[DSims]

If you have a good copy of the FA24-90/3.5-4.5 you might want to keep it. It's a nice lens. As you say, the main drawback is only 24mm at the wide end. $125 is a very low price for it.

As far as Tamron quality goes, there are rumors that the best quality copies stay in Japan. Perhaps it's just that the Tamrons don't hold up well under rough, overseas shipping conditions. Either way, if you buy locally you should have a nice chance of getting a good copy.

[offertonhatter]

I have the Tamron 17-50m and it is useful and fast, also sharp. But there is something about it. I just don't love it as a lens. I can't put my finger on it as to why. Maybe it's colour rendition does not have that Pentax look, even with processing in CameraRAW. Maybe it is the bokeh. I just don't know. The images just look a bit flat in comparison to a Pentax Lens. Hmmm.
I have not got the 24-90, only the 24-80 in that range (which lacks good detail) but then again, the colours and that Pentax POP are there.
Have you thought about getting the tiny SMC-F 35-70mm? That is a superb lens and gives me some wonderful shots. Downside is the wide angle.
You could get a mighty 21mm Limited as well, if you can afford it to give great wide angle shots.
:-D

[UncleVanya]

Anyone complaining about the 18-135 based on the reviews isn't reading much. Yes the border suffers above 100mm, but so what? Look at the pictures people make with it! I love my copy and wouldn't want to drop back to a 17-50 range (or a 16-50 pentax for that matter).

Your choices confuse me however. If you take the 24-90, why would you bring the 21 and not the 10-17 FE? That would answer the question of wider angles.

[emalvick]

I have the Tamron and the 18-135. My Tamron is much better in terms of image sharpness and clarity. I've found it pretty good all the way to f/3.5 and even wide-open it isn't bad. The 18-135 is better than the kit lens and became my everyday lens (despite the better Tamron lens) because of the available zoom range and the ability to use it as part of a super-compact travel kit. Obtaining the 60-250 recently has let me move back to using the Tamron as standard zoom, and I'm happy for it.

The Tamron and 18-135 are roughly the same size and weight, so it really comes down to whether you want the added speed (f2.8) or the added reach 135 mm. PP can work out most differences between the two otherwise.

The other nice thing on the 18-135 is the weather resistance. Third party lenses won't give that. You also don't get the ability to manual focus adjust while in AF mode as you do with the DA lenses (you don't get that with the FA lenses either). That's never mattered much to me, but I'll keep using the 18-135 as a walk around one-lens-fits-all option, and I'll use the 17-50 when quality matters or when I can carry a second lens (the 60-250) or possibly a wider lens (I have a Tamron 10-24 when I need width).

[tibbitts]

I'd compare the 18-250 sigma to the 18-135 pentax, since it seems like the extra length is a significant bonus. I tested an 18-250 sigma, and it was roughly comparable to my pentax kit lenses. By most accounts the 18-300 sigma will outperform the 18-250, but it's not quite available yet for pentax, and probably wouldn't be in the same price category.

The 17-50s are really in a different category . Discounting performance differences, there's a big difference in versatility, and of course in aperture. I've had some AF issues with my 17-50 tamron, and it's got my focus adjustment maxed out at -10, but have been pleased with the optical quality overall. Although I don't have a pentax 18-135 to compare, mechanically the tamron seems more solid than any of my several consumer-grade pentax DA zooms, and the tamron warranty is clearly superior (at least in the US.)

[geomez]

I own the 18-135 and have owned the Tamron. The Tamron has a decent build quality but the 18-135 is better. The Tamron is plastic and the 18-135 is actually half to mostly metal. My Tamron suffered from the front element getting lose and wobbly. I'm not the only one and it's been written about on here more than once. It was an easy fix btw.
Optically I feel like the Tamron was slightly better but was nothing to write home about wide open.
I chose the build quality, quick shift focus, DC motor, WR, and focal length range of the 18-135 over the Tamron.
I have no experience with the third lens.

[JPT]

If you have a good copy of the FA24-90/3.5-4.5 you might want to keep it. It's a nice lens. As you say, the main drawback is only 24mm at the wide end. $125 is a very low price for it.

The reason I say that price is because it's what I paid for it. I wouldn't expect to get any more if I sold it.

---------- Post added 03-07-15 at 05:59 PM ----------

Have you thought about getting the tiny SMC-F 35-70mm? That is a superb lens and gives me some wonderful shots. Downside is the wide angle.
You could get a mighty 21mm Limited as well, if you can afford it to give great wide angle shots.
:-D

Actually. I have both those lenses and have used that combination with my K-01 as a compact kit. It still leaves me with a lot of lens changing, though, because I tend to shoot a lot between 20mm and 40mm.

---------- Post added 03-07-15 at 06:02 PM ----------

The 17-50s are really in a different category . Discounting performance differences, there's a big difference in versatility, and of course in aperture. I've had some AF issues with my 17-50 tamron, and it's got my focus adjustment maxed out at -10, but have been pleased with the optical quality overall. Although I don't have a pentax 18-135 to compare, mechanically the tamron seems more solid than any of my several consumer-grade pentax DA zooms, and the tamron warranty is clearly superior (at least in the US.)

AF problems are a concern to me, because that's one of the main reasons for adding a K-5 II to my kit.

---------- Post added 03-07-15 at 06:16 PM ----------

Your choices confuse me however. If you take the 24-90, why would you bring the 21 and not the 10-17 FE? That would answer the question of wider angles.

I think this is what I will probably do. I'll get the camera and use the lenses I have. The 24-90 will cover quite a lot and only leave me changing for the wide end during the day. In the evening I'll use a faster prime.

I'm actually a bit surprised that more people haven't urged me to get the Tamron since it is so cheap. Perhaps that should tell me something. In any case, everyone's responses have been very helpful.

[Des]

The reason I say that price is because it's what I paid for it. I wouldn't expect to get any more if I sold it.

If it is in good condition, you would get more than $125 for the FA 24-90 if you sold in the PF marketplace. More like $250-300, going by recent sales. Might even increase in value as It would be a good standard zoom on the forthcoming FF body.

@NorthcoastGreg has written a helpful review of this lens: Pentax FA 24-90 f3.5-4.5 | Lens Reviews | The Northcoast Photographer

[audiobomber]

AF problems are a concern to me, because that's one of the main reasons for adding a K-5 II to my kit.

I've read two Pentax forums daily for seven years. It is my firm opinion that the Tamron 17-50mm has more reported AF complaints than any other lens available in K-mount. If you do a Google search, you'll see a high number of complaints with other mounts too. If you buy one, make sure you can return a bad copy, or be prepared to send the lens and body to Tamron for calibration.

[tibbitts]

Based on my experience if AF is a big deal I would probably withdraw my suggestion for the tamron 17-50. Besides my occasional-to-frequent AF disconnect problem that tamron hasn't been able to solve, the need for (at least) -10 (even post-calibration, tested on two K5s) would be a concern. The K5 is kind of limited on adjustments, at least within the supported standard features of the bodies. I don't know about newer bodies but +/- 10 seems restrictive to me.

However I'm still reasonable happy with my lens because the optical performance is good by my standards, and in terms of mechanical build quality, so far it's a huge, huge step up from the wandering front barrel in my pentax 16-45. I would still choose to use it if it was MF only. But my tamron's front end hasn't fallen off yet so maybe I should reserve judgement. Still, I'm confident tamron could identify and fix obvious failures like parts falling off, and I'm happy with the extended warranty and super-fast 3-day service. Buying a pentax lens isn't that confidence inspiring either, given the pitifully short warranty and, by many reports, non-existent service availability.

[clackers]

I use the Tamron 17-50 along with the DA* 50-135 as my two zoom kit - great picture quality.

No AF problems.

[audiobomber]

However I'm still reasonable happy with my lens because the optical performance is good by my standards, and in terms of mechanical build quality, so far it's a huge, huge step up from the wandering front barrel in my pentax 16-45. I would still choose to use it if it was MF only. But my tamron's front end hasn't fallen off yet so maybe I should reserve judgement. Still, I'm confident tamron could identify and fix obvious failures like parts falling off, and I'm happy with the extended warranty and super-fast 3-day service. Buying a pentax lens isn't that confidence inspiring either, given the pitifully short warranty and, by many reports, non-existent service availability.

Have you thought of sending your 16-45mm in for service? Mine lost sharpness a couple of years in, and I sent it for repair. The barrel is now tighter than new and IQ is really strong, easily better than my other zooms; two 18-55's, DA 18-135, DA 18-250 and even the 55-300mm. I don't use it much anymore though, now that I have a DA 15mm, Sigma 17-50 and DA 18-135.

[crewl1]

I will add that I also had a Tamron 17-50 that I could never get dialed in.
In contrast the Tamron 28-75 is wonderful.

The DA 18-135 is my standard travel lens, the range is handy as is the WR.
It is excellent in the center, the edges aren't perfect, but it still makes great shots.

[lmd91343]

Get the Tamron.

I have the Tamron, but not the other two lenses.

The Tamron bested the Sigma 17-50/2.8 and Pentax Flagship lens, the DA*16-50 in center sharpness in the Pentax forum comparison. I have the DA* also. The Tamron is sharper in the thousands of Tamron pictures I've taken vs the few hundred DA*.

The Tamron is a straight thru f2.8. The need for speed cannot be discounted for unexpected, no flash, low light travel situations. Also the subject/background separation that the wide aperture provides cannot be discounted. If your future travel kit plans include a DA*50-135, you can share 67mm filters between them.

My travel kit up to now has consisted of the Tammy 17-50/2.8, DA*50-135/2.8, DA 15/4, and the DA10-17.

[tibbitts]

Have you thought of sending your 16-45mm in for service? Mine lost sharpness a couple of years in, and I sent it for repair. The barrel is now tighter than new and IQ is really strong, easily better than my other zooms; two 18-55's, DA 18-135, DA 18-250 and even the 55-300mm. I don't use it much anymore though, now that I have a DA 15mm, Sigma 17-50 and DA 18-135.

I asked about servicing here and there were mixed reports of whether the wobbly front barrel was repairable or not, which was one motivation for buying the tamron. It's good to know it might be repairable. I thought the 16-45 performed well, slightly better overall than my other kit zooms, but my experience has been that the tamron is better.