16-45. Wow

IIRC, f/16 is about the smallest you can go with APS-C sensors before diffraction starts kicking in. (But I stand to be corrected!)
Matt

Matt, it deppends on how good the lens is.

A Perfect lens would perform best wide open, with angular resolution given by theta=arcsin(1.22*(lambda/aperture))


where theta is the minimum angular separation of two bearly resolved objects and lambda is the wavelength of light.


Even the best lenses are imperfect, so performance degrades wide open, but since imperfections tend to be worse at the edges of the lens matters usually improve for the first couple of stops as you stop down.

At some point the benefits from cutting out imperfections in the lens are outweighed by the diffraction limit and performance decreases.

Diffraction limted yes, but there are huge variations in performance levels between lenses. Diffraction is not the only consideration.

[quote:3496ace15f="Mongoose"]Matt, it deppends on how good the lens is.

A Perfect lens would perform best wide open, with angular resolution given by theta=arcsin(1.22*(lambda/aperture))


where theta is the minimum angular separation of two bearly resolved objects and lambda is the wavelength of light.



I was gonna say that

And you'd have been right.

There may be no perfect lenses, but there are plenty of perfectly good ones.

you are quite correct, I can't find anything on google about them.

Perhaps we do need to increase the time limit on edits after all.

By diffraction limited, I mean limited only by diffraction. By F22 I would be surprised if anything else makes much difference because the physical limit on placed on resolution by diffraction renders other considerations meaningless.

Obviously at F8 there are large variations between lenses, by F22 I doubt you could see the difference even if it's measureable.

Published lens tests do show significant variations even at f22.

I stand surprised

I was lost off with all the technical jargon!....but my 18/55 is still cracking at F22.....AND MY 16/45 has a sweet spot at 19mm...........just thought I would add that as a talking point!...night,night folk!............

Hi every one I have just bought my self a Samsung GX20 wich I like very much the reason I jioned this foram was to find the best Pentax lenses that I shoud buy

Welcome!

The best Pentax lenses that you should buy depend a lot on how much money you have to spend.

If you're loaded, get the '*' and limited lenses.

If you're skint, the kit lens is great for what it is.

Have a look round here, see what you think.

A lot of people here (myself included) think the best place in the UK to buy them is here.

Hi Niloc, welcome to the Pentax(Samsung) User Forum.
Good to have another new member from.........?
Before we can answer your question it is helpful to know which lens you already have, and what sort of subjects you like to photograph. And a hint of available budget might help also.


Martin.

edit: of course Chris beats me by an inch, sorry

Hello,

Please edit your profile to show your location - country is enough.

Presently I am assuming from your name that you are from West Nile.

G