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Bokeh Battle: Canon 50mm Prime Lenses

by Philippe Dame on November 15th, 2010

My friend Vinh has the Canon EF 50mm f/1.8 II and I have the Canon EF 50mm f/1.4 USM. We got together this weekend to do some comparison tests as we know these two lenses are often competing for the same lens-buying dollars. Though we didn’t have time to do extensive testing, we wanted to see how dramatically better or worse the bokeh was on each lens (bokeh is the quality of the out-of-focus areas of a photo).

A Bit of Background

Most people can appreciate crisp detail in a photo and strong isolation of the subject matter. Leading someone’s eye through a photo boils down to composition and selective focus. The more narrow your depth of field, the more your subject is going to pop out. Having a “fast lens”, one with a very wide maximum aperture, makes this much easier to achieve.

Photo Details: Canon 7D w/ EF 50mm f/1.4 USM – 1/1250s f/2.8 @ ISO 100

Really fast lenses (f/1.2, f/1.4 or f/1.8) tend to be prime, fixed focal length lenses. These are typically simple in construction, create sharp images and are lightweight. My favourite lens, as I’ve mentioned before, is my 50mm f/1.4 prime. With my 7D’s APS-C sensor, it acts more like an 80mm telephoto. This extra zoom works by forcing me to take tight, interesting shots.

This is such a popular focal length that Canon produces three EF-mount 50mm lenses of varying grades:

If you’re looking for a fun lens that’s affordable, you can forget about the “L” lens as it’s fun but not affordable. This leaves you with only two real choices, the f/1.8 II and the f/1.4 USM. The next obvious question has to be, “Is the f/1.4 really 3.5x better than the f/1.8 to justify the price jump?”

Generally speaking, I think of these four area when I consider buying a lens:

  • Optical properties (sharpness, colour saturation, contrast, distortion, chromatic aberration, etc.)
  • Build quality (plastic vs metal construction and position/feel of the focus wheel)
  • Speed & bokeh (maximum aperture and smoothness of the bokeh)
  • Autofocus (speed and noise of focus system and ability to manually focus full-time)

I can’t be sure about the first, but the f/1.4 does excel in the last three criteria.

Canon EF 50mm f/1.4 USM

I’ll start this comparison by talking about the 50mm lens I own. This thing sits on my camera body 90% of the time. It’s so “fast” at f/1.4 that I can do a ton of shots indoor without a flash and it’s equally versatile outdoors. Theses days, I only use my Canon EF-S15-85mm IS lens to shoot wide angle.

This lens is very light compared to any zoom lens (only 290g or 0.64lb). My 7D is practically 1 Kg so I find it doesn’t weigh me down at all. It’s reasonably well built with its metal mount but it’s still a plastic body. I also like that the focus ring is big and always available (no need to switch to manual focus to tweak the focus on a single shot).

The acronym USM means it has the newer ultrasonic motor but this lens has only “Micro USM” not “Ring USM” – that mean’s it’s a bit louder and slower than the most recent lenses.

I took product-style photos of the lenses myself for this post. That was quite fun but you’ll have to ignore the umbrella pattern in the reflection. I’ll place my softbox where the reflective area is next time instead of the shoot-through umbrella – lesson learned.


The bokeh, or smooth out-of-focus areas, produced by a lens is affected by the aperture setting you choose. When a lens is used “fully open” (e.g. f/1.4), the bokeh is always smoother and made up of perfect circles for bright points of light. As soon as you close the aperture (a.k.a. stop it down), strange shapes can appear. That’s one of the big differences between the two 50mm lenses. The f/1.8 II has only five blades in its aperture diaphragm while the f/1.4 has eight.

To test out each lens, we pointed them at a pile of Christmas lights in a dark room and threw the lens out of focus. This is an “extreme” test as only bright points of light like this are going to make the bokeh shape so obvious. If you shoot at night, this is common enough (e.g. street and car lights) but less so during the day. As you can see in the daytime photo of my son Keane above, there’s no obvious circles anywhere.

Non-round bokeh will translate to harsher and more distracting blurs so it is important. Here’s how my f/1.4 performed at the following apertures: 1.4 (fully open and thus round), 1.8, 2.8, 4, 5.6 and 8:

f/1.4

f/1.8

f/2.8

f/4

f/5.6

As you can see the octagon bokeh shape created by the 8-blade aperture diaphragm is obvious but not too bad. I find overall that the bokeh of this lens is very pleasing. I’m rarely, if ever, frustrated by the bokeh shape.

Here’s a video that steps through the test we did above:

Canon EF 50mm f/1.8 II

At only 131g (0.29lb), this lens is probably the lightest lens made by Canon but it’s so light that it feels like a toy. It’s an all-pastic body, including the mount so durability is not great.

The focus mechanism of this lens is not ultrasonic (USM). That automatically makes it slower than the f/1.4 and even nosier. To manually focus this lens, you have to first switch it to manual focus. The focus ring is small and located right at the front of the lens. If you use a circular polarizer, the moving focus ring will throw off the alignment of your filter.


Though we didn’t do optical quality tests, reviews we’ve read rate it as a sharp lens. My friend Vinh’s main concern has been its bokeh quality. If he shot wide open, the bokeh shape was round but as soon as he closed the aperture a bit, this lens’ five-blade aperture diaphragm started to get obvious.

Here’s the same Christmas light shots using the f/1.8 at the following aperture settings: 1.8 (fully open), 2.8, 4, 5.6 and 8:

f/1.8

f/2.8

f/4

f/5.6

And again, a video that steps through a similar test:

Conclusion

For me, one of the main purposes of having an ultra fast lens is to enjoy a lot of smooth bokeh – it can’t be distracting. Additionally, the short depth of field at wide apertures makes using these lenses very tricky (especially with moving children). It’s critical that the focusing mechanism be fast.

Although I’m not in love with 8-sided bokeh circles and the slower USM type of my 50mm f/1.4, I would recommend it over the f/1.8. I think you get what you pay for in this case and the pictures do speak for themselves. It’s your pick, octagons or pentagons.

  • Dave

    Great comparison Phil! The 50mm 1.4 has also been one of my favorites, although I am not using it as much as it is just to tight for a lot of situations. I’m still leaning towards the 24mm 1.4L this spring as more of my shots are wide, and the 1.4L will provide some phenomenal opportunities for night time shots and video.

    After ready your post, I checked out some of my shots that make good use of bokeh. Looking close, I can detect the hexagon shapes of lights in the background, but typically I am more focused on the subject itself.

    Excellent explanation and comparison of these two lenses though!

    • http://LearningDSLR.com Philippe Dame

      I’ve been considering the 24mm as well. It’s affordable and approaches a natural 50mm lens for us. Thx for you comments.

    • Vinh

      Dave,

      Another option, as you may know, is the 28mm 1.8. I am awaiting my copy in the mail as we speak. Not an “L” lens but it will probably be all that I need, at a fraction of the cost.

      The price however, has seen a spike in the recent months due to the Japanese situation and US currency taking a dive. We in Canada still get nailed, CAD729+tx retail vs USD529+tx. Just months ago, this lens used to sell for USD420!!!

  • Zamri A.

    This is such a great lesson, thanks for sharing this. I recently bought the EF 50mm f/1.8 lens, and have to say it was quite pleasing to see the bokeh produced. Really tempting to get the f/1.4, though the price is quite a ‘killer’. but given the bokeh effects if quite amazing, i think why not?

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