Sigma 17-70 OS F2.8-4 vs Tamron 17-50 2.8 VC - My Comparison

futureal33

futureal33

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For those who are interested I am doing a load of comparison pics between the above lenses (Sigma 17-70 OS f2.8 - 4 : http://www.amazon.co.uk/Sigma-optic...JB32/ref=sr_1_1?ie=UTF8&qid=1298116102&sr=8-1) and the Tamron 17-50 f2.8 VC: http://www.amazon.co.uk/Tamron-AF17...D6ZQ/ref=sr_1_3?ie=UTF8&qid=1298116137&sr=8-3)

First of my comparison pics

Sigma @ 17mm, f2.8, ISO 640, 1/500sec

Sigma 17mm f2.8 by futureal33, on Flickr

Tamron @ 17mm, f2.8, ISO 640, 1/1000sec

Tamron 17mm f2.8 by futureal33, on Flickr

100% Lightroom crop - Sigma on the left, Tamron on the right

Sigma left Tamron right - both F4 by futureal33, on Flickr

More on the way
 
scottthehat said:
the test are flawed, did you use a trypod, and both sets the tamron has a faster shutter speed(why).
also look like the focused in different places.
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a tripod was used, along with remote shutter release.

Camera was on AV Mode, so it picked its own settings based on my chosen aperture - I can only assume the Tamron must be naturally brighter

Focus was on the same place (the tree)
 
Erm, maximum image size allowed on the fourm is 1000px on the width - expect a visit from the pixel police some time soon... :police: :D
 
scottthehat said:
all my pics come out this size, its just what photobucket and flicker resize them to.
oh didnt realise some were so big sorry.
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Now I'm really lost, Scott, as it wasn't you that posted any oversized pics?? :thinking:
 
Having had two Sigma lenses, my huge issue with them is the variable quality control. Even if someone demonstrates that the Sigma they have is the sharpest thing in the world, the chances of me getting one the same are very remote.

The 17-70 I bought new had to be sent to Sigma UK to be calibrated immediately. The 24-60 I owned afterwards was so soft at f/2.8 that it rendered the lens effectively pointless.

I'm never buying a Sigma lens again I'm afraid.
 
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They look like they're focused in different places to me, obviously not on purpose, I think the sigma looks to be front focusing. Have you done a focus accuracy test for these lenses?
 
Vertigo1 said:
Having had two Sigma lenses, my huge issue with them is the variable quality control. Even if someone demonstrates that the Sigma they have is the sharpest thing in the world, the chances of me getting one the same are very remote.

The 17-70 I bought new had to be sent to Sigma UK to be calibrated immediately. The 24-60 I owned afterwards was so soft at f/2.8 that it rendered the lens effectively pointless.

I'm never buying a Sigma lens again I'm afraid.
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I was worried about sigma qc when I was looking a a 2.8 telephoto, however I'm glad I didn't let it put me off! I bought the Sigma 70-200 2.8 EX HSM II and I couldn't be happier! Tack sharp at f2.8 and beautifully built. I can't image the Canon being any better tbh? It seems to be the wider lenses that suffer from the qc issues...
 
Mahoneyd187 said:
They look like they're focused in different places to me, obviously not on purpose, I think the sigma looks to be front focusing. Have you done a focus accuracy test for these lenses?
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Interestingly yes...

The Sigma is front focusing a little bit (whether or not its enough to send back for re-cal I havent decided yet)

The Tamron is significantly front focusing, so much so that the AF point is slightly soft, but a few mm infront of it is pin sharp..

SO I got to thinking.. I reckon the Tamron pics show that small square tiled object that I zoomed in on as being so sharp because its slightly ahead of where I was focusing - hence the Tamron's severe front focus actually helped the sharpness!
Whereas with the Sigma it's focus was more accurate on where I was meant to be focusing, and that small tiled object is OOF because of DOF.... I dont know

I will upload my focus tests tonight, but the Sigma is only just front focusing so Im not sure its worth a recalibration??
 
Nick, that's not a good test of whether a lens is front or back focussing - it may just be focussing on what it determines to be the most contrasty bit of where you're aiming. I would test it with a ruler, using both auto and manual focus.

I tested the Tamron 17-50 VC not long ago and I found it lacking when compared to the non-VC version. On days when I don't want to haul around the Canon 24-70L or similar, I reach for the new Sigma 17-50 f2.8 OS - it's killer (but very expensive) and is on par with the finest optics out there.
 
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