You may have come across a couple of my threads when researching this lens before I decided to buy one. It’s certainly one of the most controversial lenses in the Canon lineup. Some people clearly hate it, while others adore it.
Here’s a sampling of some anecdotal comments you’re likely to come across when searching the forums on this particular product…
The 50L is a great lens
Wide open its a dream.
50L is a hot mess of a lens.
the 50L isn't exactly dependable
the 50L is either a dog or a wonderful piece of glass
After having owned one for a bit more than a week now, and spending the time to get it focusing properly and consistently through multiple MFA sessions, I can understand where some of these diametrically opposed views come from. But before we dive into the performance and see whether any of this is true or not, let me start by answering the most obvious question…
Why a 50L?
Owning both a 35L and 85L, you might be wondering why on earth I might want a 50L as well. As with most people, I generally use the 35L indoors for both contextual portraits and low light snap shots and use the 85L for head and shoulders portraits both indoors and out (although indoors you’re limited by it’s lengthy working distance).
I had originally looked to replacing my 24-105 with the 24-70II but came away from that comparison disappointed. So I decided that what I wanted was a wide prime I could use outdoors as part of my travel photography kit to augment my 24-105 zoom. I considered a 24L and even a 24TS-E but concluded my 24-105L is suitably sharp at 24mm and covered my tripod landscape and cityscape needs very well so deferred looking at either of those seriously for now. What I really wanted was something that could give me nice subject isolation and/or blurry backgrounds to be a bit more creative when walking around.
I used the 35L on my 7D a couple of years ago and really loved it and have missed that ever since switching to full frame. 35mm on full frame is just too wide for me when outside walking around. The 85L is too long and too heavy for a general purpose lens. Therefore 50mm seemed perfect and the f/1.2 max aperture is very appealing for creative outdoor shots as you’re often working with subjects a bit further away than typical portraits and that wide aperture really seems to help isolate subjects and offer more creative opportunities.
There seems to be a few 50Ls coming available at good prices these days, so I snatched one up. As usual, whenever I buy a new lens or camera, I spend the time to compare it to other pieces in my kit, and this one was no exception. But before you can even begin to compare it, you need to make sure it’s doing the basics correctly e.g. focusing. So let me start with that.
Focusing and MFA
Let me cut right to it... this lens requires accurate MFA to get it focusing accurately and consistently. If the MFA is off, I found the focusing could be very inconsistent - sometimes back focusing, sometimes front focusing, by varying amounts and apparently at random. It reminded me of a Sigma 30mm lens I used a few years ago.
Anyway, once you think you have the MFA dialled in, try a hundred shots (sometimes taking several shots of the same thing). I found taking images of signs at an angle particularly helpful. The idea is to see if your MFA is bang on, or still needs refinement. If necessary, go back and MFA it again. Rinse and repeat until you’re absolutely sure it’s dialled in. And don’t try to MFA it at a long distance… it gets harder to assess accuracy as the DOF increases. I found 1-3m (3-6ft) is a good range (I tested MFA at 1m and 2.5m and then a ton out on the street). Now that I’ve done that, the AF of this lens is super accurate and reliable. It will nail focus at short or long range every time.
See also member agog’s thread about MFA and this lens
Note, unlike Agog, I could not find any relationship between focus performance or sharpness and metering mode (I tried several shots at all metering modes after reading his post and couldn’t find any difference in focus or sharpness performance).
One of the often discussed characteristics of this lens is it’s tendency to shift focus when stopped down at short range. I understand this is a characteristic inherent in the design and a trade-off in achieving a more pleasing bokeh. Basically what is supposed to happen is that when photographing a subject at close distance, the focal plane will shift slightly further away if the aperture is stopped down. As the story goes, this becomes less and less problematic at smaller aperture settings as the increase in DOF will more than offset the focus shift.
I tested for this focus shift at MFD (about 1ft) and at about 1m (3ft) and couldn’t really see any issues. According to what I’ve read, the DOF should be such that 1/3rd of the in-focus area is in front of the focal plane and 2/3rds in back of the focal plane. And as far as I can tell, this very close to what is happening with my lens.
Here’s the shots at MFD with focus point on the H-key. Note that at all apertures, the H remains in focus. Of course you can see the DOF increase to the back more readily than the front, but this is consistent with the 1/3rd front, 2/3rd back rule of thumb. So you wouldn’t expect to see the B or N key in focus until the 6 and 7 keys are also in focus.
Here’s the shots of a yard stick at about 1m… the 20” mark on the yard stick is at the focal plane. Again, the DOF seems to increase roughly in line with 1/3rd front and 2/3rds behind. For example, at f2.8, the DOF extends forward about 1-2 inches and backward about 3-4 inches.
I’m guessing when you MFA the lens, you can bias it more towards front focusing or back focusing to equal out the DOF both in front and behind the focal plane if you so choose.
The bottom line is that I can’t see any significant focus shift here.
Based on a few reviews I had read, I didn’t have very high expectations for the sharpness of this lens - especially off-center. I have to say I’m pleasantly surprised.
For reference, here’s the full frame shot so you can see where the 100% crops below are coming from in the frame. It’s a 40” TV box with both some large and tiny print in the middle and in the corners. I filled the frame with it for each lens (moving back as required as FL increased).
First let’s look at center sharpness wide open. My 35L and 85L are ever so slightly sharper in the center but the 50L is certainly in the same league… In fact without 100% crops side by side, you probably couldn’t tell which lens was which. My 24-105 (which seems to have legendary sharpness :lol is a hair sharper to my eyes at the wide end, but looses out to the 85L at the telephoto end.
100% Crops from Center (wide open)...
Next, let’s look at the corner sharpness wide open for the 35L and 50L first. The 35L and 50L are still both adequately sharp. Even the tiny print is still readable. Keep in mind this is at f/1.4 and f/1.2 respectively. Impressive. The surprise here is the corner sharpness of my 24-105 at f4.
100% Crops from Corner (wide open)...
Looking at the 85L it is my sharpest prime in the corner wide open and you can see the corner sharpness of the 24-105 has really fallen off here compared to the wider focal lengths.
100% Crops from Corner (wide open)...