Canon EF 50mm 1.4 USM - Autofocus a little too slow ?

[Pav10566]

Hello, I recently acquired this lens, second hand and tested it on all my EF cameras. The lens quality is great however I "think" and find that the autofocus isn't what it should be. I have several USM lenses (25-105 and 70-210) with USM and they seem faster and more silent as well. Don't take me wrong, the AF is working but not as swift as I expected it to be and you hear it as well...do I have to believe that it is going to break down on me one of these days, is it normal maybe or does anyone know a solution?

 

[Pav10566]

Hello, I recently acquired this lens, second hand and tested it on all my EF cameras. The lens quality is great however I "think" and find that the autofocus isn't what it should be. I have several USM lenses (25-105 and 70-210) with USM and they seem faster and more silent as well. Don't take me wrong, the AF is working but not as swift as I expected it to be and you hear it as well...do I have to believe that it is going to break down on me one of these days, is it normal maybe or does anyone know a solution?

By the way...the Autofocus dramatically improved when I removed the UV filter

 

[Dao]

By the way...the Autofocus dramatically improved when I removed the UV filter

Oh wow, thanks for the information. When I bought my 50mm f/1.4 (used), it had a UV (B+W brand) filter on it and the first thing I did was removing it. However, to be honest, the AF of the EF 50mm f/1.4 USM lens is not as fast as my 85mm f/1.8 nor the EF 70-200mm f/4. Of course, it is not slow at all, just not as fast.

 

[Big Mike]

FYI, it's not widely known, but there are two different types of AF lens motors that fall under the USM badge.

The first type is a small USM (ultra sonic motor) that runs a set of gears to move/focus the lens. This is only marginally better than the non-USM lenses. This is the type in the EF 50mm F1.4.

The second type is what they call 'Ring' USM. It doesn't use a geared connection like the other type, this allows it to be fast, much quieter and also allows for FTM (full time manual), which means that you can manually adjust the focus via the focus ring, even when it's in AF mode.

 

[Pav10566]

FYI, it's not widely known, but there are two different types of AF lens motors that fall under the USM badge.

The first type is a small USM (ultra sonic motor) that runs a set of gears to move/focus the lens. This is only marginally better than the non-USM lenses. This is the type in the EF 50mm F1.4.

The second type is what they call 'Ring' USM. It doesn't use a geared connection like the other type, this allows it to be fast, much quieter and also allows for FTM (full time manual), which means that you can manually adjust the focus via the focus ring, even when it's in AF mode.

I see...thank you for this information. However, the 50mm 1. 4 has the FTM as well. Nevertheless, the optics are great...good thing I bought it second hand then, if I had spend the full monty I would certainly have been very disappointed by its slow & noisy AF

 

[Big Mike]

Ah yes, you are correct. But it only works in 'One Shot' mode. This is a bit of an oddity.

The lens is a little unusual in the global Canon lens context - it features a micro-USM AF drive including full-time manual (FTM) override in one-shot AF mode. This is, I think, a quite unique combination. FTM is usually possible with a ring-type USM drives only.
Canon EF 50mm f/1.4 USM - Review / Test Report

 

[LShooter]

Mine is wonderfully fast.

 

[Derrel]

The Canon EF 50/1.4 is known to be a little bit 'weird' in terms of AF. I owned mine from 2006 until January of this year. It "usually" focuses relatively quickly, but was occassionallty a bit lethargic, and sometimes did not want to initiate AF on either my 20D or my 5D...other 50/1.4 users have reported the same thing. I'm not quite sure, exactly, why the 50/1.4 was slower and less-responsive; my 85/1.8 EF and 135/2-L were ALWAYS, always, always much faster and more-responsive.

I think some of the issue might have to do with the relatively short focal length, combined with the "basic" class of USM motor used in the 50/1.4, The short focal length means that the "in-focus" signal data and the "out of focus" signal data that the AF system uses in its phase detection process is not as discretely IN or OUT of focus as it is on a longer lens, like an 85, or 135mm lens. With those lenses, a very SMALL movement of the focusing system makes a MAJOR difference in the degree of "in" or "out" of focus, so those lenses respond super-fast, and the system focuses with amazing ease. Shorter lenses, like 20,24,28,35,50mm have a much more-challenging set of focusing data coming in, and it's pretty common for something like a 24mm f/2.8 lens to "saw" back and forth...dtttzzz.dtzzzz.dtzzz....dtzzz, as it tries to determine exactly where "IN" focus starts and where "OUT" of focus is....there's so much depth of field that the in/out distinction is not all that concrete.

I DO think that the 50/1.4 EF has lovely bokeh, and is a must-have lens for a Canon shooter. But it's also rather outdated in terms of the "level" of the focusing motor, and it could stand to be brought up a notch, it's true. It's been made basically the same exact way since 1987, I think....it's NOT a "modern" lens. By the same token--Nikon's new 50/1.4-G focuses very slowly....but their 50/1.8 G focuses like a Ferrari....so...I dunno...

 

[Pav10566]

Gentlemen, gratitude for your relieving and instructive comments. At least I know now that the lens I bought is not "abnormal" and playing up on me
It has indeed a lovely bokeh and gives razor-sharp pictures.Recommendable for Full frame camera's. Also, much more comfortable carrying around than my Tokina Pro 28-70 /2,8, great lens and formidable optics but gets heavy carrying around