JakTrax From United Kingdom, joined Jun 2005, 4781 posts, RR: 8 Posted (6 months 1 week 3 days 8 hours ago) and read 3331 times:
Was out in the cold with the 50D and 100-400 L today, when suddenly I heard a fast, repetitive whirring sound; almost as if the AF motor was stuttering. I was just holding the camera in my hand at the time (i.e. not shooting), and looked down the lens to see the elements inside 'twitching', as though the camera were trying to continually shift focus.
This strange performance repeated a few times during the day, each time while the camera was idle in my hand. In a later episode I also noticed that, while the AF 'twitch' was going on, the aperture and shutter values displayed on the top screen would 'twitch' too, very quickly alternating between 1/400 and 1/500th and f/8 and f/9. The incidents would only last a few seconds and performance seemed unaffected.
Additionally, every time I looked through the viewfinder and held the shutter button half-way to focus, the image would 'jump' before settling down. This happened whether the IS was on or off.
Anyone had similar experiences, and should I be concerned?
NPeterman From United States of America, joined Apr 2009, 140 posts, RR: 0 Reply 1, posted (6 months 1 week 3 days 2 hours ago) and read 3256 times:
While I cannot be certain that the issue I experienced is exactly what you went through, I suffered through an eerily similar sounding ordeal. With my 50D, this was eventually followed by a complete lock-up, accompanied with a "Machine gun" sounding rapid fire from the shutter, and various error messaged. Ultimately speaking the Mechanical chassis had to be replaced, no less than 3 times. The only reason I even persisted was due to the fact that I was still in warranty. Mine appeared to be caused by an electrical issue low volting the internals.
You haven't purchased any new batteries per chance, have you? Inadvertent counterfeit batteries were found to be what caused my similar incident (bought through a reputable vendor who somehow got duped himself, but thats another story). It required a re-wiring of the body's internals in the end.
Hope you get it resolved. Feel free to write me if you have any questions or concerns.
harlequin67 From United Kingdom, joined Mar 2006, 16 posts, RR: 0 Reply 3, posted (6 months 1 week 2 days 15 hours ago) and read 3189 times:
The cold weather can have strange effects on batteries. Voltages can dip or spike and the electronic brains of the camera or lens may then act erratically. This is where 3rd party batteries maybe be showing a weakness... Also, people use old batteries and I believe that old batteries can exhibit charge issues, i.e. not hold the charge or drain quickly.
Also, in cold weather the camera can come from a warm environment into a cold one causing condensation, it should be remembered that fitting a lens in your house's warm/moist atmosphere will trap some warm/moist air in the camera body if there is a sudden change in temprature i.e. removing the camera from a camera bag packed in the warm house, condensation can form.
I own a 50D and 40D and IMHO I think the 50D has more issues than the 40D including build quality and I don't see eye to eye with my 50D! My first suspicion would be the 50D and or battery.
I would take the camera to a reputable professional camera repair shop, I use Fixation of Vauxhall, London as they are a Canon professional service centre. Ask for a service and diagnostic check and see what happens! The lens can also be checked out at the same time....
JakTrax From United Kingdom, joined Jun 2005, 4781 posts, RR: 8 Reply 4, posted (6 months 1 week 2 days 15 hours ago) and read 3182 times:
I was wondering if it could be the cold, hence my reason for mentioning it in my post. However it didn't seem to happen with my other lens that day - but in all honesty I only used the 24-105 very briefly.
I guess I will see what happens the next day I'm out at the local (tomorrow I think). Hopefully it'll just be the cold affecting the battery (official Canon battery that came with the camera nearly three years ago so I guess it's pretty old) but I can't help but feel underneath that it's a developing 100-400 IS issue. Perhaps the 'twitching' motor is just coincidently an unrelated problem.
harlequin67 From United Kingdom, joined Mar 2006, 16 posts, RR: 0 Reply 5, posted (6 months 1 week 15 hours ago) and read 3068 times:
You mention the 24-105L working for a short and appearing to be operating correctly.
It could still be the battery and or camera. The 24-105L is a smaller lens than the 100-400L and I guess that it would be a smaller IS/AF motor load? Not sure, but likely. This smaller load would not strain the battery/camera circuits than a larger lens load and the battery/camera might behave in a more "normal" manner. Large loads on bad batteries make the voltage dip and spike and do odd things, changes in voltage from battery can cause issues with equipment.
I think using different combinations of battery, lens and camera body may help narrow down the culprit.
I still think the 50D is the culprit....but I am bias against them, and I own a 50D!??!!?!
blackbird1 From Germany, joined Mar 2002, 220 posts, RR: 6 Reply 7, posted (6 months 6 days 11 hours ago) and read 2975 times:
Nothing to worry about, Karl, I've got the same lens and everytime I'll do some shooting in backlit conditions and low contrast sometimes the lens acts as described by you. Even on different bodies, 30d, 40d and 7d, always the same.
It is the lens, but it is nothing serious.
One time I had to take out the batteries and switch on the camera to get over a lock.