Canon EF 50mm f1.2 L USM vs Sigma 50mm f1.4 Art DG lens comparison and review

(all images shot on Canon 50mm f1.2 L)

1/1600th, f1.4, ISO 100 - Mitton Hall, Clitheroe, Lancashire

In this review, I am going to compare my real-world usage and experience of using both of these lenses for around 8 months. Both lenses have shot weddings, portraits, landscapes and general stuff and I feel like I am in a good position to give an honest and unbiased opinion of each lens.

Firstly, I should probably point out that I sampled 4 versions of the Sigma 50mm f1.4 Art – yes 4!! Unfortunately none of them were perfect (hence why I went through so many). While I don’t doubt there are people out there with “perfect” copies of the Sigma 50mm f1.4 Art, I unfortunately was not one of them.

I only ever owned 1 Canon 50mm f1.2 L USM lens, which is the same lens I am using today.

If you are looking for a short review - the Canon is in my opinion, the superior lens!
For more in-depth observations, please read on!


1/800th, f1.2, ISO 100 - The Villa, Wrea Green, Preston, Lancashire

Let’s start with the Sigma. I wanted to love this lens. I was excited about its release and had read countless previews about how good the lens should be when released. I knew I wanted one, so pre-ordered one to get it on its release date.

Prior to this lens, I had not been using a 50mm in my wedding photographs arsenal. I loved the Sigma 35mm f1.4 Art and also the Canon 85mm f1.2 L USM Mark II, but I felt the 50mm “gap” was a space that didn’t need filling, so wasn’t really interested in it until the Sigma 50mm f1.4 Art was announced. As with most photographers, I had a brief flirt with a Canon EF 50mm f1.8 lens which I must have owned 3 or 4 versions of throughout the years. I also owned a Sigma 50mm f1.4 EX HSM lens for a short while which I will never forget as being perhaps the most annoying, frustrating, sometimes wonderful but more often terrible lens I have ever owned. I also very briefly owned a Canon 50mm f1.4 USM lens which was actually worse than the cheap plastic 1.8 version.. So I guess you could say that I have tried most 50mm lenses on the market today.

The Sigma 50mm f1.4 Art got me interested when it promised razor sharp images at f1.4, something which none of my previous 50’s had been able to deliver. My experience with the Sigma 35mm f1.4 Art was that this lens quickly became my most used lens (and still is), stunning performance at all apertures and I can genuinely say I love that little lens to pieces. I hoped the 50mm art big brother of it could basically be the same lens as the 35mm, just with an extra 15mm.


1/125th, f8, ISO 400 (Lee 0.6 ND grad filter on sky - handheld) - Lake District

The day the Sigma 50mm f1.4 Art lens arrived I spent most of the day with it glued to my camera, taking photos of pretty much any and everything. I was impressed. It really was sharp at f1.4 and the bokeh, contrast and colours were superb – very very similar characteristics to my Sigma 35mm f1.4 Art. Happy Days…..or so I thought.

Over the next few weeks I began to run into issues with the lens and which completely changed my opinion of it, and led to me getting a second copy of the lens.

The problem was purely around its performance in Ai-Servo mode on my Canon 5D Mark III. I have never had a lens which performed in such a way as the Sigma 50mm f1.4 Art, but after owning and using 4 copies of the lens, ALL of them exhibited the same behaviour. In short, they were hopeless at tracking anything. In One-Shot mode, the lens was a totally different beast to in Ai-Servo.


1/400th, f1.6, ISO 200 - The Shireburn Arms, Hurst Green, Clitheroe, Lancashire

In One-Shot the lens was great. No problems what so ever, it was everything I hoped it would be. However, with a lens such as a 50mm f1.4, I would generally use it in Ai-Servo mode as the Depth of Field is so tiny, any movement by me or my subject would cause the image to be soft. Ai-Servo recognises any movement and adjusts focus constantly to ensure whatever it is I am focusing on (generally, the nearest eye) is tracked and locked in perfect focus. There are variations to this, but in my usage, I would primarily use a 50mm lens in Ai-Servo, probably 90% of the time.

And so came my second copy. Physically identical to the 1st copy, the only difference was the serial number, which I noted down as my only way of identifying them apart! I went out shooting with both Sigma 50mm f1.4 Art lenses and also my trusted Sigma 35mm f1.4 Art lens. Another full day’s shooting ahead.

Later that evening, using Lightroom metadata to identify the different lenses, I was seriously concerned about my results with both 50’s. Both of them seemed have massively front-focused everything when using One-Shot mode and missed everything when using Ai-Servo mode.


1/250th, f2.8, ISO 400 - The Villa, Wrea Green, Preston

I arranged a model shoot for a few days later to test further.

Following this shoot, in much more controlled conditions, I could confirm that both 50mm 1.4 Art lenses were front focusing quite significantly when the subject was more than 10ft away from me. As the model got closer, the lens did a better job at locking focus accurately. In Ai-Servo once again, the lenses did not achieve perfect focus on a single shot, with a mixture of front and back focused images.

I returned both lenses, and swapped them for a Canon 50mm f1.2 L USM and another brand new Sigma 50mm f1.4 Art lens.


1/500th, f1.2, ISO 125 - Stanley House, Preston

I had an engagement shoot that weekend, so decided to take both lenses, along with my other usual equipment with me. Infuriatingly, the 3rd Sigma lens was defective and simply hunted front and back without ever locking on anything.

I will discuss my Canon 50L experience later on.

Feeling disheartened, I sent the third Sigma 50mm f1.4 Art lens back and kept the 50L which I used for the next few weeks. A friend was religiously shooting with the Sigma 50 f1.4 Art and talked me into getting another one, to give it one more go. So I got one final copy. This lens was my final shot.

With an upcoming wedding, I took all my usual kit, and also the 50L and 50A (Sigma 50mm f1.4 Art) with me. By now I trusted the 50L and knew it well. I left the 50 in the bag for most of the day, but during a bit of the evening reception I took it for a blast. My initial impressions were good, it seemed to be doing alright. Locking focus and holding it in Ai-Servo and One-Shot. Low light shots also seemed OK and the lens seemed to be working great. I probably took about 50 images with it, checking each one on the back screen for sharpness, and all seemed OK.

When I got home, I ran a comparison between the 50L and 50A images and was instantly more drawn to the 50L images. Yes the 50A has more contrast, it is un-deniably sharper (a lot sharper) but I was still getting a very very low keeper rate, whereas my 50L was nearly 100% the Sigma was more like 10-15%. This just wasn’t good enough. Some images were miles out. Some had front focused on the nose, others rear focused on the ears. Absolutely zero consistency.

So that was my mind made up, the final Sigma 50mm f1.4 Art went back and I kept the 50L

Sigma 50mm f1.4 Art Copy 1: Unreliable in Ai-Servo mode – no consistency to front/back focus issues. One-shot seemed OK

Sigma 50mm f1.4 Art Copy 2: Unreliable in Ai-Servo mode – no consistency to front/back focus issues – no ability to track. One-shot was also hit and miss (severe front focus)

Sigma 50mm f1.4 Art Copy 3: Defective lens

Sigma 50mm f1.4 Art Copy 4: Unreliable in Ai-Servo mode and One-Shot mode – no consistency to front/back focus issues and missed focus on things it shouldn’t have


1/160th, f2.5, ISO 200 - Eaves Hall

Canon 50mm f1.2 L USM

Since I got this lens in the middle of my saga with Sigma 50mm 1.4 Art lenses, I just instantly trusted it. The lens performed right out of the box, didn’t need any micro-adjust, and provided superb images straight away.
Now I look back at it, I don’t know why I kept messing around with Sigma lenses, when the Canon L just worked straight away.

I found the Canon L lens a very hard lens to test. I think a lot of people associate the 50mm f1.2 L as being a very expensive piece of glass, which it is, and immediately assume that it is going to be the most amazing thing ever. I was one of these people, and I think that is why I did keep messing with Sigma, as I was paying £579 for each Sigma lens, whereas the Canon just cost me £1100. I expected the Canon to be twice the lens as the Sigma. In reality it didn’t appear to be… until I look back at how much trouble the Sigma lenses caused me, then I realise maybe it IS worth twice as much.
This will be the area a lot of photographers, myself included, find hard to quantify the price.

On paper… and indeed in SOME real world testing.. the Sigma is the better lens:

  • The Sigma is a hell of a lot sharper
  • The Sigma has a hell of a lot more contrast than the Canon ever has. Even wide open on the Sigma is better than the Canon is stopped down to f4
  • The Sigma doesn’t vignette as much as the Canon (not really an issue, but worth mentioning, as the Canon vignettes a lot!)
  • The Sigma has considerably less CA than the Canon

So the Sigma is clearly the more impressive lens, is £500 cheaper – why did I end up keeping the Canon?

Simply put, it works all the time.


1/80th, f11, ISO 100 - Clifton Arms Hotel

The Canon 50mm f1.2 L USM is one of those lenses that the more I use it, the more I love. Yes it does have its shortfalls, but in some ways these don’t bother me as the lens is just so unique. F1.2 is a funny aperture. Yes it’s a bit soft at 1.2 when comparing it against another image shot at f2.0 or f2.8 etc, but a lot of my images have been at f1.2 and I have printed large in wedding albums, so while technically yes it is a bit soft there, don’t confuse “soft” with meaning it is un-usable, it is far from un-usable.

Images shot at f1.2 require meticulous care to ensure they are in focus. I wont go into that here, as I’m sure most people reading this understand how to use a shallow depth of field lens, but 1.2 and close shooting distances, the tolerance level is unbelievably low, often less than a centimetre – so this is something I am very very cautious about.

Fortunately, the Canon autofocus is bullet proof. I absolutely love the autofocus on this lens. It works flawlessly, is 100% reliable
and if there was anything which justifies the £500 price difference between Canon and Sigma, it would be the autofocus. I can’t stress enough how important a good, effective auto focus system is on a lens like this. Focusing manually at f1.2 would be painful. Fortunately the lens does most of the hard work for you, and provides pin-point accurate auto focus straight out of the box.

I have extensively tested this lens in One-Shot and Ai-Servo and notice no difference in performance. Both work as they should. Focus is instant and has no problem keeping up with even the fastest of brides walking up the aisle. One-shot locks positively and accurately every time. Not much else to say. I just wished the Sigma had done this.

1/200th, f11, ISO 100 (flash) - Eaves Hall

Sharpness on the lens is subjective, and I find this subject is discussed too much, and photographers are led to only accept a lens which is studio-sharp at its most extreme apertures.. In my experience, sharpness on this lens is good enough for printing at any aperture. Sharpness increases progressively from 1.2 to around f2.5 – from there I find every aperture to be about the same.

One exception to this is the image edges. My 50L is a little “too” soft on the image edges at everything from f1.2 – f1.8.

Normally this isn’t a problem – I wouldn’t shoot group shots at these apertures and I find framing with the 50mm I tend to keep subjects quite central or on one of the vertical thirds – these are still sharp – any further towards the edge of the image it does start going softer.
Solution, shoot at f2 upwards. 50mm f2.0 on a full frame camera is still a very shallow depth of field. By shooting at f2 or f1.8 there is hardly any DOF difference – you would be hard pressed to tell. So take the safe shot and shoot at f2.

Flare. This is one area about this lens which could split opinions. Personally, I love lens flare. Some photographers see it as a lens weakness, or a problem with technique. I love it. I purposely make this lens flare by shooting it into direct light sources at the right angle. I don’t use a lens hood. The lens flare from this lens is absolutely gorgeous. Yes OK you wouldn’t want to deliver a complete set of images with bright red lens flare through every image.. but for a few select images, it adds variety, and in my experience, people like these images. By f2.8 the lens flare has all but gone.

Size/Weight. It’s a nice small compact lens. Unlike the Canon 85mm f1.2 L USM Mk II. It fits in my pocket and I hardly notice it being there. I like.

To summarise, for me, the Canon is the better lens. It does everything I want it to. It is reliable and as a wedding photographer, that is my number 1 priority.