EF vs RF 50 1.8 STM MTF chart comparison

Antono Refa

Mar 26, 2014
The group of lenses you cite as uber-fifties were SLR lenses?

I think the new lenses in the family I'm talking about (RF 50/1.2, Nikon's new 50/1.8, Leica's new APO ASPH 50/2) are fresh, computer-generated designs that don't owe much if anything to previous generations of medium teles.
No, I'm not referring to any of those. As I wrote, I'm referring to the Nikon AF-S NIKKOR 58mm f/1.4G, Sigma 50mm f/1.4 ART, ZEISS Otus 55mm f/1.4, and possibly a couple more released at the time. Note two of them have a stated focal length slightly longer than 50mm.
Upvote 0


5% of gear used 95% of the time
CR Pro
Nov 11, 2012
Yorkshire, England
1) why wouldn't the elements have been optimally placed before? 2) how can you tell from using a lens that the elements are "optimally placed?"

I think the phrase you're referring to is just marketing nonsense. The elements have always been placed optimally.

The three EF 50/1.8's indeed have identical optics.

Here's the 50mm f/1.8 MkI (the pro-quality built one), from https://global.canon/en/c-museum/product/ef259.html

View attachment 201397

Here'e the 50mm f/1.8 MkII (the plastic consumer one):

View attachment 201398

Here's the EF 50/1.8 STM: https://global.canon/en/c-museum/product/ef451.html

"In addition to maintaining the proven optical design of its predecessor, the new prime lens employs a lens coating that is optimized for shooting with digital cameras to minimize the occurrence of ghosting and flare. Furthermore, it includes a 7-bladed aperture—an improvement over the previous model’s 5-bladed aperture"

View attachment 201399
1) Poor assembly / tolerances. You don’t think that the lenses we buy for the price we pay are all perfectly assembled do you ? Far from it, hence why we get copy to copy variation.
2) Improved performance over the older versions despite using exactly the same lens formula.

Actually I don’t think it is marketing BS. Nor does Roger Cicala from Lens Rentals. If you search it on his blog I think you’ll find he had some observations regarding the matter.
Upvote 0


Aug 29, 2020
Upvote 0


1N 1V 1Ds I II III R R5
Dec 9, 2018
A truly new and good 50 1.8 without the macro capability probably could have launched for about $300 (with a sale price of $250 or so), and actually would have been worth buying over an EF 50 STM + adapter.
I don't mean to sound unfriendly but I can't figure out a nicer way to word it :-D Is there a "truly new and good 50" for $300" from any other make that shows significantly better image quality for anything like the same size and budget? What I'm seeing is that 50's are basically either double-Gaussian designs like we've had for 70 years, whereby 6-8 elements are kind of symmetrically repeated in a front half and back half that kind of match each other, or, completely new-school designs that are surely produced by computer algos and look like nothing in particular (such as the Leica 50/2APO, Otus 50/1.4, and Canon RF50/1.2). The new-school designs are far, far sharper, but also 3-4x the size of the old-style designs.

I've had the EF 50/1.8 MkI (pro build), 50/1.0, 50/1.4, 50/1.2, the new RF 50/1.2, and this. The RF 1.2 is 10x sharper than the rest but too big to carry and too expensive to break if I drop my backpack, etc. The RF 1.8 still produces far better images, to my eye, than my iPhone 13Pro, and I think it does a better job than any of my EF's. Not much, perhaps, but does.

That leaves the amount of bokeh from f/1.8. Well, in film days, to shoot friends at a dinner I'd need 800-1600 film, 1/15 at f/1.4, and between camera shake and huge grain you couldn't quite tell that DOF was also robbing you of sharpness. Today, with the 50/1.8 reliably hand-holdable at 1/6 on the R5, and practically no noise even at 2500, and of course 45MP, the sharpness lost to DOF is a lot more glaring. I simply never find myself suffering from bad subject motion, camera shake, grain and so on. If they come out with a new 50/1.4 I'm not sure I'd buy it, unless it's far sharper, and if it is I'm sure it will be far bigger. If it's much bigger at all, even the size of the EF50/1.8 on adapter, I'd probably put it in my camera bag not my backpack.

Given how much shallower it is mounted on the camera, for me the RF is a huge win even if costs more. Mine was quite cheap though.

Photo from https://snapshot.canon-asia.com/sg/article/eng/rf50mm-f18-stm-vs-ef50mm-f18-stm-6-key-comparisons

  • Like
Reactions: 1 user
Upvote 0