Using a 10-stop ND filter To Take Long Exposure Images

Kelli Cleveland studios Miami photographer

I’ve been working through taking landscape shots lately, and though I’d take a break from the basic stuff, and write and article about something fun to play around with – get away from all the Aperture, Shutter Speed, and ISO stuff – HAHA Yeah right.

Anyway…

If you aren’t familiar with this type of filter, it’s basically a very strong neutral density (ND) filter which reduces the amount of light hitting the camera’s sensor by about 1000 times. ND filters are very common but they are typically only 3-stops in strength (reducing the amount of light by 8 times) so a 10-sop one is pretty extreme. But what else are you to do, when you want to take a long exposure shot, when it’s daylight?

The first thing is find a suitable composition as you would for any shot. I wanted to achieve the misty water look so I found some moving water. In Miami, that isn’t hard to do.

*It is very important to use a stable tripod with this type of shooting. Any movement can mess up the shot.

Once I had the shot composed the next step is to work out what exposure will be needed. At this point I usually take a test shot without the filter and then multiply the shutter speed by 1000. (If using aperture f/11, ISO 100, and the shutter speed is 1/50, then the required shutter speed with the filter is 20 seconds (.02*1000)

Easy Peasy.

Here is a step-by-step guide

Step 1: Study the Weather

A day with a cloudless sky is a good day to drink a beer with friends, not to make long exposures. Likewise it cannot rain forever, so do not resign yourself to an afternoon with your  computer, PlayStation, or kids. You should study satellite images rather than the meteorological sites, trying to figure out if there is an incoming storm, or if the downpour is about to end. Watch to see which way the clouds are moving also.

Step 2: Visit the Location

Scout the location ahead of time, as you need a lot of time to find the perfect composition, or at least more than the time needed for a “short exposure”. In fact in a long exposure the world is completely different from how you see it with your own eyes. You have to try to see it with your mind, looking for a harmonious composition that includes moving subjects, trying to predict the direction of the clouds or the force of the sea. Try not to put the sun into the composition because its movement will ruin the shot and it will create area of overexposure that is not recoverable. If you cannot avoid the sun, wait for it to hide behind a cloud.

Step 3: Use a Tripod

Mount your camera on a tripod and install all the accessories such as the remote shutter release and the filter holder (if you are using drop-in filters). However, wait to actually install the filters. Very important!

Step 4: Compose the Image and Lock Focus

Refine your composition, focus on the subject and lock the focus. If you are using manual focus, just do it. If you are using the autofocus mode, you should focus by half-pressing the shutter button, and once the focus has been made, while still holding down the shutter button halfway, push the lever from Auto Focus to Manual. In this way, your camera will maintain the focus (or alternately you could use back-button focus).

Step 5: Set the Exposure

Now set your camera to Manual (M) mode or Aperture Priority (A/Av) mode. Then set the aperture to an appropriate value for the scene (for landscapes I suggest between f/8 and f/11) and take a “Test Shot”. The test is complete when you get a correct exposure. To determine if the exposure is correct, check the histogram (do not trust your display, it is too bright). It is true, there is no universally correct histogram, but there are histograms that are universally incorrect, namely moved completely to the right or left side (the image is respectively overexposed or underexposed). Once the test shot is successful, write down the shutter speed you used for that shot.

Step 6: Add Your Filter

Now add your Neutral Density (ND) filter. If the filter is very strong, for example 10 stops, you will not be able to see through the viewfinder or the Live View. Do not worry, because if you have followed the guide up to this point you will notice that we have already made the composition and the focus too. You are blind, but your camera will see everything perfectly.

Step 7: Change to Bulb Mode

Set the shooting mode to Bulb (B) in order to take over the thirty second limit of the camera. Do not change any of the other settings (ISO and aperture) used in the test shot.

Step 8: Take the Shot

It is finally time to take our long exposure shot. But how long will you to leave the shutter open? It is less difficult than you might expect. First of all, recollect the shutter speed that you noted down from the “Test Shot” you did in Step Five above. Now you must compensate by the number of stops introduced by the filter. For example, if your test shot was 1/15th of a second, adding 10 stops will get a shutter speed of approximately 60 seconds. There you have your shutter speed. No need to be stuck in the mathematics: on the internet you can easily find conversion tables and applications for your smartphone that will do the conversion for you.

Kelli Cleveland studios Miami photographer

Step 9: Check the Histogram again

Once you’ve taken the shot with the calculated shutter speed, check the histogram. If the new histogram is approximately equal to the one of the test shot, mission accomplished. If it is shifted too far to the right or to the left, repeat the shot again correcting the shutter speed.

Easy, isn’t it? Now fill your backpack with your camera and filters and go to practice in the field. For any doubt or if you need any help, don’t hesitate to ask questions in the comments below. Please share your long exposure images as well.

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