Getting Sharper Images - an Understanding of Focus Modes

Getting Sharper Images – an Understanding of Focus Modes

The longer you shoot, the larger the repertoire of subjects and assignments you photograph becomes. You start off photographing flowers in the garden, your neighbour’s dog, your sister’s kids, your friend’s wedding and then before you know it you’re doing product shots for your friend’s new company. All this happens over time and there is one pretty fundamental skill that must remain paramount throughout out your process, properly focused images. Sure we’ve all been there, we’ve all taken that shot once in while which is slightly soft (a polite photographer’s term to describe out-of-focus images). But, it’s a great shot so we keep it anyway, even tho we would still have preferred it to be tack sharp.

MG 3504flat

In focus images have been one of the most fundamental rules of photography right from the dawn of the craft. In the early 1900s it was a craft in its own right, but in the 1960s Leica introduced a rudimentary autofocus system that changed everything. Since then, autofocus has developed dramatically and it’s no longer a feature on cameras, it’s a given.

So, bringing autofocus up-to-date you have a few options to choose from in your modern DSLR. Those are some of the features I will cover in this article, along with when to use them. Both Canon and Nikon have very similar settings, albeit incorporating different technologies the results are very similar. There are also other brands like Sony and Olympus etc., that also follow suit, but here I will be discussing the four main focus modes in Canon and Nikon.

This image above was shot utilizing the AF-S (Nikon) or One Shot (Canon) autofocus mode on the camera. Here I focused on the models eyes and then recomposed my image so that she was over to the left of the frame, allowing for more space in the image in the direction she is looking.

Single Shot Mode

First off, you have the mode that’s probably been around the longest – Canon’s One Shot and Nikon’s AF-S. Both of these will do pretty much the same thing. This mode is predominantly used for stationary objects like model shoots (most of the time – more on when not to use it for model shoots later) and anything that doesn’t require your subject to move around too much in the frame. You half press the shutter in this mode, and then you can recompose the image. For example, you focus on the model’s eyes, then recompose to put her on the left hand side of the image. This autofocus mode will get you through most situations.

Active or Continuous Focus Modes

Next we have the step up from the single focus to Canon’s AI Servo, and Nikon’s AF-C modes. Essentially what this setting does is to continuously track your initial focus point and readjust the focus accordingly. This setting is ideal for moving subjects like active children, and pets that are constantly on the move.

Auto Modes

Finally out of the autofocus settings we have Canon’s AI Focus, and Nikon’s AF-A. Both of these settings actually leave it up to the camera to decide which is best out of the other two focusing modes to use. In this mode it will either choose to continuously track your chosen subject should it decide to move, or focus lock if you would like to recompose. In theory, then I needn’t of bothered explaining the other two settings as surely this is the best of both worlds? Not quite. I personally have tested this mode a fair amount with stop-start subjects and although the camera does a good job of keeping up with them it’s always more accurate to use continuous focus mode. The same also goes for its ability to determine when a subject has stopped and when to focus lock for recomposing. Personally I never use this mode as although it has the best of both, it also has the worst of both.

Infocus600px

Image above taken with an 85mm f/1.8 prime lens using manual focus. Shooting in manual focus negates the need to recompose and loose focus in autofocus modes.

So, although I have just covered the three basic settings here very briefly, there is, of course, a whole of host other technological advancements in autofocus that I haven’t covered. I know Nikon has extensive, matrix and 3D autofocusing features. As well most modern DSLR have incorporated the “back button autofocus” which also helps with focus locking. But going over all of that is not the purpose of this article.

Manual Focus Mode

The last focus mode I wanted to cover and one that is rarely used is the Manual focus mode. This mode strikes fear into the heart of nearly all modern photographers and that’s simply because they’ve probably never used it. Do you ever need to use it? That is something that only you can decide and is probably based on the type of photographs you take. If you only ever take portraits of energetic kids or fast paced sports, then autofocus is probably always your go-to mode. If however you shoot still life, architecture, landscapes and other detailed, relatively motionless subjects, then manual focus is probably a good way to go.

There are a few reasons for this. Landscape photographers will want to find the hyperfocal distance of their scene to maximize the amount of in-focus points (depth of field) in the image. This is based on an equation so autofocusing on a specific object is not always the way to go. Still life photographers will usually have their camera locked-down on a tripod so they will not want to focus and recompose once they’ve set up the shot, so it’s just far easier to focus manually. There is also another reason to want to use manual mode on some cameras and certain situations, and that was the catalyst for this article.

Outoffocus600px

This version of the image was shot using the autofocus mode AF-S/One Shot, and meant that after I had focused and recomposed the shot, the model’s eyes were left out of focus.

I recently purchased an 85mm f/1.8 prime lens, and I wanted to test the lens out and see what the sharpness was like at f/1.8. I predominately only photograph models so I set up my test and went about taking some shots at f/1.8 using my usual AF-S/One Shot autofocusing mode. When I got my shots back to the computer to take a look, I was surprised to see that most of them were very soft. It took a few minutes to realize my error and since then I’ve adjusted how I shoot with these parameters.

Recompose600px

Here you can see that the selected focal node is still situated in the middle of the viewfinder even though I have elected the outer most one when shooting in the portrait format.

I haven’t done a lot of very shallow depth of field shots up until this point so I hadn’t seen the now exaggerated results of my
poor focusing technique previously. At f/1.8 you have a very, very shallow amount in focus (depth of field). For example, a head shot with the eyes in focus, the tip of the subject’s nose will be out of focus. For the test I was photographing the model at 3/4 length and shooting up at her so my camera height was probably about her waist height. I was about 6 feet (2 meters) away from her and I was focusing on her eyes with my focal point in camera then recomposing my shot to capture the 3/4 length crop. The problem with most cameras is that although they have a lot of focusing points, they’re all clustered in the centre of the viewfinder so even though I chose the outer most focal point I still have a dramatic amount of recomposing to do.

Focusstack600px

The diagram above clearly illustrates what’s actually going on when you recompose an image after focusing in AF-S/One Shot autofocus mode. The actual part of the image that was in focus, is now out of focus.

This isn’t normally a noticeable problem when recomposing at f/16, but at f/1.8 that dramatic shift in the focal plane means the resulting image is very soft around the model’s eyes. As I recomposed it actually repositioned my focal point further back behind the model, meaning the back of her head and hair were in focus but not her eyes.

There aren’t too many ways around this pesky little issue, especially as you may not notice it on the back of the camera’s little screen. One thing that did resolve it though was by switching to manual focus. I could then compose my shot and manually focus on the model’s eyes, resulting in a fantastically sharp image where I wanted it to be sharp.

Granted there were a few things conspiring together here to really exaggerate the issue. Firstly, I was shooting at f/1.8, that’s always going to rely on critical sharpness. Secondly, I was down low shooting up. This always exaggerates the focal plane shift when recomposing and lastly I was stuck with limited focal nodes. There are many technical reasons why modern DSLRs don’t allow focal nodes towards the edges. A lot of smaller frame cameras like the mirrorless, APS-C and micro 4/3 cameras all have selectable focal nodes covering the viewfinder, but alas, DSLR technology isn’t there yet. Until it is, it’s a good idea to be aware of what’s going on in autofocus modes on your camera, and be prepared and ready to switch to manual focus when required.

Good Luck!

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Jake Hicks is an editorial and fashion photographer specializing in keeping the skill in the camera not just on the screen. For more detailed explanations of some of his shots please visit his website and for daily updates on his most recent work, tips and techniques please visit his Facebook page

  • http://jasoncollin.org Jason Collin

    I definitely agree with the author that using the AF-A focus mode is the worst of both worlds. Many of my photography students come to me asking about help getting better focus on the images, and most of the time it is because they are using AF-A so it is a simple fix to just get them to use either AF-S or AF-C when appropriate.

    For me I just summarize which mode to use for when by thinking still or moving subject as in this photo tip:

    http://jasoncollinphotography.com/blog/2012/9/26/focus-mode-af-s-or-af-c-photography-tip.html

    I really like the graphics used in this post to show setting the focus on the eyes and the recomposing. Well done.

  • shershegoes

    great post! did not know about the AF-A focus mode being the ‘worst of both’. Also really liked the diagrams!

  • LisaJDwyer

    The same also goes for its ability to determine when a subject has stopped and when to focus lock for recomposing. Personally I never use this mode as although it has the best of both, it also has the worst of both. http://goo.gl/emYxTI

  • Jake Hicks Photography

    Thanks Jason, Im glad the article resounded with your own experiences too and thanks for the link.

  • Jake Hicks Photography

    Thank you, Im glad you found it useful.

  • Michael Owens

    Wow, I have to say – this made understand the modes so much more easy! Plain talk, simple diagrams, has now made me understand what I shoot, and what modes to use when I need them!

    Thanks!

  • Jake Hicks Photography

    Thanks Michael, glad I could help :)

  • Yoram

    The drawing of the initial focus plan is not correct. It should be parallel to lens

  • Amie schmidt

    Well…….for those of us who are loosing the ability to see in lower light, the auto focus is very useful. I also sometimes have a hard time seeing when the image is tack sharp in the light, even with the “in focus” indicator.

  • Choo Chiaw Ting

    “Shooting in manual focus negates the need to recompose” is not 100% correct, it depends on which manual focus methods you use, from which 4 manual focus methods that i know.

  • Choo Chiaw Ting

    the auto focus for low light is only working for good camera bodies, those with cross sensors.

  • Amie schmidt

    Yep, I do have one of those good camera bodies. IF I am shooting in really low light then yes, I will use manual focus if need be ex: night photography and long shutter speed, and of course a tripod. My eyes are just not as sharp as they used to be,and yep I wear glasses, which I don’t use when photographing as they don’t help.

  • Spoonie

    If manual focusing is working for you in these situations, that’s great, but something that is not touched on in this article is that with the introduction of auto focus in SLR’s the focus screens were no longer needed to assist with focus so nearly all manufacturers swapped them out with matte screens. This gives you a brighter finder but increases the depth of field. This is why older manual focus SLR’s have split screens etc. Without either a focus aid in your finder, or manually focusing with live view there is no way most people can focus manually with a modern SLR, the matte screen in your finder makes this essentially impossible.

  • Choo Chiaw Ting

    There is no need a focus aid in finder or using live view for manual focus. Both manual methods are not efficient and effective and hard to get tark sharp images because the focus aid in finder make composition hard and live view introduces great delay and any movement will cause out of focus. I use 2 other manual focus methods in D5100, D3000. I believe those bodies are considered modern SLR.

  • http://gonzalobroto.blogspot.com/ Gonzalo Broto

    I always shoot in AFS and I half-pres shutter and recompose; normally my aperture is not that fast and the recomposing is minimal, but this could explain why sometimes I get images that are not tack sharp and didn’t really understand why until now. I will be more careful in this matter from now on, specially when I shoot fast lenses.
    Sharpness is key for me and I really pay a lot of attention to it in my photography. Some examples shooting graffitis in Bangkok here: http://gonzalobroto.blogspot.com/2014/05/vanishing-bangkok-walk-among-soon-to.html

  • Jake Hicks Photography

    Yeah granted the example I use here of recomposing is extreme but it suitably illustrates a point that I may not of noticed happening before too.
    Thanks for sharing your Bangkok shots, looks like an amazing place to see and photograph.

  • Leo

    There is another option: using a button other than the half-presed shutter to focus. That makes it possible to instantly turn the continuous focus mode into the single shot mode and back again.

  • http://www.flickr.com/photos/stephen_hoppe/ Stephen Hoppe

    About 18 months ago I switched to mostly manual focusing because my camera’s performance just wasn’t great with AF. It has made a dramatic difference in the level of sharpness in my images and I have learned a lot about composition since it forces me to take a little more time and really think about the focus point. Granted, I mostly shoot landscapes, but I’ve still improved focus in large aperture shots too. Even if your camera is great at AF or you can micro-adjust the settings for errors I would recommend at least trying manual focusing for awhile, I’ve found great joy in taking back control from the camera!

  • Spoonie

    That’s my point. Modern cameras are generally not suitable for manual focusing.

  • Choo Chiaw Ting

    I mean use another two manual focus methods beside using focus aid in finder or liveview. They are effective and efficient. Manual focus with modern SLR has become easier ever especially the advanced ones. That’s why Samyang lenses are so popular nowadays, and slr is used for video capture.

  • Spoonie

    You’re just repeating yourself? I think you will find Samyang lenses are popular because they are cheap and because live view in most DSLR’s makes manual focusing possible. Try focusing with the samyang 85mm just using the finder, it’s pretty much impossible for the reasons already stated

  • Jim the Photographer

    I cut my teeth on film photography back in the 1970s. The focus was totally manual, but it had a little range finder type thing in the lens that would line up. It worked well. Before I went digital, I went to bifocals and my ability to focus the camera went the way of film photography! I appreciate and utilize my auto focus. But I invariably use manual focus when shooting sunsets. I set the lens to infinity and back off a tiny bit, then I shoot until I’m done. The auto focus has trouble focusing in low light situation and my camera won’t shoot if it can’t focus in auto focus.

  • Grace

    As for manual focusing, nobody so far has mentioned the issue that it will only works for people with perfect vision in their own eyes (am I correct?)

  • ronald1216

    beautiful metalic pants

  • Dustin

    Jake the last two paragraph make so much sense. I had honestly never thought of it before that the rotation /focus shift when composing has probably been my issue lately. I will have to practice more to make sure I know how to compensate. Thanks a bunch.

  • Jake Hicks Photography

    No worries Dustin, granted these are extreme examples but the same principles are still happening at higher apertures. Of course the effect is even further reduced on cropped frame cameras too so at f4 on a DX sensor for example you would get minimal loss on sharpness. Glad you found it useful though :)

  • Nikhi;l

    i really liked your article , but the technology is there to help .I think u must have heard about Hasselblad’s True Focus feature. Like Leica , Hasselblad too came up with innovation in 2009 .We have to just wait for few more years or maybe a decade before NIKON and CANON adopts this too . The new Absolute Position Lock (APL) processor, which forms the foundation of Hasselblad’s True Focus feature logs camera movement during any re-composing, then uses these exact measurements to calculate the necessary focus adjustment, and issues the proper commands to the lens’s focus motor so it can compensate. The APL processor computes the advanced positional algorithms and undertakes the required focus corrections at such a rapid speed that Hasselblad says no shutter lag occurs.

  • Jake Hicks Photography

    Wow! I’ll throw my hands up there. I honestly hadn’t heard of that technology. That sounds amazing. Pretty complex but very useful. As you say fingers crossed it becomes ‘affordable’ tech before to long.

  • Christine

    Good points. I have an Olympus OM-D E-M5. It has a grid of 35 (yes, you read that right, 35) AF points to choose from. So, I no longer focus/recompose. I look thru the viewfinder & move the AF point to the best place, to there’s no physics error w/ the focus/recompose if the angle change is significant.

  • Jake Hicks Photography

    Yeah I’ve got a Fuji x100 with similar focus points all over the viewfinder eliminating the recomposing issue. Would be fantastic if my DSLR had a similar feature. Unfortunately I don’t know the technical reasons for why this is seemingly impossible.

  • walwit

    You may be right but it is difficult to me to understand that there is a focal plane instead of a focal circunference, I supose the existence of a focal plane is a demonstrated fact because nobody is arguing that

  • http://www.flickr.com/photos/stephen_hoppe/ Stephen Hoppe

    It is easier with better vision, but your camera should have a diopeter setting next to the viewfinder to help with that. Adjust it by looking at the indicators inside the viewfinder (not the image from the lens) if those are in focus then the lens’ image will appear correctly when focused. You can also use a focus screen, but I’ve found I can see inside the viewfinder well enough. It also takes lots of practice regardless of vision.

  • http://www.flickr.com/photos/stephen_hoppe/ Stephen Hoppe

    I agree, it is hard, but not impossible. With practice you can get pretty good at it and quick. What I don’t understand is why it is acceptable to not see if the image is in focus even when using the AF system? I’ve always liked to know my focus is sharp regardless of whether I use AF or MF, I wish camera manufacturers would agree.

  • Spoonie

    Hi Stephen, if your last question is why is it camera manufacturers include screens that create a greater depth of field, the answer is that these screens make the finder brighter. On most SLR’s that have less than 100% coverage in the finder, you can replace the screen with one that will give you the same depth of field as what your lens will give you, which assists manual focusing greatly, however any slow lenses attached to the camera will give you a dark finder image. Any thing slower than f2.8 because considerably dark. The introduction of auto focus meant the focus aids in the finder could be replaced with screens that made the finder brighter, but make manual focus pretty difficult.

  • Spoonie

    Look through your finder on a fast lens, a 50 f1.8 or something, focus on something really close and take a good look through the finder at your out of focus areas, then take the picture that you see and look at it on your camera screen. The out of focus sections will be way more blurred in the image compared to what you see. The depth of field around the focal plane will be shallower.

  • BayAreaBiker

    That’s a 44,000 dollar block you are talking about. :-)

  • Brett

    In the diagram, however, the distance to the eyes is still the same after recomposing, so the eyes will still be in focus. The back of the head will still be out of focus. The focal plane is not really a flat plane but rather actually an arc with the center being at the camera.

  • mtngirl

    I wear contact lenses and I have a hard time using the manual focus in some instances. The auto focus helps in most cases, most being the operative word here, but if I had better eyes then manual focus would be my choice. Thanks for the article.

  • Glenn Ivens

    Bottom line, if you focus on subject, no matter what your aperture and recompose your image will be sharp as long as you recompose on the same focal distance. Wide open shutter will make this noticeable whereas stopped down you would be hard pressed to notice. It all comes down to maintaining that distance from subject to sensor.

  • http://timfordphoto.com/ Tim Ford

    Great post! I’ve been playing around with focus modes a lot lately, and I thought I’d share a post I wrote recently on back button focusing. It might help anyone who’s also exploring various ways of using auto focus on their DSLR. You can check it out here – http://timfordphoto.com/how-and-why-to-use-back-button-focus/

  • Rhondar

    You need some kickass eyes to use manual focus though! :)

  • Dave Pearce

    Why not also mention using different focus points to help remove the need for focus as recompose? With some cameras having upwards of 60 AF points wouldn’t using a more suitable one be good advice?
    I like the article but I think the title is misleading. It seems to concentrate more on Manaul mode, which is basically turn AF off and do it yourself. I’d suggest it’s more about focusing than focusing modes.

    Just my thoughts.

  • https://twitter.com/pilat Vladimir Mityukov

    Wouldn’t AF-C mode fix the issue? I mean, from the camera’s point of view, either I recompose or the model’s eyes are really moving themselves — how would it know?

  • https://twitter.com/pilat Vladimir Mityukov

    Just gave it a try. The camera constantly changes the subject of focus as I recompose, making the focus of original subject even worse than it would be in AF-S. I do not more think I understand the AF-C mode at all…

  • http://photographyfoundations.com Varadha

    Awesome work bro !!

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    http://photographyfoundations.com

  • Mehemed

    Thank you so much about these Valuable information with you my wishes for more success

  • Gabriela Tábora-Sosa

    is there a feature on the D3000 that’s the equivalent to AF-C ?

  • Andy Cuthbert

    The “focus peaking” feature on Sony’s SLTs makes manual focus incredibly easy!

Some older comments

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