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Light calculator

 

Light can definitely make or break a picture, so choosing the right light is probably the biggest challenge in photography. On this page are some of the types of light with some examples, and with the calculator below you can calculate at which times some of the periods start and end (the script with the moon calculations is courtesy of Peter Hayes, used with permission). If you are interested in calculating these values for a longer period of time, use the calculator over here.

 

Definitions:

• Day:

• Sunrise/sunset:

• Civil twilight:

• Nautical twilight:

• Astronomical twilight:

• Night:

Solar latitude is more than -0.833°.*

Solar latitude is -0.833°.

Solar latitude is between -0.833° and -6°.

Solar latitude is between -6° and -12°.

Solar latitude is between -12° and -18°.

Solar latitude is below -18°.

 

* About 0.25° of this is due to the suns radius and about 0.6° is due to atmospheric refraction. Atmospheric refraction is the bending of light when it travels through our atmosphere, and close to the horizon it is about 0.6°. Since the sun is about 0.5° in diameter, it means that, when we see the bottom of the sun touching the horizon, the sun is in reality already below the horizon!

 

Year/month/day (today):

/ /

Latitude (°)*:

     

Longitude (°)**:

     

Time zone ***:

Daylight saving time:

     

Sun:

Sunrise (time/direction):

/

 

 

Sunset (time/direction):

/

 

 

Hours of daylight (h):

     

Declination (°):

     

Suns maximum altitude (°):

     

Twilight:

Civil twilight (start/end):

/    and    /

Nautical twilight (start/end):

/    and    /

Astronomical twilight (start/end):

/    and    /

Night:

Night (start/end):

/

 

 

Hours of night (h):

 

 

 

Moon:

Moonrise:

 

 

Moonset:

 

 

Moon illumination at 00:00/24:00 (%):

 

 

New moon:

/

 

First quarter:

/

Full moon:

/

Last quarter:

/

* North of the equator is positive, south of the equator is negative.

** East of Greenwich is positive, west of Greenwich is negative.

*** Fill in the time zone relative to UTC (overview). Examples: Hawaii is -10, the UK is 0, CET is +1, New Zealand is +12.

 

Daylight

 

Harsh daylight is not the most suitable light for photography most of the time, and some don't even want to shoot when conditions are like that. It definitely is the least interesting type of light as far as I'm concerned. The dynamic range is often huge and, as a result, contrasts are very big which most of the time doesn't really work very well for a photo, like in the two examples below.

 

However, it is of course perfectly possible to shoot in these conditions as well, and below are two examples where using this harsh light turned out quite ok.

 

Shooting into the sun is also a possibility, which gives a nice backlit scene. Not all scenes are suitable for this, but deciduous forests are excellent for this purpose, with their leaves lighting up nicely in the sunlight. This technique does sometimes need some dynamic range blending, since the dynamic range can be quite big. When shooting into the sun, you can either incorporate the sun in the picture as in the first example, or use something to shield it as in the second example, where the big trees blocks the sun.

 

You can also utilize the big dynamic range to turn parts of your scene into silhouettes, like the two photos below.

 

Cloudy

 

Overcast weather is great for many scenes since the light is even and gives a way more balanced dynamic range. The two examples below show this principle. In the first example, the big dynamic range is a pain to work with. The second photo was taken in overcast weather, and this time details are better visible, and the picture doesn't look as "aggressive" as the sunlit version.

The same goes more or less for the macro scene to the right, where the photo taken in overcast conditions looks a lot better. Although I have to admit that "overcast" in this case meant my hand blocking the sun. One of the advantages of macro photography!

 

Besides making the light a lot more pleasant and controllable, clouds are really cool photographic objects in themselves as well, and can give some very neat light shows as in the examples below.

 

Another advantage of cloudy weather is the fact that there can be some pretty cool optical phenomena in the sky! The first example is a corona, which can be seen as the red circle around the sun. The second example has a bright 22 degree halo around the sun.

 

Mist

 

Technically, this should probably be part of cloudy weather as well, but I wanted to treat it separately, since mist has quite a different look and atmosphere. Apart from mist also giving much more balanced lighting conditions, it has the effect of isolating objects from their background to give very simpistic compositions. Especially the picture below on the left is a perfect example of that effect. In the example on the right the mist was slowly dissolving early in the morning, allowing some nice warm light to light up the trees.

 

Mist is often also a very good filter for shooting into the sun, like the two examples below.

 

Sunset, sunrise and golden hour

 

Some very nice light can arise just before and after sunrise and sunset, which is the period of time which is often called the golden hour. (In reality, this does not last for exactly an hour, but will last for a whole range of periods, depending on your latitude and the time of the year.) During this period, the light is very soft and warm, which looks very appealing in photos. Below are some examples of this.

 

In the example below to the right you can see how much softer the light is during this period. If you compare this photo with the one taken 45 minutes earlier than you'll see the big difference in contrast and atmosphere.

 

Twilight and blue hour

 

Twilight is the time between the night and sunset/sunrise, and it is divided into three periods:

• Civil twilight (sun between 0.833° and 6° below the horizon).

• Nautical twilight (sun between 6° and 12° below the horizon).

• Astronomical twilight (sun between 12° and 18° below the horizon).

 

Examples of these phases can be seen on the right (the photos are all from the same day and location, but taken in different directions).

• The first one was taken at the beginning of civil twilight, and no stars are visible. In the distance, the Belt of Venus and Earth's shadow can be seen.

• The second one was taken at the beginning of nautical twilight. Now the brighter stars can be seen, although maybe not that clearly in the small photo on the right.

• The third one was taken at the beginning of astronomical twilight, and a lot of stars can be seen now, while the sky still looks blue from the last scattered sun light.

• The fourth one was taken at the beginning of night, and you can see the stars very clearly now, as well as some Aurora. Also notice that the sky doesn't look blue anymore! When the moon is above the horizon, it will turn the night sky blueish according to the same principle that causes the sun to make the day sky look blue. But on a moonless night like this one the night sky does not look blue.

 

I consider nautical and especially astronomical twilight to be more suitable for night photography, so I won't treat those two periods here. Civil twilight, on the other hand, can give some pretty nice shows with all sorts of colors. Below are some examples of civil twilight photos.

 

 

 

Approximately at the end of civil twilight the colors will disappear and everything will turn blueish. This is known as the blue hour, even though, like the golden hour, it usually doesn't really last for an hour either, depending on your latitude and the time of the year. Below are two examples of the blue hour.

 

Night

 

Even though the sky looks dark to our eyes, there is always some light coming from the sky, which can be used to light up the land in photos. Especially when darkness isn't complete yet, like in the example below to the left, there is still quite a bit of light to work with. Technically it was still twilight and not night when I took that photo, but my own very loose and scientifically probably not very correct definition of night photography is when the stars are visible, which is the case here.

Darkness was complete in the example below to the right, but there was some airglow lighting up the land (the greenish glow), as well as the Milky Way, so the frozen lake can easily be seen.

 

The two examples above have one advantage, they were taken during winter, and the high reflectance of snow and ice makes it fairly easy to use even such a small amount of light coming from the sky. If there is no snow or ice, a solution can be to use two different exposures and combine them.

Below are two examples of that principle. Even though darkness wasn't really complete yet in the example to the left (hence the blueish sky), the land turned up really dark, with very few details to be seen (the light in the single exposure is me finding my way back to the tent with my flashlight). So I made another exposure of about several minutes for the land only and combined that with the original sky exposure. I also lit up my tent during the long exposure, which is the tiny bright object you can see among the trees.

The example to the right is another example where I combined two different exposures. However, this time there was more light coming from the sky, so I only needed to double the exposure time to get the land correctly exposed.

 

Leaving objects as silhouettes in night photos most of the time works pretty well too since we are used to only seeing silhouettes with our own eyes during the night as well.

 

Night - using the moon

 

A great source of light during the night is the moon. Few things are as magical as walking around at night during the full moon and taking pictures. If the moon is in a different phase, you can still use it, its intensity will only differ from a full moon of course. Also a thing to keep in mind is to calculate when the moon will rise and set, so you can plan your shots.

 

On the right you can see the difference between having the moon up or down, where the first photo shows what the landscape looks like with the moon present. Even though it was only a first quarter moon (meaning it only had 50 % of the strength of a full moon), the landscape is clearly illuminated.

The second photo is taken four hours later with very similar camera settings. At this point, the moon had set and some northern light had appeared low on the horizon. As is clear from this picture, when there is no moon, the sky will turn really dark, and terrestrial objects will become silhouettes.

 

Below are some examples where the moon was used to light up the land.

 

Night - using the Aurora

 

Another nice light source during the night is the Aurora! Of course, it works best with bright displays, so there is no way of planning these kind of photos since the Aurora is notoriously difficult to predict. However, if the Aurora display is not that strong, you can still try taking one exposure for the sky, and one extra long exposure for the land, and combine those afterwards.

 

The display in the example on the right was very strong, which turned the forest all green! In fact, the Aurora was so strong that part of the Aurora in the photo was overexposed as you can see in the part in the middle, which looks a bit washed out. There was no moon present when taking this photo, so all illumination comes from the Aurora.

 

The example below on the left was a very weird display of aurora. The sky was covered by a layer of clouds, but the aurora was so strong that it would shine a very eerie light through the clouds. In fact, at the moment of taking this picture the aurora was so strong, I could walk around in the greenish landscape without a headlamp, despite the fact that there was no moon in the sky at that point.

 

In the pictures below to the right, a clear difference can be seen when the Aurora has a high activity and when it has a low activity. In this case the moon was also up, so there is light coming from both the moon and the Aurora. Both pictures were taken at exactly the same conditions (f/4, ISO 1600, 15 seconds) and processed the same way as well. The first photo has a clear greenish glow over the landscape, and more details can be seen in the dark parts as well. In the second example with low activity, the land turns pretty dark and murky.

 

 

 

Artificial light

 

While I am not the biggest fan of artificial light, it can sometimes be a nice addition to a natural scene. Below are some different examples of it.

 

Artificial light - using a flash

 

The flash is used as a source of artifical light if there is not enough natural light, or when some extra light is needed to lighten dark parts (called a fill flash). Most cameras have a built in flash, but in that case the light source is very close to the camera itself, resulting in very flat pictures. External flashes can be placed at different angles and distances which enables more creativity. To soften the very hard light of a flash, a diffusor can be used, which diffuses the light (not exactly surprising giving its name).

 

The example on the right shows the difference between built in and external flash. The first picture was taken with the built in flash, which results in a very flat picture. The second one is taken with the external flash to the left, which gives a lot more depth to the picture, but now the dark parts are a bit too dark. The solution is to combine the two flashes and to use the built in flash as a fill flash, which gives the more balanced third picture.

 

The guide number of a flash is a unit to describe the power of the flash, and the bigger the guide number, the stronger the light is and the further the light reaches. It is equal to the distance to the subject times the aperture, and is usually given for an ISO value of 100. Varying the ISO value means that a different aperture is needed since the sensitivity is changed. Furthermore, the guide number might vary at different focal lengths.

 

Apart from its use in macro photography (where it is really crucial), I don't really like using a flash, so I have very few examples of its use. Below are the only two I have more or less. The first one is a spider web, which was isolated from part of its background by holding a remote flash to the left and a bit below the spider web. The second one is a shot taken by my camera trap, and in the first case the flash simply refused.

 

 

The calculator below calculates the maximum focus distance for a given aperture, guide number and ISO value. Using a shorter focus distance means that the flash does not have to be used at full force.

Aperture (f/):

Guide number (m):

ISO value:

Focus distance* (m):

*Focus distance is the distance between sensor and subject.

 

This calculator calculates the smallest possible aperture for a given focus distance, guide number and ISO value. Using a larger aperture means that the flash does not have to be used at full force.

Focus distance* (m):

Guide number (m):

ISO value:

Aperture (f/):

*Focus distance is the distance between sensor and subject.

 

Artificial light - Tent Illuminating Device

 

As I am obsessed with taking pictures of my tent, I usually use artificial lighting when taking night shots of my tent. I used to use my flash to illuminate my tent from the inside, but that gave inconsistent results, and I hated having to carry around my flash all the time since I use it very rarely in landscape photography. So I decided to try and build something to make life easier for me, and on the right you can see the result.

It is made of a very bright wide angle LED (180 degrees angle of light) with a fresnel lens from an old IR-detector on top of it to spread the light even more. It uses a couple of AA batteries, and the button is on the end of the green wire so I can have the button outside of my tent to activate the light when taking the photo.

 

This was supposed to be a prototype, but it works so good that I never bothered to make it look better. Never change a winning team! Like every fancy new product, it needs to have a corny name, so I called it the Tent Illuminating Device (TID).

 

The best thing is that I know that with an aperture of f/4 and ISO 1600, my tent will be exposed exactly right with the Tent Illuminating Device on for five seconds. And with those values I can calculate how long to push the button of the Tent Illuminating Device when using different settings for the aperture and ISO value. So with f/4 and ISO 800, I need to have the light on for ten seconds in stead.

Below on the left is an example of my tent, and on the right an example where I used the Tent Illuminating Device to light up my hammock. Surprisingly, it works for my hammock as well.

 

Artificial light - light painting

 

Another way of using artificial light, which also happens to be a more subtle and controllable method than using a flash, is light painting. In the examples below, I used a headlamp to selectively lighten up parts of the foreground. With this technique a bit of care has to be taken with regard to which light source you choose, as the color temperature of the light source compared to the color temperature of the natural light is an important factor.

 

With light painting you can also venture into some more creative lighting experiments, or even make your own silly new year's card.