Why small apearture is worst on more MPs?

[piyush]

I just wanted to have litle technical detail on this question. If we go for any thing smaller then f16 on 10MP sensor, it becomes softer. Why is that so? If it is because of the smaller sensor area then why that is not the case with the film camera because particals (on the film surface which captures light) are much smaller then the pixel area of the 10MP sensor?

Thanks,
Piyush

[KeithB]

As Scotty would say, "I canna change the laws of Physics, Captain!"

It's diffraction and most folks would say that it starts at f/8, not f/16.

http://www.luminous-landscape.com/essays/brick-wall.shtml

(OT note, I just saw a blog topic calculating just how big Legolas' pupils would have to be in order to have eyesight as good as reported in "The Lord of The Rings" *- they would have to be a few inches across.  Birds get around this by seeing in the UV - not something we photographers can do! - and having special oil droplets on their cones.)

*When he sees the Riders of Rohan for the first time.

[Bob Atkins]

A smaller aperture is NOT worse on higher pixel count cameras (with the same physical sensor size).

I explained this in detail in an article I wrote about 6 months ago and which you can find here:

http://www.bobatkins.com/photography/digital/canon_eos_50D_resolution_confusion.html

The effects of diffraction are more noticable when the sensor is physically small (and so the image has to be enlarged more to give a given print size). That's why most digicams (with very small sensors) don't let you stop down past about f8.

The same limitation applies to very small film formats (like Minox).

[piyush]

Thanks, Thanks for the clarification.