any suggestions?

[gokenin]

I wanted to ask your opinions on my next lens the choices are the 1.either the new pentax or the tamron 18-250 lens to use as a walk around lens and travel lens 2. the 16-45 f4 lens to replace the kit lens (which will be added to my 10-17 and 50-200 lenses) or 3. the 35mm prime for pentax which is an f2.
I have to say that for the most part I have found myself draw to a lot or architecture picture taking and some landscape am not looking for a good portrait lens at this time . I am looking for a lens that will fit these two areas right now and will also give me the options for low light use as well. They will be used on the K100d by the way. Thanks for reading this and any suggestions or opinions would be helpful, I know that us pentax users are in the minority here but just wanted to ask

 

[Master Mason]

Well based on what your looking for, I would rule option 1 out, it should be horrible for low light. Option 2, f/4 is not particularly wide either, most of the "fast" zooms are f/2.8 But should be fairly good for archtecture shots. Option 3. I am not that big a fan of primes as others, although this is the fastest lens of your options, so it would be the best for low light. 35mm on a 1.5 crop is basiclly the same as 50mm on 35mm film, so it is a "standard" lenght and many folks used just this single length for years without ever having anything else.

 

[Groucho]

For architecture/landscape, I would think you'd want a lens with the best sharpness and least distortion - I think that would probably put the 18-250mm at the back of these particular options.

The 16-45mm is very well liked and while it doesn't go down to F2.8, it is reportedly still extremely sharp at F4.0, as sharp or more than most F2.8 zooms at that aperture. Still, it's very popular with its owners (and the high cost of the Pentax 16-50mm F2.8 will probably keep it popular for a while longer.)

The 35mm F2.0 is supposed to be very, very nice. That is the lens that I should probably be looking at instead of the 31mm F1.8 (which is way more expensive)... however, you'll obviously be giving up a lot of width to the 16-45mm lens, which can be important for what you're trying to take shots of.