Long exposure photography has become very popular in the last couple of years, getting a lot of coverage in landscape photography magazines and on photo sharing websites.
With the ever-increasing number of options for 10-stop neutral density (ND) filters on the market, there has never been a better time to give it a go.
However, taking photographs when using such high-density filters gives rise to a set of problems that you may not have previously considered, so this article is intended to give a few useful tips to get you started.
1. Tripod
While a tripod is considered the most important bit of kit for any landscape photographer, it is even more so for long exposures and the use of ND filters. Your exposure can easily extend past 2, 3 or even 10 minutes (I once did a shoot of South Parade Pier doing a 17 minute exposure). YOU NEED A TRIPOD.
One slight bit of wind, and your image is ruined. Some people prescribe to hanging a bag from your tripod for ballast weight. However, I think it can often act like a large sail and cause even greater instability. Get a good tripod and get it close to the ground, if you can.
2. Focus First
Given that you are putting a filter on your lens, there is a good chance your camera will not be able to focus. So focus first, put your lens (or in camera if this is an option) into manual focus, then put your ND filter on.
3. Viewfinder
You will probably want to use your live-view option (if you have one), when taking landscape shots. I know that I do all of the time. But one thing you may want to take into account, is that (especially on older model cameras), the viewfinder window is still open. And will let light in and onto your sensor. This will ruin your image. Some cameras come with a little rubber closer. Or simply put a bit of cloth over the viewfinder. This will stop unwanted light getting through.
4. Bulb Mode
For exposure longer than 30 seconds, you will need to put your camera into "BULB" mode. Switching to Bulb enables you to open the shutter for longer that the camera will go by itself. This means;
You will probably want to get a remote shutter release. These are fairly in-expensive and means that you do not have to hold the shutter down manually.
You will need a way of calculating the amount of time to have the shutter open. There are a number of good apps that can do this for you. Simply put in a base exposure, and it will calculate the extra time required, once your ND filter is attached.
5. The Right Conditions
The best conditions are when there are dappled clouds and strong winds (See Tip 1). Shooting near water - movement would be advantageous. If there are no clouds or no wind, there will be no movement in the image, therefore no interest. You may as well shot with a normal exposure.
6. Hot Pixels
Even at low ISO, super long exposures can introduce noise in the form of hot pixels. You may not be able to see these when viewing the results on the LCD screen of your camera, but when viewed at 100 % on your computer monitor, you may find a number of bright red/green/blue pixels in your image.
An effective way to remove them is to take an exposure of identical length, at the same ISO, with the lens cap on. The hot pixels will be identical in all shots, almost like a finger print of your sensor, so by replicating the exposure with the lens cap on, you will generate an entirely black image, with the same hot pixels, to subtract away from your chosen image during post-processing.
7. Colour Cast
Some brands of filter are known to leave more of a colour cast on the final image. This is a great reason (one of many) to shoot in RAW, as the colour casts can often be corrected during post-processing. Sometimes, for particularly long exposures, it may just irreversibly compromise an image and, in those instances, a black and white conversion is often the best way to overcome it.
8. Composition
A long exposure does not make up for poor composition. In fact, the you will probably be even more frustrated at the resulting photograph given the additional effort required to take and process it.
Conclusion
Whilst I have discussed quite a few additional points to consider when taking long exposures with high-density ND filters, you soon learn to adapt them into your own work pattern that becomes routine. I find that taking long exposures often requires more planning, thought and processing than with my other photography, however the results can be breathtaking and are often worth it.
Long Exposure Photography is a very popular and I do have a few workshops on this subject, running at least once a month. Please take a look at my events pages for details.
If you have any additional tips or issues that I haven’t mentioned here, I’d love to hear them in the comments.
In the meantime, have a look at my video on Long Exposure Photography where I take a 17 minute exposure;