis

Thanks mate. Will go through that article in detail some time.

From what I understand, though, at macro distances and those higher magnifications the effects become even more pronounced. I think of it like the magnifications greater than 1:1 have a bigger effect on what the lens says the aperture is. So there's like an "effective aperture" that's actually higher than what the lens/camera is reporting.

The MP-E is a special lens that's kind of got a built in set of variable distance extension tubes. It gets its higher mags by putting more distance between the sensor and lens. You'll notice how the viewfinder gets darker at higher mags like 4:1 and 5:1. That's kind of this "effective aperture" reduction effect I'm talking about.

So at 5:1, if you have the lens/camera set to f/5.6, the diffraction effects are as though it's around that f/11 ballpark. That's my way of thinking about it, anyway.

You can certainly notice the effects on sharpness if you do some testing. I used teabags and toothbrushes, shooting fibres etc.