pentax d fa 28-105

can some one in simple terms would this work ok on a k5 ii s and what would be the focal lenght be 28-105 or 42- 157.5

thanks

It should work just fine. The lens has been designed for a full frame sensor, but it will work fine on a crop as the centre images a lens produces are invariable sharper than the edges.

The focal length will always be 28-105.

It will always be a 28-105mm, but the field of view on your K-5 IIs will be similar to using a 42-157.5mm lens on a full frame format. You might find the 18-135mm lens more useful, unless you are buying with a view to upgrading to a K-1 at some point.

Thanks very much a lot clearer now

And it does exactly that - great quality on my K-5 IIs and K-70. It suits me, but be aware that its range is effectively standard lens to short telephoto on these APS-C sensor cameras. If you need wide-angle within the same zoom lens, consider the 18-135 as John suggests, or the 16-85, but those two are not full-frame. All three lenses are similar sizes and are WR.

Cheers.
Philip

will be ordering a 18-135 form srs thanks for all the advice
happy christmas

did not go for the 18-135 but went for a D-fa 100wr after a great deal from srs and so far the lens is fantastic