Apology in advance...yet another Canon 7D related post

[dan marchant]

I am going to completely disagree with Alex. I have used back button focus on the 7D and 5DIII to shoot fast moving subjects (sports) and found it is far superior to trying to use the shutter button. When shooting moving targets with AI-servo AF back button allows you to keep tracking and grab several shots, without worrying about keeping the shutter half pressed to keep focusing.

[Colin Southern]

When tracking a bird in flight there is no difference between back-button focussing and shutter-button focussing if you want to focus all the time.

The "danger" in doing it this way on cameras like the 1Dx (where the difference between the release 1/2 depressed and fully depressed isn't so much of a "movement" as it is a "pressure") is that if you're trying to track something for a while - and my finger pressure changes - is that I end up firing off a dozen shots accidentally quite a few times.

[herbert]

I am going to completely disagree with Alex. I have used back button focus on the 7D and 5DIII to shoot fast moving subjects (sports) and found it is far superior to trying to use the shutter button. When shooting moving targets with AI-servo AF back button allows you to keep tracking and grab several shots, without worrying about keeping the shutter half pressed to keep focusing.

The "danger" in doing it this way on cameras like the 1Dx (where the difference between the release 1/2 depressed and fully depressed isn't so much of a "movement" as it is a "pressure") is that if you're trying to track something for a while - and my finger pressure changes - is that I end up firing off a dozen shots accidentally quite a few times.

I shall revise my statement and say that in theory there is no difference between continuous focus using the shutter button and the back-focus button. However as pointed out by Colin and Dan in practice it can be easier to control the two actions of focus and shutter activation using two buttons, one for each action.

Sticking to my Devil's advocate position I will say that if you don't use back-button autofocus then you are not going to miss lots of shots. The camera auto-focus will still work in the same way. It does not magically work faster or better with a different button. If you have years of experience with your shutter button sensitivity then you can achieve all the control you need with a single button if you keep the focus point on the target. It is when image under the focus point will be changing independently of your desired focal length that you will need back-button focussing, e.g focus and recompose in servo focus mode, scanning a scene with pre-focus, intermittent obstruction of your view, etc.

Since the 7D and the 60D both have a back-button for focussing then either camera will let you easily try this out. The 600D does not have a back-button for focus. In that case you can reassign the * button from exposure lock to focussing using the custom functions. However I do not know if this then deactivates focus with the shutter button since I don't have one to try it.

Back-button focus can flumux a third party if you give your camera to them to take a picture. However switching to Green Box mode will deactivate back-button focus and restore the standard shutter button operation. Nice to know the Green Box is useful even when you never use it yourself.

Alex

[FlyingSquirrel]

Quick update...
I got the 7D. I ordered it from Canon as a refurb. It arrived a couple days ago. I've been reading the manual and playing around with the controls and getting used to the camera, though I haven't used it much or taken it on a real shoot yet. (Hopefully tomorrow). First impressions:
- body build, overall quality, "feel in the hand" and "handling" are excellent (at least compared to any other camera I've had)
- the features I bought it for are as good, if not better, than I hoped
- AF, metering, responsiveness, etc are the best I've ever had in any camera
- shutter is very quiet and sounds nothing like my 30D. I didn't know it would sound different, but I love it. 8FPS gives me the shivers
- Custom setting registration (C1, C2, C3) is pretty sweet and I plan to set each of those up
- although it's not really a pro body, I'm extremely happy with it and think it's a fantastic camera
- initial (non scientific) judgement of image quality is that it's about the same as my 30D. However I need to do some real comparison tests by shooting the same shots with both cameras and do a side by side at 100% to really get an accurate determination on that. I intend to post my results on that in another thread later.

Thanks to all for your help on this previously, which helped me decide to get this. I love it!

[Dave Humphries]

- initial (non scientific) judgement of image quality is that it's about the same as my 30D. However I need to do some real comparison tests by shooting the same shots with both cameras and do a side by side at 100% to really get an accurate determination on that. I intend to post my results on that in another thread later.

Hi Matt,

Why bother?
It is unlikely to be worse in any respect (that's going to matter)

If I can adapt Colin's vacuum cleaner analogy (regarding Image Quality);
if your old vacuum/broom is wearing out and keeps missing bits and you go buy a new one, you just rejoice in how much better/quicker the new one makes of the job - you do not get down on hands an knees with a magnifying glass

Just enjoy it

Congrats on new acquisition,

[rpcrowe]

I need to add one final point... The 7D can be as simple to use or as sophisticated to use as you desire. I get great results from my 7D but haven't yet mastered all the intricancies of the autofocus system such as those controlled by the Custom Functions:

C.Fn III-01 AI Servo Tracking Sensitivity and C.Fn III-02 Focus/Shutter Release Priority in Continuous Shooting...

However, IMO, some problems may be caused by photographers who don't really understand the sophistication of the auto-focus system trying to make modifications to that system which may not be to the best advantage in specific shooting situations...

I have also found that simply using the autofocus of the 7D in its default modes and switching to burst mode will give you some pretty accurate focusing.

I would recommend the book, "David Busch's Compact Field Guide for the Canon EOS 7D". I think that this book in combination with the user manual or in lieu of that manual can give you a pretty good start with this camera.

It seems that I learn something everytime I peruse this book. My latest ephiphany has been to use the Quick Menu more often when shooting outdoors. My old eyes can read the larger readout better in the Quick Menu screen than I can read the smaller informaton readout on the top LCD...

I remember when the first Canon EF 70-200mm f/4L (non-IS) lens was introduced. The Internet was flooded with owners complaining that the lens back focused. You would have thought every second camera off the Canon assembly line had that problem. In reality only a minute percentage of these lenses had the problem but, their owners were very vocal...

OTOH: There was an outburst of complaints against the Canon EF 70-300mm f/4-5.6 IS lens when it was first introduced. Owners complained that the auto focus at 300mm with the camera in the vertical position was off. This was, in fact, a problem with that lens and Canon did a recall to remedy the situation...

[FlyingSquirrel]

Dave...you are right! Thanks for pointing this out to me. I'm obviously to obsessed with the details and image quality. I am taking your advice in this case and am just going to enjoy how awesome the 7D is compared to my 30D, and leave it at that. Why waste time doing comparison shots? So true!

Richard, thanks again for your helpful input regarding this camera. I can tell that you really like it a lot, and now that I have used mine, I can see why. I do believe that all of the hullabaloo about the 7D AF is primarily from people that don't understand the complexity of it. In addition, a read through the manual clearly points out in numerous places that there are specific gotchas with this AF system. I haven't used the camera much, but I have not seen any focus issues that were not disclosed in the manual. Either way I intend to practice, practice, practice and learn this body till I can operate it quickly and easily. Gotta get those wildlife shots!

[mknittle]

Ok Im sold!LOL

[FlyingSquirrel]

Ok Im sold!LOL

If you are serious, then I suggest you really get this body. It's the best 1.6 crop factor dslr on market, IMO (unless something new and sexy has been released that I don't know about). Having used the camera quite a bit more, I can say that it's fantastic, I LOVE IT, it produces fantastic quality images for what it's worth, and I've had no AF problems.

[mknittle]

Thanks Matt,
As soon as we get our tax returns I am planning on getting one. I have been to frys{electonics store} A couple times fondeling one.LOL