Review Sigma 17-70mm f/2.8-4.5 Mini Review

danza

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#1
I've owned the above lens for a few weeks now. It's been on my camera for 99% of the time.

The pictures attatched are purely indicative of what the lens can do, although there's a bit of PP on the images anyway (not much mind, slight sharpen/saturation boost/cropping). I've not included any 100% crops, because I can't be bothered at the moment :p .

Build Quality: This lens is reasonably well built. No rattles, wobbles or tacky flimsy bits (well, I'm sure it'd be toy-like compared to L glass and the like, but it's not being compared to L glass, so it doesn't matter). The lens is solid and generally as to be expected from other Sigma lenses at this pricepoint. It's quite light weight which is a bonus, and on my 20D with both around my neck, it's barely noticable. There's a zoom lock to lock the lens at 17mm, but I really don't see much point in this, as I've not experienced any creep whatsoever. The focus and zoom rings are ok, and turn quite smoothly. The zoom ring feel is a bit variable through rotation, but not too noticably.

The build is genarally a little lower than the Nikkor 18-70mm f3.5-4.5 AFS jobbie.

Focusing: The 17-70 focuses quite quickly, with little tendance to hunt except for with the normal difficult test subjects with little light/contrast. Focusing is by no means silent, but not distractingly loud either. The Nikkor 18-70 is a little faster to focus, and a lot quieter.

Close focus ability is quite incredible. Sigma enthusiastically brands this a a 'macro' capable lens. It's not as closest focus at 70mm 'only' yields a maximum 1:2.3 magnification. Close focus sits at 20cm throughout the zoom range. At 70mm the front element is literally 1" from the subject (no good for nervous insects/spiders). Wide angle close focus give the opportunity for some interesting caricatures (as seen in the dog picture below).

Image quality: Image quality is reasonable on my copy of this lens. Wide open it has the usual non-pro lens softness, which improves after about f/4.5 at 17mm and isn't actually too bad at f/4.5 at 70mm, but improves greatly after f/7.1 upto about f/16 when it begins to go pretty damn soft (same goes for 17mm). Barrel distortion is apparent at 17mm, but it's not extreme. There's very little sign of pincushioning at 70mm, which is to be expected. Vignetting is slight at 17mm, but this all but disappears at about 25mm.

The only real gripe I've had is edge fringing between high/low contrast subjects. It can be quite severe to the extent that it's surprisingly bad. If you're sympathetic to this, and work within the lens' limitations, it doesn't pose too great a problem.

Colour definition is merely OK. Most shots seem to have a slight yellow cast (which is obviously fixable during PP). To me this isn't a great problem, and I'm comparing it to 'superior' lenses that I used to own.

I would put this lens on par with the Nikkor 18-70 (I've owned one of those before I turned Canon), as far as outright IQ is concerned. The 18-70 has little issue with fringing or colour cast, but this lens is a bit sharper. Just. The Sigma's f/2.8 at 17mm could also be deemed quite useful for environmental portraiture and similar indoor situations, but bare in mind that maximum aperture diminishes early on in the zoom range. Compared to the Canon 18-55 kit lens, there's no competition.

Should you buy this lens?

Generally, yes. If you already have a Nikkor 18-70, I'd avoid it. It is more versatile, but not worth the hassle of flogging lenses through eBay and the like to raise the funds. It's a massive step up from the Canon kit lens in terms of speed, build and IQ. I'd recommend this lens as a replacement for the kit lens if you can't warrant dropping £400 on L glass. There's also the Sigma 18-50mm f/2.8, and the Tamron 17-50mm f/2.8. These are better built, but in some cases the 17-70mm has been found to be just as sharp at like for like zoom and aperture settings. I think though, you'd have to be pretty lucky to get a real gem of a 17-70, so as long as you bare this in mind, you won't be disappointed.

The area in which the Sigma 17-70mm shines is versatility. It really is a useful lens for most every day shooting about town or on walkabout. I don't know of another lens that offers such a package in this respect. Price is similar to the Nikkor 18-70mm, so I'd recommend trying them both, and then buying the Sigma :D





This beetle shot is approx. 33% crop of original.

 
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Renee
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#3
Thanks for this. It just so happens I was having a look at replacing my kit lens and looking at this. Now to convince the husband!

I'm really finding my lenses (or lack there of) holding me back when I take shots but I can't get hubby to see that....
 
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danza

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#4
Thanks for this. It just so happens I was having a look at replacing my kit lens and looking at this. Now to convince the husband!

I'm really finding my lenses (or lack there of) holding me back when I take shots but I can't get hubby to see that....
Look around for other reviews too ;) It's generally a very well regarded lens.

As for the colour cast issues, the picture of my cat was not altered to correct the cast, and as can be seen, it's quite yellow.

I know what it's like trying to get new purchases approved by the other half. I'll be waiting until at least christmas to buy a decent 70-200!

However, if I was still single, I'd probably own a 1D of some sort and a load of expensive glass to fit on the end. I would however be totally flat broke :p :D
 
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