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On my Canon 6D, other lenses work as expected. But my 50mm f1.4 which has been very reliable for many years is not focusing correctly. It can sometimes focus when the subject is close (1-5' away). But if I were to take a photo of my front yard or subjects > 6' away, the lens can't focus. I hear the motor trying to focus but the subject is fuzzy. The focus light blinks green.

To make sure I don't have incorrect settings, I've been using Auto mode, the lens is set to AF and I've been testing outside in bright light.

Does the lens needs to be repaired or did I screw up a setting on the camera?

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  • \$\begingroup\$ My Canon 50mm f/1.8 Mk II lens is almost twenty years old and it has started to randomly fail to focus. Sometimes it's fine, other times it doesn't even try. Does your lens always focus on nearby subjects fine, or do you also see random failure at close distance? \$\endgroup\$
    – Bobulous
    Commented Jan 25, 2015 at 17:28
  • \$\begingroup\$ It doesn't reliably focus on nearby objects but it has a much easier time focusing on nearby objects rather than faraway objects. \$\endgroup\$
    – Sajee
    Commented Jan 26, 2015 at 14:08
  • \$\begingroup\$ @Arkanon, how is your lens "almost twenty years old" when 50mm 1.8 II was introduced in 2005? Even today (2 years after your comment) it's still just 12 years at most. \$\endgroup\$
    – walther
    Commented Oct 12, 2017 at 8:47
  • \$\begingroup\$ @walther the lens I'm talking about is the Canon EF 50mm f/1.8 II which, according to Ken Rockwell was released in 1990. And I bought it mid-to-late nineties. I can't find any mention of a Canon 50mm lens being released in 2005. Are you looking at data for a third-party lens? \$\endgroup\$
    – Bobulous
    Commented Oct 12, 2017 at 20:29
  • \$\begingroup\$ @Arkanon, never mind, looks like the site I checked this on provided a wrong information. \$\endgroup\$
    – walther
    Commented Oct 13, 2017 at 6:59

2 Answers 2

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This is a known issue with the EF 50mm f/1.4. The most common cause of the problem is that the guide slots at the end of the focus collar inside the lens have become bent. The most likely cause for the bent collar is an impact to the lens, such as being dropped, when the focus is set to a short distance.

Sometimes turning the manual focus ring very fast will push the focus mechanism past the 'sticking point' and allow you to get to shorter or longer focus distances. A quick twist of the focus ring provides more force than the micro-USM motor inside the lens does.

Always storing your EF 50mm f/1.4 with the focus set to infinity will help protect your lens from this problem if it experiences a sudden impact. The screws that retain the plastic guides inside the slots on the helical collar can also work loose and cause similar focusing problems. The exact same dis-assembly/assembly procedure is required to get to either problem to repair them.

There are some online resources that show you how to repair the lens yourself. Do so at your own risk, but it is not too difficult a repair as far as lenses go and if you have an aptitude for working on small mechanical devices and can follow long, detailed instructions carefully you can probably pull it off.

Good Luck!

fixing-stuck-focus-ring-on-canon-50mm

Repairing AF on the Canon 50 f/1.4

Update:

Canon has issued (September 2017) a Service Advisory for EF 50mm f/1.4 lenses with serial numbers beginning with: “4918”, “5018”, “5118”, “5119”, “5218”, “5219”, “5318”, “5319”, “5418”, or “5419". If you have a lens with such a serial number you may be able to get it repaired by Canon at no charge. For more, please see: Canon Expands Service Advisory for EF 50mm f/1.4 USMs with Focus Malfunction

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  • \$\begingroup\$ Thanks Michael. I'm not even going to think about self repair. Need to find a reputable place to repair this in the Atlanta area. Let me know if you have recommendations. \$\endgroup\$
    – Sajee
    Commented Jan 26, 2015 at 14:23
  • \$\begingroup\$ Got it repaired and now working as normal. Thanks again. \$\endgroup\$
    – Sajee
    Commented Mar 16, 2015 at 21:36
  • \$\begingroup\$ Ugh, same problem happened again. Any ideas on why this keeps happening? Now I need to weigh getting this lens repaired again or buy a new one. \$\endgroup\$
    – Sajee
    Commented Nov 30, 2015 at 17:47
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    \$\begingroup\$ @Sajee The introduction of the EF 50mm f/1.8 STM has eliminated most of the caveats of the older EF 50mm f/1.8 II. It only costs a little over $100 USD and has image quality comparable to the EF 50mm f/1.4 at shared apertures. The introduction of the EF 50mm f/1.8 STM at such a low price has also driven down the price of the EF 50mm f/1.4 from many sellers. \$\endgroup\$
    – Michael C
    Commented Oct 10, 2017 at 1:32
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Reference page 314 of your manual for how to use Auto Focus Micro Adjust (AFMA).

Each camera and lens is built to be within certain tolerances. If the camera and lens are on the edge of acceptable tolerances then the combination of them can lead to inferior results.

You can get a ruler, place it at a 45 degree angle from the focal plane (sensor) and set the aperture to 1.4. With this it should be easy to see where on the ruler the focus is hitting and you can use AFMA to adjust it back to where you're focusing.

You can do this per lens as well, as it ties AFMA settings to the lens serial number.

There are many more tutorials, with better descriptions and pictures, if you search around for AFMA.

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    \$\begingroup\$ Sounds like this is way beyond micro-adjust. \$\endgroup\$
    – mattdm
    Commented Jan 25, 2015 at 17:34
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    \$\begingroup\$ But if it is, no need to search around: we have a great series of answers here on what happens to be the first question on this site: What is the best way to micro-adjust a lens?. \$\endgroup\$
    – mattdm
    Commented Jan 25, 2015 at 17:35

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