Photozone.de, MTF question?

I'm considering replacing my Tamron 28-75, with a Canon 17-55, as I could use the shorter focal length some and faster AF. Wanting to compare sharpness I went to Photozone.DE brought up the analysis of both. They only have the Tamron tested on a 5D2, while the 17-55 is tested on a 50D. Because of that the total MTF number is reduced.

Is it fair to compare the two numbers are percentage of perfection, i.e. Tam MTF was 80% of upper limit Canon was 85% of upper limit so it's better even though the absolute MTF number is lower? I'm confused.

Seriously? Who cares about MTF numbers?

Go and read some field reviews or look at sample photos here at the board

well, the Canon is an EF-S so they had no choice but to test it on a crop sensor. To be honest, the MTF tests are in a controlled setting, all factors being controlled. In real life, things might not line up so perfectly, so a lens that tests off the charts only really tells you that it has the ability to do so in a certain scenario, not that its guaranteed to. At least thats my take. I have razor sharp pics taken on my T2i, and I have soft garbage taken on my 6D, and vice-versa. Get the focal length that suits your needs, and unless its known to be a junk lens, my guess is that you will be just fine.

travisvwright wrote in post #16342940
Is it fair to compare the two numbers are percentage of perfection, i.e. Tam MTF was 80% of upper limit Canon was 85% of upper limit so it's better even though the absolute MTF number is lower? I'm confused.

For the center, that's probably a good way to estimate.

For edges, it is complicated because those will be cropped off when using on a small sensor.

davidfarina wrote in post #16343014
Seriously? Who cares about MTF numbers?

People who want to objectively compare the resolving power of lenses.

tkbslc wrote in post #16343549
People who want to objectively compare the resolving power of lenses.

Sry but every lens has a little difference i care about what reviewers tell me and if their testing environments is similiar to what i plan to shoot with the lenses. Lookong at mtf charts seems like a waste of time to me. I want to see images and not numbers which can say what it wants. An image speaks for itself...

davidfarina wrote in post #16343572
Sry but every lens has a little difference i care about what reviewers tell me and if their testing environments is similiar to what i plan to shoot with the lenses. Lookong at mtf charts seems like a waste of time to me. I want to see images and not numbers which can say what it wants. An image speaks for itself...

An image speaks for the lighting as much as the lens. Test a kit lens in sunlight and a L lens on a cloudy day and the kit lens is sharper.

MTF under controlled conditions levels the playing field.

And besides, the OP didn't ask for opinions on MTF testing.

tkbslc wrote in post #16343831
An image speaks for the lighting as much as the lens. Test a kit lens in sunlight and a L lens on a cloudy day and the kit lens is sharper.

MTF under controlled conditions levels the playing field.

And besides, the OP didn't ask for opinions on MTF testing.

It doesn't mean opinions can't be given about what MTF charts are worth to somebody.

Let the OP either accept or discard the information. At least someone is willing to give a opinion. Are you the MTF opinion police? lol

cheers,

I used to own the 28-75 and now own the Sigma 17-50. The sigma is significantly sharper. The Canon 17-55 is certainly no worse than the Sigma 17-50. That help?

davidc502 wrote in post #16343843
Are you the MTF opinion police? lol

Mainly I don't like it when people jump all over the OP instead of attempting answering the question, and especially when their opinions are malformed.

I don't need a badge for that.

tkbslc wrote in post #16343855
Mainly I don't like it when people jump all over the OP instead of attempting answering the question, and especially when their opinions are malformed.

I don't need a badge for that.

The guy said he was sorry. What else do you want before you put the imaginary badge down?

davidc502 wrote in post #16343986
The guy said he was sorry. What else do you want before you put the imaginary badge down?

It's a sash and a beret, thank you!

tkbslc wrote in post #16343831
An image speaks for the lighting as much as the lens. Test a kit lens in sunlight and a L lens on a cloudy day and the kit lens is sharper.

MTF under controlled conditions levels the playing field.

And besides, the OP didn't ask for opinions on MTF testing.

In my mind, an image also speaks for PP technique. Where these non-real world lab testing completely removes that.

I also get somewhat irked by the posts that don't answer the OPs question. It seems incredibly arrogant to dismiss his opinions and concerns to use his thread as a chance to spew your opinion as if it's so important it's worth stopping all other discussion for. But in this case I didn't see David as doing that.

And to his point besides MTF numbers or The Digital Picture side by side (which also didn't have an ASPC to ASPC comparision) how do you compare lenses you have no chance of ever seeing in person before purchasing? Reviews can be tough as I've found few reviewers are shooting candids of their kids running around. Or pictures of my grandma at a birthday party. And I feel the Lens Sample threads are all chock full of one-off then excruciatingly post processed ideal images not necessarily representative of what you should expect.

FEChariot wrote in post #16343845
I used to own the 28-75 and now own the Sigma 17-50. The sigma is significantly sharper. The Canon 17-55 is certainly no worse than the Sigma 17-50. That help?

I owned the tamron 28-75 and found the sigma 24-60 to be much sharper.
The problem I had with Sigma was the horrible focus.
I ended up getting a 24-105 and sold the sigma. Both are great lenses, but the picture quality is better on the canon.

I own the 28-75 and I like it for what I do with it. Fast focus it isn't. I can't compare IQ directly, but here is my story. I own the 15-85 which is, IQ-wise, on par with the 17-55. IMHO, the 15-85 (and by inference the 17-55) will give you noticeably better IQ, especially away from the center of the frame. I couldn't justify the cost of the 17-55, so I went with both Tamrons: 17-50 non-VC and 28-75, instead. I got both of them used for $300 each. I don't need f/2.8 in that range often.