I should declare at the outset – I’m a huge fan of fast prime lenses and the great control they provide over depth of field, especially when used in conjunction with a full frame sensor. So I’m predisposed to liking the 50L, and this article shouldn’t be regarded as a balanced review of its merits in comparison with other 50mm lenses. My purpose really is to try to provide an honest description of its advantages and its challenges after a couple of years of ‘real world’ use, and dispel some of the commonly peddled myths. I remember when I was doing my own research prior to buying, my head was swimming with the apparently equal number of glowing reviews and condemnations. An interesting thing about those polarised opinions is that they’re not the result of product variation or poor quality control – it seems to be true that some people love this lens, and others hate it. I hope this page might help people to understand more about why that should be so.

THE TECHNICAL CHALLENGES
The 50L does suffer from some technical ‘features’ that make it challenging to use wide open – it’s not the kind of lens you can just pick up, focus, compose and shoot in the same way that you might with most other lenses. Some of these challenges cannot be overcome and must be worked around or simply regarded as limitations, but with a bit of love and patience, and a lot of testing, you’ll soon learn how to avoid disappointment.

CHROMATIC ABERRATION
This is a problem that blights most fast lenses, and the 50L is no exception. If you shoot a very contrasty scene like a winter tree against a bright sky, you’ll get strong magenta fringing for sure. Maybe some cyan fringing too, but not to the same extent as magenta. It improves as you stop down, but never really goes away. Some people declare that software tools can eliminate the problem easily in post-processing, but I’ve never had 100% success and have always had to rely on additional tricks like desaturating magenta. For my kind of hobby photography however, this is seldom an issue.

CURVED FIELD OF FOCUS
Most camera lenses are designed to project an image of an evenly-focused, flat ‘field’ onto the camera’s flat sensor (or film plane), Imagine taking a picture of a perfectly flat brick wall – the flat image of that flat wall should be projected perfectly onto the flat sensor. That’s what most people expect, and lenses normally deliver pretty well, but demanding customers still pixel-peep into the corners of their images to see if they’re as sharp as the centre. Most often the corners are not as sharp, and the degree of unsharpness can cause howls of anguish in some circles. And… then there’s the 50L! Wide open, and at distances closer than about 8ft, there’s no getting around it – it’s just really, really bad. Not just unsharp bad, but really-out-of-focus bad. It seems to be incapable of projecting a completely flat field of focus, and this is most apparent at close distances and wide open.

The effect of this is that, when shooting wide open, closer than ~8ft, AF points which are not right at the centre of the frame are unreliable. You might also be aware of the unreliability of the common ‘focus/compose’ method of shooting at very wide apertures (on any lens), which is in fact caused by the flat field of focus described above. So… could the 50L’s curved field be the answer to this problem? Sadly, no. The 50L’s focus field curvature seems to fall exactly half-way between the flat field of normal lenses, and the very curved field that would be required for wide-aperture focus/compose. In practical terms, trying to focus on a subject which is closer than 8ft and offset from the centre of the frame, at wide apertures, is probably not going to be reliable.

Workaround 1: When shooting at f2.8 or wider, and closer than 8ft, I always keep my subject in the centre of the frame, use the centre AF point only, and leave sufficient room around my subject to crop the image to my ‘composition’ afterwards. Beyond 8ft, the lens is much better behaved, and alternate AF point selection or focus/recompose become much more reliable.

Workaround 2: Manual focus. This is possible through the viewfinder of cameras with suitable focussing screens installed – note that the default screen on a 5D3 is useless for manual focus, and is not easily interchangeable. The 6D screen is interchangeable and more suitable, but still not easy. Focus confirmation (flashes red when the area is in focus) can help, but I find it very fiddly and I find myself turning backwards and forwards, wondering if I went too far. Magnified Live View mode is useful if the camera is on a tripod; otherwise it feels very ‘point & shoot’ clunky.

ULTRA-SHALLOW DEPTH OF FIELD
The fast f1.2 aperture of the 50L, its single greatest advantage and selling point, can also be its most challenging feature. When shooting at close range (head & shoulders for example) the super-shallow depth of field at f1.2 means the focus has to be absolutely bang-on. There’s no margin for error at all, and even the slightest inaccuracy will completely spoil the image. In the case of the head & shoulders shot, it could mean that the nose will be in focus but the eyes will be soft. It’s that shallow. You really do have to have complete confidence in the lens’s calibration to shoot close and wide open. If you have a camera that includes a micro-adjustment feature, I’d recommend using it to provide the confidence you need.

STRONG VIGNETTING
This took me a bit by surprise when I first saw it – blimey – there must be about 4 stops of darkness in the corners when you shoot at f1.2! It disappears really quickly as you stop down, but it’s very, very strong at wide open. Fortunately, it’s also very, very easy to correct in software if you wish. Me, on the other hand, I actually started to like it! I think it’s one of the many characteristics that adds to the ‘3D depth’ of the images that make the 50L so special.

THE NAY-SAYERS’ ARGUMENT: “IT’S SOFT WIDE OPEN, AND IF YOU CAN’T USE IT WIDE OPEN, IT HAS NO ADVANTAGE OVER A 50MM F1.4”.
This is the most common complaint I’ve read about the Canon 50L. “It’s unusable at f1.2!” they cry. Well… they’re wrong. It’s perfectly usable once you’ve learned how to use it. It’s not as sharp as a macro lens, but it’s still great! It’s sharp enough for people not to notice the difference (without a magnifying glass), but soft enough to be an advantage in portraits where you don’t necessarily want to show every wrinkle in clinical detail, and the huge pay-offs are the wonderful shallow depth of field which makes the in-focus areas look really ‘punchy’, and the amazing soft bokeh. This is what’s worth the extra money, to me at any rate. From f2.8 onwards, it’s as sharp as any competitor apart from the manual focus Zeiss Otus perhaps, but the images still retain their unique character.

Many people also seem to be under the impression that ‘bokeh’ is something that’s unique to wide apertures, and that the 50L’s bokeh advantage is therefore only relevant when shooting at f1.2. This is not true of course – bokeh refers to the aesthetic quality of the out-of-focus areas of an image, and since most apertures render some out-of-focus areas in an image, it’s possible at most apertures to see the difference between the bokeh of the 50L and another standard lens. Some lenses produce attractive bokeh; others produce noisy, busy, cluttery, ugly bokeh. The 50L produces beautiful bokeh! The 50mm f1.4? Not so much. It’s not bad, but it’s not as good as the 50L.

Footnote about bokeh: there are some subjects that will almost always produce ugly bokeh, regardless of the lens – things like foliage or anything else which is heavily patterned, for example. Many lens testers like to compare lenses’ bokeh by using such images and choosing which is the least ugly. I’d far rather see a comparison of the best that lenses can do when making a judgement about what to spend my money on.

SO… WHY SPEND SO MUCH ON A ‘STANDARD’ LENS?
Standard lenses (50mm on a 35mm film or full-frame digital camera) have been popular for most of the last hundred years, but I believe they fell out of favour in the 1980s when the quality of kit zoom lenses improved to a usable standard, and people wanted the convenience of a single ‘Swiss Army knife’ lens instead of a bag full of prime lenses. People still bought wide primes and telephoto primes for specialist purposes, but most 50mm lenses were put under the bed and forgotten about. In my view, this was a bit of a landmark moment in photography – this was when most photographers stopped composing, and started ‘framing’. I’ll write some more about this in an article about prime lenses versus zooms, but in a nutshell, when you use a prime lens you have to think about where to position yourself to obtain the image that you want. You have to move around in three dimensions and create a composition of all the elements in your picture. It was second nature to most photographers, although some were more successful than others! Zoom lenses encourage a much lazier approach on the other hand – just turn a ring clockwise if you want to ‘get closer’, or turn anti-clockwise if you want to ‘go wider’. And somewhere along the way, moving sideways was forgotten. Now, many photographers use their zoom lenses automatically to frame their subject, and value zooms with longer ‘reach’ so they can frame things which are even further away, without taking a step. It’s lazy and unimaginative, and I despair when I see new and enthusiastic photographers being instructed to buy this zoom or that zoom as their first lens. In my book, a standard lens should not only be the first lens a photographer should buy, but it should remain the most important lens in the bag.

I love my standard lens. I love its natural perspective – I think that’s much more engaging for a viewer because it’s easy to imagine being part of the scene – like you’re seeing things through the photographer’s eye. It makes me think about composition. I love the shallow depth of field and subject isolation that fast lenses (f2 or wider) provide, and the way the out-of-focus background adds a magical 3D depth. But despite being isolated in a shallow depth of field, the relationship of the subject to its background or environment is never ‘broken’ like it can be with wider lenses, which throw the background elements into the distance. Most 50mm lenses do all of the above, but the 50L is champion in my book (on a Canon AF body – there are some manual-focus Nikkor and Zeiss lenses that do an even better job, I think).

It’s impossible to say if the differences between the Canon 50L and the 50mm f1.4 (or the f1.8 for that matter) are worth the huge extra cost. Only you can make that decision. What I can say though, is that you’d be daft to buy it just because someone else says “it’s the best”. The quality of an image is subjective, and whatever floats your boat might not be another’s cup of tea. I’ve read many reviews which condemn the 50L as a useless pile of heavy junk, because its scores in various tests are rubbish, and the proof those reviewers offer is a bunch of images of test charts and super-magnified eyelashes. But in my mind, a great image is more than the sum of its parts and specifications, and the 50L offers something special that is not apparent in standard lens tests. If you’re in the market for a standard lens and you place value on quality of bokeh and subject isolation, then I think you’ll have a wonderful time with the 50L. Despite all the obstacles it presents, it’s my favourite of all the lenses I’ve ever owned.

I found the following page by Winnie Bruce to be very useful when I was trying to convince myself it was OK to ignore the haters and drop the cash on the 50L. It’s a very simple and neutral demonstration of the differences between Canon’s three 50mm standard lenses, and I believe it does display the very subtle but very attractive ‘depth’ of the image that the 50L produces compared to other lenses. It’s not only about bokeh – in fact it’s really difficult to describe in empirical terms what the differences are that I can see; but I’m not really bothered by that. It’s enough for me to say with confidence that I simply prefer the 50L images.

http://www.clickinmoms.com/blog/canon-50mm-lens-comparison-by-winnie-bruce/

If you’re not convinced, you might want to have a look at the Sigma 50mm f1.4 Art. It’s cheaper, larger, very well made and very heavy, and it’s been designed with a no-compromise approach to sharpness. The images are impressively sharp for sure, across the frame and at all apertures, and it displays none of the idiosyncrasies of the 50L so you’ll get great results out of the box*, but to me the images seem a bit clinical in character. It’s been made by engineers, not by magic photography pixies.

* Many people report inconsistent and unreliable autofocus in certain conditions with their Sigma Art lenses. My advice would be to buy only from a reputable dealer who will permit you to test the lens thoroughly before purchasing, and exchange it in the event of a fault.