OpticalLimits Reviews the Canon RF 28-70mm F2.8 IS STM

[Richard CN]

OpticalLimits is one of my favorite lens reviewers, going all the way back to when it was named photozone.de. Recently, they completed their review of the Canon RF 28-70mm F2.8 IS STM.

My summary: It's not often I pull out the bad sample card.... but maybe?

OpticalLimits Reviews the Canon RF 28-70mm F2.8 IS STM

OpticalLimits is one of my favorite lens reviewers, going all the way back to when it was named photozone.de. Recently, they completed their review of the Cano

www.canonrumors.com

 

[AlanF]

For a quite different set of measured MTFs see - https://www.ephotozine.com/article/canon-rf-28-70mm-f-2-8-is-stm-lens-review-37105

As a quantitative experimentalist, I would never rely on one set of measurements. There is such a thing as statistics, which translates to copy variation.

Here's ephotozine's summary:

Canon RF 28-70mm f/2.8 IS STM Performance​

At 28mm central sharpness is excellent from f/2.8 to f/8, very good at f/11 and f/16 and good at f/22. The edges are good from f/2.8 to f/5.6, very good at f/8 and f/11, good at f/16 and fair at f/22. Clearly this favours the centre of the image and the best overall apertures will be f/8-f/11.


At 50mm, central sharpness is very good at f/2.8, excellent at f/4, very good from f/5.6 to f/16 and good at f/22. The edges are very good at f/2.8, excellent at f/4, very good from f/5.6 to f/16 and fair at f/22.


At 70mm, central sharpness is very good at f/2.8, excellent at f/4, very good from f/5.6 to f/16 and good at f/22. The edges are very good from f/2.8 right the way through to f/16 and just fair at f/22.


The longer focal lengths clearly even out the sharpness and the standard overall is very satisfactory.

 

[Canon Rumors]

I don't see what OpticalLimits sees with mine.

I don't feel hosed paying full price, but once these hit $899 or so, that'll be great value.

 

[HMC11]

Christopher Frost's review has a similar conclusion as OpticalLimits', i.e. at 70mm wide open, it is sharp in the centre but noticeably soft at the corners; and sharp at both centre & corners from 28-45mm wide open. Perhaps the copy variation for this lens is more pronouced than usual?

 

[Del Paso]

Many sample variations with this lens if you look at the contradictory reviews.
For some, everything is fine, for others, weak corners at 28mm, sharp at 70mm or just the opposite.
I hope Canon manage to sort this out, because this lens has potential.
Presently, I find it risky to buy it.

 

[AlanF]

Many sample variations with this lens if you look at the contradictory reviews.
For some, everything is fine, for others, weak corners at 28mm, sharp at 70mm or just the opposite.
I hope Canon manage to sort this out, because this lens has potential.
Presently, I find it risky to buy it.

It's one you have to buy on an easy to return basis or test in a shop.

 

[Del Paso]

A bit off topic...
I used to rely on Gordon Laing's reviews. Unfortunately, they are no longer helpful since he has only previews (named "so-far") of all the latest Canon lenses.
I particularly liked his real pictures, instead of charts. A better method, in my opinion, to assess a lens' sharpness than charts or graphs.
After all, we use lenses to take real pictures...
Does anyone perchance know what happened to his full length reviews?

 

[Del Paso]

It's one you have to buy on an easy to return basis or test in a shop.

Or wait for the RF 24-70 II...

 

[Frodo]

This is an edit of my post on the other RF 28-70/2.8 thread, but its relevant here.
Klaus values the excellent quality at the wide to mid range, the quick AF and the compact design, and I agree.
However, he pans the edge and corner quality at 70mm, but I certainly don't see such a difference between 40 and 70 mm in my testing as I would call them close to equal. There is the unfortunate issue of lens variation, which is what I have seen in different copies of the RF 24-105/4 L, the RF 50/1.8 and the RF 16/2.8. Its a pity that his tests of the RF 24-70/2.8 and RF 24-105/4 are on the 30MP R and so not directly comparable as I have found the 28-70 to be at least similar, but usually noticeably better than the 24-105 at similar focal lengths, apertures and points in the frame.
He criticises the retractable lens design, while also appreciating the compact size of the lens. I like the small size and don't mind having to extend it to take photos, but I can't understand why some functions such as changing modes or shutter speeds are not available when the lens is retracted. He criticises auto-correction, but this enables the compact size that he praises and as far as I am concerned, its the quality of the image that matters. This lens has much less astigmatism, which is impossible to correct in astrophotography compared to distortion correction.
Elsewhere he comments that "The build quality is otherwise fine, although more in line to what you’d expect from a consumer-grade lens". Well, the inner tube wobbles less than the RF 24-105, and given the decentering issue I had with that lens, I rate the build quality of the 28-70 at least as good, if not better. He notes "There’s even some degree of weather sealing.". The lens rings appear to have the same gaskets at the 28-70/2.0, but the switches might not sealed.
James Reader did a comprehensive test of the RF 28-70/2.8, with the RF 28-70/2.0L, the RF 24-70/2.8L and the RF 24-105/4L. The little lens was similar and often better than the first two of these lenses and waaayyy better than the RF 24-105/4L. I downloaded his raw files and made the comparisons myself and concur with his findings.
So something is up with the performance at 70mm of his lens. What distance do Kalus and Chris Frost test their lenses at? James' were close to infinity. I agree that the differences are otherwise explained by sample variation.

 

[Richard CN]

For a quite different set of measured MTFs see - https://www.ephotozine.com/article/canon-rf-28-70mm-f-2-8-is-stm-lens-review-37105

As a quantitative experimentalist, I would never rely on one set of measurements. There is such a thing as statistics, which translates to copy variation.

thank you for that.

I knew i was forgetting someone else that did MTF's.

 

[Del Paso]

This is an edit of my post on the other RF 28-70/2.8 thread, but its relevant here.
Klaus values the excellent quality at the wide to mid range, the quick AF and the compact design, and I agree.
However, he pans the edge and corner quality at 70mm, but I certainly don't see such a difference between 40 and 70 mm in my testing as I would call them close to equal. There is the unfortunate issue of lens variation, which is what I have seen in different copies of the RF 24-105/4 L, the RF 50/1.8 and the RF 16/2.8. Its a pity that his tests of the RF 24-70/2.8 and RF 24-105/4 are on the 30MP R and so not directly comparable as I have found the 28-70 to be at least similar, but usually noticeably better than the 24-105 at similar focal lengths, apertures and points in the frame.
He criticises the retractable lens design, while also appreciating the compact size of the lens. I like the small size and don't mind having to extend it to take photos, but I can't understand why some functions such as changing modes or shutter speeds are not available when the lens is retracted. He criticises auto-correction, but this enables the compact size that he praises and as far as I am concerned, its the quality of the image that matters. This lens has much less astigmatism, which is impossible to correct in astrophotography compared to distortion correction.
Elsewhere he comments that "The build quality is otherwise fine, although more in line to what you’d expect from a consumer-grade lens". Well, the inner tube wobbles less than the RF 24-105, and given the decentering issue I had with that lens, I rate the build quality of the 28-70 at least as good, if not better. He notes "There’s even some degree of weather sealing.". The lens rings appear to have the same gaskets at the 28-70/2.0, but the switches might not sealed.
James Reader did a comprehensive test of the RF 28-70/2.8, with the RF 28-70/2.0L, the RF 24-70/2.8L and the RF 24-105/4L. The little lens was similar and often better than the first two of these lenses and waaayyy better than the RF 24-105/4L. I downloaded his raw files and made the comparisons myself and concur with his findings.
So something is up with the performance at 70mm of his lens. What distance do Kalus and Chris Frost test their lenses at? James' were close to infinity. I agree that the differences are otherwise explained by sample variation.

No matter what Mr. Reader says, buying a lens shouldn't be a lottery. I would definitely rather rely on the RF 28-70 f/2's and 24-70 f/2,8's optical performance.
One photographer's opinion will never convince me...

 

[Frodo]

No matter what Mr. Reader says, buying a lens shouldn't be a lottery. I would definitely rather rely on the RF 28-70 f/2's and 24-70 f/2,8's optical performance.
One photographer's opinion will never convince me...

I generally agree, which is this thread about one man's opinion (Klaus). One person's opinion that I do value is Roger Cicala's, especially when he tests multiple copies, such as this ten-year-old review of 24-70 mm lenses. https://www.lensrentals.com/blog/2015/07/24-70-f2-8-zoom-mtf-and-variation . Interestingly he noted "there’s more variation at 70mm for all three lenses" (Nikkor, Tamron, Canon EF).

 

[Del Paso]

I generally agree, which is this thread about one man's opinion (Klaus). One person's opinion that I do value is Roger Cicala's, especially when he tests multiple copies, such as this ten-year-old review of 24-70 mm lenses. https://www.lensrentals.com/blog/2015/07/24-70-f2-8-zoom-mtf-and-variation . Interestingly he noted "there’s more variation at 70mm for all three lenses" (Nikkor, Tamron, Canon EF).

TDP also noticed serious variations when he re-tested an RF 14-35...
That's why we all miss Roger's MTF testing several lenses.