How Do You Usually Focus?

[MarkBarbieri]

How do you usually focus with your camera?

 

[YEKCIM]

If you mean, AF vs MF, I use AF, exclusively (lazy and eyesight not what it used to be...). Why do you ask?

~YEKCIM

 

[MarkBarbieri]

This was going to be a poll, but I botched it. I'll just make it a discussion instead.

I'm curious as to how people focus. I'm sure that a majority of just use their shutter button to trigger autofocus. Who still focuses manually? When do you focus manually?

I don't often focus manually, but I do in a few circumstances. Sometimes when I'm particularly concerned about maximizing DOF, I'll focus manually so that I can get the focus plane in the best location.

I've also occasionally used manual focus when I'm trying to get a picture of a moving object when it reaches a particular place. I focus on that spot manually and shoot when the subject is there. I did that a lot more with my old because it's autofocus was much slower than my current camera.

Who uses a focus button rather than their shutter button? By default, I think every AF camera is set up to focus when the shutter is pressed down half way. Many cameras (well, DSLRS, I'm not sure about P&S) allow you to change that behavior and move the focus to a separate button on the camera. You press one button to focus and another to take the shot.

I had seen that you could do this several years ago, but it always sounded unnatural to me. A friend convince me to switch a while ago and after a couple of shoots, I'll never go back.

 

[gruZ]

Mark,

Good question - I'm interested in the responses. I use AF most of the time - only with the * button (CF 4 I think on the 20D) on back of the camera. I too thought this sounded odd at first, but really like the ability to pick my focus spot and not worry about it in certain situations (batter hitting a ball is a great example). I won't go back to the "one button does it all" method.

I also used to use only the center focal point, and in most occasions still do, but am branching out as well with the other focal points my camera has.

MF is still used from time to time, to adjust what the AF has done (with USM type of lenses), or completely MF in low light situations where shooting at a distance.

Thanks,

Scott

 

[MarkBarbieri]

Why do you ask?

Partly to learn and partly to teach. I'd like to learn about what other situations people find manual focus to be useful.

There was a discussion on manual metering a while ago. I was a confirmed AV priority shooter before that. Between that discussion and a presentation I attended by a sports photographer, I learned that there are several situations I commonly encounter in which manual metering is quite useful. Now I meter manually for about 10% of my shooting.

I thought the same thing might happen with a discussion on focus tools and techniques. Perhaps I'll learn more situations in which manual focus would be better.

I am also hoping to open up other people's eyes to the advantages of occasionally using MF and to the benefits of using rear-button focus. i imagine that many people here have either never heard of rear-button focusing or, like I used to be, they've heard of it and dismissed it without understanding it.

Besides, it's a better topic than market share and who's brand is better.

 

[Steve's Girl]

Very intersting! Thanks for bringing this up. Gives me more stuff to ponder.

 

[MarkBarbieri]

I also used to use only the center focal point, and in most occasions still do, but am branching out as well with the other focal points my camera has.

I usually let it pick the AF point. When shooting portrait shots, I often switch to the right-most AF point because, when I rotate the camera, it's in the upper part of the frame near the subject's eyes.

 

[GrumpyOne]

95% of the time I do standard AF. 3-4% of the time I'll AF to a different spot then move to the target I really want. I have only needed to MF about 1% of the time. Most of the time that I do MF it's because I'm trying to focus on something too transluscent or small for the camera to AF on and the camera gets lost. UW photography has a lot of special situations not often found in the air.

 

[DVC Jen]

Who uses a focus button rather than their shutter button? By default, I think every AF camera is set up to focus when the shutter is pressed down half way. Many cameras (well, DSLRS, I'm not sure about P&S) allow you to change that behavior and move the focus to a separate button on the camera. You press one button to focus and another to take the shot.

I had seen that you could do this several years ago, but it always sounded unnatural to me. A friend convince me to switch a while ago and after a couple of shoots, I'll never go back.

I have done this too. I prefer it to using the shutter button to focus as well.

Confuses the heck out of people though if I ask them to take a pic with my camera for me however.

 

[Lizziejane]

I have done this too. I prefer it to using the shutter button to focus as well.

Jen, are you able to do that on your XTi?

I very rarely use manual focus - as someone else mentioned, my eyes ain't what they used to be - but I did use MF at the zoo while trying to get pictures through the mesh or bars. It worked very well.

 

[KrazyPete]

So what exactly is the benefit of putting the focus button somewhere other than the shutter release? Is it just a matter of preference?

 

[gruZ]

I usually let it pick the AF point. When shooting portrait shots, I often switch to the right-most AF point because, when I rotate the camera, it's in the upper part of the frame near the subject's eyes.

I did this at first as well, but it was too unpredictable for my tastes. I would rather manually move the FP, or use the center and focus / recompose (assuming DOF is not too shallow for this). The 20D has fewer focal points than the 1 series, and I believe the center focal point is the only "crosshair" type of FP - the most accurate. Again, I believe the 1 series has more of these sensitive focal points.

 

[gruZ]

So what exactly is the benefit of putting the focus button somewhere other than the shutter release? Is it just a matter of preference?

The benefit is allowing one button to handle the focus (back of camera, the * button on Canon), and another button to handle the metering (typical shutter release button).

Why would you want to do this?

As I mentioned above, in sports shooting, where you know the action is going to be - like a baseball batter hitting the ball - you can pre-focus using the * button, and then trigger the shutter when you need to. If you are in shutter priority, this means that the camera will meter for whatever lighting conditions are present at the time the bat hits the ball. It also means there isn't any chance the camera will try to re-focus on something you didn't intend it to - and therefore miss the shot.

Another situation is when you want to compensate for different lighting conditions. A family in front of the castle (since this is WDW board). Press the shutter down when pointing the camera at the sky in order to not blow out the sky / castle - the camera will meter for the background. Then recompose on the family with the shutter button half down, press the * button to focus on the family, and push the shutter button the rest of the way down.

It sounds confusing, but after using this method for a while, I won't go back.

Also, if someone wants to take a picture using my camera, with the XXD series, when you move the dial to any of the auto modes (green square,etc. which I always do when someone wants to try my camera), the shutter button becomes a one-stop shop, do everything button again - there's no need to mess around with the custom functions and reset.

 

[MarkBarbieri]

I believe the center focal point is the only "crosshair" type of FP - the most accurate.

It's probably worth a brief description of how cameras autofocus so that people can better understand what a crosshair type AF point is.

The autofocus on cameras (at least the ones I'm familiar with) adjust the focus of the lens and try to maximize contrast. If you have a spot in the picture that is white adjacent to black, there is a lot of contrast between those two spots. The better your focus, the quicker the image transitions from black to white. If you are out of focus, the dividing line blurs into a range of grey tones. The camera fiddles with the focus until it can get the sharpest transition from light to dark or dark to light.

If you try to focus on a part of the picture with very little contrast (such as a clear blue sky), the focus won't work because their isn't enough contrast. The same thing can happen if there isn't enough light. The AF sensor might not be able to see in the dark well enough to see the contrast.

Most AF sensors are looking for the two colors to be side-by-side. If you have a pattern with a dark section directly above a light section, it might still be unable to focus because it is trying to compare the right side of the AF point with the left side. A "crosshair" AF point looks for both left/right AND up/down constrast.

Most AF points are not crosshair. The number that are varies from camera model to camera model from 0 to well over a dozen. Typically, more expensive cameras will have more AF points and more crosshair AF points than their less expensive siblings.

If you think about my description of AF, you can also see why wide aperture lenses tend to focus better than low aperture lenses. With a wide aperture lens, the sensor has two advantages. First, it has more light to work with. Second, the depth-of-field (how much of the picture is in focus) is shallower, so the increase in contrast is more abrupt. This is true regardless of what aperture you are shooting at because modern lenses stay wide open until you actually take the picture, so the focus is being done at the widest aperture.

If you find that you are having trouble focusing, it often helps to work with the way your AF sensor sees the world. Put the AF point right on top of something with a vertical line separating a light and dark part of your subject.

A flash can also help you focus. In low light situations, sometimes the camera uses the flash to help it see better for focusing purposes. You may have also noticed that some flash units project a weird red pattern of lines when you try to focus in low light. Those lines are their to put something contrasty on the subject so that it can focus on that contrast.

 

[MarkBarbieri]

Another useful focusing trick when using long lenses is a focus range limiter. Some lenses have a switch that restricts the focus range of the lens. It prevents the lens from focusing on anything close to you. At first that seems goofy; why would I want to limit the focus range? The answer becomes obvious when you are trying to track something moving (like a bird inflight) and you let it wonder off of your AF focus area. Without the limiter, the lens will search through its entire focus range trying to regain focus. That wastes valuable time. By restricting the range, it won't take as long for it to find the correct focus again.

This is another good situation for using a focus button rather than shutter focus. When you lose track of the bird, immediately take your finger off the button and when you get the bird back on track, start focusing again. You could do the same with the shutter button, but it's hard to operate as quickly when you have to worry about not pressing the button too hard and triggering a shot.

 

[MarkBarbieri]

Another good use is when you shoot with a tripod and a remote shutter release. When I'm shooting landscapes, I often find myself using a combination of AF and manual focus. I use AF to focus on the point that I'd like and then recompose. In the past, I used to switch the camera back to MF at this point so that the remote release wouldn't refocus. Now it happens naturally.

I find it really hard to give a convincing explanation of why I prefer using the rear focus button rather than the shutter. After doing it for a couple of shoots, it just started to seem more natural and I found myself taking advantage of the ability to instantly switch from AF to manul focus and back. All I can say is try it for a while. I've found few people that do it and want to shoot back, and none of them was a regular shooter.

 

[MICKEY88]

Another situation is when you want to compensate for different lighting conditions. A family in front of the castle (since this is WDW board). Press the shutter down when pointing the camera at the sky in order to not blow out the sky / castle - the camera will meter for the background. Then recompose on the family with the shutter button half down, press the * button to focus on the family, and push the shutter button the rest of the way down.

.

in this situation, wouldn't it be easier to meter, press the AEL button, then recompose and shoot ?

plus if your sky is so bright that it will blow out, by metering for the sky, you would then underexpose the family which is your main subject, unless you use flash...

 

[gruZ]

Another focusing trick:

As Mark described above some flashes will emit a pattern of red, barely visible light to help focus in low or no light situations. If you don't have (or can't use) this type of flash to help focus in low / no light, try this trick:

Buy an inexpensive laser pointer. Point it at what you intend to shoot, and focus on the red dot. Works great!

 

[MICKEY88]

You could do the same with the shutter button, but it's hard to operate as quickly when you have to worry about not pressing the button too hard and triggering a shot.

with enough practice focusing without triggering the shutter becomes quite natural...another option is setting the camera on focus priority, so it will not take a pic until it's in focus..

 

[MICKEY88]

Another focusing trick:

As Mark described above some flashes will emit a pattern of red, barely visible light to help focus in low or no light situations. If you don't have (or can't use) this type of flash to help focus in low / no light, try this trick:

Buy an inexpensive laser pointer. Point it at what you intend to shoot, and focus on the red dot. Works great!

just don't use this techinique when shooting people or airplanes...