The art of long exposure photography is a stunning way to capture your environment in a surreal way. It’s one of the only photographic styles that gives you the creative control to transform a scene in a way that is not visible to the human eye.
Whether your subject is seascapes, astrophotography, or simply experimental – long exposures require an added set of rules to retain image sharpness throughout the entire exposure. If you find that your photographs are still not sharp – even with a tripod – there may be other elements at play that are adding some unwanted camera shake.
Manual FocusWhen you’re performing a long exposure, you typically come across two situations: either you’re using ND filters to reduce your exposure during the day, or you’re photographing at night with little to no available light. In either instance, you are most likely photographing with very little visibility through your viewfinder, which makes it difficult for your camera to find a solid focal point.
When you use auto focus to select your focal point – whether you do it with the assistance of a flashlight or before you put your ND filters on – you need to
switch to manual focusing mode afterwards. If you keep you focus on auto, your lens will seek for a new focal point when your press down on your shutter, and it will not be able to lock in…giving you a blurry image. This becomes very problematic, especially when working with wide apertures.
If your lens comes equipped with image stabilization, vibration reduction, or some other feature that helps to reduce any unwanted effects from camera shake, you should disable it. If your camera is already properly mounted, then not only is this feature redundant, but it can actually decrease your camera stability.
The ideal situation to use this feature is when your camera is handheld and you’re trying to get a few extra stops out of your lens – it’s not designed to help when your camera is already stationary. Since you’ll always have your camera mounted for a long exposure, this feature will only be counterproductive to image sharpness.
Locking your internal mirror is one of the easiest ways to increase your long exposure clarity and sharpness. When you take a photo, the mirror inside your camera flips up, which produces some vibration. Under normal circumstances this will not affect your sharpness, but long exposures have a different set of parameters to work with – especially when it comes to eliminating camera shake.
Most digital SLR cameras have a feature that will flip your mirror long before the shutter opens, so any vibration from your mirror will have dissipated long before you start exposure. When you take a photo with mirror lock-up enabled, you’ll actually be pressing the shutter twice – once to flip your mirror, and again to open your shutter. Your camera manual will show you exactly how to enable this very helpful feature.
Remote Cable Release
Any kind of vibration can affect your long exposure – even the simple act of pressing your shutter button. With a remote cable release, your hand is physically away from the camera, so vibrations should be at a minimum.
Actually, a remote cable release is rather necessary if you’re working in bulb mode – meaning the camera isn’t automatically programmed to close the shutter after a certain amount of time. In bulb mode, the shutter is open for as long as you’re holding the shutter down since most digital SLRs can only be programmed for up to 30-second shutter speeds. Most long exposures can extend well past 30 seconds, so with a cable release, you can lock the shutter in place and let the camera do the work for you – especially since it would not be wise to hold your shutter down for minutes at a time.
A solid tripod or camera mount is the most important (and well-known) factor in retaining image sharpness during long exposures, so I won’t go into too much detail about that. Many entry-level tripods are made of flimsy materials, and are not designed to distribute the weight of a DSLR properly. This instability can make it extremely difficult to keep your mount sturdy, so you should never just assume that a tripod will always equal 100% camera stability.
However, what is commonly overlooked is not so much the tripod itself, but environmental factors that can add instability to your seemingly solid camera mount. If you’re experiencing a lack of sharpness in your long exposures, think very critically about your environment. Is there a strong wind that could be moving your camera? How about vibrations – passing traffic, footsteps, leg instability – what could possibly be moving your tripod?
So although your tripod may be of high-quality construction, environmental elements can also affect your image sharpness. A bit of critical thinking about your surroundings can go a long way when it comes to a solid mount.
Adjust Your Aperture
While this isn’t specific to long exposures, it’s definitely worth mentioning if you’re having issues with image sharpness. Each lens has a “sweet spot” f/stop where a certain aperture will produce the sharpest image – any aperture wider or smaller than this ideal f/stop will gradually chip away from the sharpness, with the most noticeable difference being at the extreme ends of your f/stop range. Although it varies for each lens, this sweet spot is usually either f/8 or f/11. So if you continually see your images looking a bit soft, try shooting at these apertures to see if it makes any difference in your clarity.
Of course, the quality of your camera lens will come into play as well – which may or may not be something you can control. However, if you follow these steps, you will definitely see an improvement in your overall sharpness of long exposure images.