If you like taking landscape photos at night, you’ll surely be familiar with one of the main challenges: successfully focusing on the stars. Often, you can’t use autofocus, since there isn’t enough light for your camera’s focusing system to lock onto anything. Unfortunately, even manual focus doesn’t always work, which means you may need to use some out-of-the-box techniques to make it work. This article goes through some of the most useful tools that you have at your disposal.
1) Focusing on the Moon
Moonlit nights have their positives and negatives for landscape photography.
On one hand, if the moon is out, you may be able to capture the landscape with enough light to see clearly. Plus, the moon is more than bright enough for your autofocus system to lock on. However, too bright of a moon (especially a full moon) will make it harder to capture detail in the Milky Way, since it often lowers the sky’s overall contrast.
You won’t always be able to plan a photoshoot around the moon. However, if you do happen to take pictures while it’s bright, this is one of the best ways to acquire proper focus on the stars. Simply put your camera on a tripod, enter live view, magnify the image as much as possible, and manually focus until everything looks sharp. (If you want to save time, you can use autofocus — in live view or through the viewfinder — although it likely won’t be as accurate as magnified manual focus.)
One other thing to mention: Use the center region of your photograph for focusing. Why is this? Due to field curvature, your “plane” of focus may not be a plane at all — it could be curved. Typically, it is more important to have the sharpest possible stars in the center of your image than all the way in the corners, which will likely be darker due to vignetting anyway (and less sharp due to coma). By focusing on the moon with your center point, you’ll ensure sharp stars in the center, even if you happen to change your composition and not include the moon.
(The only corollary to this point is if you know the exact characteristics of your lens’s field curvature and feel the need to correct it as much as possible. In that case, you may choose to focus somewhat incorrectly in the center of the image — typically by focusing a bit farther than necessary — so that the blurriness is spread more evenly throughout the sky, rather than the center being in focus and the corners being noticeably out of focus. You’ll already know if this applies to you; most people will just want to use the center point without any additional adjustments, since it’s quicker and gives fine results on most lenses.)
2) Lights in the Distance
Just as the moon provides a bright point in the sky for focusing, so do buildings or other distant lights in the background.
This won’t be the case everywhere. In fact, in places with the darkest skies (and, comparatively, the brightest stars), it is unlikely that there will be a lot of buildings or distant lights on the horizon. However, if there are, make use of them!
It’s not just buildings that count. If there’s a distant road with car headlights, it can make a great subject for focusing. Often, even if there isn’t a moon, I find that I can focus on a faraway source of light for exactly the same effect.
Of course, no matter how you focus in the distance — even if the moon is bright while you’re taking pictures — be sure to review your photos at full magnification to see if the stars are sharp. Usually, a good guide is to see whether or not the stars in the center of your image have a green or magenta fringe around them. If there is a visible color fringe, even a slight one, your focus is at least somewhat incorrect. (If the fringe is green, focus slightly more in the distance. If the fringe is magenta, focus slightly closer.)
3) Using a Flashlight
If the moon isn’t out, and if there aren’t any lights in the distance, focusing will be trickier. However, there are still some ways to get a good shot.
My personal favorite is to use a bright flashlight and shine it on any object in the distance. The farther the better — stars are so far away that you’ll want to focus on something that is, effectively, at infinity. (In practice, with a wide-angle lens, something that’s 25 feet or 7.5 meters away should be good; it depends upon your aperture and focal length, though, so you should test this yourself.)
You’ll need a bright flashlight for this. Your phone isn’t nearly good enough, unfortunately, but there are some pocket-sized flashlights that provide enough light.
If all you have is a phone, though, you aren’t necessarily out of luck. Do you have a friend with you? Get them to take your phone, run a bit into the distance (again, 25 feet or so typically works), and then shine the light on their hand or face. Now, focus on them! It’s fine if you need to change your composition in order to do so, since you can always switch back when you’re done.
Even if you’re taking pictures solo, and all you have is your phone’s flashlight, you may be able to prop it up somewhere in the distance and shine it on an object for focusing. You’ll have to see; this strongly depends upon the landscape.
4) Finding Bright Stars
If worse comes to worst, you’ll always be able to use the stars as a focusing aid.
Bright stars (or planets such as Venus) can be just barely bright enough to focus on successfully, and you could get some very sharp results.
Part of this depends upon your lens. Wide-aperture lenses will make everything brighter, and medium or telephoto lenses will magnify the size of any stars in your image. With lenses like that, focusing on the stars is easiest. However, it can be done with most any equipment — it just takes some work.
If you want to use this technique, there are a few steps to go through. First, take a moment to search for the brightest star or planet in the sky. Once you’ve found it, compose it in the center of your image and zoom into full magnification in live view. Then, use manual focus. To tell if the star is in focus, pay attention to its size — when the star is as small as possible, it will be in focus.
Also, you can use your lens’s longitudinal chromatic aberration to your advantage. This is the effect I described earlier — out-of-focus regions of your image take on a green or magenta tint. By zooming into live view at full magnification, you can move your lens’s focus ring slowly forwards and backwards, paying attention to the colors of the stars. When the star doesn’t have an obvious tint, it is likely to be in focus.
However, as hard as you try, it isn’t always possible to focus accurately on a bright star. There are a couple things you can do to combat this uncertainty.
First, an interesting product on the market is the “SharpStar2,” a filter that intentionally adds a diffraction pattern to stars (or other bright points of light in your photo). As the star moves in and out of focus, this pattern changes shape; you can focus on the star by aligning the diffraction pattern perfectly. We aren’t affiliated with Lonely Speck, and I’ve never tried the SharpStar myself, but I know of some photographers who use one with success. If you do a lot of nighttime photography and have a lens that accepts filters, you might want to check it out.
Second, no matter what technique you use, it’s a good idea to take some test photos to ensure that you’re doing everything right. However, at night, a test photo can be dozens of seconds long — it may be more time than it’s worth. So, what do you do?
Simply use a very high ISO and take much shorter photos. These aren’t photos you’ll actually keep later; they’re purely to test focus quickly. I often shoot at ISO 12,800 or ISO 25,600 with a five-second exposure purely to make sure that my focus is accurate. This is especially important if the brightest object in the image is just a star, and you don’t have something like the moon to focus on reliably. Or, if you have an older camera with poor live view, you’ll especially want to rely on this technique.
5) Infinity Focus on Your Lens?
Many lenses have a focusing scale with a little infinity symbol to help you focus.
At night, this seems like it would be incredibly useful — after all, as I mentioned earlier, you’ll only capture sharp stars if your lens is focused at infinity (or close enough not to tell the difference).
Unfortunately, there’s a problem with the infinity symbol on your focusing scale: often, it won’t be accurate at all. With my personal copy of the Nikon 20mm f/1.8, for example, the actual point of infinity focus occurs when the focusing ring is turned noticeably past the center of the infinity symbol on my focusing scale; on zoom lenses, the infinity point may even change as you zoom in and out. All lenses will be different. At a minimum, though, you’ll need to test to see if you can use yours accurately before putting it into practice. I have yet to see someone who solely uses this method to acquire focus (although it can be a good starting point when you zoom into live view and focus manually on a star).
What about lenses with a hard-stop point at infinity? These tend to be better, but, again, you’ll want to test and make sure that yours actually works before using it for something important. Lenses are all built with different manufacturing tolerances, and I have seen some lenses in the past where the hard-stop “infinity” point isn’t perfectly accurate. For very wide lenses (and those with smaller maximum apertures), you’ll have more tolerance on this front. But if you’re using something like a 24mm f/1.4 or 35mm f/1.4 with a hard stop at infinity, I would be very cautious using it in the field without testing ahead of time.
Finally, once you do successfully lock focus, it’s a good idea to secure your focusing ring with gaffer’s tape, which typically doesn’t leave residue on your lens. That way, your focus will stay locked in place all night. (Though it is always a good idea to check every dozen shots that your focus is still accurate.)
6) Conclusion
Focusing on stars at night isn’t an easy task, but it can be done. Always carry a flashlight; if the moon (or other distant lights) aren’t out, you’ll still have a way to focus reliably in the distance. Worst case scenario, just focus on the stars themselves — make sure to find a bright one, and take some test photos to ensure that your focus is accurate.
Nighttime photography is always tricky, but it’s worth the effort. Landscapes look spectacular under the stars, and I’ve taken many of my favorite photos while most people are asleep. More than anything, experiment! Focusing at night is a skill that can take some time to learn. Go out, find a beautiful scene, and take some photos for yourself.
Kudos Spencer, that is the most complete – yet still concise – article on night sky focusing that I’ve come across!
Three things I would add for the benefit of newcomers to starscape photography:
– Setting the lens to the “infinity” distance mark is almost never precise enough to render pinpoint stars (not only are those distance markers too inaccurately placed, the position of critical focus also varies slightly with temperature as the lens barrel/elements slightly shrink or expand)
– After focusing on the Moon, a planet or a very bright star, you might be able to improve focus further on a fainter star (probably only works for lenses of at least 50mm fullframe equivalent)
– Once you have acquired good focus by following Spencer’s methods, fix the zoom ring on the barrel with some non-sticky masking tape to make sure you don’t accidentally lose it again when re-positioning the camera (but keep my first point in mind, so re-check focus every now and again if temperature dropped significantly, especially with tele-lenses)
Thanks also for mentioning the SharpStar2, Spencer. It’s clearly just a variation on the traditional bahtinov mask (often used in astronomy as a focusing aid for telescopes), but optimized for photographic lenses. I once made my own bahtinov mask from a piece of carton, but it didn’t produce usable diffraction spikes when used with normal and wide angle lenses (had some slight success at 150mm on a 1.6x crop camera).
Glad you liked it – thanks for adding these points! I meant to mention the impreciseness of focus rings, but I forgot that one. I’ll add a note about that to the article tomorrow.
Update: Added.
Glad I could help!
Just to re-emphasize Greg’s point about fixing the focus ring with tape. In the dark it is very easy to knock the focus ring, particularly if you need to re-position the camera. It is very frustrating to carefully acquire focus and then find that later images are blurred because the focus ring must have moved – as I know to my cost. Of course, it also helps to re-check focus occasionally. It’s not always so easy in the dark, when it’s bitterly cold and your hands are frozen …
Thanks, Tony, I added a bit of information about gaffer’s tape to section 5.
Thanks for yet another great article. I am very new to astrophotography. I found the idea of focusing daunting. What I do is use the screen at the back to focus. My 6D allows me to increase the image by 10 times. I then focus on a bright star. I focus it until it changes from blury point to a sharp point. It takes a bit of practice.
It definitely does take practice. The LCD method you use certainly works, although it can be difficult to get everything 100% correct. No matter how you focus, though, it’s a good idea to take some test shots before creating your final composition.
Thank you for replying. As it is said astrophotography is landscape photography at night. My test shots include an overexposed shot so that I can see the fore and midground clearly. This helps me set up my composition. I do this even when I have sussed out the area during the day. Scenery during the day is very different at night. A photo is much better when it includes a foreground (say a hedge or road/track), midground (telegraph pole/house/range of hills/a single tree/rocks/the sea etc).
Great Article
Thank you, RK!
Based on the first of these recent astrophotography articles, I got all excited about trying some star photography. I instantly popped on my 50mm lens and actually got a picture with stars in it. Beginner’s luck! Then I went out and purchased a Nikkor 20mm f/1.8 lens a week or two later. On the first clear night I stepped outside my door to photograph the constellation Orion. Imagine my surprise when my autofocus wouldn’t capture! After multiple attempts, I finally switched to manual focus. But the moon was out that night which made the sky too bright, and it ended up that all I got was this sort of whitish picture with nothing in it. It turned out that my ISO was all wrong, plus for focus I used the camera’s infinity setting. HA! Now I know what went wrong. It is rather comical the way I just threw the lens on and expected a masterpiece. I am looking forward to figuring it all out with help from these articles. Now all I need is a starry night! Thank you Spencer, for introducing such a fascinating new field of study for me to learn.
Happy to hear it, Elaine. If there are enough particles in the air at night, a full moon will make it very difficult to capture clear stars. However, your 20mm f/1.8 is a great tool for this type of photography, and it sounds like you’ve found the solution to your problem as well! Best of luck.
Hi Spencer. Excellent article, but you refers to Af lens without infinity indication. Personally I use old manual focus primes because even if they are optically inferior (I can’t bet on it) they have a mechanical infinity indication. In addition I avoid ED lenses because infinity varies with temperature. I don’t know if what I told is better, but it is much more easier. I tried new AF lens at night, and it was a pain in the ass. In addition old manual focus lens can be less expensive, and in such a way reserved for astrophotography.
Good to know, thank you, Nestor. Which lens do you tend to use for nighttime photography? I’ve found that lenses with a hard-stop infinity focus point certainly can work well, but sometimes have manufacturing tolerances that cause focus to be slightly imperfect at infinity. This of course would vary with the lens, as well as the ambient temperature. (Although, perhaps since I’ve never shot at night in wildly-changing temperatures, or since I primarily use ultra-wide lenses at night, I have yet to notice this effect in my own photos. It can be an especially big deal if you use telescopes.)
Thank you very much.This is great and useful article.
Glad you liked it!
Dear Spencer, many thanks for another great tutorial.
Thank you, Vladimir.
How about determining the infinity focus point in the daylight and marking that point for easy reference at night?
Nice one. It can take some patience to wait between sunset and when the stars come out (depending upon your latitude and the time of year), but this technique also works quite well.
I’ve done this before and it’s a great starting point for getting very close. Make sure that when you do the daytime shot that you try to create the same conditions as you have at night. That means a cool or cold day and do not let the sun warm your lens since these temperature differences can result in a shift in the focus.
Great article Spencer!
Where I live, my biggest problem is street light pollution.
Even the local school yard is rimmed with lights.
Next time my scout troop goes camping, I’ll bring my kit & try as you have suggested.
Light pollution is the biggest problem for this type of photography. Where I live now, I’m lucky to see even a few stars, let alone photograph any of them!
Superb article Spencer! I will add another tip for night photography of stars. Use a red light to work on your camera. By doing this your eyed will keep the iris in a more ‘closed’ position and you won’t have to wait until your eyes are ‘accustomed’ to darkness again.
Thank you, Gustavo. That’s a useful tip — many flashlights have a built-in red light mode for this exact purpose.
Just a quick tip on using live view focussing. Be sure to open up the aperture on the lense all the way to get the most precise focus, even if you are stopping it down for the image. Otherwise you are playing around in a more nebulous zone from depth of field. The same is true for daytime work.
One possible downside of doing this, though, is if your lens has significant focus shift. Then, even though you have to use a smaller aperture (which can make it tougher to see the exact point of focus), it’s better than your focus shifting as you stop down. This varies heavily from lens to lens. If yours doesn’t have focus shift, your method definitely works!
Was out two nights ago. It was about 1am. The moon was not due to rise for a couple of hours and i could not see any human light. The sky was crystal clear and the milky way was dominating the sky. The kind of night that I had been waiting for a while. I wanted to photo the Southern cross which was so viable. On my pictures it the sky was in focus, but the Southern Cross was swamped by the other stars of the milky way. I tried all combinations from f1.4 to 2.8 and iso of 1600 up to 3200. Exposures of 15, 20 sand 25 seconds. I have a canon 6d and a 24mm prime lense. Any way around this?
This is more of an issue of how bright the Southern Cross stars are to the rest of the sky. If they’re the same brightness, no combination of exposure settings will make them stand out against their background any more; however, selectively brightening those four stars in post-production could potentially help.
If the Southern Cross stars are noticeably brighter than their surroundings, but they still don’t show up well, then you might be able to do something in the field. Your 24mm lens is very good — and, for full-sky images, one of the best nighttime lenses available — but something like a 35mm f/1.4 might do a better job highlighting specific stars that already appear larger or brighter than their surroundings, if you happen to have that lens (not a big deal if you don’t — just might give you a small improvement for this particular scene). Also, be sure not to overexpose your stars, or the truly bright ones won’t appear any brighter than the rest. You might consider a lower ISO in the field (ISO 800 or ISO 1600) with a regular aperture and exposure time (something like f/1.4 or f/2 and 20 seconds). That will give you a darker out-of-camera image, which means you can brighten certain stars selectively and have them stand out better against their background.
Either way, selectively brightening/saturating the Southern Cross stars in post-processing is probably your best bet.
Great instructional article. Thank you for this!
Gary.
Glad you found it useful, thanks!
Level 1: A simpler approach: use a manual lens with a hard infinity with low coma. Lots of them out there. Then use live view and magnify in on a bright star and carefully change focus.
Level 2: use a bahtinov mask and do the same
Level 3: use a program like Backyard Nikon or Backyard EOS and use FWHM to obtain perfect focus
Level 4: use something like iOptron SkyTracker Pro or Vixen Polarie and get far better results by stacking exposures
Level 5: bring your inner ninja out by using a top notch program like PixInisght to process the stack and process the results
I don’t fully understand. In other articles (all very good!) you write about depth of field for astrophotography: how to get a sharp foreground when photographing stars. In this article I understand that focussing on the stars is critical? Would not focussing on the hyperfocal distance given a certain focal length and aperture yield sharp stars?
Greetings!
Hans
Great question —
The definition of hyperfocal distance is the nearest point where you can focus and get a sharp background. Normally, I prefer to define “a sharp background” as “equal in sharpness to the foreground,” since it gives you the most sharpness from front to back. But that’s not quite ideal at night.
With nighttime photography, you’ll be at insanely wide apertures with very limited depth of field, by definition. So, if your background (the stars) and the foreground are “equally” sharp, both of them would be too blurry! Only a small area in the middleground would be sharp. So, this is one exception to the typical ideal place to focus — you’re prioritizing the stars more than the foreground. There is no feasible way to get both the foreground and background to be equally sharp if you’re shooting at an aperture like f/1.8 or f/2.8. The best you can do is use a wider lens and stand farther back from the foreground. (Some people try focus stacking in these conditions, but that’s a time-consuming and imperfect process.)
I hope that helps!
Thank you for the detailed procedure.
You forgot two important steps :
1) set the camera Live View screen to the maximum brightness
2) set the camera to “simulation of exposure”
Then, if I use a manual aperture lens, such as Rokinon 14mm f/2.8, I make sure to set it at the final aperture before I start focusing (abt f/3.5) becaus I don’t want to touch the lens after I found the right focus.
Fred