This is the sixth (and last!) chapter of the series Long Exposure Photography. In previous episodes:
In this week's chapter about Long Exposure Photography (the last one!), we'll talk about a few things that we have left and were hard to fit in previous posts.
How long the exposures should be?
If there's just one thing I want you to take from this series, is this: it's crucial that you know how long the final exposure should be beforehand.
Settings and ND filters need to be adjusted to achieve that exposure time and not the other way around. Choosing one or another duration will drastically change the way our image will look like.
How long the exposure should be? This is highly dependent on the subject, and on what you are trying to create!
Let's take a look at a few different sample scenes.
I'm sure you've seen those "silky" images of waterfalls or rivers before. You can create that effect with a long exposure of just 1 or 2 seconds. If your camera has IBIS, you might even be able to take the shot handheld!
A several-second-long exposure will start to hide the movement of the water and become a surface instead.
Take the image above of Latourell Falls, in the Columbia River Gorge, as an example. This exposure was about 1 minute long, and all trace of water movement is lost. It shows as a white curtain, creating an abstract effect. Some people thought it was a light leak when the first saw this image.
This shows, once again, how important it is to choose the exposure time you need to make the image you are after.
Sea (beach, rocks...)
The same principle applies here. If you want to show some of the movement of the water, you are going to need a "short" shutter speed of 1 to 2 seconds.
When you increase your exposure time to several minutes, you start getting an ethereal look. Waves breaking in the rocks become mist, while on the beach they turn into abstract patterns.
Look at the two images above.
In the first one, the waves were breaking against the rocks where some sea lions were chilling. This exposure was 5 minutes long, and that completely transformed the waves into some kind of mist. Fortunately, the sea lions didn't move much during those 5 minutes, otherwise they would've looked like ghosts.
The second one was much shorter, 1 minute. That was enough to remove almost any trace of the waves breaking on the beach. In this case, they became a white layer that marks the end of the land and the beginning of the sea.
Compare those two images to the next one:
Here, I wanted to show waves as they broke on the beach. You can still tell what they are and the movement they were making. It adds motion and a bit of drama to the image.
Different exposure time for the same composition will create a completely different image.
I can't say it enough: the exposure time is the key to what your long exposures will look like.
I think you already know by now what I'm going to say: the exposure time will dictate how clouds look in your image.
Clouds do come with a new variable that can make guessing the exposure time much more difficult: they move at different speeds, depending on the wind.
Sometimes, 1-minute-long exposure might look almost like regular shots if there's no wind. Often though, just a few seconds will add a lot of drama showing the clouds moving across the sky.
These two exposures I'm showing as examples were, respectively, 7 and 4 minutes long.
If you've ever shot stars at night, you know your exposure times should be kept shorter than 15-20 seconds if you want to get the stars as sharp fixed points in the sky. Any longer and you'll start recording their trail.
But what if you want to show that movement, though? How long does a long exposure have to be to create a star trail?
Take this exposure of the night sky I took in Nevada as an example. I had the shutter open for 45 minutes.
You can get star trails with shorter exposures, like 30 or even 15 minutes (see: Photographing Star Trails from the backyard).
Long Exposures at night
Night photography is a whole topic in itself. It comes with a lot of new challenges, and we could fill a whole book talking about them.
Most of your night shots will be long exposures, so I thought we could talk really quick about it.
How to meter
Composing an image through the viewfinder might be hard or even impossible with a film camera, unless the subject is illuminated or we can use a flashlight to temporarily light it up.
How do we meter something that we can't see?
Digital is straightforward: take a test shot, check the histogram, and repeat until you get the desired exposure.
If it's very dark, you want to have your lens wide open and the ISO as high as it can go without totally destroying the image. Once you get the histogram where you want it to be, you can step that lens down and lower the ISO. Of course, you'll need to adjust the shutter speed when you do this.
What about film? Well, my advice here is to use a digital camera to meter for the scene. It is by far the best way to do it, in my opinion. Don't forget to apply compensation for the reciprocity failure!
Do we need ND filters?
It depends. If you are shooting in an urban area, you might need ND filters even at night.
If you are out in the country though, chances are you won't need any ND filter to make long exposures for several seconds and even minutes.
Careful with lights (cars, flashlights...)
If you aren't using ND filters for your long exposure, you need to keep in mind that your camera is "naked" and any light could ruin your image.
Think car lights, for example. A passing car is your worst enemy out there, only second to your very own flashlight.
My advice here is to have a cloth always within reach if there's any danger of getting unexpected new light sources. If you see a car approaching, you can just cover your lens and wait. This will still ruin long exposures of just a few seconds, but if your exposure is longer than, say, 1 minute, you can just add whatever time you were covering the lens for to the end of the exposure.
Extreme Long Exposures
The longest exposure I've ever taken was almost 8 hours long. This is nothing compared to long exposures so extreme that they last several days.
These kind of exposures are impossible with a regular camera. Not even a 15-stop ND filter can block the light so much that you can leave your camera taking the photo for days.
This is almost pinhole photography exclusive territory. Pinhole cameras are just boxes with a tiny hole that lets the light in. They don't have lenses per se, but the equivalent aperture of one of these cameras can be as crazy as f/256 or f/512.
Example of an extreme long exposure, using Ilford Pan F exposed at ISO 50 and a pinhole camera with an aperture of f/256:
Sunny 16 rule: 1/50th of a second for f/16 on a sunny day. There are 8 stops from f/16 to f/256, so the exposure would be of 4 seconds... without any filter! If we use a 15-stop ND filter, the exposure time will go all the way up to 68 hours! Without counting for the reciprocity failure! Following Ilford's formula, it'd be of 252 hours, or more than 10 days!
This is it
I hope you've learnt something with this series. I love long exposure photography because it allows me to create something that doesn't necessarily exists, and you should take it as just that: another tool for your photography belt.
If you have any (any!) questions about long exposures -on film or digital- don't hesitate to contact me or leave a comment below.
Remember that you can find the 6 chapters of this series following the link down below:
Long Exposure Photography: the book
I'm currently working on an eBook about Long Exposure Photography. It will be mostly a compilation of this series, with additional information about some topics I would've loved to talk a bit more about, and with new sample images.
The release date will be Sunday, September 30th, only for subscribers of my newsletter! If you want your free copy, join now!
The book will be available to the general public a few weeks later, but I'm sure you won't regret joining us :)