Like how I change the title of Friday Foto Talk when I’m late! Let’s talk long exposure! It’s a whole world of possibilities to be sure, where reality can be stretched and manipulated with your camera. But going beyond the realm of the real world is not the only thing you can do with long exposure. For me, it’s another way to try and get at the character of a place or subject, and of a particular time and mood in that place or with that subject. Does that make sense? This is where I’m at with photography. Trying techniques to get certain looks is not.
The first thing people think of when they want to go long is what filters they need to buy. This is typical in a capitalist world: “What else do I need to buy?” The fact is that your camera and lens, combined with a good choice of what light you shoot in, will get you going on long exposures in no time, no extra money out of pocket.
But it is true that you’ll want to get a filter or three in order to really get into long-exposure photography. The neutral density (ND) filter is commonly used to lengthen shutter speeds. These are made of darkened glass or plastic that blocks some of the light from reaching your lens.
But hold on! Do you have a circular polarizer? If so, it can do double duty and block some light, giving you longer exposures. Depending on your polarizer, it can block as much as two stops of light. Of course if you don’t want to polarize the light and reduce reflections while you’re shooting longer exposure, a polarizer is not the thing to use.
So while they’re not necessary to begin, ND filters are key to gaining a lot of control over how much light you stop. They also allow you to shoot with longer exposures even in bright natural light. A two or three stop ND filter is probably all you need, at least to start. But as always the correct advice depends on what kind of shooting/subjects you’re after. Many photogs. get a small set of two or three NDs.
You can get screw-in ND filters, which are accurate and easy to use. Buy the size that fits the largest lens you think you’ll use, and then get step-up rings to fit any smaller lenses you plant to use. You can also get rectangular ND filters (like graduated NDs) and place them in front of your lens, either in a holder or using your hand to hold it.
You can also get a vari-ND where you dial in (like with a circular polarizer) the right amount of light-stopping power. But those tend to cause pretty bad artifacts when you dial them down darker and/or the light is strongly directional. Then you can easily get ugly black bands through your pictures. They do work under many conditions however.
I do a lot of long exposure (LE), but not so much in bright conditions where I’m panning or blurring moving subjects. When I am doing that sort of thing, I often go for a wider aperture (f/5.6 or even larger). That’s when a small set of screw-in ND filters makes a lot of sense. But I’m usually shooting with fairly small apertures in lower light where a polarizer and lower ISOs are all I need. In fact my favorite time to do LEs is that moment in blue hour when no filters and ISO 100 or 50 yields the perfect long exposure.
I don’t usually want to go long in bright conditions or super-long in any daylight, where a dark ND filter is necessary. But if you want to try that, you’ll need an ND like the Lee Big Stopper, which blocks 10 full stops of light! How popular is this filter? I just checked B&H for the price, and despite the fact it’s $140, they are out of stock! By the way, it’s not a screw-in; it’s rectangular.
So what are the conditions where a major ND like the Lee become necessary? One is certainly when you want to have that very long exposure look while shooting into a setting or rising sun. If the sun is in frame (or behind a thin veil of clouds), it usually doesn’t matter what you do, you can’t go very long without a serious ND filter.
For example, say you’re near a large body of water, with at least some ripples if not outright waves. You want to completely flatten out the water for a surreal look (if you have a pier front and center it’s a perfect cliche!). But let’s say you cant resist! Well it isn’t happening without blocking at least 4 stops of light and usually more. And in that situation where you’re shooting into the sun, you want a single filter (no stacking) to minimize flare. A vari-ND in here will almost always produce artifacts.
There are plenty of myths out there regarding longer exposures. (It’s funny but photography is becoming littered with misconceptions) One example: You’ll hear people say the colors are more vibrant and “colorful” when you go long. Something to do with more light collecting on the film/sensor, resulting in richer color. That’s not really true, though it can seem that way under certain conditions.
When the light is low our eyes start losing the ability to perceive color, and a long exposure is like dialing that light back up so we can perceive it again. But it isn’t a linear effect, and as usual the look you get, the richness of the color, depend mostly on light conditions, not on how long you go. Also, when people go long they often wind up on the right side of the histogram (brighter). Then when on the computer they darken, the colors appear to be richer and more saturated. And they’ll add contrast, which saturates colors as well. It’s not the long exposure giving them rich colors but everything else!
You’ll find when going long that there can be unintended consequences. Continuing with the example above, where you’re shooting very long over a body of water or other reflective surface, the reflected color can get washed out. I have to admit I don’t like that look; too unnatural. If your goal is to increase color saturation, going too long can actually have the opposite effect.
In general about 20 seconds is the limit where more is not getting you a different look in your water texture-wise. There are a few exceptions. But like I just mentioned, very long exposures will give you a brighter water surface. And if you’re also using a graduated ND filter in order to block the light from the brighter sky, a super long exposure will yield an unnaturally brighter reflection off the water. Though I will often darken my skies to bring out details, I try to keep relative brightness between areas of the picture closer to reality than you often see in popular photos on the web.
I think many fans of long exposure go through a phase where they’re always trying to go longer and longer, simply for its own sake. This is a big reason Lee’s Big Stopper sells so well. Don’t get me wrong. I’m all for exploring the limits and experimenting with your photography. But at some point you have to pull back and ask yourself if you’re not losing sight of the objective – to capture a good photograph.
By the way, there is another way I get around using an ND (besides the polarizer). I only have a vari-ND and I limit its use). But I have one oversize graduated ND filter. I got it for my ultrawide lens, which has a big honkin’ front element. The filter blocks 2.5 stops of light and I just hold it up in front of the lens. But if I switch to a smaller lens for a shot of the sunset, I’ll sometimes use that grad. as a standard ND, since the darker half of it covers the opening for some of my lenses.
I can do this with my 50 mm. lens, and with my 24-105 f/4 for most of its focal lengths. Even if you don’t have a big ultrawide lens (but need a grad ND), you can buy one that’s too big for your lenses. Just one more way to postpone shelling out for a set of NDs, that is if you buy an extra-large rectangular ND like I did.
So to summarize, I would say if you want to show motion blur, pan, etc. in daylight conditions, then sure, get yourself a small set of regular ND filters. But if you simply want to do some long-exposure nature/landscape photography, picking the right light to shoot in (most important) combined with choosing the correct settings (lower ISO & smaller aperture) will give you shutter speeds that are long enough.
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