Focus on 7D - 50mm 1.4 v 17-50 2.8

[dviv]

I took Surenj's advice at the last netball game of the season a couple of weeks ago and switched from using the 50mm 1.4 to the Tammy 17-50 2.8.

With the 17-50 set to 50mm the whole time, using the same focus mode (centre expanded) and AI Servo, with the AF lock button to focus, my keeper rate went from around 40 percent, to around 90 percent.

And it wasn't the difference due to DOF. With the 1.4, I was constantly getting AF lock on the crowd behind the players.
The 2.8 kept locking directly on the players and was (mostly) perfect.

While this made me feel a bit better about my technique and once again highlights just how good the Tammy is, I am still puzzled as to why.

Any ideas?

[aim54x]

It may have something to do with the 50mm f/1.4's USM being a bit overzealous and the thinner DOF making a difference. The 17-50 is slower to get around and in many ways is more surefooted (in my experience) and tends not to like to jump around, this may be helping with the player lock.

[DaveB]

What have you got C.Fn III-1 (AI Servo tracking sensitivity) set to?

The value of C.Fn III-3 might also affect the behaviour. From your description I would guess 0 would be appropriate.

Even though the 50mm/1.4 is much faster to focus, with these settings you should be able to avoid it snapping to the background crowd when you miss your subject.

The settings in C.Fn III-6 may also change the behaviour. I have Auto select and AF point expansion enabled, and everything else disabled. With this I can choose which AF point is going to be used for AF acquisition, and it will then track the subject as it moves around the frame. Hopefully this might help avoid the underlying problem of losing track of your subject in the first place.

[photomarcs]

What have you got C.Fn III-1 (AI Servo tracking sensitivity) set to?

The value of C.Fn III-3 might also affect the behaviour. From your description I would guess 0 would be appropriate.

Even though the 50mm/1.4 is much faster to focus, with these settings you should be able to avoid it snapping to the background crowd when you miss your subject.

The settings in C.Fn III-6 may also change the behaviour. I have Auto select and AF point expansion enabled, and everything else disabled. With this I can choose which AF point is going to be used for AF acquisition, and it will then track the subject as it moves around the frame. Hopefully this might help avoid the underlying problem of losing track of your subject in the first place.

I think all thats needed to be said has been said on this issue, tracking sensitivity on the 7D is a very large concept. I surprisingly have mine set slightly slower when i photograph basketball for friends, assists in more ways that one

[dviv]

Thanks guys, good points.

Dave, I'll muck around with those settings next time to see if it makes a difference.

While your suggestion should help with the focus on the 50, It does seem wierd that I was getting such a different result with the 17-50, without changing anything.

[photomarcs]

Thanks guys, good points.

Dave, I'll muck around with those settings next time to see if it makes a difference.

While your suggestion should help with the focus on the 50, It does seem wierd that I was getting such a different result with the 17-50, without changing anything.

Hey dude,

Also note, the 50mm f1.4 is canon's most troublesome lens in terms of the AF drive. I regularly have customers who have 50 1.4's that the AF has either come loose and is not responding or the ring inside doesn't spin even on MF. Just thought I'd let you know also. It's not much of an issue for most, but as something to bring to your attention too

[dviv]

Also note, the 50mm f1.4 is canon's most troublesome lens in terms of the AF drive. I regularly have customers who have 50 1.4's that the AF has either come loose and is not responding or the ring inside doesn't spin even on MF. Just thought I'd let you know also. It's not much of an issue for most, but as something to bring to your attention too

Thanks for the heads up Definately something to keep an eye on.

Apparently there's a new 50 1.4 coming (don't hold your breath ) with much better build quality and better USM.

[photomarcs]

Also note, the 50mm f1.4 is canon's most troublesome lens in terms of the AF drive. I regularly have customers who have 50 1.4's that the AF has either come loose and is not responding or the ring inside doesn't spin even on MF. Just thought I'd let you know also. It's not much of an issue for most, but as something to bring to your attention too

Thanks for the heads up Definately something to keep an eye on.

Apparently there's a new 50 1.4 coming (don't hold your breath ) with much better build quality and better USM.

Oh, Canon know about the lens AF drive, and it's covered under warranty. might be worth investing in extended warranty if it's still within the 1 year of purchase you can buy extended warranty for it which I kinda reccommend... for the lens..


will keep my eye out for something as such... lucky i just purchased the 85mm f1.8... hahaha was tempted by the 50 so bad!! now i know I'm in good hands

[dviv]

Oh, Canon know about the lens AF drive, and it's covered under warranty. might be worth investing in extended warranty if it's still within the 1 year of purchase you can buy extended warranty for it which I kinda reccommend... for the lens..

I wish! - It's a few years old now - although it's never missed a beat (I don't count the above as a lens issue).

Fingers crossed

[surenj]

Hey David,

Did you shoot with the 17-50 at ISO 3200? I'd like to see those photos if possible. I am sure the high ISO shooters in the forum can give you some tips etc.

I must say, the AF system in the 7D sounds very complicated! It's going to have some teething issues as Canon have only come to AF party so late in the game.

[DaveB]

I must say, the AF system in the 7D sounds very complicated! It's going to have some teething issues as Canon have only come to AF party so late in the game.

This seems a strange assertion. Came "late in the game"? Teething issues? Say what?

The AF has a lot of configuration controls, yes. It's almost as comprehensive as the 1-series AF. It's obviously not targeted at the same audience as the 550D for example.

[surenj]

Came "late in the game"? Teething issues? Say what?

Late in the game = nearly 18 months after the D300 (which has better AF than 5D or 50D) was released.

Nikon seems to have had better AF systems (+ better wireless flash intergration) in their mid range cameras D300, D700 etc while canon hasn't had this until the 7D.
I have read alot of problems re: 7D focus simply because the midrange users were not used to such sophistication. = teething issues

This is how I've understood it although this could be completely wrong!

Thoughts?

[DaveB]

Ok, the D300/D700 AF was good. Nikon and Canon are continually leapfrogging each other. BTW, even today I keep hearing of users getting confused about fine-tuning the AF of those cameras too!

As for wireless flash, yes the 7D is the first Canon body that has wireless master ("commander" in Nikon terms) built into the body (Nikon has had this for ages). But with an ST-E2 or a 500-series flash on the camera the Canon system has been "competitive" for years (and still is).

Yes I do agree that most of the problems new users report with the 7D's AF are due to users not understanding the tool. Whether that's Canon fault for putting too much into it, the users' fault for not reading the manual, or something else I'm not going to argue.
But I suppose "teething issues" makes me think of technical faults, not (l)user error.

[aim54x]

I'll vouch for the 50mm f/1.4 being prone to AF issues, I have seen a few go in for service for AF problems. That pesky Error 99 is also possibly AF related (as well as power aperture unit and shutter).

[dviv]

Surenj,

There is a learning curve with the AF modes on the 7D, but it's soooooo worth spending the time to learn and practice. It's extremely accurate and AI servo tracks moving objects very well.

It was a relief when I switched to the 17-50 because I realised that I was using the right modes and my technique was adequate, and that it had been the lens that was the cause of the low keeper rate. Considering how hard netball is to shoot, I was not overly dissapointed with the low keeper rate - until I relaised how high it should be

[surenj]

It was a relief when I switched to the 17-50 because I realised that I was using the right modes and my technique was adequate

Sounds good Dave. Post some pics for us to see.

But with an ST-E2 or a 500-series flash on the camera the Canon system has been "competitive" for years (and still is).

Fair enough DaveB. The STE2 can't do rear curtain and it's too restrictive on the individual flash power controls (Which should be the main focus when you build a wireless flash commander). The SU800 is way better (also built better). Canon needs to address these issues I think. There is Yongnuo STE2 which is about to be released soon. They may well release a better STE2 unless canon beats them to it.

[dviv]

Sounds good Dave. Post some pics for us to see.

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