Long Exposure Photography Lesson 2 (Of 4)

Long Exposure Photography Lesson 2 (of 4)

1) Filters a) Fixed neutral density (ND) filters b) Variable neutral density (Variable ND) filters c) Polarizing filters 2) Photographing motion blur: a) Waterfalls, ocean, etc. b) Car trails and other moving vehicles c) People moving through a static scene d) Panning 3) Assignment

Filters

After the discussion in Lesson 1 about extending the exposure time to achieve creative effects, the question remains: How do you get a long or relatively long exposure time in daylight? If you don’t have a filter to use, you will be somewhat limited, but you can get some extra exposure time just by adjusting your camera settings. Remember that the exposure triangle you saw in Lesson 1 has three sides – shutter speed (exposure time), aperture, and ISO. In order to lengthen the exposure time, the aperture and ISO sides need to be adjusted. Specifically, keeping the ISO at lowest native ISO (LNI) will maximize exposure time as well as image quality (remember, the higher the ISO, the faster the shutter speed and the noisier the image). In addition, decreasing the third element, aperture, can help to increase the exposure time (decreasing the lens aperture happens when you increase the f-number – larger f-number = smaller lens aperture). Because you are decreasing the area of the lens aperture that is letting light reach the sensor, it takes longer to get a correct exposure. To get a correct exposure after stopping the aperture down, you will need to lengthen the exposure time. For example, if you were originally at f/4, 1 second with the polarizer for a correct exposure, stopping down to f/8 is a total 2 stops less light coming in (f/4 to f/5.6 = 1 stop; f/5.6 to © Beth Ruggiero-York f/8 = 1 stop). Because you have eliminated 2 stops of light with the aperture change, you now need to add 2 stops of exposure time – 1 second to 2 seconds to 4 seconds. So without filters, set your camera at LNI and a high f-number, and then determine the exposure time needed for a correct exposure. The larger the f- number, the longer the time.

What about filters?

There are lens filters that can help you increase your exposure time much more than just adjusting your camera settings. The most basic is a polarizing filter. If you have one, you have probably noticed that it reduces the amount of light reaching your sensor and therefore increases the exposure time by about 1.5 to 2 stops, depending on the specific polarizer you are using. This can be troublesome when trying to shoot wildlife or any action subjects with a polarizer. On the other hand, though, it can give you a little boost for long exposure photography in a pinch. The best filter choice for long exposure photography is the neutral density (ND) filter. ND filters are gray filters designed to reduce the intensity of all light reaching the sensor in order to increase exposure times without affecting the color of the image. Available in different styles – circular ones that screw onto the lens directly or square ones that mount in a filter holder attached to the lens. They are available in different densities that cut light transmission by a certain number of stops.

Circular ND Filters of Various Densities

The table below shows the translation between the filter’s optical density (column 1), the ND filter number notation, the reduction in number of f-stops (higher f-number) (column 3), and equivalent shutter speed (column 4).

ND Filter Optical ND Filter Light Reduction Shutter Speed Density Number (number of stops) (seconds) Notation No Filter No Filter 0 1/60 0.3 ND ND2 1 1/30 0.6 ND ND4 2 1/15 0.9 ND ND8 3 1/8 1.2 ND ND16 4 ¼ 1.5 ND ND32 5 ½ 1.8 ND ND64 6 1 2.1 ND ND128 7 2 2.4 ND ND256 8 4 2.7 ND ND512 9 8 3.0 ND ND1024 (aka 10 15 ND1000)

The circular screw-on filters can be stacked on your lens to get their cumulative effect, though you do risk vignetting in your image. Another option is the variable neutral density filter, which is a circular screw-on filter that allows you to “dial in” the desired number of stops of light you want to reduce, usually from 2 to 8 stops of light control, but at wide apertures, there still is the risk of vignetting.

There are many companies that manufacture circular polarizing filters and circular ND and variable ND filters of varying quality and price. If you are in the market for a circular filter, try to find one that is high quality glass. The quality of the glass will affect the quality of your image. © Beth Ruggiero-York

That said, my preferred choice is the rectangular filter mounted in a holder that attaches to your lens. While not as convenient and quick to mount as the screw on filters, the risk of vignetting is eliminated. Lee Filters makes two square filters and corresponding filter holder that I consider indispensable for long exposure photography during the day – they are called the “Big Stopper” and the “Little Stopper”.

The Big Stopper is a 10-stop 3.0 ND filter for daylight images to get the maximum effects of a multi-second exposure. For example, if you photograph a scene properly exposed at 1/50 second, then using a 10-stop ND such as the Big Stopper will allow you to shoot the same scene at 20 seconds.

The Little Stopper is a 6-stop 1.8 ND filter for daylight images to get less blurring/smoothing effect than the Big Stopper (4 less stops). If you photograph a scene properly exposed at 1/50 second, using a 6-stop ND such as the Little Stopper allows you to shoot the same scene at 1.3 seconds.

If you don’t already own an ND filter/filters, it is an additional investment in your camera gear, but it will vastly expand the creative possibilities of your images in addition to the fun you have shooting!

Below is an image taken at f/11 and then again at f/16, 8 seconds and 20 seconds, respectively, with a 10-stop ND filter (the Lee Big Stopper). Without the filter, the exposure was 1/160 second, f/8, at ISO 100. Adding 10 stops in time and aperture gave an exposure of 8 seconds at f/11. I then took one stop from the aperture (f/11 to f/16) and added 1 1/3 stops to the exposure time (8 seconds to 20 seconds) to achieve more of the long exposure effect on the water and clouds and to add more light to the exposure (the extra 1/3 of a stop).

8 seconds, f/11, ISO 100

20 seconds, f/16, ISO 100 © Beth Ruggiero-York

In the Field in Daylight

In the field with digital cameras, the photographer can see the image on the rear LCD right away and choose the appropriate number of stops/appropriate filter for the scene by first knowing the best aperture to use for the desired depth of field:

1. Put camera in aperture priority mode (this will not work when we start doing long exposure night photography because the light meter in your camera doesn’t work when it’s dark); 2. Determine the correct exposure for the ambient light at the desired aperture (ISO should be at the lowest native ISO for your camera – i.e., Canon is ISO 100, Nikon is either ISO 64, 100, or 200, depending on the model); 3. Add the filter, switch to manual exposure mode, and increase the exposure time by the number of stops of the filter (if you are using a polarizer, start with 2 stops and check the exposure); 4. Take a test shot to see if the effect is as you wanted and adjust with aperture or a different ND filter if needed.

NOTE 1: As we will discuss later, filters should not be used for night scenes.

NOTE 2: A big problem with long exposures during the day, especially midday, is ‘light leak’ – stray light coming into the viewfinder during the long exposure. Light leak causes irregular color toning in the image that is difficult to remove in post-processing. To prevent light leak, cover your viewfinder with a piece of black tape (some cameras have a switch to the side of the viewfinder that closes it; check if your camera has that feature). It is important to know that light leak does not happen with mirrorless cameras!

Photographing Motion Blur

• Water – Waterfalls, ocean, rivers, etc.

Even though we are shooting still images as opposed to video or timelapse, long exposures allow us to imply motion in a variety of subjects. The most basic of these subjects is moving water – waterfalls, ocean waves, and other water scenes. By using a long exposure when photographing moving water, the motion is recorded over a longer period of time, resulting in a softness and smoothness that the eye would otherwise not perceive. For many photographers, this effect is most intriguing on a waterfall, but extending it to swirling oceans, running streams, or any other moving water increases the possibilities.

Below is an example of photographing a waterfall at different exposure times without the use of a filter. If I had a ND filter at the time, the effect would have been 10-fold.

1/10 second, f/11, ISO 100 No filter Nikon D300S, Nikon 16-85mm f/3.5-5.6 @ 24mm effective focal length

Only one tenth of a second was needed to begin to get some of the blurring effect on this waterfall in Vermont.

1/6 second, f/8, ISO 100 No filter Nikon D300S, Nikon 16-85mm f/3.5-5.6 @ 24mm effective focal length

1/4 second, f/18, ISO 100 No filter Nikon D300S, Nikon 16-85mm f/3.5-5.6 @ 24mm effective focal length

4.0 seconds, f/16, ISO 200 Variable ND filter @ 8 stops Nikon D800E, Tamron 28-300mm f/3.5-5.6 lens @ 44mm

Reducing the light by 8 stops in this sunset shot allowed the motion of the ocean to extended to a 4-second exposure. © Beth Ruggiero-York

25 seconds, f/2.8, ISO 200 Variable ND filter @ 5 stops Nikon D800E, Nikon 14-24mm f/2.8 lens @ 17mm

Because this image was shot after sunset during civil twilight (about 20 minutes after sunset), only 5 stops of light reduction were needed to take the exposure time to a desired level of 25 seconds. The longer exposure gave the effects I wanted in both the water and the clouds. It also smoothed out the reflection of Venus in the water. Typically during daylight hours, 10 stops would have been needed to get to 25 seconds of exposure time.

The amount of exposure time you use is purely an aesthetic choice. Some photographers prefer less of the effect while others prefer the maximum. As I mentioned above, an important advantage of the ND filter for light reduction as opposed to simply narrowing your aperture without a filter or with just a polarizer, you are able to dedicate the aperture to control your depth of field © Beth Ruggiero-York rather than the exposure time. In other words, you gain creative control in more ways when using ND filters.

• Car Trails and Other Moving Vehicles

The implied motion effect of cars and other moving vehicles is usually referred to as “trails”, such as car trails, which consist of red or white streaks (red if the cars are moving away from you or white if the cars are moving toward you). Of course, you can also get both red and white if you are photographing a two- way road with cars moving in both directions. When photographing other types of vehicles, such as trains or busses, there is the chance for more colors than just red and white.

This type of long exposure photography involves finding an ideal location where the trails will be an interesting addition to the rest of the scene. Often, the trails can be used as the “leading lines”, leading the viewer’s eye into and through the image. With car trails, you have the possibility of winding streaks if your composition includes a winding road, but this would not be typical for train trails.

Car trails and other vehicle trails are photographed after dark, so it is much easier to get the long exposure time you need. How long does it need to be? That depends on the composition. If there is a long road in the image, and you want car trails to extend most or all of the distance of the road, then longer exposure time will be needed. Initially, there may be some trial-and-error before you settle on the exposure time needed to cover what you want. If there is a shorter piece of road in the image, less time will be needed. The procedure for lengthening the exposure time using aperture rather than filters is used.

51 seconds, f/16, ISO 100 No filter Nikon Df, Nikon 24-120mm f/4 lens @ 62mm

This image was shot at night, so no ND filter was needed. By stopping the aperture down to f/16, I was able to get the exposure time needed for enough uninterrupted car trails. When photographing car trails, some trial and error is needed to see how much time is needed for the specific scene and composition so that the trails do not appear “choppy.”

8.0 seconds, f/9, ISO 100 No filter Nikon D810, Sigma 35mm f/1.4 Art lens @ 35mm

Another example of a train crossing the bridge at Tempe Town Lake in Arizona, this image shows how too short of an exposure time results in the trails being “cut off” too soon (upper right of image). One more stop of light by decreasing the aperture would have allowed for the complete trail.

People Moving through a Static Scene

Often called ‘ghosting,’ long exposures involving people moving through a static scene is another form of motion blur. As with the other forms of motion blur discussed above, it communicates in a still image the movement that is actually taking place. To achieve the ghosting effect, the subjects to be ‘ghosted’ need to be actively moving during the exposure against a stationary background. Busy city scenes with pedestrians make good subjects as do musicians playing their instruments rapidly. Because the rate of movement of the subject(s) (e.g., pedestrians, arms moving while playing a violin, etc.) varies from scene to scene, experimentation is needed to achieve the degree of the desired effect. If the exposure time is too long, figures moving through the scene will ‘disappear’ from the image! As with all long exposure photography, this is your chance to be as creative as you can in coming up with compositions. Sometimes you will have a preconceived idea of an image, but there will also be the times when an unexpected scene provides the perfect setup. Remember to be open to these spontaneous situations at all times. For these types of images shot in daylight, a filter will be needed. At night, a filter is not needed.

1/60 second, f/1.4, ISO 5000 No filter Nikon Df, Sigma 50mm f/1.4 lens

This night street scene was shot at Roosevelt Row in Phoenix, Arizona. I split the image into two distinct sections – one with moving people, the other with a fixed wall painting. Interestingly, the wall painting itself is conveying a moving figure, in this case a musician. I was handholding the camera for this shot, so a balance needed to be struck between a short enough exposure for sharpness in the right half of the image and a long enough exposure to ghost the movement of the people. One sixtieth of a second accomplished that. © Beth Ruggiero-York

1/3 second, f/7.1, ISO 100 No filter Canon PowerShot G1X

While only a small part of the image here is ghosted – the musician’s arm and hand – because that is the portion of the image to which I wanted to direct the viewer’s attention. As in the figure above, because I was handholding the camera for this shot, a balance needed to be struck between a short enough exposure for a sharp background and a long enough exposure to capture the movement of the cellist’s arm and hand. One third of a second accomplished that.

6 seconds, f/6.3, ISO 100 No filter Nikon D800E, Nikon 28-300mm f/3.5-5.6 @ 48mm

Another type of ghosting subject was used for this image. The moving boats in the canal in Venice, with the church across the water as the stationary background. It is important to remember that, in all ghosting shots, a strong stationary background is essential.

Panning

The opposite of the ghosting effect described in the section above, panning is a creative method for which you move the camera through the scene in a long exposure, blurring the subject against a blurred background. The secret to a successful panning image is a lot of practice… or a bit of luck. A successfully panned image gives a feeling of movement; it creates an artistic abstract image.

Here are the steps to follow for panning:

1) Consider your composition and what you hope to achieve. Position yourself to meet that expectation. Consider the background (that will be blurred) – monochrome or plain backgrounds do the best job of enhancing your subject. Also make sure your subject will not be obstructed at any point during your panning as this will interrupt the flow of the image. Position yourself so that the panning movement is in a direct parallel to you. 2) Start with a slower exposure time (shutter speed) than you would normally use. Start with 1/40 second and then move to slower ones as you become comfortable. Depending on the ambient light, you could end up between about 1/60 and 1/8 second. You will need to shoot multiple images to get the “right” one. 3) Use the Shutter Delay mode on your camera to delay the opening of the shutter by a few seconds. Then begin the camera movement, starting during the ‘shutter delay’. 4) Continue to pan even after the shot has completed. This will ensure that the motion blur is smooth from start to finish in the image.

1 second, f/22, ISO 100 Polarizing filter Nikon D7200, Nikon 28-300mm f/3.5-6.3 @ 42mm

1/8 second, f/40, ISO 100 No filter Nikon D7000, Tamron 18-270mm f/3.5-6.3 @ 250mm

Abstract examples of panning in which both subject and background have been blurred.

ASSIGNMENT

Select two of the motion blur subjects discussed in this lesson (waterfalls, ocean, etc.; car trails and other moving vehicles; people moving through a static scene (ghosting); panning) and shoot three of the same image (i.e., same waterfall, same street scene, etc.) of each at different exposure times. If you have a polarizing filter or ND filters, be sure to use them for at least two of the shots. Submit the group of three that you think is the best.

Be sure to pay attention to good photography practices – use a sturdy tripod, get sharp focus, and consider your composition.

When you submit your images, include the camera settings you used for each one (i.e., exposure time (shutter speed), aperture, ISO) and what filter(s) you © Beth Ruggiero-York used. Also include any comments or questions you had while making the images.