The Exposure Triangle shows us that there are 3 things we can change in our camera settings in order to achieve proper exposure for the light conditions in our intended scene. The combination of these 3 variables are changed in response to the Exposure Value of the scene.
Long exposure photography still uses the Exposure Triangle and Exposure Values in order to capture a workable and viewable image. Have fun with these ultra-long exposure tips which will allow you to make outstanding images.
What is Exposure Value (EV)?
Exposure value can be defined in two ways, both of them being a correct definition and both definitions being related to each other. The brightness of a scene determines what the exposure value is, and the resulting settings are also called the EV.
What this means for you as a photographer is that there are any number of combinations of camera settings for any scene brightness level. This remains true for long exposure photography as well as general photography.
If we say that a common EV of a daytime scene is EV +15, the resulting camera settings for proper exposure could be ISO 200, 1/250th, and f/16. However, we could change up the settings in order to achieve the same exposure. So, 1/1000th at f/5.6 could work with ISO 100, and so could 1/30th and f/22 at ISO 50.
Therefore, what you see is that you could slow down shutter speeds for any given scene brightness by adjusting ISO and aperture to match the scene’s EV.
When To Use Longer Shutter Speeds
There are many occasions when using longer (or slower) shutter speeds will create an image that you want to capture and share.
Adding a sense of motion to action is one situation that benefits from a slower shutter speed. Instead of trying to freeze movement with a fast shutter speed, we slow down our speed and trip the shutter while panning with the action. This creates an interesting blur effect which says “motion” to viewers.
Another situation is also related to motion, and that’s water or cloud blur. Those images with a soft stream of blurred water or streaking clouds are made with long exposure photography. Sometimes the shutter speed is measured in multiple seconds in order to get the desired result.
Well, let’s say you’re in New York City and you want a picture of the Lions in front of the New York Public Library, but you don’t want a lot of people in the view. You could get creative in framing the shot, moving around to capture just the right angle that eliminates passers by.
As an alternative, you could frame up the view of the NYPL that you really want and then use a shutter speed that is so extremely long that anyone walking by won’t register in the image file. That’s a nifty trick! This technique has actually been in use since Louis Dagguerre invented his signature innovation in the 1830s.
Digital photography gives us an additional way to accomplish ghosting, but it requires some post-processing after the fact. It involves a specific way to use photographic stitching. Maybe we can examine that idea some time later because it’s not really long exposure photography.
Neutral Density (ND) Filters to the Rescue!
In order to get exposure times measuring in multiple seconds or minutes, we need quite a lot of density. A 2X (1 stop) or 8X (3 stop) is a good start, but there are even darker alternatives for our long exposure photography gear.
Using the previous EV and settings, that creates a possible exposure of 3072 seconds, or over 50 minutes! What could you do with an exposure time measured in full minutes?
Besides needing a camera mount of some type, either tripods or specialty mounts, you need to be sure that the mount is very secure. Wind vibration is a common problem. A lot can happen in several minutes.
Using a remote shutter release is a good idea. There are several excellent wireless remote controls that can come in handy for ultra long exposure photography.
SInce our sensors are electronic, heat can become a problem as well. That’s because keeping the power on to anything electrical causes heat build up. Like Scotty told (will tell?) Kirk, “I canna change the laws of physics!”
Physical heat in our imaging system degrades our image with electronic noise. Noise is similar to super fast film graininess. Might look cool for some special effect idea, but it doesn’t improve the look of most of our images.
Keeping the camera body itself out of direct sunlight will help. You don’t want to obscure the lens in any way, but a shade over the camera body can keep temperatures lower.
This applies primarily towards film, but there are some aspects of it we may need to consider for our digital imaging. A thorough reading of our instruction manual or a google search of our specific camera will provide what we may need to know.
One more tip is specific to the square ND filters and their holders. Make sure your filter mount gasket is in good shape to guard against light leaking in behind the filter. You’ll see it right away if it isn’t tight enough.
How Slow Can You Go?
Whenever considering photographic extremes, you pretty much have to start experimenting with your own equipment. Take good notes of what you are doing and all the variables involved.
Using ultra long exposure photography gear like ND filters, camera mounts, and sunshades, you can capture amazing images in any scene brightness level.