Which is which?

[Basil]

So I have a nearly 30 year old EF 135 f/2 lens, which I can use on my R5 with an adaptor. I also have a new RF 70-200 f/4 lens. Just for grins, I wanted to shoot some comparison shots between the 30 year old EF glass and the brand new RF glass. To make the comparison fair, I shot all images at f/4, ISO 100 and set the focal length for the 70-200 at 135mm. In the two sets of images, can you tell which would be the 30 year old EF lens and which is the RF?

First Set:

Lens A


Lens B



Second set:

Lens C



Lens D




So, just from looking at the images, which would you think is the 30 year old lens and which is the new lens?

 

[GregW]

I'm gonna say lens B and D are the 135 f2 images.

 

[Basil]

I'm gonna say lens B and D are the 135 f2 images.

You are 1/2 right. But which one did you get right? One of those two is the 135 f/2 (at f4), but the other is the 70-200 at 135 f/4.

 

[GregW]

OK, I'll switch C and D. So B and C are the 135mm. They are very close though.

 

[Basil]

OK, I'll switch C and D. So B and C are the 135mm. They are very close though.

Congratulations! You are now 100% incorrect (you had a 50-50 chance)

A and D were shot with the EF 135 and B and C were shot with the new RF 70-200, all shots at f4.

My conclusion is I’m keeping that old EF lens!

 

[GregW]

Well, shows what I know.

 

[Basil]

Well, shows what I know.

That it’s hard to tell speaks well of a 30 year old lens. Of course this was just one test at one f-stop and one distance. If I get bored I might try other test shots at other f-stops and subject distances.

 

[DrEntropy]

I'd have "guessed" the same ones as Greg did initially. But they're really indistinguishable. Quite a result considering the differences in design and construction. And the time between the two.

It has amazed me how far optical quality of the zoom lenses has progressed since that 135 was new. Back then, a multi-focal length lens was a compromise to convenience, not necessarily optimum sharpness. In '78 I got one of Vivitar's Series-1 VMC 70~210mm zooms, at the time considered to be state-of-the-art crisp. I doubt it could stand up to that 70~200 in a digital comparison test.

My conclusion is I’m keeping that old EF lens!

I'd say that's a good call. I feel the same about my 90mm Micro S-1 Vivitar.

 

[GregW]

So I took all your photos into Gimp and layered A with B and C with D. Turning the opacity on and off, the first thing that jumped at me was the color shift between A and B. B is much warmer and I realized that the lighting had changed. There is a warmer fill light off camera left that brings up the shadows of the cactus branches. Also the background to the right is noticeably brighter. I also noted a time change with both shots with cloud formation, shadow movement, the stamens spreading and a spider arriving on the scene. I think for an exact comparison, a move indoors with controlled lighting would help.

The depth of field was a surprise to me. In the past at least, the DOF for a prime was usually 1/3 in front of the focus point and 2/3's behind. Zooms were usually 1/2 split front and behind the focus plane. I don't see any difference here between your two lenses in regards to falloff behind the flower.

 

[DrEntropy]

B is much warmer and I realized that the lighting had changed. There is a warmer fill light off camera left that brings up the shadows of the cactus branches. Also the background to the right is noticeably brighter.

My WAG was B for the 135 just based on background lighting. Thinking a prime would be a bit brighter overall due to design. Hadn't anything else to go on, really. Didn't think to consider ambient light changing. DUH.

As for C vs. D, just an opinionated guess. Less sharpness (not DoF) of the needles left and low of the blossom, in shadow, had me guessing "older glass". Again, pure guessing.

I suppose doing a controlled lighting comparison with a lens chart may be more definitive, but this real-world "cactus test" is proof enough the 135 has stood the test of time well enough.

 

[GregW]

Thinking a prime would be a bit brighter overall due to design.

That was my thinking as well. Fewer elements equals less transmission losses. Making an overlap towards the center to avoid vignetting, there is a very slight brightenerness for the D Lens (the 135). I think the background sky was not effected by the lighting change.

 

[DrEntropy]

I never though to run the shots thru GIMP for comparison, but:

there is a very slight brightenerness for the D Lens (the 135).

When ya put it that way,