[mikesbike]

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Well, you have stated aperture speed is important, so this eliminates the otherwise very good-performing Pentax HD DA 18-50mm f/4-5.6 DC WR lens or the DA 16-45mm f/4 as well. When you need the f/2.8 aperture or close to it, this is important. One other possiblity is the HD DA 20-40mm f/2.8-4mm Limited. Fine imaging, but of shorter zoom range, it offers f/2.8 at the short end and just one stop off at the long end. it has steller build quality, and WR, but it offers much more compactness compared to others having an aperture of f/2.8 capability. In fact, it is my preferred choice for compact carrying. However, as UncleVanya says, not very budget. This is a premium Limited lens.

Otherwise, I too recommend the Sigma 17-50mm f/2.8 EX DC HSM lens if you can find one in perfect condition. Well-built, well-designed, excellent imaging. I have all but the DA 16-45mm of these lenses.

---------- Post added 04-05-23 at 08:07 PM ----------

I had a Sigma 17-50 2.8 and used it a lot a few years ago. It was a good lens, as long as you didn’t shoot wide open. However I needed a weather resistant lens and got the Pentax 20-40 which ended up replacing it. Again, the Sigma is good, but it’s quite a chunky lens for not really being a usable 2.8, but then maybe that was just my copy.

Yes, another reason I often choose to go with the HD DA 20-40mm f/2.8-4 DC WR Ltd. And it is probably better than most for avoiding flair for improved clarity. The Sigma 17-50mm is chunky, but not for its range and what it can do. It is actually sharper wide open than the older Pentax DA* 16-50mm f/2.8, but as far as shooting at f/2.8 with this Sigma lens, just a tad of stop-down to f/3.2 makes for a big imiprovement! The Tamron was shown to underexpose slightly, making it actualy f/3.2 anyway, and it has very high field curvature. OTOH, the Sigma 17-50mm has been tested as having essentially zero field curvature, which is remarkable for any lens, especially a zoom lens with WA capabilities.

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Last edited by mikesbike; 04-05-2023 at 09:46 PM.

[Wasp]

Keep in mind that on APS-C the gap between 16mm and 18mm is bigger than you might think. The difference is about the same as 24mm and 28mm on full frame. The Sigma 17-50/2.8 occupies the middle ground and it has a fast aperture - what's not to like?

[artrasa]

I used to have the DA 18-55 II lens and found its images were very sharp only on one side of the frame, the other side being quite blurry. That lens only worked well for close-up pictures, where the subject was near the center of the frame and the sides were out of focus. I replaced it with an SMC-F35-80 lens and was very happy with that one.

[kypfer]

I would now like to find a drop-in replacement for my 18-55 DAL lens. I know that many find this lens to be quite sharp, but that is not my experience. Maybe my copy is flawed; I don't know. But there are a few others I have seen.

Not my experience
I have several Pentax 18-55mm lenses in various configurations, the "cheapy" DAL with no focus scale or Quick-Shift, the "normal", and a WR version, all of which are perfectly acceptable!
I do find the little "window" in the (optional?) lens hood to be very useful for adjusting a polariser.
As for "alternatives" :-
The Sigma 17-35mm f/2.8-4 EX is bulky by comparison, but good, the Sigma 18-50mm f/3.5-5.6 is "almost" a direct replacement, but has neither the manual focus over-ride ("quick-shift") or the little "window" in the lens hood for controlling a polariser, possibly because the front element rotates when focussing, but at least the lens hood is included!
My HD Pentax-DA DC WR RE 18-50mm f/4-5.6 covers most bases, having got used to the extract/retract mechanism and learnt not to try to hurry it, but the lens hood arrangement again makes the use of a polariser difficult, if not impossible!

My conclusion : the "normal" Pentax-DA 18-55mm AL is hard to beat for overall performance, especially when you factor in the close-focus capability of just 0.25m, the ease of use of a polariser, and the Quick-Shift feature

[K2 to K50]

I have little to no experience with the general 18-50/55 mm ranges, and am not sure about comparative weights/sizes, but am a little surprised to see no one here has suggested the 16-85mm. It is sharp, and has a short minimum focal distance. But I don't know how it fares on the 2nd hand market (or how often it shows up in the 2nd-hand market), and may not be in your budget range. It has been on significant specials brand new at B&H et al from time to time.

A quick search on "Used Pentax 16-85mm" brought up this:
https://www.ebay.com/b/Pentax-DA-16-85mm-Focal-Camera-Lenses/3323/bn_115913314
Quite a range from lowest to highest price on this page.

[Jonathan Mac]

I have little to no experience with the general 18-50/55 mm ranges, and am not sure about comparative weights/sizes, but am a little surprised to see no one here has suggested the 16-85mm. It is sharp, and has a short minimum focal distance. But I don't know how it fares on the 2nd hand market (or how often it shows up in the 2nd-hand market), and may not be in your budget range. It has been on significant specials brand new at B&H et al from time to time.

A quick search on "Used Pentax 16-85mm" brought up this:
Pentax DA 16-85mm Focal Camera Lenses for sale | eBay
Quite a range from lowest to highest price on this page.

The 16-85mm is an excellent lens, arguably better than the Sigma 17-50mm, but it's a lot more expensive than any of the other options which is probably why it's been omitted.

[calsan]

15mm limited is always the correct choice. Even when you think you want a fast zoom. 😄
It's so much nicer than any other wide angle I've used. I've found the 18-135 is very good between 18 and 70mm approx. So I use that mostly and carry the 15mm for wide angle fun. This setup is fairly small and light and you get 135mm as a bonus if there's plenty of light.

[AfterPentax Mark II]

Looking at the prices you quoted, perhaps you can find the Pentax 18-135 for a reasonable price. A lens which, like me, is enjoyed by many people here. It starts near what you wish for wide angle and ends up way beyond at 135mm. Very good and silent focusing lens, producing nice (even better than nice colours. Bought it for my first DSLR and now when attached to my KP it really shines. Recommended!

PS.: Nice to know perhaps that the Sigma 17-50 f2.8 was not meant as a budget lens, when just on the market it was aimed at more serious photographers and the price then was accordingly.

[gatorguy]

Looking at the prices you quoted, perhaps you can find the Pentax 18-135 for a reasonable price. A lens which, like me, is enjoyed by many people here. It starts near what you wish for wide angle and ends up way beyond at 135mm. Very good and silent focusing lens, producing nice (even better than nice colours. Bought it for my first DSLR and now when attached to my KP it really shines. Recommended!

PS.: Nice to know perhaps that the Sigma 17-50 f2.8 was not meant as a budget lens, when just on the market it was aimed at more serious photographers and the price then was accordingly.

I keep the 18-135 in my truck along with a K-70. You're right, it makes a nice do-it-all kit.