Can you tell which lens is which?

Just call me Al

Active Member
Following advice from this and another forum I went along to test 6 lenses. Unfortunatly I could only find two of the lenses.
One is "The Canon 28-105 3.5-4.5 usm 11"
The other is a Sigma 17-70.

Both lenses are around £220-00.

I took a number inside & outside. Then took the sharpest & cropped a small area. These are the results.

Can you tell which is which?


Well-known Member
Well I think I'd go for the 2nd lens. Looks sharper and more controlled. I am viewing on a laptop though and it's pretty difficult to tell differences in sharpness and contrast, though the 1st is more colour saturated.

I'd say #2 is the Canon but only a guess really.

More interesting would be a £2000 lens -v- a £200 lens - that would be telling.


Novice Member
If they are both center crops then its really hard to tell..on a laptop the first ones looks sharper.

try to post up corner crops at 100% - much easier to tell...also what was the aperture? if one is wide open and the other is stopped down then that will make a hell of a difference.


2nd one is definteley sharper in the 2nd photo - other one is too small to tell.


Active Member
I would also take the 2nd one. The first is brighter, but the second is definitely sharper. I would also guess the second being the Sigma, but I'm not very god at lenses
The 2nd photo in each set is easily the better, the first photo suffers from excessive blur (probably motion blur, what shutter speed where you using?).

I'd personally not buy the lens that took the 1st photo in each set and I think that this may be the Canon.


Well-known Member
Judging from the colours on the first, I'd say it was the Canon. Either way it seems to be the more faithful if not the sharpest.

Just call me Al

Active Member
Yes the top one is the Canon in both pictures. Both lenses gave sharp results but I'm amazed at how good the Sigma is allowing for it being 70mm Tele & the Canon being 105mm Tele. As the Sigma starts at 17mm it looks to me as a good buy. I know it's not the best of tests but I think it gives a reasonable idea of the lenses. Thanks for helping.

Just call me Al

Active Member
Here are the two inside pictures before they were croped. I havn't touched them up apart from resizing to upload to Flickr.

I had to set the ISO on the canon to 400 to get a sharpish picture. Below that they were all out of focus, however the Sigma took the picture on ISO 100.

There is also the fact that it is hand held & the canon has a longer tele so that could make a difference.



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