Damage to Canon EF 50 mm f/1.4 USM

Scott Larson wrote:

If it still focuses then it's OK. But don't do that. Just one tap against a hard surface can destroy the focusing mechanism and you won't even be able to manually focus it.

thanks for the warning.  i use the 1.8 and use a rubber lens hood to act like a rubber bumper on most of my lens.

bridge77 wrote:

thanks for the warning. i use the 1.8 and use a rubber lens hood to act like a rubber bumper on most of my lens.

With the 1.8 you are probably safe because they are stronger but with lenses like the 1.4 where the front section moves in and out when focusing a rubber hood is not a good idea.

The reason is that a rubber hood fits into the filter threads so a knock could still cause damage whereas the correct canon hood fits onto the body of the lens and any knock on that does not affect any moving parts.

Ray UK wrote:

bridge77 wrote:

thanks for the warning. i use the 1.8 and use a rubber lens hood to act like a rubber bumper on most of my lens.

With the 1.8 you are probably safe because they are stronger but with lenses like the 1.4 where the front section moves in and out when focusing a rubber hood is not a good idea.

ok, then i am comparing apples and oranges.

The reason is that a rubber hood fits into the filter threads so a knock could still cause damage whereas the correct canon hood fits onto the body of the lens and any knock on that does not affect any moving parts.

the rubber i feel offers some shock absorption to lenses, until the lens becomes a frisbee or bumper car.

it would seem that any lens shock would affect moving parts regardless of the lens?

the 1.8 lens seems to have it's own stories of the thing failing after much use, the new EF STM lens  has a metal lens mount to the camera body, perhaps an improvement?

gipper51 wrote:

Yes you can. This lens is known to be fragile and very easy to damage the focus system with front impact. If it's acting up this probably caused some damage, unfortunately.

Thank you for the warning! I honestly thought lenses were more durable.

Would you say I can judge if there is any damage by checking whether the lens can autofocus or not? Or do I have to evaluate the sharpness of the pictures (which would be a bit problematic as my pictures aren't really all that sharp even under the best circumstances)?

rmexpress22 wrote:

Sure, it can. But if it works fine, then you're probably okay.

Thank you. I will be keeping an eye on this lens to make sure it works correctly.

Scott Larson wrote:

If it still focuses then it's OK. But don't do that. Just one tap against a hard surface can destroy the focusing mechanism and you won't even be able to manually focus it.

Thanks for the heads-up! I will definitely try to be more careful from now on.

Would you say I can judge if the focusing mechanism is damaged by checking whether the lens can autofocus or not (by which I mean, notify me it achieved focus through focus confirmation light and beeping)? Or do I have to evaluate the sharpness of the pictures?

bridge77 wrote:

...

it would seem that any lens shock would affect moving parts regardless of the lens?

the 1.8 lens seems to have it's own stories of the thing failing after much use, the new EF STM lens has a metal lens mount to the camera body, perhaps an improvement?

The metal bayonet feels and looks nicer, but it's the other end of the lens that breaks.

The hood clips into a groove in the main body of the lens, outside the lens cell that moves for focussing.  It is plastic, not the same plastic as a crash helmet or a riot shield, but still one that absorbs a lot of impact energy.  The bayonet lens hood stops any impact directly onto the focussing mechanism, while a rubber hood screwed into the filter thread just reduces minor impacts on the focussing mechanism.

msowsun wrote:

Ray UK wrote:

What happens when the 1.4 is damaged, is as follows:

As the front assembly rotates during focusing it relies on small lugs which run in sloping grooves of plastic tube affixed to the main body. This plastic tube is quite flimsy and any pressure on the front can cause this to be damaged by the lugs.

If the damage is only slight then focusing will still work but the lugs will cause an indentation in the grooves so the focus will tend to stick in this position, this can usually be felt when using manual focus

If the lens has sustained greater damage then the plastic tube will be broken and the front section will not turn at all, so neither AF or MF will work.

Damage caused by pressure on the front of the lens will not affect the lens sharpness unless of course if the lens is unable to focus.

This is the part that is easily damaged by pressure on the front filter threads.

If the lens falls face down and is at the longer part of the focus range the groove can/will be forced open (in the area shown in red). Sloppy focus with lots of backlash is one of the possible outcomes in both manual and auto focus. Unpredictable and difficult to diagnose from a single picture.

I got a used one cheap with this fault and was able to press the "distorsions" back but it took some fancy mechanical measuring equipment to get the ring round and the groove width constant (with a DIY round feeler gauge).

Sittatunga wrote:

bridge77 wrote:

...

it would seem that any lens shock would affect moving parts regardless of the lens?

the 1.8 lens seems to have it's own stories of the thing failing after much use, the new EF STM lens has a metal lens mount to the camera body, perhaps an improvement?

The metal bayonet feels and looks nicer, but it's the other end of the lens that breaks.

The hood clips into a groove in the main body of the lens, outside the lens cell that moves for focussing. It is plastic, not the same plastic as a crash helmet or a riot shield, but still one that absorbs a lot of impact energy. The bayonet lens hood stops any impact directly onto the focussing mechanism, while a rubber hood screwed into the filter thread just reduces minor impacts on the focussing mechanism.

One other advantage to an OEM-type hood is that it provides slightly more rain deflection than a rubber hood screwed into the lens threads. The rubber hood moves with the lens, exposing the lens barrel to rain. Since the OEM-style hood fits to the lens body it provides a bit of shelter to the lens barrel when it is extended in shooting position.  This does not make the lens any more weather resistant, but may keep a few drops off the lens barrel if one is caught out in the rain without a rain cover for the camera.

Scott Larson wrote:

If it's broken, it will not focus at all, no AF, no manual focus. You'll turn the focus ring and nothing will happen. It's not subtle at all.

Thank you for clearing it up. The lens seems to be working normally so I'll go ahead and assume there is no permanent damage.

Ray UK wrote:

What happens when the 1.4 is damaged, is as follows:

As the front assembly rotates during focusing it relies on small lugs which run in sloping grooves of plastic tube affixed to the main body. This plastic tube is quite flimsy and any pressure on the front can cause this to be damaged by the lugs.

If the damage is only slight then focusing will still work but the lugs will cause an indentation in the grooves so the focus will tend to stick in this position, this can usually be felt when using manual focus

If the lens has sustained greater damage then the plastic tube will be broken and the front section will not turn at all, so neither AF or MF will work.

Damage caused by pressure on the front of the lens will not affect the lens sharpness unless of course if the lens is unable to focus.

Thank you for the in-depth explanation. I think I understand the inner workings of this lens much better now. There seems to be no serious damage but I'll be on the lookout for indentations making the focus stick.

msowsun wrote:

Ray UK wrote:

What happens when the 1.4 is damaged, is as follows:

As the front assembly rotates during focusing it relies on small lugs which run in sloping grooves of plastic tube affixed to the main body. This plastic tube is quite flimsy and any pressure on the front can cause this to be damaged by the lugs.

If the damage is only slight then focusing will still work but the lugs will cause an indentation in the grooves so the focus will tend to stick in this position, this can usually be felt when using manual focus

If the lens has sustained greater damage then the plastic tube will be broken and the front section will not turn at all, so neither AF or MF will work.

Damage caused by pressure on the front of the lens will not affect the lens sharpness unless of course if the lens is unable to focus.

This is the part that is easily damaged by pressure on the front filter threads.

thank you all for warning us concerning this lens.  it may  be better to just use canon's 40mm or the 50mm 1.8

both are cheaper and the 1.8 is plentiful used.