Six Tips For Better DSLR Autofocus And Sharper Images – Q&A
Question: How To get Perfect Focus On a DSLR?
By far one of the biggest hurdles in mastering your DSLR, especially for portraits and candid / action photos, is mastering the art of autofocus. AF systems are so complex these days, I frequently do private coaching that is ENTIRELY focused (pun intended?) on achieving more consistent focus and sharpness!
You may think you’re doing the right thing, you may know your camera pretty well, but you still find that photos seem to be “okay” on your camera yet definitely soft when you get them on your computer. This morning I answered a question in which someone mentioned holding their breath every time they click, and having everything look okay in the viewfinder / camera LCD, …but to no avail.
Nailing focus in poor light or in close quarters at fast apertures
is not easy, but with practice you can get very consistent results!
Canon 5D Mk2, Canon 16-35mm f/2.8,
Nikon D700, Nikon 50mm f/1.8 G, Nikon 14-24mm f/2.8
Answer: 6 Tips For Better Autofocus and Sharpness
First, an easy tip: as any archery expert will tell you, holding your breath while you pull the trigger is almost the right idea, but not quite. Actually, you should gently exhale as you click the shutter.
Secondly, as we learned from Zombieland Rule #2: Double Tap! If you ever find yourself trying to hand-hold at 1/20 sec, two or three clicks will give you a better chance at eliminating camera shake. Also, if you ever find yourself trying to hand-hold photos of a close-up subject at f/1.4, again you want to click 2-3 shots every time.
Unfortunately, that’s only a small portion of the whole sharpness equation, and since this is such a complex subject, let’s break it down point by point:
1.) Never trust your viewfinder
Unfortunately, your DSLR’s optical viewfinder is just not designed to display precise focus. This is because consumers these days want bright viewfinders. If you’ve ever looked through the ground glass of a view camera or a medium format camera, you’ve seen just how dim they are and yet how much better you can see the plane of focus and depth of field.
Yes, some cameras have manual focus assist options that can work well, but the bottom line is that your viewfinder is not the optimal gauge of focus, even if you are photographing landscapes at f/11.
2.) Learn to discern sharpness on your LCD
Unlike your viewfinder, and contrary to popular belief, you can indeed determine PERFECT focus on the back of your camera. New photographers sometimes express frustration because sharpness seems to be different on their camera and their computer. Thankfully, this is only true if you don’t know what to look for on the LCD screen.
There are two things you can do to help with this: First, determine which level of zoom best represents “actual size” on your computer. Some DSLRs like the Canon 6D and Canon 5D Mk3 use the term “actual size” for one of their zoom ratios, as do many modern Nikons.
Second, crank your in-camera sharpening WAY up. (Picture Style / Picture Controls) This is only advisable when shooting RAW, however, and don’t forget to turn it back down afterward, if you ever shoot JPG or video. Excessive in-camera sharpening is DEATH to fine detail in JPG images and video files. Still, it makes a jaw-dropping difference for determining focus quickly on the back of your camera when shooting RAW still photos!
Get your camera on a tripod, get focus in the general vicinity of an immobile subject such as a tree trunk in a park, and slowly adjust focus manually as you click photos. Especially at f/1.4-f/2.8, you will see a VERY definite “perfect focus” point. More importantly, you will also start to see what “just slightly soft” looks like. That is actually the critical part; being able to spot “not quite sharp” photos immediately.
3.) See if your camera has the 1-click 100% zoom customization for image playback
If your camera is able, you ABSOLUTELY MUST program the custom function for one-click zooming to 100% during image playback. Older cameras such as the Canon 5D Mk2 might not have it, but most modern cameras do.
Are you wondering what “1-click 100% zoom” even means? It’s quite simple: The moment after you click an image, and it appears on the rear camera LCD, you would usually have to hit various different buttons… “zoom in, zoom in, zoom in, scroll left, scroll left, scroll left” …just to check the sharpness of one off-center face in a portrait.
However with the 1-click 100% zoom customization, a single click (usually the “OK” or “SET” button) takes you right to 100% magnification, and if you used a confirmed AF point, (not the focus+recompose method) it will even zoom in to that exact off-center spot! On Canon, you want to set your zoom to “Actual Size”. On Nikon, you want to set it to “Medium Magnification” if 100% is not mentioned. Sony, Fuji, Pentax, and others are similar.
Bonus Tip: If you have a recent Nikon camera, then after you have zoomed in to 100%, if you are shooting portraits you may be able to use a very exciting feature- face detection scrolling! When zoomed in, look for “instructions” in the lower-left of your LCD. Usually, dialing the front sub-command dial will scroll from face to face, allowing you to check for blinking eyes and smiles in a group portrait extremely rapidly!
Okay, now that we’ve got the “interpretation” of sharpness down, let’s talk about actually ACHIEVING consistent focus and sharpness while shooting.
4.) Master all your Autofocus modes
Practice single and continuous focus, (One-Shot and AI-Servo, for you Canon users) …on subjects that are moving slightly, or not at all, or all over the place. Try both focus modes in every situation, and see what works. Oh, and ignore those new “auto” modes that let the camera decide. Anyways, chances are you’ll find that single focus is just not really a good idea unless you are a good distance away from your subject, and they are holding relatively still. In every other scenario, continuous focus is a good idea.
On the other hand, continuous focus works, well, continuously! If your finger is on the trigger, the camera is focusing. This can be annoying if your focus point can’t be perfectly positioned over a subjects’ face, …or if that focus point is not very reliable. What to do? Read on…
First I still need to mention that on most newer cameras, there are also dynamic AF modes that use multiple AF points to try and grab and track moving subjects more consistently. I like Nikon and Canon’s newest 9-point focus assist modes a lot, for things like aisle processionals and dance floor madness. Otherwise, I just leave my camera in the regular one-point focus mode. (Beware of Canon’s “pin-point” focus mode, it is extremely finnicky for anything that moves even the slightest and I only recommend it if you really know what you’re doing!)
5.) Figure out your preference and customizations for Autofocus
Okay, about the continuous focus / AI-Servo problem. Indeed, most people use the shutter release button to focus, simply because that’s the first logical way to do it. However this really only works if you’re in single focus and you focus+recompose. Or if you move your focus point around constantly, to the exact spot you need it at the exact composition you want to click. (And, like I said, if you can TRUST that off-center focus point in the first place!)
Personally, I use the AF-ON focus customization 90% of the time. Also known as “back-button focus” or “thumb focus”, it is an advanced technique that moves the AF function to the back of the camera to be operated by your thumb only. Needless to say it takes a while to get used to, however it is oh-so-liberating once you get the hang of it! Since your shutter no longer performs AF, you can shoot photos any time without worrying about perfectly placing your focus point at the exact moment you click. Of course if you’re in single focus, your camera may refuse to fire if you haven’t locked onto something yet, but that is a separate function that can be turned off anyways. (Though I don’t usually use that customization.)
6.) Think like a tripod!
In portrait and wedding photography, it is not uncommon to be doing things like bending over or crouching / leaning awkwardly to get a creative angle, or shooting hand-held at rather telephoto focal lenghts and/or shallow apertures. These conditions are just begging to result in a terribly low keeper rate for any subjects that are closer than ~10 feet away at a fast aperture, and/or at any distance when shooting around 200mm. All the camera knowledge in the world (and sometimes even stabilization) cannot save you, if you shoot “sloppy”. Shifting your body/balance by just an inch can throw an f/1.4 close-up portrait totally out of focus, for example.
There are plenty of websites out there that talk about stance, how to hold the camera, and how to click the shutter. Plenty of people can not only match but handsomely beat the “shutter speed rule of thumb” …for example pulling off a 1/25 sec shutter speed on a 50mm prime would be considered quite incredible, while hand-holding at 1/50mm would be just decently impressive. Either way, play it safe whenever possible. Keep shutter speeds as fast as possible, and steady your stance so that your body doesn’t sway back or forth as you shoot. Also, it may sound like a cliche joke, but your caffeine intake can indeed affect the steadiness of your shots, too. ;-)
At the end of the day, sometimes your camera just isn’t cooperating. It’s time to calibrate your autofocus! You can simply take all your cameras and lenses in for service if they are under warranty, or if you feel like paying quite a bit, however the technique of AF microadjustment itself is pretty simple, and harmless to experiment with.
Simply start off by shooting a static photo (from a tripod) of a static subject, such as a tree in the park, and frame the shot so that you can see the grass or other textured surfaces in front of and behind the subject, with a clear transition from foreground to background. With your in-camera sharpening turned all the way up, you should have no difficulty identifying front-focus or back-focus errors.
Topics like this are the fundamentals that can make a significant difference in how you operate, and if you’re looking to go from the ground up then check out Photography 101 as your fundamentals crash course. Of course, SLR Lounge Premium members get to stream it along with all other courses.
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Until next time,
*This article was originally published in 2013