24-70 focusing issues?

Hey guys,

not sure if someone can direct me to a relevant thread but... is there focusing issues on the 24-70? Seems to be quite slow and hunts a fair bit especially in low light. Not sure if this means i need to send it off...

on another note however regarding getting it serviced. Where can i get this done in the uk, who do i contact or is it direct to canon?

i got my lens from kerso/ebay, will canon accept receipts like that?

Either you're expecting the world from your lens, or there's something wrong. Also, "low light" is a subjective term. We'd have to know just how low. As a rule, the 24-70L is very fast and accurate, even in low light.

I agree with Ron, how low is the low-light that you are talking about. In order for the auto focus to function it needs to be able to lock onto a change in contrast in the scene. If it doesn't have that it is going to hunt.

While they are wonderful pieces of electronics, you have to remember they are just that and don't replace the human eye and brain. I quite often will switch to manual focus in lower lighting conditions.

I can honestly say that there has not been a "focussing issue" with the 24-70 that I am aware of. There are the occasional copy that might have a problem but tell me what of anything that you buy these days might not have a problem.

I have no idea if Canon will accept an ebay receipt. You can find the locations of the UK Service Centers here

When shooting lowlight, find a good contrast point. Maybe a speck of light bouncing off the subject or something. That's how the camera locks focus.

If you're concerned with an actual focus problem, test it in good light. Any issues will come up at that point. AF difficulties when it's dark don't necessarily mean the lens is bad.

well, i been shooting on monday for my mates wedding... and i cant seem to focus properly... maybe it was my shutter speed, i dont know, i was using roughly 1/50th of a shutter speed.

If you just depress the shutter speed, the camera usually locks focus and takes the pic doesnt it? I do that sometimes rather than holding it halfway to lock focus before taking the pic.

But then i had some group shots outside of the building in bright light where it didnt focus properly

This will sound strange, but if you're talking stationary low light objects, I'll always keep a mini-maglite in my pocket on my keychain. If it's too low to lock on, I'll shine the light on it quick to let it focus. Also, you have a 580. You can disable the flash and use the AF-assist beam alone.

Yella Fella wrote in post #2012214
well, i been shooting on monday for my mates wedding... and i cant seem to focus properly... maybe it was my shutter speed, i dont know, i was using roughly 1/50th of a shutter speed.

If you just depress the shutter speed, the camera usually locks focus and takes the pic doesnt it? I do that sometimes rather than holding it halfway to lock focus before taking the pic.

But then i had some group shots outside of the building in bright light where it didnt focus properly

Depending on your focal length, 1/50th could be inducing camera shake. Just enough to appear to be misfocus when it's actually not. I've forgotten about the fact that I may be at 70mm and need more than the 1/40th I just used at 24mm before.

I always prefocus. I also repeatedly prefocus when I'm in on-shot focus mode to maintain that focus. I've never tried to just jam through the button without prefocusing but I'm willing to bet you're getting some shake from doing that as well. Jamming all the way through would most likely mean you're pushing harder than you would if you halfpress then fire off gently, thus letting the camera twist in your hand. You could also be "losing" the focus if your subject is moving...ie by the time you jammed all the way through, they moved out of the plane of focus. Not likely but possible.

I can't really say anything about the bright light. I wasn't there and have no idea of your settings. Were you stopped down enough to get everyone in focus? Too shallow of depth of field can make some people appear misfocused when they're simply not within the plane of focus.

Yella Fella wrote in post #2012214
i was using roughly 1/50th of a shutter speed.

Too slow if you're near that focal length, and too slow for people period, most of the time, if they're moving.

My camera, while the lens is on AF, won't let me take the pic until it's focused. that said, I always use the * button to focus now, so that's negated. In suitable conditions for that lens, it focuses quickly enough that you can usually just press the shutter and it will focus that fast. However, you may be shooting before it focuses. Check it out.

No offense, but sounds like a lot of user error on your part.

It's also a 20D body - while the AF system is good, it's not the best at low light either.

Using the 580EX's focus beam is ideal in these situations. And try to focus on high contrast areas on your subject. If it doesn't focus when holding the camera one way, try it the opposite (e.g. portrait vs. landscape orientation).

i have to post some of these pics up when i get time to edit them down to acceptable web levels just to show you.

I totally forgot about using the as beam alone to be fair... but i didnt want to shine this red patch on the B&G when they were reading their vows and with about 4 camcorders filming it

Yella Fella wrote in post #2012314
i have to post some of these pics up when i get time to edit them down to acceptable web levels just to show you.

I totally forgot about using the as beam alone to be fair... but i didnt want to shine this red patch on the B&G when they were reading their vows and with about 4 camcorders filming it

Chances are they'd never notice the beam...to them it's just a wee red light in the distance, not a patch of light.

...and screw the videographers.

On second thought...don't video cameras have IR filters just like digital cameras do? If so...then am I right in saying the beam wouldn't even show up on video?