We Simplify The Technical!

Lewis Kemper tells us how to capture the passage of time in a single image
and create stunning images of streaking clouds with long mid-day exposures.

*Please scroll to the bottom of the post for more images from our guest.*

Episode 177

Long Exposures Using Strong ND Filters
with Lewis Kemper

About ND Filters

  • ND (Neutral Density) filters allow less light into your camera to allow for longer exposures.
    – They come in a variety of strengths and can be stacked together to create a stronger filter.
    – Stacking several filters may produce lens flare from sunlight reflecting between the layers.
  • Quality ND filters are a neutral gray and will not affect the color of your image.
    – If there is a color cast, use your camera’s white balance to correct it.
  • Graduated ND filters reduce exposure by 3 stops at the top edge and gradually fade to clear about half way through.
    – Helps to even out a bright sky with a darker foreground.
    – Problem: anything in your foreground that pokes up above the horizon will be darker.
    – Effects from graduated filters can now be done easier in post-processing.  In high contrast situations like these, bracket your images.

“I’m trying to capture something that you can’t see,
I’m trying to capture the passage of time in an instant.”

Strong ND Filter Technique

  • Attach the camera to the tripod and compose your image.
  • Using Aperture Priority, spin the aperture until your shutter speed is at 1/125s. This is usually f/16 or f/11 at a specific ISO (start at your camera’s base ISO).
  • Switch to manual. Set the camera at that ISO and aperture and take a test picture for reference.  Adjust your ISO if necessary.
  • Turn off all buttons and switch to back button focus so you don’t accidentally change any settings while trying to put the filter on.
  • Set your bulb timer for 4.5 minutes. (This is the correct exposure for a 15 stop ND filter at these settings. A 10 stop filter at 1/125s only brings the final exposure to 8s, not enough time for streaking clouds.)
    – Exposure settings can also be determined using apps like PhotoPills and Photographer’s Ephemeris for other strength filters.

Long Exposures in High Heat

  • Leaving your camera sensors exposed for long periods of time in high temperatures can create hot pixel noise in the shadows as the sensors become too hot.
  • Long Exposure Noise Reduction will remove most of the color noise, but takes twice as long to process in camera.
  • Canon cameras seem to be more susceptible to hot pixel noise than Nikon. Sony AR3 also has a fair amount of hot pixel noise.

Streaking Clouds

  • For beautiful streaking clouds, the best time is mid-day.
  • Look for puffy clouds with blue sky showing in between.
  • Be aware of the direction of cloud movement. To avoid painting the sky white with clouds, be sure they are moving either towards or away from you rather than horizontally past you.
  • If color doesn’t add anything special to your image, consider converting to black and white to increase drama.
  • Sunset can also be a great time for long exposures, although you only have time for 1 or 2 shots.


“The tripod is the only piece of equipment you can buy
that will last you your whole photographic career.”

Gear Recommendations

Tripod – Feisol

  • Light enough for you to carry.
  • Tall enough for you to use comfortably without having to bend over.
  • Able to support your heaviest gear.


Mentioned on the Show

Hot Pixel Noise article

Finding Lewis





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Lewis Kemper Mono Lake
Lewis Kemper 4900-20191209-_WAL0689_BW-IG
Lewis Kemper 4010-180427-_DWA3646-Edit
Lewis Kemper online
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