Autofocus?

[Bill Pierce]

For many autofocus cameras there are two ways you can autofocus. Out of the box most of them work just by pushing the shutter button. The camera autofocuses and then trips the shutter. The other way the camera autofocuses and then locks on the focus without tripping the shutter. Sometimes this is done by pressing a second button after you focus; sometimes, by pressing a different button to focus. In a sense this is close to the way you took pictures before autofocus. You focused; then you took pictures until you needed to refocus.

Although this option is available, I often see folks focusing with every frame even though the subject hasn’t moved. No problem if your subject is a tree or a rock or a still life. But with a human being or any rapidly changing scene where the precise moment is important, you are introducing a delay between the time you push the button and the picture is taken and an even greater delay if you are using a central focusing spot and reframing.

But sometimes I find myself guilty of this. It’s so easy just to push the button. Maybe manual focus wasn’t such a bad thing. Your thoughts?

 

[burancap]

Try a Contax G2 with the rear Focus Lock Button. Love it.

 

[newsgrunt]

I use back button focusing (Nikon D4s) for most assignments. Will grab the focus manually if I need to. Rarely do I use release tracking focus.

 

[rscheffler]

The refocus between each shot 'habit' at least in my case with AF is due to past experiences when the camera didn't get the focus quite right, and a whole sequence ended up soft enough to be problematic. Focusing between each shot shifts the odds a bit so that it's not all or nothing. Some might end up a bit softer than desired, but the majority should be well focused. If the optical viewfinders and focusing screens were better in current DSLRs (and I'm basing my opinion on Canon 1D series cameras) for confirming focus accuracy by eye, I'd probably be less concerned about this, since I would be able to eyeball whether AF was good or not and even trust focusing manually. But as it is now, especially with ~50mm and wider lenses, it's often really tough to get an exact feel for where the focus is. For some time I used the special Canon 'S' screen designed for a better, more precise manual focus experience, but have found the latest stock focusing screens close enough to the S, which itself didn't entirely resolve the problems I had.

It's a primary reason I decided to try the M9 back in 2010 and have remained with the system as a complement to my DSLRs. I found the manual focus rangefinder precision with normal to wide angle lenses to be amazingly good, to the point where I trust it much more than AF with similar focal lengths. And with an M series camera and lenses, I indeed will focus once and leave it until my camera to subject distance has changed. Eliminating the time to focus again, unnecessarily, means a much better chance of timing the shot, if it's critical to the image.

Back to AF: for moving subjects I switch to AI Servo and with all AF modes I use Canon's 'AF ON' thumb button to activate AF when desired. I never liked having AF and shutter release tied to the same button.

 

[John E Earley]

I use back button focusing on my DSLR's, CSC's and autofocus SLR's. Consistency in focusing has helped me and allows more energy for composing.

I do however really like manual focus lenses for the same reason rscheffler states regarding his M9.

 

[jsrockit]

I guess I'm in the minority. I like single point AF and focus and recompose. Sometimes I use MF. However, never do I separate AF from the shutter release. I do see how it could be advantageous in certain situations, so I'll have to rethink that a little.

 

[back alley]

i use the shutter button...focus and keep pressed half way...and then re-compose.

i tried the back button focus but could not get used to it.

 

[RichC]

I guess I'm in the minority. I like single point AF and focus and recompose. Sometimes I use MF. However, never do I separate AF from the shutter release. I do see how it could be advantageous in certain situations, so I'll have to rethink that a little.

Mainly manual focus on my Nikon D800E - I've added ye olde worlde focusing screen with a microprism circle.

But when I use autofocus I do the same as jrockit. With one exception: I notice people use "focus/recompose "- why!? <scratches head>

Modern dSLRs have a zillion focus points, so if you set the camera to single-point autofocus you can move that point all around the viewfinder. More accurate and far quicker then "focus/recompose" because, well, it's just "focus"!

 

[Glenn2]

I use the back button and AFC setting on the camera (Nikon D800e). This makes it work the same as my Leicas for single photos, focus, compose, shoot. Now if the subject is moving all you need to do is hold down the back button rather than press and release and focus will track any movement, it's the best of both worlds.

Sure wish all my other AF cameras could decouple autofocus from the shutter.

 

[BillBingham2]

I strongly prefer to have the ability to set the focus manually and lock it there until I change it (either to a new distance or back to auto).

I'd like to see a button that I could push once the focus is set to lock the camera into manual focus at the distance until I say please auto focus again for me.

When using film I preferred pushing the shutter button half way to lock the focus. This was because I was waiting for the moment. With digital I find myself shooting sets of pictures. More around shoot groups of people (e.g. sons & friends after plays) that anything else. Not as worried about being wasteful no days as I was with film. Not sure if that's good or bad (lazy).

B2 (;->

 

[Bill Pierce]

Here's an article on back button focusing that may be useful or interesting.

http://www.slrlounge.com/back-button-focus-try/

 

[johannielscom]

I guess I'm in the minority. I like single point AF and focus and recompose. Sometimes I use MF. However, never do I separate AF from the shutter release. I do see how it could be advantageous in certain situations, so I'll have to rethink that a little.

+1 on that all the way.

Nikon D700 and D300 I shoot like this. Rethinking: yes, might be advantageous.

Here's an article on back button focusing that may be useful or interesting.

http://www.slrlounge.com/back-button-focus-try/

Thanks Bill, interesting!

 

[Ronald M]

Nikon repair shop told me the single center point is most accurate. If you are not a sports photog when multiple points might be necessary, I believe it is the best.

I use the back button because I do portraits, landscaps, and flowers. I do not have to hold a shutter half down and recompose which is a pain when on a tripod or do not focus on the center.

That is for slr. Leica M, there is no choice and I never have problems with out of focus.

 

[charjohncarter]

I've been fooled too many times by autofocus. It is OK with a wide lenses but 40mm and up be careful. I put the AF SLRs I have on 'spot' then hit my focus spot, hold the button half way down and compose, then shoot. I still like my Rolleiflex T with the split screen and I have a couple of Pentax P3ns with split screens that I prefer over AF. Of course the really good way to focus is a Rangefinder.

 

[aizan]

if a lens doesn't have a focusing tab so you can focus by feel, it really needs fast autofocus so you can switch focus distances ASAP. in those situations, i like having AF assigned to the shutter button.

but, yeah, back button AF is usually the way to go.

 

[CMur12]

I'm a little mystified by all of this, as I still shoot film in manual-focus/manual-exposure cameras. I do have a couple of SLRs that also offer Aperture Priority Automation.

From the controls I see on many new digital cameras, there is a single AEL/AFL button on the back.

For my purposes, any form of exposure automation without AEL is useless. So, I need AEL. Then, of course, I would need a way to lock focus.

Is there any way to lock exposure and focus separately on these cameras without setting the back button to AEL and using the shutter button for AFL?

Thanks.

- Murray

 

[willie_901]

I guess I'm in the minority. I like single point AF and focus and recompose. Sometimes I use MF. However, never do I separate AF from the shutter release. I do see how it could be advantageous in certain situations, so I'll have to rethink that a little.

Me too.

Of course sometimes continuous AF is required for subjects in motion.

Focus and recompose is what I prefer. When DOF becomes limited I move the AF region around. This is easier to do on some cameras than others. It takes some practice to do it well with any camera I've tried.

I also move the AF region around when the camera is on a tripod. Often I use supplemental strobes camera lighting an have to choose the widest practical aperture to make the most of the strobes' light while achieving reasonable sharpness for 4 to as much as 20 ft or so. So choosing a focus object at the right distance is important.

 

[Daniel Teoli Jr.]

For many autofocus cameras there are two ways you can autofocus. Out of the box most of them work just by pushing the shutter button. The camera autofocuses and then trips the shutter. The other way the camera autofocuses and then locks on the focus without tripping the shutter. Sometimes this is done by pressing a second button after you focus; sometimes, by pressing a different button to focus. In a sense this is close to the way you took pictures before autofocus. You focused; then you took pictures until you needed to refocus.

Although this option is available, I often see folks focusing with every frame even though the subject hasn’t moved. No problem if your subject is a tree or a rock or a still life. But with a human being or any rapidly changing scene where the precise moment is important, you are introducing a delay between the time you push the button and the picture is taken and an even greater delay if you are using a central focusing spot and reframing.

But sometimes I find myself guilty of this. It’s so easy just to push the button. Maybe manual focus wasn’t such a bad thing. Your thoughts?

Most of my work is zone focus. I shoot in very fast situations where there is no time for focus to set and / I shoot in very poor light. The Fuji esp has terrible AF. The 'focus by wire' is a BIG a sad joke Fuji unleashed upon us. Sometimes AF works OK, if it does I use it. But most of the time I have trouble with it. It is too bad, but the trend is to dummy down the lenses and remove controls to make it harder to do zone work. No distance scales or manual focus ability is an easy way to save $ for the cam company. No aperture ring on many lenses too...sad.

 

[Fraser]

I always use back button with continuous focus, you can shoot like one shot press the button then recompose and let's you concentrate on the shutter release.

 

[Pioneer]

When I press the shutter button on my M-A it does not seem to focus before it fires the shutter. I assume AF must have been assigned to the back button at the factory but I'll be darned if I can even find that silly thing.

Guess I'm just going to have to send it to Leica and insist they calibrate the AF properly!!



I don't know what I am going to do with my Rollei. Harry Fleenor refuses to answer my e-mails.