[Imp]

Here is my question: I have heard that the Sigma 17-50mm f/2.8 is a better quality optics than the Sigma 17-70mm. However, the PentaxForums reviews for these two lenses has given a higher rating to the 17-70. Which one do you think is better and why? I realize the the 17-70 has a variable aperture. But beside that, is it a better lens (after the new firmware update)?

Secondly, how does the better Sigma lens compare to the Tamron 17-50mm f/2.8? The reviews seem slightly biased because of the price, and both seem to have their pros and cons. Which do you think is better and why?

Also, ignore any price differences in your replies please, because the prices have now dropped so they are all the same.

Thanks!

[JinDesu]

The Sigma 17-70 is not better than either of the 17-50 in optical qualities.

[Adam]

The Sigma 17-70 is not better than either of the 17-50 in optical qualities.

Right, but it's more versatile with the longer range. So if you want be best from an optical standpoint, go for the 17-50, but if you just want a good walkaround lens, the other is the way to go.

[Imp]

Since they are now the same price, which one - Tamron or Sigma 17-50mm f/2.8?

[DSims]

Since they are now the same price, which one - Tamron or Sigma 17-50mm f/2.8?

Perhaps others will reply regarding ergonomics, reliability, and usage, but other than that you should decide for yourself which renders images more to your liking. On that account I'd prefer the Tamron, but others would prefer the Sigma. Take a look at photos from them for yourself. If you like one better, choose it - if the differences are too subtle for you to notice or care, then it doesn't matter.

Tamron SP AF17-50mm F/2.8 XR Di-II LD Aspherical Lens Sample Photos and Specifications
https://pixelpeeper.com/adv/?lens=13315&camera=1263&perpage=25&focal_min=non...max=none&res=3

[mr.b.snowden]

I would go with the Sigma, as I have it myself. The lens is quiet due to HSM and is very fast to focus. Great quality construction too.


It's a fantastic lens, great for portraits, landscapes, and events. Here's the shots I've taken with it on Flickr https://www.flickr.com/search/?q=sigma+17-50&ss=2&ct=0&mt=all&w=63342440%40N04&adv=1

[RAART]

Just wondering how compares Sigma 18-50mm F2.8 DC EX Macro to Sigma 17-50mm F2.8 in terms of optical quality. Sorry for hi-jacking.

[Imp]

I would assume the 17-50mm would be better because it is the newer, updated version. It is also HSM vs. DC motor.

hehe, but for my own question - so far it seems it is still 50-50 sigma tamron. lols

[brelip]

I've owned all three, though not at same time. I only have the Sigma 17-50/2.8 now. Got it just a few months ago for $310 brand new! It is much better than the others IMO. The 17-70 is generally fine but at 50mm, 1 F stop makes a difference is rendering. 17-50 focuses very accurately and I regret i should have bought it earlier!

[Imp]

Do you have any reverse-vignetting problems when shooting into a light? Or focusing issues at short focal lengths? Those are problem i've heard of the Sigma 17-50mm

[audiobomber]

I researched standard f2.8 zooms recently. In all the reviews I read, the Sigma performed better than the Tamron and is better built. I've had the Sigma for a week and I'm very pleased. It is very sharp, and f2.8 is a great feature. My only complaint is the zoom turns the wrong way, but that's trivial compared to the performance. I did have to add +6 in AF Adjust, but otherwise focus is ideal.

Have a look at DXOMark results for a detailed comparison at different focal lengths and apertures. MEASUREMENTS TAB > SHARPNESS > FIELD MAP. The Sigma performs significantly stronger wide open.

Tamron SP AF 17-50mm F/2.8 XR Di II LD Aspherical [IF] Nikon on Nikon D7100 versus Sigma 17-50mm F2.8 EX DC HSM Pentax on Pentax K-3 versus Sigma 17-50mm F2.8 EX DC OS HSM Nikon on Nikon D7100 - Side by side lens comparison - DxOMark


I believe the Sigma 17-50 @ f4 and cropped to 70mm would be sharper than the 17-70. The 17-70 is pretty soft wide open above 50mm.

[RonakG]

I researched standard f2.8 zooms recently. In all the reviews I read, the Sigma performed better than the Tamron and is better built. I've had the Sigma for a week and I'm very pleased. It is very sharp, and f2.8 is a great feature. My only complaint is the zoom turns the wrong way, but that's trivial compared to the performance. I did have to add +6 in AF Adjust, but otherwise focus is ideal.

Have a look at DXOMark results for a detailed comparison at different focal lengths and apertures. MEASUREMENTS TAB > SHARPNESS > FIELD MAP. The Sigma performs is significantly stronger wide open.

Tamron SP AF 17-50mm F/2.8 XR Di II LD Aspherical [IF] Nikon on Nikon D7100 versus Sigma 17-50mm F2.8 EX DC HSM Pentax on Pentax K-3 versus Sigma 17-50mm F2.8 EX DC OS HSM Nikon on Nikon D7100 - Side by side lens comparison - DxOMark


I believe the Sigma 17-50 @ f4 and cropped to 70mm would be sharper than the 17-70. The 17-70 is pretty soft wide open above 50mm.

I concur with audiobomber. I too did the same research work for last few weeks and got the Sigma 17-50 2.8 last week. Rated highest among the 3 optically, better built, very fast and silent focus.

---------- Post added Jan 25th, 2015 at 10:32 AM ----------

I've owned all three, though not at same time. I only have the Sigma 17-50/2.8 now. Got it just a few months ago for $310 brand new! It is much better than the others IMO. The 17-70 is generally fine but at 50mm, 1 F stop makes a difference is rendering. 17-50 focuses very accurately and I regret i should have bought it earlier!

$310 is awesome price for this lens, specially brand-new. I just got it last week for $520.

[AldaCZ]

What about the flare resistance of the Sigma and Tamron ? Tamron is very good but I haven!t used the Sigma

[audiobomber]

What about the flare resistance of the Sigma and Tamron ? Tamron is very good but I haven!t used the Sigma

I suspect the Tamron handles flare better. I tested the Sigma 17-50 specifically for flare to see how it would do.

Sun in the frame could be better for sure, but not a deal breaker, IMO.



In this one the sun is just outside the frame. This is a big problem for some lenses, no problem here.



It held on to the detail in this sunlit snow very well. I believe this image and the one above show quite good resistance to veiling flare.



BTW, long before I was seriously interested in an f2.8 standard zoom, I had the opinion that the Tamron 17-50 was the most problematic lens for auto-focus of any lens I had ever heard of, for any mount, not just K.