7D Mark II - Focus Discussions

CyberDyneSystems wrote in post #17675265
How? As soon as you recompose and take another shot, the camera will AF a second time for the re-composed shot.

Unless we are talking about BBF, in which case, both one shot and AI servo will provide the same functionality of NOT refocusing when the shutter is released. In this situation AI servo and One shot will behave the same way.

Most of the time I use Servo AF & BBF now for birds. But before, I used focus on the shutter and One Shot AF, recomposing as necessary. For each shot I repurchased focus on the eye. Either way works fine, but now I prefer BBF/Servo AF.

wisv1k wrote in post #17675221
I spoke to a Senior Tech in the Professional Services Department (I have his name but see no reason to name him here) who told me when using one shot AF you should NEVER be using ANY of the continuous drive modes. One shot AF = Single image drive.

This still makes no goddamn sense then, because if that's the case, you shouldn't be able to set shutter drive vs AF move independently all willy-nilly. If One Shot should only be used in single drive, and continuous drive should use Ai-Servo, then why do I have to change BOTH settings, ever? Why can't it be that I set "single" and get One Shot/ single, or set "continuous" and get Ai-Servo/ continuous? That's horrible interface design if that's how they intend them to be used.

I'm with you on that. When I get some time I intend to test it out for myself.

I did my normal processing on this one, shot with AIservo 10 frames a second, Number 10 in a string of 18 was the tack sharp one, The one below, but all were super without one being out of focus. On the other hand one shot was much harder to do as the wind was rocking the flower just a tiny bit and I found there were a bunch of images with just ever so slightly out of focus on some part of the wing. I found myself waiting for the flower to stop moving as the Monarch moved around on the flower in Oneshot.

Thanks for making me confirm that I was doing it right. AIservo, BBF, 10 fps,

IMAGE LINK: https://flic.kr/p/wBN6​ei

wisv1k wrote in post #17675221
I spoke to a Senior Tech in the Professional Services Department (I have his name but see no reason to name him here) who told me when using one shot AF you should NEVER be using ANY of the continuous drive modes. One shot AF = Single image drive.

A tech does not a photographer make....

There are very valid reasons to shoot burst while in one shoot mode, during landscapes, portraits, etc.

Now you see, Thanks team speed..That phrase would not come to me, LOL

I'm not defending him or implying he is correct but I would be happy to provide his info via PM if you would like to contact him and discuss it yourself. Perhaps you could understand his logic better than me.

Pondrader wrote in post #17675408
Ha,...while One shot can and will work with half press most would say your on the wrong side of the tracks.

For some definition of "most" that means most people here who prefer BBF I know some think it's a noob technique, but that's really only true if you don't know any other way. It's an entirely different matter if you understand all focus techniques and prefer this way.

In fact, there is a subtle upside to using One Shot, which is why I use it so much on my 6D, whereas I use BBF and AI Servo almost exclusively with my 60D shooting birds. It has to do with the accuracy of auto-focus, particularly with fast lenses:

If you focus on something with one-shot, recompose, take a shot (or burst) and release the shutter button fully, you need to re-acquire the auto-focus lock and recompose again to retake the shot. The ability to focus once and then take multiple shots without this back-and-forth re-focus and recompose dance is one of the main benefits to using BBF. I don't dispute this, it's a time savings in a lot of shooting situations.

That said, there is also a benefit to re-acquiring focus lock with each shot. With lenses faster than f/2.8, phase-detection auto-focus is not accurate enough to guarantee a good focus lock. By re-acquiring each time (especially if you deliberately de-focus in between shots), you have a better chance of one of your shots hitting critical focus. If you focused once, and it missed, all your shots will be consistently out of focus (unless you're physically rocking back and forth, or the subject moved). I've found this to be a real issue when using my 85L II in the field as AF just misses a lot, with both of my bodies. If you are going to shoot this way most of the time, it doesn't matter so much whether you use the shutter half-press or the AF-ON for focus. On my 6D, I use the shutter half-press, just because I prefer the one-button-to-rule-them-all simplicity.

CyberDyneSystems wrote in post #17675255
I agree here, in fact. However, once AF is achieved on your tripod set up, why give the camera reason to adjust? One shot or AI servo, in either case, don't refocus.

IMHO in this example we are just using bad practices to force the camera to find a way to mess up.

Obviously it would be bad practice, but we're just discussing theoretical stuff now, not good photography habits.

I think I proved that one shot works in my first image, and I know some that think one shot and shutter button is the way to go, , lets say you use BBF and you focus on a subject and now you lift your thumb and recompose, you can now take multiple images or string's and your still holding focus. and all you did was lift your thumb. if focus is required again well that would be your thumb one more time. Im not condemning you for staying with the old ways. Just don't be afraid of the new.!!

wisv1k wrote in post #17675561
I'm not defending him or implying he is correct but I would be happy to provide his info via PM if you would like to contact him and discuss it yourself. Perhaps you could understand his logic better than me.

I would have much better things to do with my time than to argue with a tech, and don't have to prove to him that he is wrong. I personally know several situations where one shot + burst provides a better product than single shots.

- During group portraits, taking a burst greatly raises the chances of getting one shot where everyone is looking the right way and not blinking, especially important if there are kids in the shoot.
- During landscapes, doing a burst at a bracketed set gives you greater DR in the final product when combining the shots.
- During high ISO static scenes, taking a set of 3-5 identical images that you do a Photoshop HDR merge on will create a much lower noise final result (a trick that the 7D2 now does quite well in camera)
- If you are doing a portrait with one shot, chances are that either you or the subject will move, and having a burst may also raise the chances of getting that one "in focus" shot, although I almost always shoot portrait in AI Servo.

There are other cases too, but these are the first few that came to mind from experience.

I haven't taken any landscape photographs lately. I will have to reread the manual to figure out how to get back to the shutter button doing metering, AF and final shot for when I use a remote shutter release. I guess I should practice at home.

We did some photographs of us together while we were on vacation but I used the 10 second timer. I focused with the back button, then hit the shutter button...and ran.

Pondrader wrote in post #17675540
I did my normal processing on this one, shot with AIservo 10 frames a second, Number 10 in a string of 18 was the tack sharp one, The one below, but all were super without one being out of focus. On the other hand one shot was much harder to do as the wind was rocking the flower just a tiny bit and I found there were a bunch of images with just ever so slightly out of focus on some part of the wing. I found myself waiting for the flower to stop moving as the Monarch moved around on the flower in Oneshot.

Thanks for making me confirm that I was doing it right. AIservo, BBF, 10 fps,

IMAGE LINK: https://flic.kr/p/wBN6​ei IMG_7103-Edit by Wild Photography, on Flickr

I am with you with this, now I just need to put more money in the piggy bank

Archibald wrote in post #17675222
There are differences...

Check out what Chuck Westfall has to say about it here. (Scroll down a bit.)

Excellent quote, this agrees with my experience on the accuracy being the same because I always set first and second image to focus priority.

absplastic wrote in post #17675267
One really interesting takeaway from Chuck's explanation is that in lower light conditions, One-Shot AF mode is superior to mimicking one-shot by using one of the AI servo modes combined with a quick press and release of the AF-ON button (BBF, long enough to get focus confirmation). He mentions that the One Shot mode actually takes more time to converge on more accurate focus under these conditions. I had always figured these techniques were equivalent in all scenarios, and that BBF users had no reason to ever use One-Shot AF. Now I know better!

That is interesting, I wonder at what EV it becomes important for various camera models.

Might be something to try and test out.

I can say that by relatively low light (domestic lighting) I don't believe I have seen a difference, but I would have to retest to confirm that.