old 28-80 lens on new digital body

Some years ago I bought my Pentax MZ7 with a Pentax standard zoom 28-80 f/3.5-

5.6, a cheap one but not bad at all. Now I'd like to go digital and buy a

Pentax *Ist Dl or next to come K100 with standard zoom 18-55 or maybe 16-45.

Can the 28-80 still be useful, considering that the only tele lens I have is

an old 200 f/4 with no "A" position, very good but also limited in the usa

with an AF DSLR? I don't know if it has a worthy number of lines per mm at the

telelens end (80mm that should be like a 120mm on APS-C)

Or should I consider buying a Pentax 50-200 a or a Tamron 70-300?

And what about 18-55 vs 16-45. The first is much cheaper, is the second worth

the difference in price?

The A lenses are convenient. Using the older M and K only involves setting a switch to manual when you mount the lens and pressing a little button to lock in the shutter speed before each exposure.

I bought the kit-included 18-55 and it's been roundly criticised. I haven't used it much, since I like fast fixed focal length lenses. Regarding all the criticism, I think a recent issue of Popular Photography reviews DSLRs, and suggested that a kit lens labeled Scheider-Kreuznach is actually a rebranded Pentax 18-55. I compared the picture with my lens and the only visible difference was the texture of the aperture ring. If this is so, well, welcome to the 21sth Century, when nothing is sacred any more.

All that said, use what you have. Your 28-80 will produce an effective DSLR zoom of 56-120mm, not a bad range. In new/used purchases, price-to-value often comes down on the side of older Pentax glass. I personally have found that when my photos have problems, the problems originated with me. Blaming equipment verges on delusion.

The 18-55 is pretty poor IMHO. I've compared mine to various lenses (including SMC-FA 28-200 and 28-80's) and not been impressed - centre resolution isn't too bad but the corners are the softest I've ever experienced from a lens.

I haven't used the 16-45 but it's supposed to be much, much better.

The 18-55 is probably a better lens than the 28-80. Unlike the Canon and Nikon 18-55's the Pentax is pretty good. When I had my D, I shot with the 18-55 until I could get my mitts on a Tamron 28-75 f2.8. And I was never disappointed by the optical quality. The build quality of the 18-55 isn't bad and like all DA lenses it offers full-time manual focusing.

Your 28-80 will be usable as a short telephoto zoom (42-120 equivalent), but at the wide end I suspect you'll come to prefer the 18-55.

That said, as good as the 18-55 is, the 16-45 is better. the 16-45 is noticably wider, faster at the long, has less distortion and is sharper with higher contrast. It is truly a superb lens.

You might want to hold off for the upcoming 16-50 f2.8 DA though.

The 18-55 is not a stellar performer but not a useless junk either.

You just have to remember to step down (to f:8 at 18 mm and f:11 at 55 mm) and it is good to know that there is a lot of distortion at the wide angle end. So, don't shoot horisont at 18 mm. The 16-45 is said to be much better.

I have the F 28-80 and it is quite useable. I suspect that it is optically the same as the A version. I think F28-80 is better than the 18-55 but of course neither of them can compete with fixed focal length lenses (oddly called primes). The Pentax DSLRs have the nice feature that you can shoot with any optics which you can attach on the front of the body. So there is no need to get rid of old lenses.

Thank you all for your advice!

So I think I'll buy just one standard lens, 18-55, 16-45 or 16-50, it depends on the prices I will find in Italy and then I'll use my old lenses as you suggested.

I don't want to spend much, so 18-55 could be good if you say it's not bad at all, unless I find 16-45 at a good price.

For the telelens, that I don't use so often I'll use the 28-80 long end and the 200 I already have. Of course my 200/4, although it's very old (early eighties) is better than any new cheap zoom like the one I could buy. I forgot to say my brother can lend me when I need a Pentax 28/2.8 M and a 50/1.7 M, very good low cost manual lenses, and even a 20/4 by Carl Zeiss with screw mount, with a very low distortion.