How To: Digital Night and Low Light Photography

Rio Vista Bridge by J. DeRuosi ISO 100 f/4.5 @ 20 & 30 sec HDR

Written by J. DeRuosi
jderuosiphotography.com

Why Take Low Light or Night Photos?

• Pictures taken in the same spot in different lighting conditions can make for very different images. Images taken at night are usually vastly different than those taken in bright light. Ambient light varies from morning to noon to evening making subjects look a little different in each position of the sun in the sky. The light available at night gives you another category in which to experiment. A subject that is boring during the day may be beautiful at night.
• Low light conditions allow for more creative control over the light that reaches your camera’s sensor. There are things you can do in low light because the shutter is open for long periods of time that you can’t do in daylight--light trails, geometric light tracing designs, motion blur, ghosting.

The technical goal in night photography is to get the...

• composition you want
• in the shortest amount of time
• with the lowest noise possible.

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Getting Started

1. Camera & Gear Tips

• Bring a flash light. To see, for focusing, and light painting.
• Remove all filters. Filters will cause lens flares.
• Turn down display brightness. The next to the darkest setting is usually good, but each camera is different. 
• You can use the eyepiece cover for long exposures to block unwanted light entering from the view finder. It’s that rubber thing on many manufacturers’ stock camera straps.
• Turn off Image Stabilization when on a tripod. IS is for handheld shots. IS can create blur on a stationary, solid tripod. However, IS might help on a tripod being jiggled in strong wind.
• Use a hot shoe level if your tripod or camera doesn’t have one built in.
• Have plenty of fresh batteries. Long shutter times and noise reduction drain batteries. Also batteries don’t work well in the cold. Keep spares in your pockets to help keep them warm.
• Photography gloves allow you to use your finger tips without having to remove your gloves. You can always cut slits in old gloves for the same effect.

2a. Keep the Camera Steady.
Limit camera shake to keep pictures from blurring.

• Use a tripod. You can also set the camera on something—a table or camera bag in a pinch.
• Use a cable release, remote, or the self timer to limit camera shake. Most cameras have a 30 second max automatic shutter speed. You need to use a remote with the BULB setting to use a longer shutter speed. In Manual Mode, BULB is the last longest shutter speed setting.
• Use mirror lockup to limit camera shake. One click of the shutter button raises the mirror. Second click activates the shutter. Mirror lockup is usually under the custom functions setting in the menu.
• Use a detachable camera strap, wrap the strap around the tripod, or hold it still if it is windy out. A strap can act like a sail in wind causing camera shake.
• Sand bags can be attached to many tripods if there is a strong wind. There are also sling bags that rocks can be placed in for the same effect.
• Step on a jury-rigged bungee cord loop connected to the tripod to stabilize the tripod in wind.

2b. On the Flip Side, Don’t Keep the Camera Steady.

• Move it, spin it, or throw it for abstract light patterns while hanging on to the strap. Just be careful with your gear. There is always a risk of damage here.
• With a zoom lens, zoom in or out or both while the shutter is open.

3. Focusing
Auto focus doesn’t work well in low light on most cameras and it’s difficult to see through the view finder to manually focus. Live view is a little better, but not much.

• Use an existing light source in the frame. Auto focus on light source at the distance you want to be in focus—a light bulb, reflection, the moon. Put a focus point over the light. When the camera acquires focus switch AF off to keep it from readjusting and then recompose your shot. You can always fine tune with manual focus if you can see well enough. You can look for a light or bright object completely outside of your composition that your camera can focus on at the same distance as the subject in your composition.
• Add a light source in the frame. Temporarily place a bright light where you want your focus to be and auto focus on it. Place or have someone stand next to your subject with flash light pointed at the camera. Lock AF then switch to manual.
• Shine a light into the frame. Shine a powerful flashlight on your subject to auto focus then switch to manual.
  Sometimes a laser pointer will work for this, too. I hear the green ones work best. NOTE: Never shine a laser pointer at your camera. It can permanently damage the sensor just like it can damage your eyes.

• Preplan. If you have plenty of time, you could set up your shot and determine focus during the daylight, lock it in by switching to manual focus and leave the camera in position, then take the shot later when it is dark. Placing gaffer's tape across the focus ring can help keep it from being bumped out of focus by accident in the dark.
• You can use smaller apertures with their greater depth of field to help with focusing problems. (Although this will increase how long the shutter stays open.) Start with larger apertures (f2.8 to 5.6) and work toward smaller ones until you get the depth of field you need, i.e. enough of your subject in focus.
• Manual focus is not easy to do at night. It’s hard to see through the viewfinder. If you have a distance scale on the lens barrel you can try to use that as a guide.
• Live view. If your camera has a “live view” feature, you may be able to manually focus using that. A Hoodman loupe viewer would be beneficial. It allows you to see your LCD screen better.
• What seems to have worked best in workshops for those with live view is to shine a flashlight with a strong, focused beam (500 lumens or greater) on your point of focus, auto focus on that, then zoom in with live view and switch to manual focus to make minor tweaks if necessary.

4a. Noise
Noise=hot pixels in low light photography. The camera’s sensor builds up heat with long exposures. That heat temporarily burns out random pixels causing noise. Noise also increases as you increase the ISO due to how the sensor electronics work.

Note: Film can be better at dealing with noise for extremely long exposures (e.g., star trails), but also requires a longer time with the shutter open than for the same exposure with a digital camera, especially at extremely long shutter speeds due to how film's sensitivity to light works. Look up "Film Reciprocity Failure" for more info. http://digitalfilmphotographer.wordpress.com/2011/06/09/long-exposures-film-reciprocity-failure/

• LENR. If your camera has Long Exposure Noise Reduction (LENR) on, the camera will need to process for as long as the shutter was open. LENR takes a second shot at same length of time as the first with the shutter closed to duplicate noise. It uses the second exposure to remove/cancel out noise. You can move your camera during the second exposure with the closed shutter if you want to set up for your next shot, etc.
• LENR Auto setting usually doesn't activate unless the shutter is open for longer than 15 or 30 seconds.  It depends on the camera.
• You can clean up noise in editing software. You can use noise reduction software like Nik Software's Dfine or do some clean up manually in Photoshop.
  
  Getting the Light Out Technique to merge exposures manually in software:
  From http://www.isi.edu/~johnh/PAPERS/Heidemann01b.pdf 

1. Take several exposures of the exact same image at the same setting, at least three, maybe more.
2. Bring all of the images into Photoshop and put them all on top of each others in layers
3. Leave the base layer at 100% opacity
4. Set the second layer at 50% opacity
5. Set the third layer at 33% opacity
6. Set the forth layer at 25% etc. etc. The overlapping of all the noise in all the layers effectively cancels each other out; the more layers the better.

4b. ISO

• Shoot at ISO 100 to keep noise at its lowest.
• Many cameras can shoot at higher ISOs and still have low noise. Experiment with your camera to see what is acceptable. Higher ISOs mean a shorter shutter speed.
• Use high ISOs as a test to more quickly determine exposure. Then retake the photo at a lower ISO. See below: #5 Technique for Calculating Exposure.

5. Exposure

• Aperture—is usually a creative choice for depth of field. You can use it to help with focusing—more will be in focus with a narrow aperture (e.g., f/22). You can use it to have a shorter shutter speed (wide apertures). If you use a wide aperture (e.g., f4--a wider opening allows more light in) you can use shorter shutter speeds which are nice if time is an issue, but you will lose some depth of field.
• If you are in a well lit setting like a city, choose an aperture (I recommend between f/4 to f/8 as a starting point as you learn) in Aperture Priority Mode and let the camera determine shutter speed. Take a picture and see if you are happy with the exposure. If not, adjust exposure compensation. If that isn't enough switch to Manual Mode using the previous readings as a baseline. If you were using f/4 and the camera chose 30 seconds, but that was still a little too dark, then in manual mode choose f/4 and try 45 or 60 seconds. Keep increasing the time the shutter stays open until you have an exposure you are happy with.
• Manual Mode and shutter speeds.
  City--using f/5.6, shutter speeds in cities usually run from 10 to 30 seconds.
  Country—shutter speeds will run from 30 seconds to minutes. Star trails can take hours.
  
  Technique for calculating exposure:
  Taken fom http://www.gdanmitchell.com/2009/02/11/hints-for-night-photography (Some of the math was a little off in the link; it's fixed below.)

• Shoot wide open at high ISO to calculate basic exposure.
• If you have an f/1.4 lens and can set your camera to ISO 3200, do so.
• Let your camera make an automatic exposure and use that as a starting point.
• For example, if you get a decent (though noisy and otherwise awful looking) exposure at ISO 3200, f/1.4, and 1 second you can work backwards from there to get a better exposure.
• Switching back to ISO 100 means that you need 5 stops more light, so your exposure time will go from 1 second to 32 seconds. (Count 1, 2, 4, 8, 16, 32.)
• Changing your aperture back to f/11 means adding another 3 stops for 4 minutes 15 seconds.
• (At ISO 6400 you can do a straight conversion from seconds to minutes – e.g. if the exposure at some aperture is 1 second at ISO 6400 the claim is that it will be 1 minute at ISO 100 at that same aperture.) Note: It’s close; it’s technically 64 seconds so this works for shorter intervals of time. The longer the time the more this shortcut will be off.

• Remember most cameras have a 30 second max automatic shutter speed. If you have a wireless or wired remote you can use the Bulb setting and have the shutter open as long as you want. The longer the shutter is open the more noise you will have.

6. White Balance

• Streetlight color, multiple light sources, etc. issues. It’s easiest to shoot in raw and adjust white balance in software.
• Purposefully choosing a cooler temperature white balance can help your image have moonlight feel with the blue color cast that it creates, if that is the look you want. 
• You can try a custom white balance with a white piece of paper; you might have more luck with an expo disk. (I've never tried it for low light photography. It might be too dark to work. You can't shine a light on the paper, because that sets your white balance for that light source which you probably aren't using as the light source in your shot.)

Spinnin' by J. DeRuosi

7. Rear Curtain Flash

• Allows light trails to follow behind the subject instead of in front of it. It causes the flash to fire at the end of the shot instead of at the beginning. You can usually turn this setting on under the custom functions setting in the menu.

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Special Subjects

1. Moon
The moon is very bright and moves quickly. It’s very difficult if not impossible to expose properly for both the moon and the landscape. You can take two shots and blend them in Photoshop.

To shoot the moon close up:

• 200 mm lens minimum

• ISO 100 f/8 at 1/200 to 1/400 sec (Colby Brown’s recommendation)

• ISO 100 f/11 at 1/125 or 1/250 (not longer than 1/100sec or will blur) from http://mansurovs.com/how-to-photograph-moon
  

She Danced by the Light of the Moon by J. DeRuosi (Bliss Dance on Treasure Island): ISO 100 f/8 @ 10 sec. Moon layered over actual full moon: ISO 100 f/11 @ 1/100 & 1/200 HDR.

2. Starbursts from Lights
Narrower apertures create better starbursts than wide ones.  Try f/22 to start.

Sentinels by J. DeRuosi

3. Static Stars

Milky Way from Emerald Bay by J. DeRuosi. My first star shot. 18mm ISO 6400 f/3.5 @ 30 sec

• Watch Landscape Astrophotography Tutorial
  "First Night Out" by Ben Canales:http://vimeo.com/16833554http://www.flickr.com/photos/bencanales/
• http://www.lonelyspeck.com/ is another good resource.
  
  

• Rule of 600.
  600/(Focal Length) = Maximum Exposure Time in seconds before star trails start to form. 
  
  This is for 35mm cameras. You need to take into account the effective focal length of your camera due to sensor size. My Canon XTi has a 1.6 effective focal length so a 50 mm lens on my camera is like an 80 mm on a 35mm camera. On my camera the rule becomes 375/(Focal length). Some people just round up and use 400/(Focal Length) = Maximum Exposure Time
  
  Here’s the math using a 50mm lens: 
  35mm camera:  600/50 = 12 seconds
  Canon XTi (1.6x Sensor):  600 / (50x1.6) = 600/80 = 7.5 seconds 
  on XTi Rule 375:  (600/1.6) / 50 = 375/50 = 7.5 seconds

4. Star Trails

• Some inspiration by Lincoln Harrison. Check out his blog, too.
• Best shot on a moonless night.
• Can take several hours to get full trails. Digital sensors get very hot and create a lot of noise.
• Can take multiple exposures to reduce noise with star trails instead of one long exposure.  You probably want to turn off LENR (Long exposure noise reduction) to do this or you will have big gaps in the trails. The setting is usually under the custom functions in the menu. 

You can then take your multiple sequential short exposures and use stacking in Photoshop.
Copied from: http://photoburner.net/category/night-photography/

1. Load images into Adobe Bridge.
2. In Bridge I compiled them into a stack by selecting them all and right clicking and selecting group as stack.
3. You can then open tools–>Photoshop–>open in Photoshop layers. Or you can download Russell Brown’s scripts which will add a Dr Brown’s Services menu item under tools and one of those services is Dr Brown’s Stack-o-matic. He seems to be having a problem with the scripts but they will show up on this page. He has CS3 and CS4 versions. He has a lot of good Photoshop material on that page too and the scripts do more than stacking. Select maximum mode from his script.
4. Anyway, without Dr Brown’s help, go into CS4(or 3) and select all the layers then go to Edit->Auto blend layers. You may need to auto align the layers first but do not unless you have to do so. • Then Layers–>smart objects–> convert to smart objects
5. Finally the Stack Modes menu item will be visible on the layers menu, select maximum mode there. There are a lot of modes and you can play with them.
6. If you have a lot of layers in the stack, be prepared for long waits as Photoshop does the work.
   
   If you don’t have PS Extended: in that case load the shots into layers in Photoshop as above then try to combine them using blend modes and opacity. Screen or lighten mode are likely to work the best and the opacities should probably be 30 percent or so. But you will have to experiment yourself or check Google.

5. Consider Using HDR.
You can even just use two images. (I often don't use the brightest exposure shot (+2) because it makes the final image look like it was taken in daylight and I want my night photography to look like night.)

6. Consider Black & White.
HDR images converted to black and white often work very well with night photography.

Get Out by J. DeRuosi

7. Light Painting

• Use an off camera speedlight flash to creatively light subjects in the foreground as your long exposure is gathering light info from the background. You can fire the flash manually with the test button.
• Or use flashlights to illuminate an area. Try this on the background and/or foreground/subject.
• Use color gels or colored bulbs for light painting. (I print colors on transparency sheets and shine a flashlight through the tinted sheets.)
• Use a blacklight.
• Costco has been carrying Duracell 500 and 1000 lumen l.e.d. flashlights that I love for around $20.  They have an evenly spread light beam that you can focus and the color temperature is close to that of flash.

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8. Light Tracing—Creating Patterns.

• Tie a flashlight with the bulb exposed on a string and swing it to make patterns. Any portable light source works. Use your imagination and try everything.
• Buy colored lights and move them around in your camera's field of view with the shutter open.  I use these light wands by Niteize that most hardware or camping stores carry.
• Use a laser pointer to write or make patterns. (Again, NEVER shine it in your eyes or directly into the camera.) A tightly focused flashlight beam can sometimes work, too.
• Light tracing video for inspiration. http://vimeo.com/30193271 

9. Look Close to Home
You don't even have to leave the house to try low light photography. Practice at home first and/or get creative with what you have at hand in your home, yard, or garage.   

Taken by J. DeRuosi (Well, yes, that, too, but Taken is also the title.) ISO 100 f/4 @ 1, 3, & 10 sec, HDR

10. Be Safe!
Dress warmly (it gets cold standing still at night).  Always be aware of your surroundings and bring a friend if you can.

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More on the Technique for Calculating Exposure

A stop is a doubling or halving of the light reaching the sensor. ISO, Aperture, and Shutter Speed all affect the incoming light. ISO controls how sensitive the sensor is to light. Aperture controls the size of the hole for light to enter the camera. Shutter speed controls how much time the light has to enter the camera and be detected by the sensor. If you take a shot then change one of the three, but want the same exposure in your next shot, you have to alter another of the three in a balanced way. Basically, you want the same mathematical quantity of light to reach the sensor for each of those shots.

Assuming aperture stays constant, the exposure for a picture taken at ISO 100 for 64 seconds will be the same as a picture taken at ISO 6400 for 1 second. The difference being that the shot at ISO 6400 will have much more noise than the one taken at ISO 100. When you are trying to compose in the dark or figure out exposure, a short shutter time is a wonderful thing so we take test shots at a high ISO. After you have composition, focus, and exposure dialed in at a high ISO, you switch to ISO 100 and proportionately increase your shutter speed to take your “real” shot. Below is a visual aid for the halving and doubling relationship. Remember, if your correct exposure at ISO 6400 for a given situation were say 3 seconds, you’d be doubling starting with 3.

ISO

100
200
400
800
1600
3200
6400

Shutter Speed

64 seconds
32
16
8
4
2
1 (meter reading)

Shutter Speed

192 seconds
96
48
24
12
6
3 (meter reading)

A slight short cut is to use the numbers below. For each change in stop from a high ISO to a low ISO you multiply your seconds by the numbers below. For example, if your camera metered at ISO 1600 for 6 seconds to get the exposure you wanted. Switching to ISO 100 is 4 stops (4 halvings of 1600). Look at the numbers below. 4 stops has you multiply by 16 so you would take 6 seconds and multiply it by 16. 6x16=96. So at ISO 100 you would open your shutter for 96 seconds to get the same exposure you had at ISO 1600 for 6 seconds.

1 stop x2
2 stops x4
3 stops x8
4 stops x16
5 stops x32
6 stops x64

Note: exposure calculator apps exist.  I haven't tried any yet to recommend.

Links Used Above

Film Reciprocity Failure
http://digitalfilmphotographer.wordpress.com/2011/06/09/long-exposures-film-reciprocity-failure/

Getting the Light Out--John Heidemann
http://www.isi.edu/~johnh/PAPERS/Heidemann01b.pdf

Technique for Calculating Exposure--G. Dan Mitchell
http://www.gdanmitchell.com/2009/02/11/hints-for-night-photography 

Photographing the Moon--Nasim Mansurov
http://mansurovs.com/how-to-photograph-moon

Landscape Astrophotography Tutorial - First Night Out by Ben Canales
http://vimeo.com/16833554 

Ben Canales Flickr Star Photography
http://www.flickr.com/photos/bencanales/ 

Lonely Speck
http://www.lonelyspeck.com/

Lincoln Harrison. Check out his blog, too.
http://www.lincolnharrison.com/startrails

Stacking Star Trails
http://photoburner.net/category/night-photography/ 

Alister Benn's eBooks (no longer free)
http://availablelightimages.com/blog/night-photography/ 

Light Tracing--Joe Morahan
http://vimeo.com/30193271 

© 2012 Janelle DeRuosi
For Educational Purposes.
Some material included from other sources.  Website links to original authors provided.

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