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Long Exposure Photography

March 14, 2017.

First of all, have you seen the new Turner sculpture we recently installed at the waterfall?  It’s a gorgeous depiction of two great blue herons that Mr. Charles Banks donated in honor of his wife, Mari Ann, to celebrate her recent birthday.  The Banks are long-time supporters of the Museum, Heron Society members, and have served diligently for many years on our Board of Advisors.  They also donated the waterfall, too, which was dedicated to their children and grandchildren in 2009.  I must say this water feature is a favorite for many visitors, and is one of my personal favorites.  Which is why it’s the subject of my latest photographic venture:  long exposure photography using a 10-stop neutral density filter.

Let me say that except for the very last photo, all the photos in this post are NOT post-processed.  As a general rule I always do some editing of my photos using Adobe Lightroom and/or Adobe Photoshop Elements.  But in order to show the photographic process, I’m showing you the unedited photos exactly as they were shot.  Here’s a test shot–notice the water is basically “frozen in time”:

Auto Mode, f/7.1, 1/200 sec, ISO 100, 22 mm

Here’s the same shot using a 10-stop neutral density (ND) filter.  An ND filter reduces the amount of light hitting the camera’s sensor, allowing you to leave the shutter open for a longer period of time.  There are many kinds of ND filters, but a 10-stop filter reduces the amount of light hitting the sensor by about 1000 times.  Why would I want to do that?  To make an artistic effect–it will blur anything that’s moving (like water) giving it a silky or creamy “texture.”  Like this:

Manual Mode, f/25, 59 sec, ISO 100, 22 mm

Here’s how I set up the shot:

  • Put in a fresh camera battery (long exposure shots use a lot of battery power!)
  • Used an 18-300 mm zoom lens (I kept the same focal length for each series of shots for consistency.)
  • Used a tripod
  • Camera set to Manual Mode (manual control of both the shutter speed and aperture settings)
  • ISO 100 (ISO is how sensitive your camera’s sensor is to light–the higher the ISO, the more sensitive to light–but that comes at a price since higher ISO numbers tend to have more “noise” or look “grainy.”  I chose ISO 100 which is the lowest possible setting and turned off the “Auto ISO” feature.)
  • After all test shots in Auto Mode to get an idea of “normal” exposure times, I switched the camera and the lens to manual focus.
  • Set the shutter to “Time” release mode (some people prefer to use “Bulb” mode) and used a remote release.  I used the second-hand sweep of my watch to time the exposures–which is why some shots have such odd times–like “59 seconds” instead of an even “60 seconds.”
  • After composing the shot, I used a piece of black tape to cover my viewfinder to prevent stray light from hitting the sensor (yes, I know there’s a plastic cover I could use, but I didn’t want take off the rubber eye guard since I switched back to the viewfinder every time I re-composed the shots)

This was my first foray into long-exposure photography so I did a lot of experimenting.  I’m sure I’ll improve with more practice!  For this next series, I recomposed the shot and tried an exposure around 2 minutes–hopefully to get a “smoother” effect of the water.   However, as I did a few shots, clouds moved in and you can see that even though the first two shots were virtually identical, the results were drastically different:

Overexposed shot (bright conditions), f/25, 119 sec, ISO 100, 28 mm

Underexposed shot (cloudy conditions), f/25, 120 sec, ISO 100, 28 mm

Good exposure (bright conditions), f/25, 86 sec, ISO 100, 28 mm

The 86-second shot was the best of that series.  Notice I had the aperture (lens opening) “stopped down” or closed up to a smaller opening at f/25.  The smaller opening allowed me to keep the shutter open longer to give a more “silky” appearance to the water.  (The smaller apertures also give a greater depth of field–but I’ll save that topic for another post!)  Generally, when doing long-exposure photography you should keep the aperture the same and just adjust the shutter times.  I know there are handy exposure charts and even apps for your smart phone to help you calculate proper exposure times based on the strength of your ND filter.  But you can do the math yourself–take the “normal” (without filter) exposure time, usually expressed as a fraction, convert the fraction to decimal form (easier to do the math), then multiply by 1000 (for a 10-stop filter.)  So for example, for a normal 1/50th of a second shot:  1 divided by 50 = .02, then multiply by 1000 = 20 second exposure using an ND filter.  For you math geeks out there, each “stop” photographically speaking represents a doubling in value–so 10 stops means 2 to the 10th power, which ends up being precisely 1024–but it’s close enough to just use 1000 when doing your calculations.  Often the “correct” exposure is a bit subjective anyway, and as the shots above show, calculated exposures go out the window when other variables change!

For this last series I zoomed in to the bottom part of the waterfall to emphasize the water.  I played around with the aperture just because I was curious to see what the extreme ends of the aperture range would look like.  I put in the second shot so you could see that lengthening the exposure to even just 1/20th of a second is not possible without over-exposing the shot (though I could have “stopped down” a lot more.)  For the third shot, 239 seconds (about 4 minutes) was probably too long an exposure, but at least it gave a nice silkiness to the water.

No filter, test shot, f/5.3, 1/250 sec, ISO 100, 56 mm

No filter, over exposed shot, f /5.3, 1/20 sec, ISO 100, 56 mm

With 10-stop ND filter, f/32, 239 sec, ISO 100, 56 mm

Same photo as above with adjusted contrast, brightness, sharpness

The final photo is the only photo that I edited in Adobe Lightroom–I increased the contrast, brightness and sharpness.  It’s much easier to make adjustments on an under-exposed photo rather than an over-exposed photo.  It’s purely subjective–some people may prefer the “softer” look of the untouched third photo, but I like the high-contrast look of the adjusted photo.  It still preserves the silky texture of the water while giving the static parts of the photo an edgy look with more depth.   I hope you enjoyed this post!  Cheers, Lisa


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