What is unquestionable is that this is a great lens to look at!  Here are few more shots of this beauty:

Autofocus Findings

First of all, it is actually somewhat incredible that a lens like this has autofocus. This is a huge engineering accomplishment. The strain put on an autofocus system by such a large aperture is incredible, as is the amount of force required to move such heavy elements.  There are a number of lenses with an f/1.2 maximum aperture, and even a few rarities with a [very] slightly faster maximum aperture than this lens, but only the Canon lenses f/1.2 and wider have autofocus. Canon managed this in a unique way, combining a focus by wire system that isn’t dissimilar in that sense to modern STM lenses, though the actual focus motor here is a ring USM (Ultrasonic Motor). Considering the challenges presented by the extreme nature of this lens, the autofocus is really quite a success. It actually probably works better today than it did at the time that it was manufactured because of better autofocus systems along with the ability to perform microadjustment to calibrate the lens to the camera body.

Overall resolution isn't fantastic, but this f/1.0 shot is certainly nailed as far as focus.

It is interesting to calibrate such a massive aperture lens. The amount of glass in it is incredible, and knowing how shallow that depth of field is makes me leery that the lens would be able to accurately autofocus. Although the lens needed a -12 (a fairly large adjustment), it focused quite consistently at that setting in my tests.

Autofocus performance is actually fairly good, particularly at close to medium distances. The relatively low sharpness (combination of low contrast, relatively low resolution, and high chromatic aberrations) on the subject in comparison to many high resolution lenses might tempt you to think the image isn’t focused well, but I found that in the majority of my shots good focus had been achieved. You also have to focus very carefully, as depth of field is very, very thin at f/1.0 at most focus distances. Using the focus and recompose technique may not work in some instances.  A lens like this doesn’t only put pressure on the AF system; it puts a lot of pressure on the photographer. Still, my feeling is that the aging AF system in the 50mm f/1.0L is still doing a pretty impressive job considering the challenge it faces – at 5 feet the depth of field is a tiny 2 inches; an f/1.8 has twice as much DOF to play with. I will admit that my expectations were lower with this lens than modern ones, but while not perfect, the AF system in the 50mm f/1.0L really does quite a decent job of accurately focusing.

Autofocus speed is not nearly as impressive. The 85mm f/1.2L II inherited the “shell” of this lens (they are physically almost identical), but it seems like they share leisurely autofocus speed as well. Minor focus changes are relatively quick, but major changes (particularly towards minimum focus) are very slow. You definitely get a sliding noise as the elements move into place, though the actual AF motor is relatively quiet.

There is full time manual override, but only if the shutter button is held down halfway while turning the focus ring. On that point, even if the lens is switched into MF the focus ring will only do something if the camera is powered on and active. The actual action of the focus ring is quite smooth, in part because the connection to the moving of the elements is electronic, not mechanical. Even in manual focus mode it is actually the USM motor that moves the elements, much like modern STM lenses. The copy that I’m reviewing is sometimes sluggish to “wake up” and accept manual input, so occasionally it can be a little exasperating.

Still, this lens is definitely unique in its ability to accurately autofocus at such a massive aperture value and in many ways behaves like any other lens.

Image Quality

This is a demanding lens…period. It is capable of producing very unique results, but it challenges you to use it the right way. If you plan to shoot outdoors, for example, know that at wide apertures you are likely to be butting up against the limits of your camera’s shutter speed all the time. My 6D’s limit is a weak 1/4000^th, but even the 1/8000^th limit of my 70D is regularly exceeded. My solution was to use a three stop ND filter (ND8), but even with that on a bright sunny day I was regularly hitting max shutter speed. The inverse of this, of course, is that you can shoot in very low lighting conditions and maintain a slow shutter speed. Just to give you an example: I was calibrating a Tamron SP 45mm f/1.8 VC lens, and with the lighting on the test chart it was metering at 1/400^th second (ISO 100, f/1.8). Just for the fun of it, I aimed the 50L at the chart at f/1.0 – the camera metered at 1/2500^th of a second!!! That shows the difference between f/1.0 and f/1.8 and demonstrates just how much light this baby can suck in.

Clearly an area where this lens shines in its very shallow depth of field and subject isolation. A great application of this lens is not only throw backgrounds out of focus but also foregrounds. If you isolate your subject between a diffused foreground and background you maximize that huge aperture. Shoot with corners in the frame, or foreground bushes, trees, or other objects. They disappear into a defused blur and allow you to creatively frame subjects in a very unique way.  I shot the photo above through a chair.  The wooden slats are only a vague frame here.

I ran an Aperture Sharpness Profile on the lens. At no aperture is it as sharp as most of the modern lenses that I review, with peak sharpness coming at f/4 and consistently high results coming between f/3.2 and f/5. The lens doesn’t really reach a high level of sharpness until f/2.2. Diffraction sets in at f/10, but the lens stays as sharp through f/16 as it is at f/2.

Apparent resolution takes a hit because of some other optical defects, namely low contrast at wide apertures and strong amounts of chromatic aberrations. This tends to make the details a little hazy and mushy when viewed at a pixel level. The whole picture has a different look than what I’m familiar with; almost like a slight filter has been applied. You will either love or hate the look. I shot a few video segments with it and I was personally less than thrilled with the final product.  The shot below shows this “look” at f/1.0:

This “haze” makes details indistinct due to the chromatic aberrations, lack of contrast, and low resolution.  I dinged the new Tamron 45mm f/1.8 VC for its chromatic aberrations, but this shot shows how stunningly different its contrast and CA control is compared to the f/1.0L:

Chromatic aberration correction is a challenge with this lens because of the width of the aberrations. Fine lines often don’t resolve with hard edges but are blurred, meaning that the chromatic aberrations can cover a wide area and don’t clean up particularly well.  This shows a particularly bad example and what it looks like after extensive processing to remove the CA:

Another area where the lens fails modern standards is in its flare control. It flares strongly and uniquely when the sun is in the frame. Curved ghosting lines head out towards the edges of the frame, and a general loss of contrast (veiling) occurs.

The lens also heavily vignettes at wide apertures, but not necessarily much more than many other wide aperture lenses. There isn’t a standard profile for the lens, so you will need to find your preferred look manually if you want to correct for it. Vignette is mostly gone by f/4 (except extreme edges).

All of this aside, in real life testing sharpness is actually very adequate…with a major caveat. The lens is clearly optimized for portrait distances, and resolution isn’t very impressive at wide aperture beyond about 15 feet to infinity. This is one area where I feel modern primes have made great strides, and recent lenses like the 35L II, Zeiss Otus lenses, Sigma ART primes along with the new Tamron primes have demonstrated the ability to resolve highly at all focus distances, not just a certain “optimized” zone. In this case, however, one is hardly well served using this lens as a wide aperture landscape lens – that isn’t at all what it is about.

But for some photographers all of these flaws are welcome; they enjoy shooting with this lens because of them and the distinct look that it gives their photos.  Different strokes for different folks!

Check out the image gallery for this lens to see a lot more photos.

Bokeh Monster?

I encourage you to check out this video segment where I interactively break down the bokeh and image quality from the lens: