Autofocus and Night Photography

And There Will Always Be a Moon Over Marin

Recently a reader, Jeremy, left a comment one of my photos about focusing in low light situations.

“Yes, actually, I do have a question: How do you focus? In my experiences with night/low light photography, the autofocus tends to hunt and never converge. (No matter if I am using a tripod or not. Actually, the tripod isn’t even the issue, given the low contrast of the scene itself.)”

Which is a good point. In the example that Jeremy was talking about with night blur photography autofocus isn’t so much of a problem because there is enough light on the ride or whatever you are shooting to lock in and set the focus there.

So let’s talk about autofocus at night. The first situation you have is where you are shooting something with plenty of light. This can be a cityscape at night, an amusement park ride, the moon, a lit bridge, etc. Well here usually the first part of autofocus isn’t a problem. You simply point your camera at where you want and it locks right in.

So when you have enough light, what you want to do is find your focal spot and press the shutter button halfway down. This will position the lens in focus with where you want it to be. Then before you fire your shot either with your finger, your cable release or your timer release, you set the lens to manual focus. The lens will remember the focus point and you can shoot there. If you don’t lock the focus in manual mode first, often times the autofocus will start hunting around again and you’ll miss your originally positioned focal point.

The next situation comes into play when you *don’t* even have enough light to get autofocus to lock in in the first place. I’ve found some lenses autofocus better in the dark than others. For instance. My Canon 24mm f/1.4 does a far better job in the dark than my Canon 50mm f/1.2 which does a crappy job in my opinon.

But anyways, sometimes you just can’t get the autofocus to lock in period. And this is where if what you are shooting is close enough a flashlight comes in. With this technique you simply shine a flashlight on whatever you want to focus on and then push your shutter halfway down locking in on that focal spot. The flashlight provides enough light to lock in the focus and then you turn your flashlight off, switch the camera to manual focus (locking in the autofocus setting you just set) and shoot your shot. This technique is helpful for getting things like night silhouettes especially crisp.

The other benefit of bringing a flashlight with you when you are shooting at night is that you you can use it to add a tad more light to a subject you are shooting in the foreground if need be, or you can use it to actually do some light painting in super dark locations.

Recently I was shooting the bunkers out in the Marin Headlands at night (the shot above as example). It was way too dark to actually shoot in the bunkers, but by painting with a flashlight (literally shining the flashlight over the subject with strokes while my shutter was open for long exposure shots), I was able to get my subject with an interesting lighting effect from the light painting.

Night shooting is one of my favorite ways to shoot and a flashlight definitely always comes with for those shoots. By the way if you want to check out some work by some great Bay Area night photographers check out these pages by Andy Frazer, Troy Paiva and Joe Reifer.

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10 Comments

  1. Andy Frazer says:

    Thomas,

    This was a great post about focusing in low-light conditions. I know a lot of people struggle with this problem when they begin night photography.

    And thanks for the link to my site. However, my last name is spelled “Frazer”, not “Frazier”.

    Thanks again!

    Andy

  2. Do you need to worry about white balance issues with flashlights, or are they close enough to incandescent to use that setting? I shoot in RAW so it’s not as big of an issue, but even so it’s nice to get white balance as close as possible in the camera.

  3. Two other tips I have:

    1) A laser pointer can also work well because it leaves a single sharp high-contrast point to focus on. Whereas using a flashlight to shine on a gray wall might still leave autofocus searching.

    2) You can also set a flashlight (turned on) at your focal point (if it’s within reason) and set your focus on that. Similarly, it provides a nice sharp high-contrast point on which to focus. This is helpful if your flashlight is too weak to sufficiently illuminate what you’re shooting.

  4. jeremy says:

    Ok, thank you. That makes a lot of sense. So when the object of focus is near, you can use the flashlight trick.

    And I presume that when the object of focus is far and a flashlight will not light it up, e.g. a mountain or other night landscape or wide-open street scene, you can just switch to manual and focus to infinity, correct?

    But what about those cases in the middle? What if the object is too far for the flashlight, but also not quite the “infinity” distance of a landscape?

    For example, what if I am using a telephoto to get a night shot of a collapsed pier out in the Bay? A flashlight isn’t strong enough. A photographic assistant can’t really run out into the Bay to light it for me, etc.

    How does one cope, then?

  5. Kevin says:

    jus my 2cents, your 24mm focuses better probably cos the hyperfocal depth is better for wide angle lenses so its easier to hit the sweet spot where everything is in focus…

  6. Charlie Owen says:

    Thanks for the tips Thomas. I’ve been replying on the rapid flash built in to the camera to take care of this for years. The flashlight tip is worth it’s weight in gold — plus it’s pretty neat what you can do with the light painting technique.

    Thanks for this most excellent post.

  7. Anonymous says:

    Great post. This is definitely an area that I am struggling with.

    I am sure everyone will laugh but I cannot pull off a clear picture of the moon no matter what I try. I’ve gone as far as a tripod with timer delay on a Pentax SLR and still have light distorting the edges. This confirms it’s not my shaking in anticipation.. I’m a little baffled by this one. Thanks.

  8. For wide lenses at night it’s a lot easier to scale focus than to try to get the AF to work, at least as long as you have a lens with a decent focusing scale, which rules out most AF lenses. I bought my Leica 19 for the image quality, but it turns out I love it more for the great focusing/DOF scale. Still not as good as my Mamiya Universal but immensely better than my Canon glass–the scale on my 24/1.4 I’d call “rather bad” and the scales on my 50/1.4, 135/2 and 200/2.8 I’d call “utterly useless”.

    For longer glass I’ve found I can do better than the AF manualy focusing with the 2.5x magnification of the Canon Angle Finder. It’s amazing how a situation that seems impossible both for the AF and for normal manual focus snaps into focus effortlessly at 2.5x magnification.

  9. Ron Carney says:

    Wow Thomas, what serendipity. This past weekend I was at a friends wedding, high on a hill overlooking Cincinatti. The grooms mother wanted me to shoot some family portraits, and I have everyone standing on the hill with teh skyline behind them for the portraits. I had a dickens of a time getting the focus set, and the whole time, I was thinking, I just wish I had brought a flashlight! I am not sure why the speedlight’s red crosshairs weren’t coming out to help focus, but I didn’t have time to research it then and there and a flashlight would have been a quick and easy way out.

  10. Joe Reifer says:

    Calibrating the focus scale on your lens by testing before shooting at night is a repeatable, reliable way to avoid the problem of inconsistent & difficult AF at night. More on this topic in this article on night photography.

    Cheers,

    Joe