Tamron 28-75 vs Sigma 24-70...the showdown!

I posted in a different thread last week and said I'd come up with a bit of a comparison between these two lenses since I have them both in my possession for a couple of days. Here's the story:

I originally ordered the Sigma 24-70 from Dell when my girlfriend ordered the Xti she gave me for my birthday (thanks babe!). I've been reading tons and tons about SLR photography and the differences between lenses and such in the last 8 months or so. I had pretty much settled on the Sigma 17-70, the 24-70, or the Tamron 28-75. The Tamron example thread is pretty impressive, and it has gotten rave reviews all over the web. That would've been my first choice, with the Sigma 17-70 as second, and 24-70 third. Dell doesn't offer the other two lenses, and so I ended up ordering the one they had.

When the lens arrived, I was astonished at how big it was compared to what I had expected from photos I've seen of it. To me, that was a bit of a turn-off. Mostly because I realized that it has an 82mm filter size, and those tend to be insanely expensive. All in all though, it has a nice heft to it, and feels very solidly built. The focus ring clutch was a bit strange to get used to, but once I realized I could just click it back so it didn't turn during auto focus, it was a lot better. The Sigma lens also comes with a really nice lens case that stores the lens vertically with the hood and both caps. It has a belt loop on the back, but the case is a bit too big to really use effectively on one's belt.

The zoom and focus rings are both really tight, and I didn't have any issues with zoom creep. The autofocus is a little noisy, but I've never owned a lens with USM, so it's not that big of a bother to me. I can see it being a little annoying in a quiet setting, but so far all my shooting has been outdoors or in my home. It's pretty accurate for the most part, but like most lenses, tends to hunt a little in low light, especially on scenes with little texture.

The cost of the filters and the sheer size of the lens turned me off a little, so I decided to order a Tamron in to see how they compared and send back the one I didn't like. I received the Tamron yesterday evening, and had a bit of time to go shoot with it last night as well as some non-scientific testing this morning before work.

My first impressions of the Tamron were very positive. It was considerably smaller than the Sigma, and a bit lighter as well, which feels better on my Rebel. Zoom and focus rings are smooth, and the auto focus seems quite accurate. It also hunts a little in the same scenarios as the Sigma does, so I'll assume that's common.

I shot a few test pictures of some things on my desk, and thought I'd see about making some comparisons between the two to help decide which one I feel takes better images. A slight disclaimer before I start posting images though. I didn't realize until afterward that I was shooting in Aperture priority, so the camera metered a bit differently between the two lenses. So, take these with a grain of salt for now, I'll try to take a few more of some different things tonight when I get home or tomorrow. All shots are lit by morning sunlight from a window to the right.

Sigma 24-70 @ 70mm: f/5.6 1/15 @ISO200

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f/5.6? That's 2 stops down. Such stopped-down apertures usually give extremely sharp images even on the crappiest lenses such as the kit lens. My Tokina 28-80/2.8 is extremely sharp at f/5.6 80mm, but gives a soft-focus effect at f/2.8 (perfect for portraits but hardly for anything else). Could you rather post shots that were taken from a tripod, wide open at f/2.8 at full telephoto - 70mm (Sigma) and 75mm (Tamron)? That would make a nice comparison!

I am VERY curious why you didn't do the comparison at f/2.8?

Would like to see a 2.8 test also, maybe getting the Sigma soon and seeing what it can do against the Tamron would be nice to see. Cheers

I figured he was using a tripod. =T Most people would have some shake since he took them at 75mm @ 1/20 and 75 @ 1/15.

aoleg wrote in post #3739590
f/5.6? That's 2 stops down. Such stopped-down apertures usually give extremely sharp images even on the crappiest lenses such as the kit lens.

Well F/5.6 seems like a realistic aperture people would be shooting outdoors with their standard zooms, to me anyway.

Thanks for the examples nebular .

laxx wrote in post #3739631
I figured he was using a tripod. =T Most people would have some shake since he took them at 75mm @ 1/20 and 75 @ 1/15.

Cheers from Head-Fi

asylumxl wrote in post #3739750
Well F/5.6 seems like a realistic aperture people would be shooting outdoors with their standard zooms, to me anyway.

Thanks for the examples nebular .

It's not as much a factor of light as it is for the look. I know a lot of people would rather have the isolating look of f/2.8 and would shoot at f/2.8 in any sort of light.

I have 2.8 shots of the same piece of pottery; I'll post them a little later this evening.

One thing, the 4mm on the wide is way more important than the 5mm on the long end. I want to see the 2.8 shots as well.

I had to return the Sigma today, Dell sent a militant UPS driver to my house and demanded the box! I think I have some decent wide angle comparisons as well, I believe that I at least have the focus chart at 24 & 28mm @ f2.8. I'll post those as well when I go in to work later tonight.

How is the Sigma's crop so much closer?

angryhampster wrote in post #3741005
How is the Sigma's crop so much closer?

He probably moved the tripod.

I have the Tamron 28-75 and it's sharp and wonderful at 2.8 on a 30D and MKII. I was thinking of eventually "upgrading" to the 24-70L, but the lens is so great already that there's nothing that would justify the 3.5x price tag.

Mrvile wrote in post #3741055
He probably moved the tripod.

When I went to Photoshop and entered 800 px by 800 px into the crop tool, it let me drag a square however big I wanted, like I said I probably just did it wrong.