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The Canon RF 45mm f/1.2 STM, which was announced towards the end of 2025, brought a fresh outlook to Canon’s RF mirrorless system. With a price tag of about $469, this small lens (78 x 75mm, 346g) promised to deliver shallow depth of field, beautifully blurred backgrounds, and nighttime performance without the high-end price tag of its L-series siblings, such as the Canon RF 50mm f/1.2L USM. It entered the market positioned between Canon’s budget offering, such as the RF 50mm f/1.8 STM, and high-end models. Now the internet has responded with different reviews of the Canon RF 45mm f/1.2 STM, so it’s time to revisit this.
I, of course, weighed in with the MTF inspection of this lens, and left the conclusion that it really depends on your use case for the lens. I personally wasn’t a fan.
Since that time, the reviews for this lens are divided into two camps, and they form a fascinating narrative of scientific versus real-world reviews. Usually, the two meet in the middle and more or less agree on the lens’s worthiness, but then there’s this lens where they are far apart from each other.
Canon RF 45mm f/1.2 STM
On one side of the fence, a serious and very clinical assessment was conducted by OpticalLimits that examines optical performance. Then there are the “real-world” reviews on photography websites like PhotographyBlog and PetaPixel that focus on usability, value for money, and the enjoyment factor of using the lens for photography.
The OpticalLimits’ Harsh Judgment
At OpticalLimits, the approach to lenses is that of examining the technical characteristics of the lens under test. A little background on opticallimits. Klauss has been doing this for longer than I know, back when OpticalLimits was named photozone.de. He has a wealth of experience in lens testing, and I doubt there are too many people on the planet with his level of experience in instrumental lens testing across various brands. He subjects the lenses to standardized tests for sharpness, distortion, vignetting, and various aberrations. If you are looking to purchase a lens and you know you will demand the most out of its optical performance, OpticalLimits is really the place to go to see how it performs.
For those who love this little Canon RF 45mm f/1.2 STM, the Optical Limits review of the RF 45mm f/1.2 STM is perhaps not something you should read.
At f/1.2, sharpness in the center is “okay” but tapers off significantly towards the edges, deemed “rather terrible” until f/2.8, where sharpness jumps significantly. Optimal image quality is obtained starting at f/4, rated “very good to great” across the image. The lens suffers from strong barrel distortion in RAW images (corrected by camera profiles), severe vignetting (in excess of 5 stops at f/1.2, though reduced to 2 stops after correction).
To add insult to injury, the lens exhibits strong lateral CA, strong axial (longitudinal) CA. The Longitudinal CA shows up with fairly significant purple or green fringing in the bokeh. Focus shift is “very pronounced,” while field curvature is wavy, reminiscent of designs from the 1960s-1970s.
Bokeh performance is a mixed bag: it produces a great central blur at f/1.2, but exhibits “cat’s eye” corners, which is to be expected for a fast prime. The bokeh also appears more harsh in the foreground, and a greenish haze from longitudinal CA.
The verdict from OpticalLimits is that it’s optically borderline passable and a decent budget f/1.2 option. However, it becomes problematic at wide apertures, relying too heavily on firmware correction and stopping down. Its performance is reminiscent of vintage prime designs, but not quite up to high-end optical performance. It is better suited to stopped-down photography than pixel-peeping shots taken at wide apertures.
Sure, f/1.2 is nice on paper, allowing very shallow depth-of-field photography. However, the fact that it has an f/1.2 setting is almost the only glorious aspect of this lens – and for some, this may be enough, and that’s perfectly fine. In terms of performance, it resembles lenses from the 1960s or 1970s. At f/1.2, the center quality is passable by today’s standards, but the corners fall completely apart. Things do get better the more you stop down.
https://opticallimits.com/canon/canon-rf/canon-rf-45mm-f-1-2-stm-review/
To be fair to Klaus here, all the lenses that pass through his testing are tested with the same rigour. He’s not going to change his tests because the lens’s intention is different.
The User Perspective and Praise
By contrast, Photography Blog and PetaPixel offer more user-centric experiences where the photography experience takes precedence over charts.
Photography Blog appreciates the compact and lightweight design (all-plastic construction but sturdy with a metal mount), fast STM autofocus (smooth in stills, almost silent, with little hunting), and full-time manual focus capability. While preferring different designs for some features, such as the control ring that adjusts the camera’s assignable function, the 9-blade aperture provides “quite nice” Bokeh for a 45mm lens.
if you can buy into the amount of digital correction that Canon is automatically applying in-camera, then we can highly recommend the RF 45mm F1.2 STM as a classic fast prime that every Canon full-frame and APS-C owner should seriously consider adding to their kit-bag.
https://www.photographyblog.com/reviews/canon_rf_45mm_f1_2_stm_review/conclusion
Disadvantages in the form of the lack of weather sealing and in-lens stabilization are mentioned, but the street price of “just” 469 dollars provides “bright f/1.2 aperture in a compact package” that rivals the quality of the legendary EF 50mm f/1.2L after correction.
This is agreed upon by PetaPixel, which describes the lens as “affordable and usable.” At only 346g, the damped focus ring and strong control ring make this lens a pleasure to use, even in the absence of a hood or protection against the elements. Autofocus speed is “acceptably fast,” accompanied by an audible buzz, while bokeh in f/1.2 portraits results in “beautiful, soft backgrounds,” whose creamy bokeh is especially pleasant in terms of cat’s eye highlights, though LoCA demands occasional stops.
Long have the Chinese lens houses specialized in ultra-fast aperture optics at a low price but you won’t find many of these options available with compatible autofocus and full-frame coverage for the Canon RF mount. This makes the new $479 Canon RF 45mm f/1.2 a very smart play, both on the part of Canon and as a good decision for the consumer. I hope Canon make many more of these fast-apertured options for the consumer at an affordable price. Especially if the optical performance holds true in the future. Consider this 45mm lens for general-purpose photography and as a shallow depth of field portrait option.
https://petapixel.com/2025/11/27/canon-rf-45mm-f-1-2-stm-review-affordable-and-usable-wide-aperture/
To this end, sharpness is merely okay, with decent contrast wide open, favoring center-focused subjects, but excellent from f/2.8 on.
These reviews all tend to highlight Canon’s intention of the lens, excellent subject separation of an f/1.2 lens, and leave the rest to the image processing pipeline in software or the camera’s JPEG engine.
My Thoughts
I could say I wasn’t surprised by the reviews, because we mentioned the divide between the artistic and the clinical aspects of lens designs that this one was going to cause.
As many of you know, I’m pretty huge on the bang for the buck lenses, but this lens, I think, prioritizes “character” a little too much to make it a general-purpose lens that would have a greater utility. If you are the type of photographer who loves candid portraits, in the studio, or even street shooting, then this may be an incredibly wonderful bargain lens to add to your kit. For me, I don’t shoot those disciplines much anymore, and if I did want to have that option, I’d probably find the RF 50mm F1.8 STM perfectly suitable as a substitute at 50% of the price.
For those seeking to reclaim the magic of the Canon EF 50mm f1.2L USM in a lighter, smaller, and more modern lens, this is a lens absolutely for you.
https://www.canonrumors.com/a-closer-look-into-the-canon-rf-45mm-f-1-2-stm/
Conclusion
These review differences are not disparities but reflect compromises in design and the intended user of the lens. To be fair, Canon did warn us about this before the lens was even available for reviews.
OpticalLimits’ lab testing reveals what the optical compromises of an affordable compact f/1.2 are. Severe vignetting, fringing, and significant softness in the corners are there by design because the lower cost and weight were the main drivers of the lens from a design criterion. You simply are not going to get $2000 worth of optical performance for under $500.
On the other hand, it is shown by Photography Blog and PetaPixel (and others), is that these issues don’t necessarily impact images enough to be problematic, basically the proverbial “get out there and shoot”. Canon’s corrections will work to suppress distortion and vignetting. LoCA and Bokeh issues can be corrected in post if needed (or turn on DLO in camera for JPEGS or use DPP with DLO for RAW images). And also don’t forget that at f/1.2, it allows great subject separation with a center-focused target, and that does not usually require crisp corner performance, especially for portraiture.
In other words, embrace the aberrations and lack of resolution and use them to your advantage. What this really indicates to me, through the reviews and my own thoughts, is that this lens matches the target audience, with perfect alignment.