Tamron 28-75 sharper than Canon EF70-200 f/2.8L?

grego wrote in post #2606788
IS version!!

Where does it say that?
I thought we were talking about the 70-200mm f/2.8L.. not the IS

I'm not sure if anyone already mentioned this, but you're also shooting at different ISOs.

While I appreciate all of the comments here, I don't believe that IS will help at a shutter speed of 1/4000 nor do I believe that any substantial camera shake occurs at that speed. Nor do I believe that ISO settings will affect the sharpness. ISO will add grain to the image, maybe visible as noise in some extreme cases but certainly not as blur.

Maybe some blur is due to shake but when I view the raw images in DPP with sharpness set at 0 the 70-200 is definitely blurry. The same lens shot at f/8 is sharp and clear. Wouldn't camera shake be present in both cases? The f/8 shot was even at a lower shutter speed.

Dan

Based on my experience with both lenses, I think it's very likely your Tamron is sharperthan your Canon 70-200 2.8 at f2.8.

Dan, I still insist on tripod use to eliminate all the variables; you may well be right about 1/4000, but you can dispell doubt simply with use of the tripod for the testing!

Now having said that, look at the MTF measurements on photozone.de and you will see the Tamron 28-75 has peak center MTF values of 2073-2148 (I am using 'peak center MTF' to show max MTF for the lens at different focal lengths) and at f/2.8 it has center MTF values of 1785-1889. In comparison, the 70-200 f/4L has peak center MTF of 1805-2032, and wide open f/4 center MTF of 1805-1952. The 70-200 f/2.8 IS has peak center MTF of 1781-1960 and f/2.8 MTF of 1781-1795. The 70-200 f/2.8 (non IS) has peak center MTF of 1888-1937, and at f/2.8 center MTF of 1728-1810.

What this shows is that the Tamron and the 70-200 f/4 are about the same...one excels wide open, the other has higher ultimate performance it is optimum f/stop. But the Tamron is clearly superior to the 70-200 f/2.8 IS in MTF measurement. And the Tamron had an advantage over the 70-200 f/2.8 wide open, but negligle (the advantage might shift the other way around with two other sample lenses in the test).

Grego - IS is on my mind

I appreciate all of the comments and sorry to project my frustration.

I did forget something very important - buried in an earlier post is a comment that nobody has mentioned and I forgot this morning. I shot one image yesterday afternoon with the 70-200 L at 200mm, f/2.8, ISO 100, 1/4000". It was the sharpest image of this "test pattern" that I have taken at f/2.8 so far. The only difference was that I removed my UV/Haze filter. It's a Canon Sharp Cut filter.

Could that be the entire problem? (caffeine, shakes, ISO diff, focal length aside)

Thanks again for your comments. I really appreciate the help that I get from POTN.

Dan

I have both lenses and have to admit that on more than 1 occasion i've mistaken pics taken with the Tamron as ones taken with the 70-200L, both lenses are wicked sharp. It wasn't until examining EXIF info that I was amazed at which lens I had used. And my 70-200 is tack sharp, often I try to sharpen in photoshop only to realize that I can't sharpen the photo anymore than it is straight from the camera.

Canon filters do not meet the same standards as the SHMC Hoyas and B+W and Heliopan. It has been suggested that they are made by Tiffen... I have owned a Tiffen polarizer that acted like a prism (discovered during simple eyeball exam when I was comparing a linear to a circular polarizer over a decade ago) and I promptly threw it out and never bought another Tiffen ever again!

asabet wrote in post #2608365
Based on my experience with both lenses, I think it's very likely your Tamron is sharperthan your Canon 70-200 2.8 at f2.8.

My Tamron 28-75 is a very good performer. I do wish it were a tad wider, but I'd hate to give it up.

My understanding of the need for a tripod is that you are attempting to do a basic "laboratory" test. You've got to eliminate as many variables as possible to ensure the most accurate results.

A tripod will do that. How can you be certain you are in the exact same position when handholding? You can't. You will be off an inch or two or even more. If you want an apples to apples comparison, you have to use the same condition for each lens. Otherwise the test is nothing more than photos of a piece of paper.

Just my thoughts on this. I'll be interested to see your future results. I own the Tamron and love it, but am considering the 70-200.

dlpasco wrote in post #2608305
While I appreciate all of the comments here, I don't believe that IS will help at a shutter speed of 1/4000 nor do I believe that any substantial camera shake occurs at that speed. Nor do I believe that ISO settings will affect the sharpness. ISO will add grain to the image, maybe visible as noise in some extreme cases but certainly not as blur.

Dan

You are correct that a different ISO would not make a difference in sharpness in RAW, but if you are comparing JPEGs, then it will make a difference. The noise reduction software in camera does blur the image slightly while it reduces noise. If you were to shoot the same image at iso 100 and iso 1600 and compare the JPEGs, you would have a significant diference in sharpness at a 100% crop.

I'll admit I didn't check the EXIF to see your shutter speed. 1/4000 would most likely have no shake but one can't rule it out completely.