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Photography / Tips and Solutions

10 Essential Tips for Night Photography

         

Making pictures by night is a curious practice. While specialists of this subject embrace it as a deep-seated passion and have a never-ending quest for technical and creative advancement, those more familiar with daytime photography are often unaware that tried and true photography rules often need to be adapted or even overlooked at night. With this in mind, consider the following tips the next time you venture out in the darkness, to help you to adapt.

1. Take a Chance and Explore the Unknown

What’s my exposure time? This is the number one question asked by a night photography novice setting up his or her camera for the first time. A basic understanding of the functions of aperture and shutter speed take on mind-expanding dimensions at night, when stopping down your aperture can turn street lights into starbursts and setting your shutter speed to bulb offers you the ability to capture the unseen. Contrary to the view of photography as an exact science, nocturnal image making provides an opportunity to experiment, explore, play, and have fun. So, instead of freezing up and following someone else’s exposure suggestions by rote, explore all the variables at your fingertips with your own camera. Then, make this into a veritable learning experience by noting down your exposure settings in writing (or audio) so you can study the results after downloading your files. To economize on power when taking notes, keep things simple and stow a small waterproof notepad and pen in your camera bag or coat pocket.

Moving cars become ribbons of light in this long-exposure image, which also displays the variety of color temperatures in the artificially lit apartment windows and predominantly sodium vapor street lights.
 

Devoting time to this effort will help you to determine what worked best so you can incorporate the same exposure strategies in future shoots. In the words of noted night photography author Lance Keimig, “There are no bad exposures at night, only different ones!”

2. Use High ISO Testing as an Exposure Guide

If you’re still unsure about how to determine exposures from scratch, use a trick called High ISO Testing as your guide. Here’s how it works. For each successive increase of your ISO dial and full stop in opening the aperture notch of your lens, your subsequent exposure time will be cut in half. Let’s say you boosted your ISO to 6400—a 6x difference from ISO 100—and fully opened your aperture to f/2.0—increasing the amount of light from a mid-range setting of f/8.0. While these settings will potentially yield an image with unappealing contrast, increased grain and limited depth of field, you can save valuable time by shooting an exposure bracket to identify a well exposed histogram at these settings. Let’s say the ideal histogram for this scene corresponds with a shutter speed of 4 seconds. You can then do the math to calculate the required exposure time for the same scene captured at ISO 100 and f/8, which would be a total of 32 minutes.

To determine exposure options efficiently for this long-exposure cityscape, I made a High ISO test at ISO 6400 with the lens closed down to f/16 (left-hand frame), which yielded a decent histogram at 15 seconds. I then calculated the exposure difference needed to capture the same scene at ISO 100  (a 6x difference from 6400 ISO). After adjusting the ISO, I made an 8-minute exposure (right-hand frame), which gave me a very similar histogram as the first exposure, yet with improved acuity and grain. Images © Jill Waterman 
 

In addition to being an efficient way to calculate exposure, doing test shots at high ISOs is also helpful for quickly evaluating your framing and basic details of the image composition. Most important—when using this method, make sure to change your ISO and aperture back to the desired settings after you’ve finished calculations, otherwise you’ll find yourself with a final image that is grossly overexposed, yet took more than 30 minutes to make.

3. Learn & Memorize Gear Functions in Advance

Locating that pesky button or dial to change camera settings or pull up a menu is much more challenging at night, not to mention locating the accessories buried in your camera bag! Low light shooting makes it even more essential to study your camera manual to memorize how your gear functions and locate access points for essential dials and menu options before you go out into the darkness. When photographing at night, you should be shooting with your camera and lens in manual mode. If you’ll be breaking new ground with this, get comfortable with your gear’s manual functions under low pressure circumstances, so you can act with calm efficiency when conditions are less than ideal. One item I always rely on in low light is a basic magnifying light, which serves the double purpose of casting a concentrated beam of light where I need it and magnifying the text of tiny dials or digital readouts, so I don’t need to pull out my reading glasses.

Keep a magnifying light handy and you won't have to fumble around in the dark hunting for your reading glasses when you need to make fine adjustments to your equipment.
 

4. Know your Destination and Scout it in Advance

One challenging repercussion to low-light shooting is that everything in sight takes on an otherworldly appeal, which can complicate attempts to pinpoint one specific composition or picture subject. To avoid this dilemma, as well as to prepare yourself for unexpected surprises, you should familiarize yourself with your destination, ideally by scouting the site in advance. Plan to arrive at your location before sunset and take your time setting up, while also gaining the advantage of making pictures during magic hour lighting. This will add to your understanding of how changing light conditions can impact a scene.

Jumpstart your night photography by arriving on site before sunset. Not only will you be able to photograph the magical effects of sunset and twilight, you’ll get a better sense of the landscape and how to move around in the location, minimizing the risk of accidents in the dark and injury to yourself or your gear.
 

In addition to scouting your location directly, you can also let your computer help out during a remote scouting session. Photo sharing websites such as Flickr are readily searchable by descriptive terms, or even specific GPS coordinates. Scrolling through the results from other photographers can provide innumerable tips about site conditions, camera angles and much more.

Lastly, consider bringing along a digital compass to log GPS data, as well as to determine your orientation in relation to the heavens. This can prove critical when shooting star trail images, especially if you want to make images of star trails encircling the North Star.


Where's Polaris? A compass will keep you oriented, especially useful for photographing star trails.
 

5. Adapt your Image Capture to Address High Contrast Levels and Color Casts

Night photography often involves working in situations with extremely high contrast and widely ranging colorcasts. This makes it particularly important to shoot in RAW file format, for greater leeway in controlling contrast and white balance in postproduction.

For optimum control of color, you can manually set your camera’s white balance to a specific Kelvin temperature. This can be particularly useful if you’re looking to achieve the cool blue tungsten hue (3200K) that many people associate with nocturnal images. Your camera also has white balance presets for various lighting conditions, as well as an auto white balance option. Auto white balance is quick and convenient, but this setting functions within a limited range and can be fooled by mixed lighting conditions or the predominance of one color in a scene.

Keimig exposed this mixed-lighting scene for 10 seconds at ISO 400, using Nikon’s Fluorescent 1 (sodium vapor) white balance setting. He made two adjustments to the white balance in post: (left) balanced for the sodium vapor lights in the scene by clicking on a neutral area of the concrete at left of the smoke stack, and (right) balanced for the metal halide light source by clicking on a neutral area of the light emanating from the building at back right. He prefers the version on the left. Images © Lance Keimig  
 

Mixed lighting situations—where artificial lights of different color temperatures are adjacent in a scene—are extremely common at night. These can be difficult to identify visually and nearly impossible to control 100 percent. Under these conditions, decisions must be made about which color cast to neutralize and how the neutralization of a dominant or distracting color cast will shift colors from competing lights. In recent years, many cities have made strides to replace traditional sodium-vapor streetlights (which exude a yellow-orange color cast) with more energy-efficient LED lighting. This produces a clearer, whiter light—thereby simplifying the issue of color casts, while simultaneously reducing opportunities for night photographers to explore creative compositions that highlight mixed light.

6. Plan for a Sturdy Shooting Platform to Avoid Vibration of All Types

Another key concern when photographing at night is camera vibration as a result of long exposure times. The importance of a sturdy tripod cannot be underestimated in such circumstances. While the bulk and unwieldiness of working on a tripod can take some getting used to, it is essential for image clarity at night. This can also offer a big advantage when perfecting composition, as well as for general mindfulness of your actions. The use of a tripod generally goes hand-in-hand with a remote or cabled shutter release, or your camera’s mirror lock-up function (which you can find in the Custom Functions menu).

Using a tripod and cabled shutter release at night is essential for sharp exposures, yet equally important in situations such as this is avoiding vibrations on the metal walkway. The very faint vertical lines on the pathway indicate the ghosting of a pedestrian who passed through the frame during the exposure. Heavy footsteps or other forms of vibration could shake the legs of a flimsy tripod enough to cause camera shake. Image © Jill Waterman 

Keep in mind that issues with vibration can extend well beyond direct contact between you and your camera. Attention should be given to potential vibration caused by unsecured accessories such as camera straps, cable releases or loose tripod connections, and even environmental interference from passing footsteps, automobile traffic or the rumbling of underground transport. Every little bit counts towards getting maximum stability.

7. Condition Your Gear to the Outside Environment

A pesky external condition that’s likely to hamper every night photographer on occasion is the occurrence of lens fog. This can be caused by moving gear from dry cold to warm, humid conditions, or it can occur due to changes in temperature and humidity levels—such as when the temperature nears the dew point. Accumulating moisture can totally interfere with or block light passing through the lens, which can result in soft, blurry images or frames that register no exposure at all. This can be particularly frustrating when it occurs in the process of a long exposure.

Don’t underestimate the importance of acclimating your gear to outside conditions, especially when shooting long exposures at night. Changes in temperature and humidity, either from atmospheric changes that build in a location over time or moving from a location with different relative levels, can fog your lenses and seriously hamper or even prevent your photography efforts.
 

In conditions that are prone to lens fog, adding a clear filter can protect the optical glass from direct exposure to moisture, however this may cause ghosting or flare in an image if lights are present in the scene. A lens hood can also help reduce moisture build-up. Other methods to prevent lens fog involve heating the lens to make it warmer than the dew point.  Astronomy buffs use portable, electric heating devices to keep telescope optics free of moisture. Another possibility is to attach portable hand warmers to the lens barrel. In these situations, it’s advisable to attach the heating device before the lens fogs up, since it can be time consuming and difficult to eliminate moisture that has already condensed.

Without ignoring proper safety measures, you can also circumvent this issue by keeping your camera gear in an environment similar to where you will be working for several hours in advance of a shoot. This will allow gear to acclimate to existing temperature and humidity levels, and will keep your glass fog-free until the levels change.

8. Dress for Success in all Conditions—Winter, Water, and Bug-Proof Yourself and Your Gear

Proper wardrobe is a key concern when photographing at night. Plunging temperatures or sudden weather inversions can quickly turn an enjoyable evening into an endurance test for the unprepared, even in temperate climates. Dress in thin layers that you can add or subtract as outside conditions change, and bring along items to keep everything warm, dry and comfortable—from your core to your extremities to your gear.

It was well below freezing in Prospect Park when Vorenkamp captured this image of fellow night photographer Gabriel Biderman in the snow. Spending hours outside shooting long exposures at night makes it essential to bundle up in warm clothing. Even in non-frigid conditions, your extremities can get painfully cold when outside for hours on end. In these circumstances, hand and foot warmers can really pay off. Image © Todd Vorenkamp 
 

Increasingly popular in recent years, gloves with pullback fingertips offer substantial protection while being a practical way to access camera controls in cold climates. A more moderate option for those who have a hard time working encumbered are lightweight glove liners, which protect hands from wind and weather and can be coupled with heavy gloves or mittens in extreme climates.

Gloves with peel-back fingertips give you more dexterity for fine-tuning camera settings without having to remove your glove.
 

Cold or wet conditions are not the only concerns facing intrepid night photographers. Insects can be nearly invisible and are an extremely hard to predict nuisance with lasting after-effects. Bug spray can help, but if you’ll be venturing into buggy territory, consider arming yourself with a bug jacket.

9. Pack Extra Power and Plan for Calamity

Making long exposures for hours at a time can drain your battery quicker than you think, so make sure to bring plenty of back-up power for cameras and other electronic gear that require batteries to function. You can also conserve power by turning off your camera’s Live View function and LCD display. If you’re shooting on a tripod turn off the Image Stabilization as well.

Making long exposures at night is especially taxing on camera batteries, and adding frigid temperatures to the mix can cause batteries to deplete at many times the normal speed. In addition to having plenty of extra batteries on hand to shoot with (and keeping them warm!), disabling the electronic controls on your camera such as Live View, the LCD screen, or image stabilization can also help maximize battery life.
 

Extreme cold also has a tremendous impact on battery drain. If carrying multiple packs in cold weather, keep extra batteries warm by placing them in interior pockets or insulating them with hand warmers. If a battery becomes exhausted by the cold, warming it up may provide a temporary revival of power, allowing you to fire another few shots.

If you’re shooting in a remote location and have traveled there by car, you can recharge batteries using your car battery as a generator, or better yet, bring along a portable generator to ensure you don’t tax your car battery to the point of exhaustion. And, as an added safety precaution, inform friends or family about your shooting destination and overall plans, then follow up to let them know you’ve returned safely, especially if you’re working alone.

10. Don’t be a Couch Potato, Go Out and Give it a Try

As the adage goes, you can’t be successful at something if you don’t first apply yourself. This is particularly applicable to night photography, when the motivation to gear up and go into the darkness after a full day of work or other pursuits can be easily foiled by inertia.

An overnight display of historic helicopters provided the motivation for this once-in-a-lifetime night shoot. Preparing a list of potential locations, celestial, atmospheric or weather phenomena, cultural activities, and special events to target for nocturnal photo excursions can help you get out the door with your gear. Image © Jill Waterman
 

Veteran night photographers use a number of different strategies to kick-start their motivation—from making a commitment to shoot during particular astronomical conditions such as a full moon, high or low tide, to capturing weather events such as fog, mist, or snow. While the idea of going out with your camera during inclement weather seems less than appealing, the aesthetic results from these types of conditions can pay off in spades.

You can also consider planning a group expedition with one or more cohorts. This can yield benefits far exceeding the simple matter of accountability in getting you out the door. There is both safety and camaraderie in numbers, attributes that can be especially important in the still of the night. The practice of night photography is rich with community engagement. At the end of the day, connecting with—and learning from—like-minded colleagues, is what night photography is all about.

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Great article!!!

I have done several night photo shoots and had good success on the whole expect with star trails. When I have tried to photograph star trails which is fine with short exposure times but when I have tried longer ones to get the circular effect you see around the pole star the battery usually runs out of gas. I've tried using new batteries and generally the vernight temperature hasn't been low. Do I need a special battery pack or I'm I missing something. Any help would be apprecialted. 

Glad you enjoyed the article B Rees, and sorry to hear that you've been running into battery issues with long exposures at night. What camera were you shooting with and how long of an exposure time were you attempting? Also, what ISO and aperture were you using? If you like the look of long star trails, you might want to try what's called image stacking, whereby you capture many consecutive short exposures of a star-filled nocturnal landscape and combine these exposures in post using stacking software. I'll add this to our list for a future article. In the meantime, here's a link to a different Explora article about photographing the starry sky at night: http://www.bhphotovideo.com/explora/content/epic-battle-between-choosing-star-trails-over-star-points
Thanks for reading and happy shooting!

Thanks...

You're very welcome Rustu Erata. Thank you for reading and commenting on the blog!

PhotoPills is another great app.   Not only does it includes exposures, but hyperfocal, dof, and some other planning tools.

Hi Robert, thanks so much for writing in and recommending the PhotoPills app. As you'll note from the discussion below, a number of other commentors also recommend this app, in addition to the free apps First Exposure and Exposure Calculator by Quicosoft (for android users). There are tremendous resources to assist with night photography and long exposure calculations these days, but I'd encourage using these things as a starting point in getting comfortable with the process and then pushing the envelope from there. Happy shooting and thanks so much for reading the blog!

I think the problem here is the old mixing apples and oranges, mixing linear arithmetic with geometric arithmetic;  1, 2, 3, 4~ are linear but apertures are a geometic progression.  That's why an f/2.8 lens lets in 2 times the amount of light that an f/4.0 lens does.  You calculate the change taking place by squaring each of the numbers and comparing 'the squares'.  2.8 times 2.8 is 7.84 (rounded up to 8) and 4 times 4 is 16.  Since we are dealing with fractions of a whole— the whole being the theoretical maximum a lens could produce, f/1.0— we are actually comparing 1/8 and 1/16 (the f in the description of a lens's speed stands in place of "1", the slash represents the horizontal line in a fraction:  f/8 means the lens delivers 1/8th of the theoretical capacity of the lens being discussed.  That is why f/8 on an 12mm, 24mm, 100mm, 500mm lens all deliver the same per/area amount of light to film/sensor/whatever— despite the fact that the physical size of the apertures are immensely different.  

Bwana's linear arithmetic is correct.  Jill's chart is correct only if the 'f/' symbol and concept is substituted for the 'x', which is what I think she really meant to express.  

Cambridgevet has a pretty excellent explanation.  

Way back when, such as in some Rolleis, there was a mechanical linkage that locked together ISO and aperture (f/) and shutter speed with a resulting display of an 'EV number'.  Once a correct exposure was set as an 'EV number"(which could also be read in a window on a handheld light meter), with EV22 being about the top of the scale— white snow in full sun— adjusting an aperture or shutter setting would result in an appropriate change in the complimentary:  going to a higher ss would result in a wider open lens setting, a smaller numerical number (but a larger absolute number if you remember f/ is a fraction— 1/4 is larger than 1/8).  The EV concept remains in calculations of a camera's sensor's sensitivity, such as 'down to –3EV' for a pretty sensitive ability to measure.

This geometic progression is found in measuring sound levels, and in markings on filters for their reduction in transmission, a.9 ND filter requires an 8x change in exposure, or 3 f/stops— to maintain an equivalent exposure.

I've tried the touch screen on my Rebel and find that as long as shutter speeds and apertures and ISO numbers are set in the same unit, that is, 1/3rd stop (f/) and 1/3 ss, or 1/2 and 1/2, counting the number of 'clicks' in changing scales will result in the 'locked-in' EV number established in the preliminary, high-ISO test exposure.

Or, you could use the old formula:  at twilight, take a look at city lights against the blue sky 90 degrees away from sunset, 10 minutes after sunset;  take an exposure.  In the resulting image, the difficult-to-measure lights and the sky will have a comparable value. A surprising number of times it coincides with one over the ISO at f4.5..    This is your medium gray measurement for the lights, but it doesn't make allowances for a multiple of lights crossing the same path— the source of highlight overexposure.  Some photographers will make multiple exposures (and meld in PhotoShop), avoiding overlaps, or holding a black card in front of the lens, at appropriate times.  This also works well for fireworks.  

I thought f stops were the aperture's diameter as a fraction of the focal length, rather than just some arbitrary fraction of light theoretically passed through the lens.

I don't know what "some arbitrary fraction of light theoretically passed through the lens" means but the light is passed thru lens by the area of the aperture, and 'area' is a geometric, not linear, term.  Things get even more complicated when we consider that very few lenses today are 'balanced' designs.  Nobody— well, maybe astronomers— want to carry around true long-focus lenses.  We prefer telephotos, where one or more negative elements are included in the formula to reduce the physical length;  and many— most in the case of small cameras— wide angles are retro-focus designs.  If you look at a balanced design from the front, and then the rear, the image of the iris opening will be exactly the same.  If you do that with teles or retro WAs, one image will be smaller than the other.  This means the effective FL is different from the actual FL, and almost any real world measurement we try to make will give us misleading info.

You might enjoy reading the first 4 chapters of Introduction to Photographic Principles, Lewis Larmore.  There probably have been some recent attempts to make the info more popularly presented, but the concepts are mathematical and the vocabulary originally set up by engineers, and Larmore, an engineer at Lockheed, claims he has made 'a clear and comprehensive statement of the scientific laws of photography'. 

First Exposure works like a charm. But if you forget your phone or fogot to charge it, knowing how to do the arithmetic would be nice. As Jill points out , ISO 6400 to 100 is a six (6) stop change (6400, 3200, 1600, 800, 400, 200, 100), and going from an aperture of 2 down to 8 is a four (4) stop change (full F stops = 1.0, 1.4, 2.0, 2.8, 4.0, 5.6, 8.0, 11, 16,22, 32). So the original 4 second exposure must be increased by a factor of 2^6 X 2^4, or 4 sec X 64 X16 = 4096 sec ~ 68-1/4 minutes. Guess I would keep a calculator in the camera bag also and the f-stop table along with the iPhone. But I have a question: does the camera sensor record the same at these very long exposures as it does at more normal exposure times. I am no engineer, far from it in fact, but I do remember reading somewhere that the response is not linear. Maybe Jill's "under"-exposure really worked because of some response characteristics of the camera's sensor.  Any techie types who can comment?

A small note...smart phones can have digital compass as well as calculator apps, all for free. Also LED head strap lights are great for hands free work illumination.

Great suggestions about the digital compass, calculator apps and the LED headlights, Quizicat. These are all very beneficial whn working at night. Another free smartphone accessory is the stopwatch/timer. Thanks so much for reading the blog and for commenting on my article!

Thanks for writing in cambridgevet. What you mention about forgetting to charge your phone before a night shoot has definitely happened to me before, and I totally agree about the benefits to learning how to do the math.

Regarding your question about how the digital sensor records exposure time. From my understanding, the sensor’s response is linear, whereas the response time of analog film is not, due to reciprocity failure.

About the High ISO exposure calculation that I mention in the article text, I think a lot of the confusion with this lies in the fact that I suggested making adjustments to both the ISO and the aperture in the same equation. I wanted to use an example that shows how both of these variables are factors to consider, but I think this has resulted in overly complicating the process from a practical standpoint. It’s far more straightforward to keep the aperture consistent when doing High ISO testing. But, if changing the aperture is essential, then make it a two-step process.

I’m not sure whether that point will help clarify (or cause further confusion about) the inconsistency between my calculations for the High ISO test pictured below and the figure that you and others have mentioned. Here’s a visual reference for how I did the math:

ISO                         f-stop                    Exposure time

6400                       f/2.0                      4 sec.

3200                       f/2.0                      8 sec.

800                         f/2.0                      16 sec.

400                         f/2.0                      32 sec.

200                         f/2.0                      64 sec. (1 min, 4 sec.)

100                         f/2.0                      128 sec. (2 min, 8 sec.)

100                         f/2.8                      256 sec. (4 min, 16 sec)

100                         f/4                          512 sec. (8 min, 32 sec)

100                         f/5.6                      1024 sec. (17 min, 4 sec)

100                         f/8                          2048 sec. (34 min, 8 sec)

Thanks so much for reading the blog, and for all your comments folks!

Hi Jill,

Is there a reason why you didn't use ISO 1600 in your calculation? I've been wondering why my math didn't add up, so I now see why!

Thanks so much for the great post!

Thanks so much for catching my error John S.! I have to admit that working with numbers has never been my strong suit. I'm much better working with letters ...smiley ... and images! Thanks again for reading Explora!

Over the years I have shot a lot at night, starting w/ film. I did a lot of trial and error.  I found that shooting at night in cities, particularly San Francisco, using ISO 400, aperture f16 and bracketing w/ 4s, 6s, 8s and 10s would give me great results.  If shooting movement the above would be problematic. In the field I don't worry very much about white balance, histiograms, etc. When I get my image on my computer I use the software that came w/ the camera to get that. I also use the Pentax software as my RAW Converter.  I have a Pentax K5 IIs and prior to that the Pentax K-20D and all the adjusments available in the camera are available in my software. It's just easier for me to do it this way. Even w/ the K-20D, notorious for bad high ISO exposure, 400 worked great.
 

Hi Steve, thanks for writing in. San Francisco is a great place for night photography and that city has an incredibly vibrant and knowledgeable night photography community to boot!

It sounds like you have a pretty good system in place for balancing trial and error with some kind of predicable framework. That is really important and hugely beneficial to the process. While the technical aspects might seem daunting initially, night photography offers a lot of room for personal expression, which is what it’s all about. So here’s to the starburst lighting in all of your f/16 cityscapes, and thanks again for your comment!

"Let’s say you boosted your ISO to 6400—a 6x difference from ISO 100"  Actually a 64x difference in exposure time.

It actually is a 6 stop difference - the ISO is doubled 6 times.

Hi RickJo, thanks for responding to bwana's comment. Your calculation is correct, it's a matter of doubling the ISO figures (not straight multiplication) to get the difference between ISO 100 and 6400. Here's a visual reference:

Starting ISO: 100

1x ISO: 200

2x ISO: 400

3x ISO: 800

4x ISO: 1600

5x ISO: 3200

6x ISO: 6400

bwana, I hope the visual reference above helps to make this clearer for you. The best way to really get this under your belt though is to go out and make exposure notes while trying the process. Happy shooting and thanks for reading the blog!

The high ISO expsoure test is a great idea. As others have mentioned, doing the math is intially confusing, but like most things becomes easier with practice. I've wasted so much time doing long "wrong" exposures in the past, so I'll be sure to give this a try in the future. Thanks for the suggestion.

Thanks for your comment David. You might also want to check out one of the apps mentioned here in other comments. I haven't tried any of them yet but they definitely seem to hold promise for helping make the process clearer. As you say, these kinds of things become easier with practice. Here's to your future night photography efforts, and many thanks for reading the blog!

With film one can integrate exposure over a virtually unlimited time.  An elctronic sensor, however, collects electric charge which can leak off.  What, if any, are the limits on exposure time with a digital camera? 

Hi Jonathan, I love your comment about analog film, as deep down I’m a huge fan of the alchemy that reciprocity failure can conjure (as examples of this, check out photographers such as Michael Wesely and Abelardo Morell, among many others).

But, your question about limits to exposure time with a digital camera is hard to quantify with precision for a couple of reasons. While digital sensors do not suffer from reciprocity failure, as mentioned in one of the comments above, long exposures with a digital camera are adversely affected by digital noise. This is influenced by a number of elements, from the age and power of the sensor itself, to the length of the exposure, to the temperature of the sensor, to the camera ISO being used. Digital noise can be minimized by a process called dark-frame subtraction or by noise reduction software, which results in doubling the exposure time of the image being captured. Yet another issue with using a digital camera for extremely long exposures is the camera’s battery life. Once the battery is depleted, the exposure ends. Although the quality of an image generated by pushing a digital long exposure to this extreme is likely questionable, you might say that the ultimate limitation to a digital exposure time is the camera’s battery life. Hope this helps clarify things (rather than causing confusion). And thanks for reading the Explora blog! 

A small word of caution when using the chemical heating packs such as Grabber.  One of the by-products of the process is water vapor.  On very still and cold nights, I have had some problems with frost from the water vapor emitted by the Grabber.  So far, mostly on the barrel of the lens and not the glass, but it is a good idea to watch for it.
 

Thanks so much for the heads' up about this L. Wolfe, you bring up a very important point. Photographing in very cold weather adds an extra layer to the challenges of night photography and makes it essential to be extra vigilent about the performance of your gear out in the elements. Keeping plastic bags and dehumidifying packets on hand can be helpful in a situation like this, so to slowly transition the lens (as well as the rest of your gear) to drier and more temperate conditions. Thanks again for your insightful comment and for reading the Explora blog!

Hi Jill,

I am a bit new to exposure calculations so I was not able to follow your High ISO test calculation that closely.  This is a great idea BTW.  

At 6400 ISO and f/2, you had a 4 sec exposure.  And then at 100 ISO and f/8, 32 minutes.

From 6400 to 100 is 6 stops and from f/2 t0 f/8 is 4 stops.  Do you add stops, for a factor of 10?

Each stop is doubling the time.  Doubling 9 times is 2048 secs or 34.1 minutes.  So thats pretty close or close enough for engineers.  Ten times would have been 4096 secs or 68 min.

Am I close?

Thanks John

Hi John, thanks so much for writing in about High ISO testing. Please have a look at my response to cambridgevet's comments for further discussion about these calculations. As mentioned there, I think a lot of the ensuing confusion lies in the fact that I suggested making adjustments to both the ISO and the aperture in the same equation. I wanted to use an example that shows how both of these variables are factors to consider, but this seems to have resulted in overly complicating the process from a practical standpoint. When doing High ISO testing, it’s far more straightforward to keep the aperture consistent, but if changing the aperture is essential, you should make it a two-step process. I hope this helps to clear things up for you. Happy shooting and thanks for reading the Explora blog!

I used an Iphone App (PhotoPills) with zero ND stops to see if I could use for High ISO test shots-- I get twice the shutter speed - 16 min vs 8 min. for the article example. Can any one explain and help--I think the technique is great and would like to use an app. Thanks

I've read this article twice but I'm embarrassed to say, I don't see where you tell us how to work out the exposure times. It's not all all clear to me what you calculated. I can't actually see what calculation you did to get to your exposure conclusion. I guess I might try the app suggested by others.

Thanks for your comment Richard, I hope the subsequent discussion about High ISO testing/exposure times and the calculations referenced in comments have helped to clarify things for you. The best way to make it crystal clear however is to try it out with your camera, while also using the app as a point of reference. Thanks very much for reading ... happy shooting!

For ISO/shutter speed/aperture conversion there is a very nifty app available named "First Exposure". I took some test shots at IS25600 and f2.8 to get the exposure I wanted then opened the app, entered those values with the shutter speed and told it I want to use f11 and ISO100. After timing the shot for the shutter speed it gave me I ended up with a  very similar exposure. I highly recommend this app. 

First Exposure is made by which software company ? I looked for it on Google but could not find it

THANK YOU

Thanks so much for adding the link geordienz. I just downloaded a copy to try out myself!

It's available in app store if you have an Iphone.

A similar free app for Android users is Exposure Calculator, by Quicosoft. 

Hi Dave, thanks for providing a link for Android users... Most helpful!

Hi Flashhog, thanks so much for the tip about this exposure app. I wasn't familiar with it but it sounds really helpful. It definitely beats trying to make these kinds of exposure calculations directly in the field. But, when shooting at night and relying on a mobile phone as a resource, make sure to have plenty of power and a back-up for your phone battery so that you don't exhaust the battery before the night is out! Thanks again for reading and for writing in!

Jill, thanks for the tips & solutions for night photography. It is one of my favorite subjects. I recently purchased my first DSLR: Nikon D3. I am a self-thought photographer, beginning  with black & white, and have always taken properly exposed photos. Being new to digital photography, I didn't have any problems capturing night photos. You are correct about using the formula. That is how I start with all my night shots. And more importantly, like you said, set the camera in manual mode.      

Hi Robert, thanks for your comment and congratulations on your recent transition to digital! Glad to hear that you're not experiencing a steep learning curve with this or exposure issues with nighttime captures. Some people find night photography to be a challenging subject area, but a comfort level in using manual settings definitely helps. Happy shooting and thanks again for writing in!

Hello. I was wondering if there is a formula I could use for High ISO Testing.

For example, say I took a test at 6400 ISO like you did in the article for an image I wanted to shoot at ISO 100 and the ideal shutter speed turned out to be 5". The ideal histogram turns out to be a 4 second exposure at ISO 6400. What would the correct shutter speed be for ISO 100?

Hi Joshua, thanks so much for writing in! I'm a bit confused by your mention of 5" (which, from what I understand means 5 seconds). Did you mean 5' (minutes) instead?

In terms of a High ISO testing formula, here's a visual representation of how the math works:

ISO              Exposure Time

6400            4 sec.

3200            8 sec.

1600            16 sec.

800              32 sec.

400              64 sec. (1 min, 4 sec.)

200              128 sec. (2 min, 8 sec.)

100              256 sec. (4 min, 16 sec.)

So, if you did mean 5 minutes, your histogram for that exposure would be slightly overexposed based on the calculations above. If there are no direct lights or extreme highlights within the frame this might produce a file that can be tweaked to your liking in post, however a general rule of thumb for night photography recommends exposing a bit to the right side of the histogram for shadow detail.

Hope this helps ... thanks so much for reading the blog!

Yes I did mean 5'. And thank you so much! This made it perfectly clear!

Your example here makes me even more confused about what you had in the article:

I made a High ISO test at ISO 6400 with the lens closed down to f/16 (left-hand frame), which yielded a decent histogram at 15 seconds. I then calculated the exposure difference needed to capture the same scene at ISO 100  (a 6x difference from 6400 ISO). After adjusting the ISO, I made an 8-minute exposure

With your example above, it seems that it should be this:

ISO              Exposure Time

6400            15 sec.

3200            30 sec.

1600            60 sec.

800              120 sec.

400              240 sec.

200              480 sec.

100              960 sec. = 16 minutes, not 8 minutes!

So why did you do an 8 minute exposure instead of 16 minutes to get the same histogram?

Also, looking at the example you first give of testing with aperture 2, ISO 6400, giving a shutter time of 4 seconds, the "First Exposure" app linked in the comments translates that to aperture 8, ISO 100, and shutter time of 1 hour 8 minutes (68 minutes). Once again, this is more than DOUBLE what you state as your result of 32 minutes. I was pulling my hair out trying to see how you got 32 minutes, thinking I must be crazy, but then the app supported what I thought should be the answer. I double checked the other one I that I just commented on in the previous comment and see that the app also gets 32 minutes! Why are all of yours half what it seems they should be? Is there some rule of thumb I am missing???

The next to last sentence of this previous comment should read "also gets 16 minutes!" not 32. Sorry for any confusion. The point being that the app shows double what you say in both examples.

I uised PhotoPills app on Iphone and also got 16 minutes???

The difference between ISO 6400 and ISO 100 is indeed 6 stops.  Two raised to the power of Six, 2^6, equals 36. This is the difference in light energy produced by 6 stops difference.  The time exposure at ISO 100 must be 36 times the exposure at ISO 6400 to get an equivalent exposure.  15 seconds times 36 equals 540 seconds, or 9 minutes.  The 8 minute exposure at ISO 100 is only 0.17 stops less than the calculated 9 minute exposure, which is hardly noticible.

Hi,

I also wondered about this. And 2^6 = 64 (not 36...36 is not part of the power series of 2 at all).

Hi Richard.  You are correct.  I shouldn't attempt math late on a Sunday evening!  I thought about my answer later and realized it wasn't correct.  Thanks, and that makes John's answer also correct.  15 seconds times 64 gives 960 seconds, or 16 minutes.  I wonder why the photo needed 1 stop less.  Is there some kind of nonlinearity in the sensor with long exposures?  Or maybe the f-stop was different between the two photos?

Hi, I was wondering if you could explain the math of this a bit more. I get that ISO 6400 is 6X that of 100, but I am not sure how you got 8 mintues. And is this chart for a particular f/stop?

Thanks

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