Relevance of LR MTF tests

Del Paso

M3 Singlestroke
Aug 9, 2018
357
302
My aim is definitely not to criticize Lens Rentals, whose professionalism is above any doubt.
Yet, I keep wondering whether tests performed at maximal aperture are really relevant in daily life. They certainly are, if one is using 1,2 lenses, more even for the likes of Noctilux 0,95 lenses, but what about macro or landscape photographers, whose favorite aperture is rather around f. 11 :unsure:.
I know that a lens which is, like the RF 1,2/50, excellent at f.1,2, can't be bad at - say- f.8.
But, what about an ultra wide-angle, which could be poor at f. 2,8, couldn't it be great a f. 11? Additionally, I still recall Leica's optical- division head saying that lenses were made to shoot 3D objects, not charts or MTFs.
Any opinions?
 

AlanF

5DSR
Aug 16, 2012
4,862
1,509
I shoot my main lenses wide open most of the time! There are many sites that publish MTFs over a wide range of f-numbers like opticallimits, ephotozine etc. Or go to TDP and use your own eyes. So go to them if you want to see stopped-down values. What they don’t do is to test 10 or more of each so you can see the copy variation or measure MTFs over a wide range of frequencies. And, if all you are interested in is how 3D objects look like, why are you even bothered with charts?
 

Del Paso

M3 Singlestroke
Aug 9, 2018
357
302
I shoot my main lenses wide open most of the time! There are many sites that publish MTFs over a wide range of f-numbers like opticallimits, ephotozine etc. Or go to TDP and use your own eyes. So go to them if you want to see stopped-down values. What they don’t do is to test 10 or more of each so you can see the copy variation or measure MTFs over a wide range of frequencies. And, if all you are interested in is how 3D objects look like, why are you even bothered with charts?
As you just said, the trouble with the other sites is that, unlike LR, they just test one sample.Example: if I had relied on Optical Limits, I would never have bought the EF100 f.2,8 IS L.
As to being bothered with charts, I'm not, it's particularly for that reason that I emitted doubts about the "real life" relevance of such tests.
But for you, shooting wide open , these tests are absolutely valuable!
 

BillB

EOS 6D MK II
May 11, 2017
903
129
My aim is definitely not to criticize Lens Rentals, whose professionalism is above any doubt.
Yet, I keep wondering whether tests performed at maximal aperture are really relevant in daily life. They certainly are, if one is using 1,2 lenses, more even for the likes of Noctilux 0,95 lenses, but what about macro or landscape photographers, whose favorite aperture is rather around f. 11 :unsure:.
I know that a lens which is, like the RF 1,2/50, excellent at f.1,2, can't be bad at - say- f.8.
But, what about an ultra wide-angle, which could be poor at f. 2,8, couldn't it be great a f. 11? Additionally, I still recall Leica's optical- division head saying that lenses were made to shoot 3D objects, not charts or MTFs.
Any opinions?
My opinion is that it is very easy to overthink the lens quality issue, except maybe for the variance issue, where Lens Rental stands out by itself. This is especially true if you usually shoot stopped down and if your are not printing really big.
 

AlanF

5DSR
Aug 16, 2012
4,862
1,509
Most lenses perform quite well stopped down, even inexpensive ones like the ‘nifty-fifty’.
Very true. The nifty fifty stopped down is as good as anything. If you shoot only stopped down then don't waste your cash on expensive lenses.
 

koenkooi

EOS RP
Feb 25, 2015
242
106
My aim is definitely not to criticize Lens Rentals, whose professionalism is above any doubt.
Yet, I keep wondering whether tests performed at maximal aperture are really relevant in daily life. They certainly are, if one is using 1,2 lenses, more even for the likes of Noctilux 0,95 lenses, but what about macro or landscape photographers, whose favorite aperture is rather around f. 11 :unsure:.
[..]
For macro MTF testing has 2 strikes against it: the first being measured wide open, the second being measured at infinity. I curious about the difference in MTF between MFD and infinity, especially with lenses that have a lot of focus breathing, like the EF100mm macro.
 

docsmith

EOS 6D MK II
Sep 17, 2010
835
182
They used to have stopped down data for some lenses, but it has been removed. I get that many lenses are primarily used wide open, but I do still find it useful to know about stopped down performance. For example:
  • Lenses like the EF 24 f/1.4 II look comparatively bad wide open, but fine once you get past f/2 or so.
  • I like to really know my lenses and understanding where they are sharpest or when they start getting really sharp is helpful. Since many are talking about the 50 f/1.8, when I owned it, I knew it was good f/2.8 and higher. Amazing at f/4 to f/8.
  • It is useful to know that, which lenses are sharp stopped down. Landscapes are usually shot wide open but people tend to want supreme sharpness. So, is it worth an expensive lens for high end landscapes or will a 24 f/2.8 do?
While I still find the information useful, I would really like to see stopped down information as well. But, I appreciate all that TDP and LR do as I really am getting great information for free, all I have to do is use affiliate links.
 

AlanF

5DSR
Aug 16, 2012
4,862
1,509
For macro MTF testing has 2 strikes against it: the first being measured wide open, the second being measured at infinity. I curious about the difference in MTF between MFD and infinity, especially with lenses that have a lot of focus breathing, like the EF100mm macro.
MTF testing is done at different distances by different testers, depending on their methods and equipment, which is a problem. Lensrentals do theirs generally at infinity with an optical bench, others at varying and unreported shorter distances. It's known, for example, that the Nikon 200-500 f/5.6 is at its best sharpness closer up in the distances used by many for Imatest, whereas telephotos are often used for far distances (Tamron 150-600 is better for long distances). I tend to use lenses wide open at long distances so Lensrentals is particularly useful to me. In general, the best way to sample a lens is to do it yourself under the conditions you generally use, and on the lens you have at hand because sample variation can be large.