Why Focus-Recompose Sucks

fish

In most modern SLR cameras, the autofocus sensor located at the center of the frame is generally designed to be more sensitive and more accurate than most or all of the camera's other AF sensors. In low-light situations, it is possible for the center AF sensor to be the only one that will reliably lock on to the subject and achieve focus lock. This has given rise to the technique of center point focus-recompose, which involves placing the center AF sensor on the portion of the subject that needs to be the most clearly focused, and activating autofocus. Once focus has been achieved, then the camera is reoriented until the desired framing is achieved, and then the shutter is released. There's just one problem with this idea: it is 100% guaranteed to cause focus to be behind the intended center of focus.


Check out Jonathan Wienke's essay at Outback Photo.

dkapp

Good post. I ran into this a lot when using this technique on my D70. It wasn't until many, many OOF shots before I sat down & figured it out.

This could have saved me a lot of frustration & many wasted shots 6 months ago

The good news is my D2H has a lot more focus points to pick from, and will usually give me what I want.

Another problem that I ran into was I used the 1/2 press method to focus lock. This would also lock the exposure, and cause more problems than OOF, like blown highlights & underexposed images. Now I have the AF/AE lock button set to AF lock only. Learning curves make me want to :cry

Dave

Michiel de Brieder

Yeah try focus-recompose @ F/1.4 I made one mistake last sunday by doing just that, luckily I chimped!
Thanks for the heads up Fish!

fish

I used to focus-recompose all the time with film...and I still do it occasionally out of habit with digital. Gotta untrain myself.

Good tip on the reprogramming of the AF button, deadbeat. I'm going to go do that now.

dkapp

fish wrote:

Good tip on the reprogramming of the AF button, deadbeat. I'm going to go do that now.

No problem

BTW. You can call me DB for short. deadbeat just seems so formal :lol

-DB

wxwax

Sure, the guy's right. And what he says makes perfect sense -- for a static situation. But your options are limited in a highly dynamic shooting environment.

I'm not quick enough to constantly change my focus point. And experience has taught me that if I let the camera decide, the microphone or the drumkit will be in focus, not the musician.

So I can either manually focus, at which I appear to suck. It may be my eyesight, but I have a hard time telling when I have precise (as opposed to ballpark) focus. Or I can center focus/recompose, which is what I elect to do. And so far, it seems to work. If I'm close, I focus on the eye and then reframe. If I'm far, it usually doesn't matter.

pathfinder

wxwax wrote:

Sure, the guy's right. And what he says makes perfect sense -- for a static situation. But your options are limited in a highly dynamic shooting environment.

But what Jonathon describes about focus/recompose only matters in the first 20 feet or so. For distant objects, landscapes, the point is moot as he says. I was shooting candids at Christmas at f1.4 at 4 feet and the AF point had to be right on the eye - no focus and recompose allowed at F1.4

I'm not quick enough to constantly change my focus point. And experience has taught me that if I let the camera decide, the microphone or the drumkit will be in focus, not the musician.

I never let the camera chose my AF point - It always seems to disagree with me - I try to only permit a solitary AF point to be active in my ground glass

So I can either manually focus, at which I appear to suck. It may be my eyesight, but I have a hard time telling when I have precise (as opposed to ballpark) focus. Or I can center focus/recompose, which is what I elect to do. And so far, it seems to work. If I'm close, I focus on the eye and then reframe. If I'm far, it usually doesn't matter.

The reason you have difficulties with manual focus is because most of the digital SLRs are poorly set up for manual focusing - they are not bright and they gave up the split image range finder. The view finders in most DSLRs suck in comparison to the older manual focusing view finders like in the Olympus OM-4 or the Nikon FM-3a or the PRO level Nikon and Canon film cameras. And it is impossible to see focus with them in a club lighting situation.
The Canon 1 series DSLRs are bright enough but lack split image range finders as stock, but the split image rangefinder ground glasses ARE interchangeable and available for the 1D and 1Ds. For club shooting Sid, I think you might consider replacing the stock ground glass in your 1D, for one with a split image range finder.

fish

pathfinder wrote:

The reason you have difficulties with manual focus is because most of the digital SLRs are poorly set up for manual focusing - they are not bright and they gave up the split image range finder. The view finders in most DSLRs suck in comparison to the older manual focusing view finders like in the Olympus OM-4 or the Nikon FM-3a or the PRO level Nikon and Canon film cameras. And it is impossible to see focus with them in a club lighting situation.

They don't need to be for the most part. AF works amazingly well. Place a square over what you want to be in focus, push halfway, wait for the beep, snap! Easy. The only time I try to do MF is on macros, and the lens is almost always more accurate than I am.

rutt

pathfinder wrote:

I never let the camera chose my AF point - It always seems to disagree with me - I try to only permit a solitary AF point to be active in my ground glass

With 10D and 20D, that was the absolute right thing to do. With 1Dmkii, there is something I like much better. You can set up the useless WB buttons (right under you left thumb with both shutters) to selsect you preferred auto focus point. When you don't push the button the camera does its thing. When you do push the button, you get "pathfinder mode" (as I think of it.)

The AF point selection algorithm in this camera is way more sophisticated than in the mid range models. It doesn't just pick the closest point, but instead the points "vote" and it tries to find the largest, closest, clump. I'd like to know the exact rule. Anyway, it's good when you either have a lot of time or no time at all. With a lot of time, you can review the points that the camera has chosen and make sure they are what you want. With no time at all, as in action, well as Andy says, it's a gattling gun. You don't have time and you are shooting a ton and usually the camera will find something reasonable to focus on. But I love being able to switch back to single focus point mode with such a convinient button. It's become a habit.

Very interesting thread; I had never considered this before.

wxwax

fish wrote:

They don't need to be for the most part. AF works amazingly well. Place a square over what you want to be in focus, push halfway, wait for the beep, snap! Easy. The only time I try to do MF is on macros, and the lens is almost always more accurate than I am.

As I said, that's easy enough in a static situation. But when I'm moving around a stage, constantly changing compositions, putting that square on what you want in focus takes more time and experience than I have. I suspect it's not intended to be used that way, either.

fish

wxwax wrote:

As I said, that's easy enough in a static situation. But when I'm moving around a stage, constantly changing compositions, putting that square on what you want in focus takes more time and experience than I have. I suspect it's not intended to be used that way, either.

butt waxy, you are talking about a special situation, and there are many ways to get around that. What I don't understand is how you can focus and recompose with a bunch of action going on.

How about setting to AI servo, assign a focus point to your main subject and let 'er rip?

gus

Fish...remind me to ask you to explain it to me at yosemite....






BEFORE...you have a drink.

wxwax

fish wrote:

butt waxy, you are talking about a special situation, and there are many ways to get around that. What I don't understand is how you can focus and recompose with a bunch of action going on.

How about setting to AI servo, assign a focus point to your main subject and let 'er rip?

Because my main subject changes places in my frame every minute or two, as I walk around the front of the stage. That's what I'm trying to say, that I can't assign a point, because the part of the frame that I want in focus changes rapidly.

What other ways were you thinking of?

fish

Humungus wrote:

Fish...remind me to ask you to explain it to me at yosemite....

I gotta wait four months to hear your drivel?

BEFORE...you have a drink.

bite me, greenburnedfaceboy :slosh

fish

wxwax wrote:

Because my main subject changes places in my frame every minute or two, as I walk around the front of the stage. That's what I'm trying to say, that I can't assign a point, because the part of the frame that I want in focus changes rapidly.

Have you tried AI servo, Sam-I-Am? Just assign one of the focus points...lets say the center one for example. Everytime you half-press the shutter release, it's going to focus on that center square. Just make sure that you put the square over your main subject. I'm not sure what your fancy camera is like, but with the 20D, you can use the joystick thingy on the back to manipulate the AF point on the fly. With AI servo, just put the assigned AF point on the subject, half-press the SR, and let your subject move about, and it will keep tracking. Easy peasy.

What other ways were you thinking of?

Some other right answers:

(1) manually prefocus and shoot when your subject moves into the focus area.
(2) use very high ISO, slow shutter, and small aperture to get max DOF.
(3) yell "FREEZE" and when everyone stops moving, take a piccy.

Come on, waxy...do I have to do ALL your thinking for you? :lol

wxwax

Can't manually focus, esp. in low light - as I said, I find it very difficult.

High ISO, check.

Slow shutter, uncheck. Those darned musicians are soooo fond of moving when they play. Something about a beat... can't say I really know what that is, I'm afraid.

Small aperature .... um, we're talking about club lighting, here. I'm shooting a f1.4 wide open at 1000 ISO and getting blur when their heads move.

Ergo, only solution for rapid, accurate focus is to center point, aim for the eye, then recompose. Quickly. Because when they step forward with this 'beat' thing, they're out of focus again. I shoot a lot of frames.

Like I said, I don't agree that center focus/recompose is always a bad idea. Sometimes it's the only way to get the shot.

Whew. Enough already.

fish

wxwax wrote:

Can't manually focus...blah blah blah...Ergo, only solution for rapid, accurate focus is to center point, aim for the eye, then recompose. Quickly. Because when they step forward with this 'beat' thing, they're out of focus again. I shoot a lot of frames.

Have you tried AI servo yet?

Like I said, I don't agree that center focus/recompose is always a bad idea. Sometimes it's the only way to get the shot.

You need to watch that Dewitt Jones video again, pally. There's no one right answer.

gus

fish wrote:

There's no one right answer.

Thats the best admission of defeat i have EVER seen with fish in an argument waxed bikini.

Personally...i'd take it & run.

wxwax

fish wrote:

Have you tried AI servo yet?


You need to watch that Dewitt Jones video again, pally. There's no one right answer.

Yes.

And that's what I said in my very first response, bub.

wxwax

Humungus wrote:

Thats the best admission of defeat i have EVER seen with fish in an argument waxed bikini.

Personally...i'd take it & run.

fish

wxwax wrote:

Yes.

And that's what I said in my very first response, bub.

Really? I didn't see anything about that in your first response.

Sure, the guy's right. And what he says makes perfect sense -- for a static situation. But your options are limited in a highly dynamic shooting environment.

I'm not quick enough to constantly change my focus point. And experience has taught me that if I let the camera decide, the microphone or the drumkit will be in focus, not the musician.

So I can either manually focus, at which I appear to suck. It may be my eyesight, but I have a hard time telling when I have precise (as opposed to ballpark) focus. Or I can center focus/recompose, which is what I elect to do. And so far, it seems to work. If I'm close, I focus on the eye and then reframe. If I'm far, it usually doesn't matter.

Is something about AI servo in there and I'm just not seeing it?




:duel

wxwax

fish wrote:

Really? I didn't see anything about that in your first response.


Is something about AI servo in there and I'm just not seeing it?

:duel

Time to use one of your new smilies.



"And experience has taught me that if I let the camera decide, the microphone or the drumkit will be in focus, not the musician. "

Hint: it's the part that's underlined.

And from Canon documentation:
"The performance of any automatic focusing system depends primarily on its ability to recognize the subject to be photographed."
"An essential requirement for a phase detection AF system is an adequate volume of light."
"A third requirement for phase detection AF is a sufficient level of subject contrast."
"The EOS 1 AI Servo AF system performs best with subjects that pass at least the minimum requirements for light level, subject position, subject contrast, camera shake, and subject motion."

My experience: f1.4, ISO 1000, less than 20 feet from the subject. Microphone in focus, singer not. 30 feet from the subject: cymbals nice and crisp, drummer out of focus.

'Course, that's firsthand experience, not something I read on the web, so take it with a grain of salt.

OK, I think that's enough of that.

fish

wxwax wrote:

"And experience has taught me that if I let the camera decide, the microphone or the drumkit will be in focus, not the musician. "

Hint: it's the part that's underlined.

I read that underlined part five times and have yet to find the word "servo" in there.

Must just be me, huh?


And sidney, I must say that I'm quite shocked you would post an image with the "F" word in it. You really should be ashamed of yourself. :lynn



Wanna chat about the Palestinian situation?

I have a feeling this thread might be destined for Wide Angle any moment now. :uhoh

Andy

can we take up a collection, for fish?

fish wrote:

I gotta wait four months to hear your drivel?




bite me, greenburnedfaceboy :slosh

i think he needs more bran in his diet...

pathfinder

wxwax wrote:

Time to use one of your new smilies.



"And experience has taught me that if I let the camera decide, the microphone or the drumkit will be in focus, not the musician. "

Hint: it's the part that's underlined.

And from Canon documentation:
"The performance of any automatic focusing system depends primarily on its ability to recognize the subject to be photographed."
"An essential requirement for a phase detection AF system is an adequate volume of light."
"A third requirement for phase detection AF is a sufficient level of subject contrast."
"The EOS 1 AI Servo AF system performs best with subjects that pass at least the minimum requirements for light level, subject position, subject contrast, camera shake, and subject motion."

My experience: f1.4, ISO 1000, less than 20 feet from the subject. Microphone in focus, singer not. 30 feet from the subject: cymbals nice and crisp, drummer out of focus.

'Course, that's firsthand experience, not something I read on the web, so take it with a grain of salt.

OK, I think that's enough of that.



Waxy - What exactly is that Foundation again?? Did I read that right?? Surely that must be a mistake Maybe we should move this thread to a more private area??

AF will always pick a nice straight sharp high contrast target to a smooth organic flowing target - that IS the problem with letting the AF system chose which AF point to use. The Canon EOS 3 35mm film camera has a neat system - It uses the AF point the photographer is looking at in the viewfinder - Kind of like the tracking -aiming helmets in helicopter gunships!

gus

andy wrote:

i think he need more bran in his diet...

And you lot ...less carbs & more protein.

wxwax

Oop, sorry about the fine print on the poster, folks. See, that's why I can't manually focus well, eyesight not up to the task. I'll remove the poster, that was a mistake.

And after posting that last night, it finally dawned on me why the camera's picking out the mic stand and cymbal instead of the performers. The mic stand and cymbal are nice and shiny and give the autofocus something to grab onto in a murky environment, whereas the musicians are much darker and less contrasty. So that explains that.

As I said, there are times when center focus and recompose is the best solution.

gubbs

wxwax wrote:

Oop, sorry about the fine print on the poster, folks. See, that's why I can't manually focus well, eyesight not up to the task. I'll remove the poster, that was a mistake.

And after posting that last night, it finally dawned on me why the camera's picking out the mic stand and cymbal instead of the performers. The mic stand and cymbal are nice and shiny and give the autofocus something to grab onto in a murky environment, whereas the musicians are much darker and less contrasty. So that explains that.

As I said, there are times when center focus and recompose is the best solution.

Get the band to wear foil covered baseball caps

wxwax

gubbs wrote:

Get the band to wear foil covered baseball caps

gubbs

this started out being an interesting and informative thread

wxwax

Uh-oh, you've fallen for that smiley.



It's still a good thread. There are obviously valid reasons why focus/recompose can hurt your shot, and I'm glad Fish brought it up. Focal plane/depth of field is an excellent point. Also, exposure control when you're not in Manual.

But IMHO there are situations where it's the best alternative. My experience is that it's the best choice when I'm in super low light, low contrast environments where I change positions a lot.

Thanks to this thread, I felt compelled to read Canon's literature on how AI servo works, and I discovered what I think the problem is: shiny bits of equipment, like mics and cymbals, appeal to the autofocus more than dark, low contrast performers.

So, as long as I'm far enough away that the depth-of-field isn't an issue, center focus/recompose seems like the only reasonable way for me to grab focus.

Fishie apparently disagrees, but perhaps he hasn't shot bands in a low-light clubs with his 10D or 20D? I'm always shocked at how little light they throw on the performers. I've now shot in 6 different clubs/bars, and only one has had decent light. Surprise, surprise, that's the one that produced the most usable images.

I still do other things wrong, and I'm still learning. I've figured out the center focus/recompose solution to autofocus and manual focus problems, and of course, fast glass helps. But I don't trust high ISO enough. I believe this is the first time I've shot in a club with the mkII. The 1D made really noisy images above 1000 ISO, so that's where I kept the mkII. Big mistake, and one I won't make the next time out. You live, you learn!