[heatherslightbox]

I have an older Sigma 17-70 (2nd gen) that developed some AF issues, so I sent it in to Sigma to see what the problem was and get an estimate on how much it would be to repair ($120). In the meantime, I got a sweet deal on a DA 18-135. I’m not sure as to whether it would be worth it to get the Sigma fixed or to have them send it back to me so I can sell it for parts or repair.

Thoughts? TIA!

[pepperberry farm]

how do the photos from the Sigma compare?

[Vmax911]

Weather sealing on the 18-135mm is a big plus (to me) for a walk around lens. I've never used the Sigma, but for a long time it was the walk around lens to have. Guess you will have to compare the IQ and if you need the faster aperture of the sigma.

[UncleVanya]

Objectively:

17-70 is wider but like the 16-85 it is shorter only more so.
17-70 is faster wide open.

18-135 is weather sealed
18-135 will support in camera jpg corrections
18-135 has typical Pentax color rendering

18-135 lacks edge sharpness over 70-80mm (but I haven't found this a limitation for how I use the lens)

Sigma has had an excellent support reputation, but their future has no k mount plans in their future.

Ultimately I would compare the weight size and pictures... Then pick.

[luftfluss]

I would pay $120 to get it fixed, because I would want to compare it directly to the DA 18-135. It should be easy to sell the Sigma for more than the repair cost, if you decided you didn't want it.

[hcc]

One advantage of the DA18-135mm is its WR plus its small size and light weight (405 g). On both counts, the DA18-135mm is more friendly when you bush-walk IMHO. For me, that is an important aspect as I do a lot of outdoor photography and bushwalking.


My 5 cents.

[beachgardener]

wouldn't touch sigma with a forty foot barge pole,

the 18-135 is a nice general purpose lens, I enjoy mine.

[kiwi_jono]

Personally I had a first gen SIgma 17-70 which I wasn't that fussed with (although obviously a lot of people enjoy it) and I sold it even before I got a DA 18-135. This was a few years back now but optically the DA 18-135 compared to 17-70 (over the common 18-70mm range) was much better in my tests (I took photos of same fence etc with a range of apertures).. You do miss out on 1mm at the wide end (which is noticeable) and maybe a half stop of aperture but otherwise the DA 18-135 was the winner for me.

That said it would be fun to do some side by side tests - if you think $120 is worth it (I imagine you might recover this if you sold it?).

[mkgd1]

I would pay $120 to get it fixed, because I would want to compare it directly to the DA 18-135. It should be easy to sell the Sigma for more than the repair cost, if you decided you didn't want it.

I agree with luftfluss, for $120 you will either have a lens as good as new which you can keep or easily sell. The market for working lens is much better that the parts market.

[tokyoscape]

it is depended on the price of the sigma in the second hand market. From a quick look on ebay If i am looking at the right one, I would fix it.

[Apet-Sure]

I bought a used copy of this lens about two years ago:
Sigma 17-70mm F2.8-4.5 DC Macro Lens Reviews - Sigma Lenses - Pentax Lens Review Database

I have been very happy with it. Several of the shots in my albums were taken with it. Though not a true 1:1 macro, it's max. magnification is about 0.43X, compared to 0.24X for the 18-135. This is important to me. If it broke, I would be tempted to get it fixed, or try to figure out a way to afford the Pentax 16-85mm. When I read lens reviews, I usually only consider lenses that have sharpness and aberration ratings of 8.5 or higher. The 18-135 doesn't quite measure up on paper, though it may be a fine lens in practice. The focal range is certainly attractive, but personally I would rather have higher IQ.

[mikesbike]

Actually, the DA 18-135mm performs better in real use than on paper. it is quite competitive and then some with the Sigma lens in question, since like most other zoom lenses the Sigma will not be quite as good at its extreme long end. While the edge performance of the Pentax lens starts to lose at around that 70mm FL, central area remans in the excellent range, while the Sigma's edge performance is not all that hot either at wider apertures, and its central area performance is reduced as it is zoomed to its longer end. As one goes more into the tele range, for most scenarios edge performance becomes less important, but the Pentax lens does very well in the central area indeed throughout, even coming in as excellent, while the Sigma lens does not. The DA18-135mm can even provide good bokeh in portraits and other closeups.

The above information is from test results- see OptiaLimits. The Sigma lens can be found there under the Nkon APS-C section. But I tend to ignore many of their rating conclusions, and just look at the results for myself. They often get carried away with minor concerns- like corner performance while edge performance is ok. Or edge performance at the tele end of a longer range zoom lens. How relatively important are those factors in most actual photographs?

Again, the Pentax lens even at the edges is good to excellent up to 70mm, even for landscapes when stopped down a little, where it is very good to excellent, and stopping down is best for landscapes anyway. Central area is excellent even as it is zoomed well into the tele range even out to 135mm!. Exceptional for a lens of such zoom range and compactness.

Together with its very wide and very useful zoom range, its fine performance, its compactness but very good build quality, its quiet, fast, accurate AF (one of the best), WR construction, and communication with Pentax bodies for all the benefits that entails, if it is a matter of either-or, I would take the DA 18-135mm in a heartbeat. I have many top-rated lenses, but I would definitely not want to be without this very capable and useful lens.

Incidentally, the DA 18-135mm can hold to f/3.5-4.5 up to70mm.

[heatherslightbox]

Just an update—I’m going to go ahead and have the Sigma lens fixed. As to which lens I wind up keeping, I haven’t made a definite decision yet. I know that the Sigma is a perfectly good lens, but I like the fact that the 18-135 has a wider focal length range and that it’s a good bit lighter in weight than the Sigma. I also love the rendering that the Pentax lenses give, which as good as the Sigma is, it doesn’t have. Even though it’s slower in aperture, I’m OK with running up the ISO if I need to. I’ll have some time off next week to get out and put it through it’s paces.

[UncleVanya]

I'd go for the Pentax lens as well for all the same reasons. One additional point, of which you're probably already aware, but there are two versions of the 18-135, the cheapo "kit lens" that has a "DAL" designation and the "real one", the DA WR version. I'm told they're optically identical but I think the housing matters, especially (for me, as I do outoorsy stuff) the water resistance.

I think you are confused. There are DA L versions of a few lenses but not that lens. See here: Pentax DA L Zoom Lenses - Reviews and Specifications - SLR and Interchangeable Lenses - Pentax Lens Reviews & Lens Database

My DA 18-135 came in my k-50 kit and is identical to other copies I have seen. It has an original Pentax hood and quickshift which typically are missing from DA L lenses.