In general, there are four different ways you can focus for night photography. We will review them here.
For each of the following methods you should be using the widest angle lens you own, at its widest focal length (field of view ). Also open your aperture to the widest setting, meaning the number under the “f” is the smallest possible.
For example, if I was shooting with my 14-35mm, f/2.8 lens, it would be set at 14mm and f/2.8. The lens settings provided above are the most forgiving. This is why they are best to use the first time through.
Once you change your focal length, you will need to make sure you are in focus, again. Once you have done this a few times, you can use any lens you would like.
Method 1: Preset Your Focus Point During the Day (not the method I use)
It’s easier to focus during the day than at night, for both you and your camera’s auto-focus software. Since focusing is one of the hardest parts of night and low light photography, getting this step out of the way during the daytime is always best practice. If you’re ever stuck finding focus this trick will solve 99% of your problems.
Set up your camera during the day with the lens you will be using to take your night and low light photos. You can do this at your house or anywhere else that’s easy to access. It doesn’t have to be at the location where you plan on taking night photos.
Adjust your lens to focus at infinity or a far away horizon. I use my camera’s Live View Mode, zoomed in, and focus on the furthest horizon in my composition. This will ensure that you’ve focused at infinity. You can also focus by looking through your camera’s view finder. TIP: If you decide to use Live View for this step, try finding your initial focus using Auto Focus. Next, manually make the final adjustments, if required, using the focus ring. I find that Auto Focus usually does very well during the day, but sometimes needs manual input in low light.
Take some more practice shots at an aperture of f/8 - f/11 and make sure the entire photo is in focus.
If it isn’t focused, repeat Step 2 and Step 3.
Now your lens is focused at infinity.
Using a permanent marker, mark both the focus ring, and the barrel of the lens (non-rotating part of lens). Tape works as well, but may fall off over time. This is a reference point that you will be able to use when returning to shoot at night or in low light.
Now you can easily return to this “infinity mark” on any future shoot to find sharp focus.
Method 2: Focusing at Night Using Live View (my "go to" method)
In the case that you forget to focus during the day, or just don’t want to,
this is another excellent option. This only works for photographers that have
Live View Mode on their cameras.
Turn on your Live View in shooting mode, and adjust your lens focus ring to the“∞” marker. Next use the “+”(zoom button) on your live view to zoom in on the brightest star in the sky. TIP: If you have a built in camera level, by all means, turn it on. A level horizon never hurt anyone.
Once you’ve zoomed all the way in on this star, slightly turn the focus ring on your lens clockwise, then counterclockwise. You will see that the star you have zoomed in on gets bigger, then smaller, then bigger again. You will also notice that the star moves slightly side to side.
Turn your focus ring until the star is the smallest it can be, prior to growing larger again. The star is now in focus. You are also focused at infinity. TIP: The star you have zoomed in on may look blurry in Live View, this is okay. You should only be worried about finding the focus point where the star is smallest, as noted in Step 2 and 3.
Turn off your live view, take a practice shot, and make sure all of the stars are in focus.
In the case that the stars are still not in focus, repeat Steps 1 - 3 until they are.
Method 3: Focusing at Night with Artificial Light
Focusing with artificial light can be used in addition to any of the other 3 methods, given you are close enough to shine a light on the subject you want to focus on. It can also be used by itself. Using Live View works very well for this. You can also look through your camera’s view finder and manually focus on the subject.
To do this:
Turn on your camera’s Live View or look through your view finder.
Shine your light source on the subject of focus.
Manually focus your lens on the lighted subject.
Upon focusing, you can turn the light off and take the photo.
Method 4: High Contrast Focusing
At times there is a very high contrast (abrupt transition from light to dark) between the subjects on the landscape’s horizon and the sky. Effective use of this method depends on the time of night and the amount of light pollution present where you’re shooting.
This method works best during the time of day when the ground (directly below the horizon) is very dark, but there is still some light from the recent rise or set of a large celestial body (Sun and / or Moon). It also works well any time of night when the ground is dark and there is significant light pollution near the horizon. Perform the following steps to focus using my High
Contrast Focusing Method:
Turn on your camera’s Live View in shooting mode and adjust your lenses focus ring to the “∞” marker. Next use the “+” (zoom button) on your live view to zoom in on the high contrast distant (30+ feet away)horizon or object. Another option is to look through the camera’s view finder and manually focus. I believe Live View works much better. TIP: You should be able to see the high contrast line where horizon transitions to sky.
Once you’ve zoomed in all the way on this horizon, slightly turn the focus ring on your lens clockwise. Then, counterclockwise. You will notice this high contrast line becomes blurry (less contrasted), then get’s sharper again (more contrasted). You want to find the lens focal setting where the line is most contrasted and sharp.
Turn off your Live View and take a practice shot. Make sure all of the stars are now in focus.
In the case that the stars are not in focus, repeat Steps 1 –3 until they are.