0

I recently bought a factory refurbished Canon EF 50/1.4, bought directly from Canon. When autofocusing, the focus ring does not move, like all other USM lenses I've used. However, when autofocus goes to the minimum focus distance, the focus ring will turn a bit. Is this normal?

I know that this lens doesn't have the best build quality. If it's not normal, I can potentially get it repaired, replaced, and/or refunded from Canon.

Update: I called Canon and spoke to a tech support representative. While on the phone, he got a copy of the lens and the same body I was using. He experienced the same movement of the focus ring when focusing at the minimum distance. Therefore, he concluded that it was normal behavior for this lens. He did offer to have it sent in to Canon to check it out, though. I said that since it didn't seem to be affecting picture quality or AF accuracy, I would continue using it a bit longer. If it does appear to be a problem, I have a whole year within the warranty to return it for repairs. If/when I do that, I will post an update.

  • If I were you, I would just call Canon and ask if that is normal and if not, than ask for a refund. – Dragos Aug 15 '16 at 16:54
2

The Canon 50mm f/1.4 has a feature called full-time manual focus (FTM) : you can use the ring while your camera/lens is focusing (in AF mode). You don't have to switch to Manual Focus to manually focus the lens. To do so, the lens has a coupling between the ring and the focusing system.

The fact that the ring isn't moving in AF mode when the camera is focusing is normal. You can look at this video comparing the canon 50mm 1.4 and 1.8 : https://www.youtube.com/watch?v=b8pO7buEFhM

Now, concerning your problem, the 50mm f/1.4 I borrowed from a friend displayed the same characteristics. As everything else is working fine (no weird noise, no mechanical shock, no vibration and AF working as expected), I suspect that this movement is caused by the coupling between the ring and the focusing system when extremes focusing positions are reached. You can look at the Canon 50mm f/1.4 parts catalog to have some information about the internal working of this lens.

As a sidenote, as far as I know, the Canon 50mm f/1.4 is the only one (at least from Canon) using simultaneously this clutch mechanism to allow FTM focusing and micromotor USM (instead of ring USM).

2

When autofocus goes to minimum or maximum focus distance, the focus ring will turn a bit. Is this normal?

Not really. The external ring should not move at all when the AF motor is moving the lens elements with the EF 50mm f/1.4. Mine never has. If I had received the lens you got I would be sending it right back to Canon service to be fixed or I would be demanding a different lens. I have bought refurbished lenses directly from Canon in the past and would consider doing so in the future. I've always received them in like new condition and have never experienced a single issue with any of them.

The full time manual focus with micro-USM design of the EF 50mm f/1.4 is a kind of one-off thing and has some known issues with the helicoids on the focusing collar inside the lens getting bent and causing the focus mechanism to get stuck. The damage usually occurs when the front of the lens takes a glancing blow or is dropped while it is extended for focusing at shorter distances. This will eventually manifest itself by providing too much resistance for the AF motor to overcome when trying to move the focus mechanism. If the user continues to attempt to get the lens to focus when stuck it can lead to damage to the AF motor. If care is taken to always park the lens with the focusing barrel fully retracted (i.e the lens focus set at infinity) it's much less likely to be damaged by any bumps and bangs it may encounter.

There has been a lot of discussion on the internet about this issue and a simple search for "EF 50mm f/1.4 AF stuck" will pull up a plethora of links. Please note that no one is saying that all EF 50mm f/1.4 copies are bad or eventually will go bad. But if the lens is dropped or the front of the lens suffers impact while the focusing tube is extended it is known that it can lead to this issue.

You can read more about this issue in this discussion regarding the various lower priced Canon 50mm EF lenses.

I've owned an EF 50mm f/1.4 that I bought new for several years and have always followed the recommendation of parking the lens in the infinity focus position. Within the past year I was shooting in a moderately cold and very humid environment when the AF started occasionally getting stuck at a point close to, but not all the way at, the minimum focus distance (MFD). I switched the AF off, rotated the focus ring towards infinity while gently pushing the front of the protruding lens barrel straight back into the lens housing and everything would free up. I was shooting in very low light and if the camera started to hunt for focus it would stick each time it reached the same point in the AF travel. Once I figured out what was going on, for the remainder of that shoot I took care to not allow the camera to hunt and move the focus mechanism too close to MFD.

Since that time if the lens occasionally sticks when passing through that same point on the focus scale (approx. the 2 foot mark) a very quick twist of the focus ring in either direction will free it up. A more normal turning of the focus ring will only slip as the focus mechanism doesn't move.

There are some rather good videos and blogs posted on the internet that show how a capable DIYer can repair the helicoids in the focus collar of the EF 50mm f/1.4. There are a few links in some of the other photo.stackexchange answers referenced above. If I used the areas of focus near the MFD more I would probably attempt this repair myself since the lens is long out of warranty. But in the way I use the lens it hasn't been a real issue so I've just learned to live with it and use that quick twist when needed.

The fact that your refurbished lens shows signs of this issue right out of the box would indicate to me that whatever the issue was that necessitated it being sold as refurbished has not been properly addressed. If I were in your shoes and had just purchased a refurbished lens that already demonstrates symptoms of this issue I would be insisting on Canon honoring the warranty they provide for refurbished lenses and getting this fixed.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.