Canon AF problem

[McCrackus]

First-time poster, site looks really cool and I'll definitely stick around. Have a question that someone might be able to answer.

I shoot concerts with a Canon EOS 7D, a Canon 1.8 50mm prime and a Sigma 2.8 17-70mm zoom. For the most part, all equipment has made me happy...until now.

I've recently noticed that my 50mm prime will simply not auto-focus AT ALL in low lighting conditions anymore. I used the lens to shoot a band in good light earlier this week and had no trouble. Last night, took the same lens to a dimly-lit show and couldn't AF the entire time, leaving me extremely frustrated. I tried the Sigma and it did a better job focusing, so I'm thinking it's a lens problem and not a zoom problem.

Now, I am aware that every lens has its breaking point and you will always reach a point where it is too dark to autofocus with any lens. The thing is, I've shoot the same venues in town for almost 2 years, so I know what kind of lighting situations I can get away with. The lighting last night was not great but certainly was not the worst I've seen and have easily focused on my subject in similar lighting in the past. Not sure what is causing this recent problem with the 50mm.

A couple facts:

1. The problem seems to strangely (perhaps coincidentally) have started around the time I bought the 7D. Previously, I was shooting with a Rebel XSI and didn't have this problem.

2. Unlike the Sigma zoom, for which the lens hood just snaps in place, the Canon 50mm lens hood has threads that have to be screwed in. This process inevitably causes my fingers to move around the focus while in AF-mode, so I'm curious if over the years, this process has caused enough wear and tear to weaken the lens' AF.

Can anyone weigh in? Perhaps this is a common problem, or perhaps I need a new lens. Any advice would help, thanks!

 

[gsgary]

The focus ring on the 50F1.8 should not be turn by hand when in auto focus so it could be ****ed or you may not have your camera set up properly are you using center focus only

 

[McCrackus]

The focus ring on the 50F1.8 should not be turn by hand when in auto focus so it could be ****ed or you may not have your camera set up properly are you using center focus only

That's my fear. But it still works fine if the light permits - is it possible that I broke it only bad enough to not work in dim light, but not enough that it effects ALL shooting conditions?

And I do not use center focus only.

 

[subscuck]

Next time bring your Reb along. If you have the same issue, I suppose it's possible you've stripped it out a little over time. At a hundred bucks, you're not paying for build quality, after all. OTOH, if you're really serious about shooting live shows, get an all around better performer. I'd upgrade to a Canon or Sigma 1.4. Yeah, I know, Sigmas always back/front focus, you gotta go thru like a couple dozen copies before you get a "good copy". I'm on my first copy, it's my favorite lens, and it works flawlessly. Shoulda bought a lottery ticket the day I bought it, I guess.

 

[vtf]

I screwed up my 50mm by shooting in low light where I would auto focus with the light on and switch to manual when the light was off. I accidentally adjusted the focus while on auto and now it just bounces and never locks. So I use it manual 100%. I had seen the warnings and was very careful but this one time did it. I still love the lens. This can also happen when adjusting you cpl or adjusting the hood so care should always be used.

 

[gsgary]

The focus ring on the 50F1.8 should not be turn by hand when in auto focus so it could be ****ed or you may not have your camera set up properly are you using center focus only

That's my fear. But it still works fine if the light permits - is it possible that I broke it only bad enough to not work in dim light, but not enough that it effects ALL shooting conditions?

And I do not use center focus only.

Well you should be for this sort of shot,because the 50F1.8 is not a good focusing lens in bad light

 

[McCrackus]

The focus ring on the 50F1.8 should not be turn by hand when in auto focus so it could be ****ed or you may not have your camera set up properly are you using center focus only

That's my fear. But it still works fine if the light permits - is it possible that I broke it only bad enough to not work in dim light, but not enough that it effects ALL shooting conditions?

And I do not use center focus only.

Well you should be for this sort of shot,because the 50F1.8 is not a good focusing lens in bad light

It's never given me issues until this problem, and it's really not helpful to be limited to the center focus point when shooting a live performance with the subject constantly moving around.

For the other poster talking about upgrading, if I do need to replace it I will probably do so with the 1.4

 

[gsgary]

That's my fear. But it still works fine if the light permits - is it possible that I broke it only bad enough to not work in dim light, but not enough that it effects ALL shooting conditions?

And I do not use center focus only.

Well you should be for this sort of shot,because the 50F1.8 is not a good focusing lens in bad light

It's never given me issues until this problem, and it's really not helpful to be limited to the center focus point when shooting a live performance with the subject constantly moving around.

For the other poster talking about upgrading, if I do need to replace it I will probably do so with the 1.4

Thats rubbish i shoot lots of concerts in dark conditions and never have trouble getting sharp shots

 

[McCrackus]

Well you should be for this sort of shot,because the 50F1.8 is not a good focusing lens in bad light

It's never given me issues until this problem, and it's really not helpful to be limited to the center focus point when shooting a live performance with the subject constantly moving around.

For the other poster talking about upgrading, if I do need to replace it I will probably do so with the 1.4

Thats rubbish i shoot lots of concerts in dark conditions and never have trouble getting sharp shots

Not sure of your point? I have always shot in low light with fine results. The fact that my lens suddenly stopped focusing in low light is where my problem is.

*EDIT* After reading this again, I'm guessing you're responding to the post saying the 1.8 doesn't focus well in poor light? In which case, I'd agree with you. Until now, I think the lens focused just fine in low light.

 

[gsgary]

Yes but it will focus better with just the center focus only it is a known fact with Canon, i only use center focus on my 1Dmk2's and 5D

 

[subscuck]

Center point and AI Servo, if your subject is moving. Multiple focus points allows the camera to choose what to focus on. I think you'll find it's better when you tell the camera what to focus on.

 

[McCrackus]

Center point and AI Servo, if your subject is moving. Multiple focus points allows the camera to choose what to focus on. I think you'll find it's better when you tell the camera what to focus on.

Maybe I wasn't clear, I work with a single focus point and manually change the focus point on the fly. I would certainly not call myself a professional-level photographer at this juncture, but I don't understand how someone can shoot a performance like a concert using only the center focus point - the composition will be the same for every shot. If I want to incorporate the rule of thirds or shoot two subjects side by side, I don't see how this can easily be done without moving to different focus points.

 

[gsgary]

Center point and AI Servo, if your subject is moving. Multiple focus points allows the camera to choose what to focus on. I think you'll find it's better when you tell the camera what to focus on.

Maybe I wasn't clear, I work with a single focus point and manually change the focus point on the fly. I would certainly not call myself a professional-level photographer at this juncture, but I don't understand how someone can shoot a performance like a concert using only the center focus point - the composition will be the same for every shot. If I want to incorporate the rule of thirds or shoot two subjects side by side, I don't see how this can easily be done without moving to different focus points.

Do it your way i couldn't give a **** anymore

 

[McCrackus]

Center point and AI Servo, if your subject is moving. Multiple focus points allows the camera to choose what to focus on. I think you'll find it's better when you tell the camera what to focus on.

Maybe I wasn't clear, I work with a single focus point and manually change the focus point on the fly. I would certainly not call myself a professional-level photographer at this juncture, but I don't understand how someone can shoot a performance like a concert using only the center focus point - the composition will be the same for every shot. If I want to incorporate the rule of thirds or shoot two subjects side by side, I don't see how this can easily be done without moving to different focus points.

Do it your way i couldn't give a **** anymore

Alrighty then, well thanks for your help :scratch:

 

[Bitter Jeweler]

You focus and recompose McCrackus. Do a little reading on focus points and you will learn the center point is the most useful. It detects contrast both horizontally and vertically, while the outer points will only do one or the other, but not both. The manual should discuss this, and it might vary with the grade of camera.

Yes you can have issues with focus and recomposing with narrow depth of field.