[outsider]

Hmmm. I'll do my best to describe my question. I do a fair amount of closeup portraiture of faces and am wondering what the best techniques/settings are for getting the focus more accurately on the eyes (for obvious reasons). This is very important, especially when there is not a second chance to get it right. In many scenarios, I may have 10-15 seconds to lock focus onto the subjects face and take the picture. I've noticed more pictures than I would like turn out slightly misfocused. Not terribly so, but a little too far back or forward. Nothing disasterous, but we here at pentax forums don't accept anything but perfection in the long run (at least for me). I'm using the k-x, which doesn't have the focus point indicator, but it's a non issue. I'm young and have good eyes. I usually almost always use the center focus point and haven't been convinced that multipoint, or face detection would be anywhere near as good. What's the trick for getting the focus dead on the eyes when shooting in an insanely large apertures and the dof is very narrow? I'm assuming the closer I get to the face, the more capable the I.Q. will be of locking on to the focus point. I was also thinking that it may be a good idea to focus on one eye instead of the bridge of the nose, assuming you can still get most of the head in the picture, then crop to liking. Is there something I don't know? Is there a cardinal sin one should never commit when taking closeup portraits of faces? What's your trick? Maybe most do manual focusing, but that would be unacceptable in the fast moving scenarios I shoot in. I have a few seconds to get it right. The picture featured here was a hail mary of sorts. The last of about 5 or so shots I took hoping that one would be perfect. The last 2 were perfect and I think I zoomed in closer about 125mm. The first shots were slightly off (too far forward).

Attached Images

 

[SpecialK]

You already identified the problem - large aperture with very thin DOF. So, either stop down for DOF, or shoot more shots. You can perhaps get a focusing aid for the K-x, and manually focus.

[tranq78]

You have to learn to manual focus.

Most people gravitate to the eyes first in a portrait so you have to practice until you can nail it down. A couple seconds is all you'll need once you get the hang of it.

You may have to get one of those split screen thingies as well to help.

[outsider]

Thanks. I've heard that large apertures can cause difficulty with autofocusing. Never understood why this is.

[JohnBee]

There's no sure shot answer tbh.

Though if I had to guess, I'd say it will be a combination of lens and style(your own) that will get you in the zone(so to speak). Thin DOF can be quite tricky and it might take some practice to get the hang of it. But it can be done.

One simple trick is to use spot focus and aim for the eyes or bridge of the nose(if your DOF is sufficient)
Another, is to use the right lens and distance so as to get a DOF that will allow your subject to come through successfully.
Which I think comes down to a combination of; working distance, focal range and aperture setting.

Otherwise, if you're working in a controlled setting, you can invest in a good tripod on wheels. This way you can cart your rig around the model and shoot manually(which is my preference). I like to keep the subject in LV and use the DOF preview to get an idea of what I'm working with. But the real truth always come in the previews.

If memory serves me right, it was trial and error at first, but once I got used to my kit, I found myself spending less time trying and more time working.

Hope this helps.

PS. a split screen helps too, but the LV system on the latest camera's pretty much make those obsolete now.

[Wheatfield]

+1 on learn how to manual focus.
It's pretty easy to learn, but requires some practice.
If you watch the image as you focus slowly over and past what you want to focus on, you will see that part of the subject "pop" for lack of a better word.
So, focus slightly past the point where you see the image snap into focus, then adjust slightly to get back to it.
A good accessory screen such as a Katz Eye can really help. I prefer the microprism collar to the split image as I can see the subject pop into focus easier than I can align the split image.
And don't be afraid to stop down a little bit. Taking an f/1.4 lens down to f/2 will still leave a very shallow depth of field, but will give you an edge in keeping the eyes in focus, as well as giving an overall increase in sharpness.

[Chex]

Manual focus is definitely the best method, There are ways to get better manual focus viewfinders.. look to things like Katz-Eye and other makers of viewfinders, sure they can run upto a $200-300.. but when they improve every shot you take with it... its well worth it. I'm currently deciding which Katz-eye to order (multiple setups available). Also remember the further away from your subject, and the narrower the aperture, the deeper the DoF that will give you some extra workable focal range as you practice and can narrow it up.

[Class A]

MF surely has its place but I think for such an application AF should work, provided that your lens is properly calibrated (even the K-x can be fine-adjusted through the service menu) and you are using the right technique.

I usually almost always use the center focus point and haven't been convinced that multipoint, or face detection would be anywhere near as good.

You shouldn't be using multi-point AF, but manually select the AF point/area that is closest to the position in the frame where to you want the eyes to end up. This way, the amount of recomposition will be either minimised or eliminated (if you are happy with the AF point/area position or shot slightly large and crop in later). Using a "centre point/area focus & recomposition" technique will introduce focus errors which will be noticeable with the thin DOF you are using.

P.S.: I realise that the K-x doesn't have the AF indicators in the viewfinder, but by resetting to the centre position and then counting the clicks, you can select the one you need without even stopping to look through the viewfinder.

[Digitalis]

+1 on learning to use manual focus, I often use the Pentax 50mm f/1.2 @ f/1.2 for studio portraiture and DOF can get wafer thin, and I only have several seconds to get it right...don't worry the more you practice you get the sooner you will be able to reliably nail the focus.

[rparmar]

Like they said: manual focus.

If you have difficulty in low light you can try putting the drive on high-speed. Drill out a sequence of images while slightly changing the focus plane. One shot might then be in focus.

Also, use fill flash to provide a catch light in the eyes and lighten shade. This is essential unless you carefully plan ambient light.

[BrianR]

...
If you watch the image as you focus slowly over and past what you want to focus on, you will see that part of the subject "pop" for lack of a better word...

Pay close attention to this! The gradual change as you turn the focus ring is a big help when trying to manually focus and shooting at wide apertures. I don't think the viewfinders are accurate enough to be able to tell on first sight if you are within the depth of field at f/1.4 (or even f/2.8 for that matter), so the changes will give important hints on when you've nailed the focus.

You might also try locking the focus to "pretty close" then moving your head in and out until you get the eyes in focus. Same idea as above applies except you move the camera instead of turning the focus ring. This is my favored macro focusing technique that I've started to like for the few portraits I take.

Also, make sure your diopter is properly set for your eyes or you don't have a chance at manually focusing.

[Class A]

With the exception of JohnBee all of the posters in this thread have been put on a list of people who must not complain about AF issues with Pentax cameras.

Just joking, of course, but I don't see the OP's situation as "must MF" case. I've used AF on my K100D for portraits and sometimes the DOF is so thin that I don't get both eyes into focus when the head is slightly turned but I consistently get shots with the one eye I aimed for in sharp focus using AF.

Stock screens for modern DSLRs aren't great for manual focusing below f/2.8. The idea to pay $200-$300 for a replacement screen seems just insane for me. That's 40%-60% of a new K-x. Imagine you had to pay that kind of money for every part in it that is more complicated than a focusing screen.

I use manual focus a lot myself -- with MF lenses and for macro photography -- but the vast majority of portraits really don't need it in my experience.

[Wheatfield]

With the exception of JohnBee all of the posters in this thread have been put on a list of people who must not complain about AF issues with Pentax cameras.

Just joking, of course, but I don't see the OP's situation as "must MF" case. I've used AF on my K100D for portraits and sometimes the DOF is so thin that I don't get both eyes into focus when the head is slightly turned but I consistently get shots with the one eye I aimed for in sharp focus using AF.

Stock screens for modern DSLRs aren't great for manual focusing below f/2.8. The idea to pay $200-$300 for a replacement screen seems just insane for me. That's 40%-60% of a new K-x. Imagine you had to pay that kind of money for every part in it that is more complicated than a focusing screen.

I use manual focus a lot myself -- with MF lenses and for macro photography -- but the vast majority of portraits really don't need it in my experience.

If the AF isn't giving you perfectly sharp focus (and most of the time it won't), then it's either manual focus time or stop down a little bit time.
The problem with AF in a short DOF situation is knowing exactly what it is locking onto, and also knowing what the AF system resolution is.
Sometimes it works, sometimes it doesn't work so well, and sometimes it fails altogether, and it will fail more often in the short distance wide aperture shooting that is typical of portraiture.
In a low speed situation such as portraiture, AF isn't an absolute necessity, and since it is prone to fail, it makes sense to learn how to focus manually and then use that skill rather than to depend on a technology which may or may not work.

[Lab]

In one of the links Adam posted re:manual lenses there was a link to an article that suggested to take a series of shots with slight focus adjustments to try to determine where a particular lens focused. After a few series of shots (using a tripod and a remote) I found little difference that would help me in real situations, but having said that, the number of shots that are on focus are improving from about 1 in 10 to half that many, and the few really good ones that come out make it worthwhile (and I try to forget the what if shots).

I think I am going to try focusing on the bridge of the nose as JohnBee suggested.

[Todd Adamson]

When your DOF is razor thin, tiny movements of you and/or your subject can throw it off. Another thing that can make a huge error in your optimal focus plane is using the focus and recompose method of shooting, which I assume you're doing, since you mentioned you use the center point most of the time. That right there can kill you, and that will be instantly solved by using manual focus.

As far as your own movement, that can be overcome with a tripod. I shoot a ton of wide aperture portraits, and when I would shoot at f/1.4 on full-frame, I was just very careful and repeated lots of shots, and my keeper rate would hover around 50% or lower.

It went up a little when I started using a tripod, and went up even more dramatically when I switched to manual focus.

If your situation does not permit MF or a tripod, you'll just have to take more shots. However, manual focus is not nearly as difficult as many seem to think it is. I had trouble at first, but improved steadily with practice, and my eyes are honestly not that good.