How to Achieve Fast Autofocus In Low Light Situations

How to Achieve Fast Autofocus In Low Light Situations

Getting accurate Autofocus must be one of the most frustrating things an event or wedding photographer deals with on a daily basis. How many times have you been in the right place at the right time, taken a photo at the absolute peak of the action, and then found yourself cursing under your breath when you review the image only to find it wasn't in focus? This used to happen to me a lot at weddings, and I still see many of my assistants struggling with autofocus in extremely low light situations. Luckily there is a very simple solution that works everytime.

I have found that by far the most accurate and reliable way to achieve razor sharp images in low light situations is to use your on camera flash's AutoFocus Illuminator. The AutoFocus Illuminator, sometimes called AF Assist, is a fancy infrared light that throws a large grid pattern out in front of your camera. It is important to understand that what I am talking about is the assist lamp on your speedlight and not on your actual camera body. Unlike the camera's bright white autofocus lamp, the AF Illuminator's light is less intrusive and much more accurate because it projects a very sharp contrast pattern on your subjects. Also, because the Autofocus Illuminator is projected from your hotshoe flash which sits a few inches above your lens there is little chance that the light will be blocked by your lens's hood. The image below shows the difference between the AF Illuminator on your speedlight and the bright white AF Illuminator on your camera body. 

 

The Autofocus Illuminator helps you nail focus without distracting bright lights

It has always shocked me when I see so many event photographers who do not know what the AF Illuminator is or how to activate it. From my experience shooting wedding receptions and outdoor night events, I can pretty comfortably say that more than half of my images would be out of focus if I completely relied on dim ambient light for my autofocus. It will be near impossible to lock your focus correctly if your subject is backlit, there is fog or smoke, or the DJ's lights are constantly moving randomly across everyone on the dance floor. Things get even worse if the DJ or venue decide to turn their lights off or if you are simply hired to shoot outdoors at night with absolutely zero event lighting setup. 

Once you start relying on your speedlight's Autofocus Illuminator to help light your subjects, you will find that you can increase your in focus shots from 50% to almost 100%. The lamp also makes it incredibly easy to shoot from the hip or shoot from over your head and guarantee that you are focusing on the correct subject without even looking through the camera's viewfinder. Simply trigger the autofocus on your camera and point the red grid at your subject. With a little luck you can take great compositions from unique angles that wouldn't easily be possible otherwise. 

Shooting over your head without looking through the viewfinder is much much easier

So how does the Autofocus Illuminator work? Here are a few steps and tips you need to know to make sure that your AF assist lamp is always projecting in low light situations.

1) Add The AF Lamp - First you need a hotshoe flash or accessory that projects a red autofocus assist light onto your subjects. Most of the Nikon Speedlights and Canon Speedlights do this natively. Some Yongnuo speedlights do it but others do not have this feature so consider that before purchasing the absolute cheapest flash model. If you have wireless remote triggers like Nikon's SU-800 commander or Yongnuo's YN622 radio triggers, they also have Autofocus assist lamps built in. These are great if you don't actually want to mount a speedlight on your camera and want the absolute smallest trigger on your hotshoe.

2) Check The Focus Mode - Next you need to turn your camera to one of the focusing modes that supports AF Illumination. Most DSLR cameras cannot project the autofocus assist lamp while they are in continuous focusing mode, so make sure you are in the single focus mode (single servo). This is the mode that snaps into focus and doesn't track your subject as they move.

3) Set The Focus Points -  Depending on which camera you own, you also need to set the correct number of focus points. In the past, if you shot with a Nikon camera you had to have the focus point set to the center AF point in the view finder. With newer cameras they have expanded those focus points to include a bunch of points around the middle of the view finder. For years I simply used the middle point but now with my Nikon D750s, I prefer using the Group focusing mode. Do note that even if you use Group focusing or another cluster focusing mode, you still have to set the general group area to be near the middle of the frame. The AF Illuminator cannot accurately focus on the far edges of the frame and therefore many cameras will not even let it activate if you have an autofocus point set too far to one side.  

If for some reason you find the AF Illuminator isn't projecting, chances are you have either set your camera into Continuous focusing OR your focus point is not set near the middle of the frame.  

4) Activate AF - To actually project the focusing grid from your speedlight, you need to simply press the shutter halfway down to start the autofocus process. This will activate the infrared grid. If you have set one of your rear AE-L / AF-L buttons to work as autofocus, those buttons will also activate your flash's AutoFocus Illuminator as well.

5) Beep Confirmation - Finally, now that your AF Illuminator is working you can simply snap the photo once correct autofocus has been achieved. I like to keep my camera's AF beep option turned on so I can easily hear when autofocus has been confirmed since it can be tough making out sharp objects in the tiny viewfinder. This also lets you shoot without looking through the viewfinder and know exactly when your camera has locked onto your subject.  

6) An extra little tip - I will throw this tip that I use every time I pick up a camera, and it involves the AF-L button on the back of the camera. I have configured my rear AF-L button to lock focus only when it is pressed and held. This allows me to autofocus with the shutter button pressed halfway, and then when I'm ready to take a photograph I can simply hold the AF-L button down to prevent my camera from trying to refocus as I press my shutter button down to snap the photo. This has been such a life saver in situations where your subject isn't moving towards or away from your camera but the peak of the action is taking longer than you want. With this technique, I can prefocus for the first kiss or for a bouquet toss, let go of the shutter and wait for the moment of action, and then quickly fire the shutter while holding the AF-L button and know for certain that my camera is going to fire instantly and that my focus is locked on the last thing I focused on. When I was first shown this technique it instantly helped me improve the number of in focus images I was taking at every wedding.  

But I hate shooting with flash!

At this point you might be asking "What if I hate bouncing my on camera flash and prefer shooting with natural light only?" Well the good news is that most speedlights that have an Auto Focus Illuminator will also let you turn off the flash while still keeping the AF assist lamp on. Since I'm only familiar with Nikon speedlights I'll outline that process below but most other brands will have a similar menu option as well.

With a menu option, you can turn off your flash while keeping the AF Illuminator on

First you need to go into your flash's menu. Each brand of flash and model are going to be a little different so resort to your user manual for the specific menu location. On the Nikon SB-910 there is a menu option called AF where you can choose a few options. The "ON" mode is how your flash is shipped from Nikon, and it allows both the AF Illuminator and the Flash to both fire when the camera is triggered. If you set the mode to "OFF," you can turn off the AF Illuminator which I would never recommend unless you are on set of a big movie and can't have any AF assistance at all. The third option is "AF Only" and that mode allows you to use the AF Illuminator without activating the Flash when the shutter is triggered. 

I rarely ever turn my flash to AF ONLY but if you do use this mode, make sure you remember to turn it back on when you are done or you might drive yourself crazy trying to figure out why the AF Illuminator isn't working next time you pick up your camera. Another little tip I use for when I want natural looking shots in low light, but still need AF assistance, I will turn my flash down to the lowest setting (1/128) and bounce the flash behind me or far away from my subject. In many cases this tiny amount of bounce flash will not affect the exposure in any way and you can keep your AF lamp working without having to dig into the menus.  

 

 

How to turn off your camera's bright AF Illuminator

One final suggestion I would give when it comes to autofocus assistance is to go ahead and completely turn off the On Camera Autofocus Assist Lamp (the bright white one). This lamp is supposed to help with autofocus but it usually doesn't work well with large professional 2.8 lenses because they often block the lamp altogether. Also because the light is so bright, it works great for red eye reduction, but it completely destroys any chance of you taking a candid photo because it lights up the entire area in front of you. Unlike the autofocus illuminator in your speedlight, this lamp is rarely useful and becomes obnoxious in low light settings. My recommendation is to turn it off entirely.

Autofocus in completely darkness can be a nightmare if you don't use your AF Illuminator

This is a super simple Photography 101 tip that for some reason photographers often fail to incorporate into their event work. Even though it's a simple tip, it is one that can literally save your ass over and over. I require every one of my wedding assistants to use the AF Illuminator during the reception because the results are night and day. If you do not have an on camera speedlight that has this feature, I would highly recommend you picking up one or two just to use on your main cameras. Remember some radio triggers also have built in AF Illuminators too so you don't always have to buy a new flash to gain this feature. I hope this simple yet effective focusing technique can help many of you gain confidence in your low light shooting and wind up with many more images you mark as keepers and deliver to your clients.  

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60 Comments

Dennis Qualls's picture

Great article Patrick, thanks for sharing.

Jack Alexander's picture

I concur, really helpful post

Barry Chapman's picture

A couple of notes for Sony users. My SLT A Mount body (A77) has the same red grid type of AF illuminator included in flashes. It's far enough from the lens mount to be usable with large lenses with hoods mounted. But in the updated version of my camera (A77ii) Sony removed the AF illuminator. User reviews claim the AF in low light is good enough not to need it but I remain to be convinced.

For its mirrorless FE Mount cameras Sony, for some reason, decided to disable the AF illuminator on its flashes. Third party flash manufacturers (Nissin, I'm not sure about Phottix) seem also to have done so. The mirrorless bodies (at least some of them) have AF illuminators, but they're blocked by large lenses, including some made by Sony, and by the adapters many people like to use on them.

Since the flash system is the same for A Mount and FE Mount, any current flash bought to use with the A77ii or other A Mount bodies won't add an AF illuminator. I really wish Sony hadn't decided to disable it, or that other manufacturers would allow them to be enabled.

Patrick Hall's picture

Good to hear these tips from the Sony side. I have to say though, once again, I'm a little disappointed that Sony has removed such an important feature like the AF Illuminator. Sure, cameras are getting better and better at fast AF in low light but the AF Illuminator makes AF near flawless. I hope they bring that feature back down the road.

Luca Rubino's picture

I have Nissin i40, with AF lamp... but it doesn't work on A7 camera series.

Barry Chapman's picture

Correct - just as the AF lamp doesn't work on my Nissin Di700A.

Another tip that's not auto focus reliant is to use "Zone Focusing" by using flash you are going to be able to access F8 and create that really deep DOF with consistent results, never have to wait for AF to lock again, Snap like a mad man.

Chris Adval's picture

I wasn't sure when I saw so many glamour photographers shooting on-location with a speedlite on their camera + 70-200mm lens (with OCF lights too), at first I thought they're just skimping on a trigger to trigger the other lights, but later learned what's mentioned here, for sharpness. Now I will have to try this to see for myself, as my Tamron 70-200 2.8 (non-VC) which tends to be mostly out of focus in natural low light situations.

John Teague's picture

Very timely article for me. I've volunteered to shoot a Valentine's Day dance next weekend, but I rarely shoot events. I don't know what the lighting conditions will be, but I assume the lighting will be dim, making focus an issue. However, this article makes me feel much more confident that I'll be able to nail the shots.

Jacques Cornell's picture

"The AutoFocus Illuminator...is a fancy infrared light"
FWIW, this applies only to DSLRs.
On mirrorless cameras, AF illuminators produce white or yellow light. I've been told that this is because CDAF requires light in the visible spectrum, not IR, to operate. This would explain why Panasonic and Olympus flashes rely on a built-in double-duty white LED for both video and AF assist. It may also explain why IR AF aid lights on Sony flashes designed for DSLRs are disabled on Sony mirrorless cameras.

Patrick Hall's picture

Just to clear a few things up, in many (most) cases, the illuminator isn't actually an IR light like I stated in the article. Many documents and sites do reference it as an IR light but it is truly visible to the naked eye.

It's a bit disappointing that Mirrorless cameras aren't using this method for autofocus and instead are relying on the much more invasive bright light illuminators. One way to think about this is with military flashlights that use a red filter for night time. The red light affects your pupils less and is less blinding to those already adjusted to low light. So in my opinion, I do not think brighter and more visible AF Assist lights are better but actually worse.

From the perspective of your subject, they do not actually such a super bright grid being projected on them. The red AF Illuminator looks much like a laser pointer in that you can see it is being activated but it isn't very blinding because unlike a laser it isn't a tight narrow beam of light but rather a wide grid pattern.

Having an AF Illuminator that can double as a video light is not something I would want as a photographer shooting in low light. Those are two completely separate functions.

Jacques Cornell's picture

I can understand your disappointment, but you don't seem to be understanding that it's likely a technical requirement. Otherwise, why would Olympus have redesigned their old DSLR flashes for mirrorless duty and Sony crippled theirs? As for the double-duty light, what's the problem? If you need a bright light for both AF and video, why not use the same one, "separate functions" notwithstanding? You'd be happier with two?
I think the point you're trying to make is simply that you don't like bright AF lights. In that case, mirrorless is not an option for you.
OTOH, I know lots of wedding shooters who use a video light for both AF and exposure at dark receptions. This ability is built right into my Panasonic flashes. FWIW, my Panasonic cameras AF nicely down to -4EV, which means the AF light is rarely needed except on the darkest dance floors, where flashing lights are just part of the ambience.

Luca Rubino's picture

Unfortunately, Sony doesn't support AF Lamp on flashes on their mirrorless cameras.

Patrick Hall's picture

That's a shame. I know we have been harsh on Sony lately but this is a HUGE reason why I wouldn't rely on a Sony Mirrorless for low light event work. The AF Illuminator makes such a big difference in achieve crucial AF that I would consider that a deal breaker for sure.

Anonymous's picture

As a natural light photographer, I wish they would make a read beam device for the camera's hot shoe. So just the red beam for focus assist, no flash. I should actually check if there is such a thing.

Edit: just checked and it does exist: http://flashhavoc.com/yongnuo-yn12af-af-assistant/

Barry Chapman's picture

Interesting idea but try to find one. I just checked and it doesn't seem it made it to market.

Patrick Hall's picture

What do you mean? The Yongnuo triggers I referenced have AF Assist and so does the Nikon SU-800.

Barry Chapman's picture

Cassandra and Marc above referred to a hotshoe mounted device (not a flash) that would add an AF assist lamp. They found that Yongnuo had announced one for Canon and linked to the announcement. One of the benefits was that it could be used with triggers which didn't include AF assist. I pointed out that despite the announcement in early 2014 the AF assist device was never released.

Patrick Hall's picture

Well they do have one....it's not JUST an AF Illuminator but also a wireless trigger but if you are looking for something small that doesn't weigh anything I'd get this one (the same one mentioned in my article above).

http://flashhavoc.com/wp/wp-content/uploads/2013/11/AF_Light_3.gif

Patrick Hall's picture

Glad this article pointed you in the right direction. Trust me, the AF Illuminator even without the Flash feature is a massive advantage when shooting in low light.

Sean Molin's picture

Concert photographer here: DO NOT USE THESE SHOOTING CONCERTS.

Oh my god, we had a photographer in the pit last year for a show and he was using this exact unit. None of us had ever seen one before so we couldn't figure out why half of our shots were ruined by these red laser lines.

Not to mention I'm sure it annoyed the hell out of the artist. This was a major international touring act, too.

First of all let me play smart ass and note that it is not infrared, but just red :)

AF is really great help, the only problem with it is that people start to pose for the camera as soon as they notice tis light. Or just stare at you while you are trying to capture genuine moment.

So, it's a good tool for the part when everyone is drunk and much slower than you :)

I was gonna write the same. During events I mostly go for candid shots therefore cannot really use this :) If I'm using the flash, it's already enabled though.

Patrick Hall's picture

Thanks for pointing that out Alex. I addressed this in a comment above and you are right, while many other sites and even some flash documentation calls it an IR light, it really is visible and should fall under the visible light spectrum.

I will argue with you and Can Canan below that I do not find that the AF Illuminator takes away from my ability to shoot a candid photo much at all. There is a sort of hierarchy when it comes to people being aware of the camera and while I do think the lamp does make people aware to some degree, I would say it is much much less of an issue than the bright white AF lamp on the camera.

Here is my hierarchy theory:

1) point any camera at someone the first time and they notice you
2) step back and point a telephoto camera at someone and they notice you less
3) when shooting events, people notice you no matter what but then start to ignore you as they get more comfortable and ignore the cameras in general. This probably happens on a reality tv show as well
4) as people stop noticing you, they will start noticing bright video lights and AF assist lights more
5) eventually your subjects will just completely tune you out entirely (this is the stage you want to get to for the best candids)
6) Hand the guests your camera and let them take photos...become a photography god in their eyes :)

On a serious note, if you get fast at reacting to candid moments and employ the prefocus/lock focus method I explain in the article, you can easily capture true candid moments even a few moments after your subject notices you watching them. Part of a great candid photographer is observing interesting people, preparing for the shot, and then waiting. IMO having an image in focus is paramount so I personally wouldn't ever sacrifice my AF Illuminator and focus in order to be a little more stealth in most situations. You just have to get better at distracting your subjects from not thinking you are actually photographing them.

Just keep in mind that if you have a videographer there, filming in that low light (A7s), that red grid makes for REALLY distracting video. Just something to consider, and coordinate with the other crew members there.

Patrick Hall's picture

Very true and thanks for the comment. I will say something that I have found important when dealing with videographers (and vice versa), the best approach in my opinion is to place yourself 90 degrees or 180 degrees opposite from each other. If you do this, you can use their lighting in a more pleasing and dramatic way (side lighting or backlighting instead of front lighting), and you can eliminate distracting things like AF illuminators.

The trick you both have to be aware of is you need to hide each other from the other person's shot. Usually I crouch down behind my subjects so that the videographer who is shooting horizontally can easily frame his shot without me being in it. Sometimes this is harder for the photographer because the videographer usually has a tripod or larger steadicam system but I feel I'm also more mobile than they are and can quickly change my position.

On another note, my experience has taught me that the DJ's lights and pro lighting is usually much brighter than my AF Illuminator. So even though it helps me out tremendously in terms of fast AF, if you expose for the natural light, the ambient lighting usually is a few stops brighter than my AF light.

There is obviously a way for both creatives to be profesisonal and not become obnoxious with their use of AF lights and LED lights but at the end of the day, as a photographer, I still wouldn't completely turn off my AF Illuminator just to appease the videographer if we both have to be working at the same moment (first dance, cake cutting, garter toss, etc). I have buddies who shoot video and together we have been able to work around each other fine without any major problems throughout the entire event.

Paulo Macedo's picture

I have been using the YN 622C-TX AF laser grid, works like a charm for the center focusing point. If i want to use other AF points, well, i apply a bit of opaque tape to the laser glass and the red light is enough to help the other not so good af points to focus the image :)

Patrick Hall's picture

One other thing I just thought about is the Flash itself. Flash in general is problematic for videographers to some degree especially if you are able to shoot a faster frame rates (60/120 etc). Depending on the ISO setting, the flash might even be more distracting than the AF lamp especially if you convert your video to B&W which will mitigate the red light but not the burst of flash.

I personally feel like flash photography adds a sense of mood and excitement to video and makes it seem more glamorous and emotional than it might look without any flash popping off. Also, you will always have guests firing off cell phones and cameras so I don't think a professional photographer's use of flash looks too out of place for an event or reception. Just my personal opinion of course.

You can also buy an aftermarket af assist light cheaply such as the Yongnuo YN12AF, which is a little easier to wield if you're not using the flash.

Barry Chapman's picture

But can you? I haven't been able to find anywhere that it's available and it seems to me that they announced it (in early 2014) but then it was never released.

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