Photozone.de, MTF question?

YashicaFX2 wrote in post #16345453
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.

Can you compare the Tamrons please? Both IQ and AF.

http://www.photozone.d​e …canon-test-report--review


http://www.photozone.d​e …_ff/418-tamron_2875_28_5d


The above reviews are pretty accurate as compared to my experience. Notice they ding the 28-75 on full-frame. I use it on a 60D, mostly, and it is quite good. Both of them are a bit soft at f/2.8, and both are MUCH better by f/3.5. AF on both of them is fine for chasing dogs and kids around the park. On the 5D, the 28-75 is about useless with all but the center point. I attribute that more to the camera than the lens, but my 28-135 does work better with the outer points on the 5D.

For $300 or so each, you can't go wrong. I am keeping mine.

travisvwright wrote in post #16342940
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.

Not sure if this was answered or not. The numbers are the highest rating you can get for the size of the sensor or at least this is my understanding. Since FF is a larger sensor it's max is 3800 while the crop sensor is a smaller sensor it's max is 2800 or there abouts.

one thing I can say is Photozone.de MTF numbers definately reflect what I find in all of the lenses I've owned.

I know this... for me anything at 3300+ is tack sharp. This is the reason I didn't like my 85 1.8 it took to about F4 for me to really like it.

Talley wrote in post #16348511
Not sure if this was answered or not. The numbers are the highest rating you can get for the size of the sensor or at least this is my understanding. Since FF is a larger sensor it's max is 3800 while the crop sensor is a smaller sensor it's max is 2800 or there abouts.

one thing I can say is Photozone.de MTF numbers definitely reflect what I find in all of the lenses I've owned.

I know this... for me anything at 3300+ is tack sharp. This is the reason I didn't like my 85 1.8 it took to about F4 for me to really like it.

I'd rather use controlled testing results than a subjective "test" from anyone.

Too often I read, "my lens is tack sharp". It might well be, but without controlled comparative images or hi-res JPEGS/RAWS, the statement is not verifiable and falls into the realm of hear-say.

On DPR one can DL full size RAW images to check, but a small lo-res image posted on line isn't going to prove much. Photozone makes high-res JPEG files available (I DL'd one for the 17-55 - it is 5.5 MB).

And of course, the images posted by Photozone ARE field shots (aka real world shots).

Glenn

Biggest difference will probably be the 17mm vs 28mm. The 17-55 is supposed to be very, very sharp, does it even matter exactly how sharp it is?