17-70

With the debate over the 18-135 (not wishing to retread that!) my search for a walkaround lens is leading me towards the 17-70, which I had previously discounted. I had been planning that my walkaround kit would be the three macro primes and the Sigma 10-20, but having used the Sigma a lot I'm coming to prefer zooms for landscape/cityscape stuff due to the versatility in composition. My 'walkaround kit' would then be 10-20, 17-70, and the DA35 for closeups, which would have the additional advantage of fitting in my smaller camera bag.

Could owners of the 17-70 give me ideas as to what the IQ is like in actual use? My aversion to SDM was what put me off the lens before, but am I correct in thinking that such problems as Pentax had with the tech have been sorted?

I have the Sigma 17-70 os and it is a great lens.

It's really a very good lens indeed and a very useful range. I have no qualms about using it wide open (admittedly only f4) at any focal length as it performs very well from the get go. Colour, contrast, sharpness and bokeh are all excellent. It's very well built, supposedly (though not officially) having some weather resistance.

I recall early after its release some people complained about its performance at the long end, but I think that was sorted out and mine is excellent from 17 to 70. I'd say it was approaching the performance of the DA12-24 (not quite as sharp - the 12-24 is very sharp - but nicer colours); and it has significantly better IQ all round than the DA55-300.

Photozone gives a glowing review of this lens, and in my experience it is quite justified.

Though, of course, no lens is perfect. The weaknesses from my point of view are as follows:
1. Barrel distortion is quite high at the wide end, though this can be easily rectified (but you thereby lose a bit of width);
2. It can hunt for focus over 50mm. For some this is a clincher (against), but the recommended solution is to very gently rest your finger on the focus ring (exerting the most negligible pressure). I find this works very well when it occurs. The focusing issue, is I gather, connected to the very short focus throw on the lens and has nothing to do with sdm.
3. I do sometimes miss the ability to easily throw b/g's due to the widest aperture being f4 not f2.8.

But for me these are all quite minor issues, and I would wholeheartedly recommend the lens. I've no experience of the 18-135, but I suspect that noticeably better IQ of the 17-70 (probably) would make it the preferable walkaround option.

Not again, just try googling SDM malfunctions for the 17-70, you will find 1 or 2 but those are solved by cleaning the contacts so not the crazy things you read about the DA*16-50 and the DA*50-135 lenses.

I've read though that the lens might hunt a bit at the higher focal lengths because it isn't able to lock on but besides that it looks like a fine lens.

I got one recently from a PU member and I'm loving it, despite having a DA*16-50/2.8. Very sharp even wide open, no more distortion than the 16-50 at the wide end, lovely punchy colour rendering. Occasionally will not lock focus between 50-70 but the finger on the focus ring techbique works every time, very fast focus most of the time even when shooting steam trains hurtling towards me at 60mph+. Oh and the close focus setting is a bonus, a fine walkabout lens IMHO.

John

I have the Sigma 17-70 non OS version and I think it is a great lens. Certainly better than it's price tag would suggest. Highly recommended, and the close focussing is a great bonus too!!

The distortion at the wide end doesn't bother me much - it never bothers me with the kit lens (which has about the same distortion IIRC) and on the odd occasions where it would matter I can always use the longer end of the 10-20.

Mhuni covers most of what needs to be said but just to add..

In the 17-70 range, whilst the Sigma is a very good lens, for me the Pentax DA beats it, not for sharpness as they're about equal, but definitely for colour/contrast rendition - the Pentax just produces nicer looking images (in my mind anyway).

The DA17-70 is a very good lens, the DA18-135 doesn't appeal as much to me, partly due to the Photozone review but also of all the images I've seen posted from it I've seen little that really impressed me.

Now to the slight negative...the DA 17-70 does struggle occasionally in low contrast scenes, particularly towards the 70mm end - for my use I've never really found this a significant issue. I'm not convinced this issue is unique to the 17-70 either or as a result of SDM, my DA55-300 does exactly the same on the odd occasion.

Simon

Actually, I find my DA17-70 an astonishingly good lens.

I've mentioned all the following points before in various threads...

The range is perfect for me (I like the long end!), and the contrast and colour are superb. I have some landscape shots taken with it that are almost too sharp!

For me the OOF rendition is sublime. It's as good as the FA24-90, and similar to the 50/1.4 at f/4. In fact, with the K-7 and K-5 I find I use the DA17-70 in situations where the 50/1.4 would have gone.

Having close focus ability is also useful. As mentioned, it can hunt a little at the 70mm end - but I tend to use centre focus only and the hunting occasions are rare.

The distortion isn't normally a problem, and is easily and quickly corrected in LR3

HTH!
Matt