How to Use Slower Shutter

A question that I’ve received a few times lately is “How do you use Slower Shutter?”

The confusion seems to stem from the fact that the app only asks you to input your base shutter speed and ND strength – and the folks asking me are used to taking the aperture and ISO into the exposure equation. It dawned on me that perhaps I was taking too much for granted and that others didn’t have my same approach to calculating a long exposure.

As such, here’s my suggestion for how Slower Shutter is intended to help you, followed by an example.

Step 1 – Establish your “base” shutter speed

You’ll first need to determine your shutter speed, aperture and ISO for your “normal” exposure. Remember these values. Do this WITHOUT the ND filter in front of  your camera.

Step 2 – Calculate your new shutter speed

Go to the Slower Shutter app and enter your shutter speed from step 1.

Next, enter the strength of your neutral density filter. You will see the new shutter speed appear automatically under the circular countdown timer.

If this new shutter speed is 30 seconds or less, you should be able to set this on your camera in Manual mode. For ISO and Aperture, refer to the values from step 1 above.

Optional Step

If your new shutter speed is greater than 30 seconds, set your camera to Bulb mode, dial in your settings for ISO and Aperture from step one and then use a cable release for the duration of the new shutter speed.

Press the Set Timer label in the Slower Shutter app and this time will become the value/duration for a timer. Next double tap on the center of the timer to start the countdown. If you need to start over before the countdown is finished, tap once on the countdown progress to pause and then tap Start Timer again. At this point, you only need to tap the countdown indicator once to get it started again.

Real World Example

Recently, I went on a trip to Yosemite National Park with the intention of getting some long exposure photos that I could share here. This is a photo of Tenaya Lake. Without a neutral density filter, I set my camera up on a tripod then set the camera setting to P to allow my Canon 6D to calculate the “proper” exposure. Please note, I set the ISO manually to 100.

Using the fully automated P mode on my camera, this is the photo that I got.

Baseline exposure in P mode. 1/80 sec at f/16 and ISO 100.
Baseline exposure in P mode. 1/80 sec at f/16 and ISO 100.

So this isn’t a long exposure at all. There’s way too much texture in the water for my personal preference. But I needed to take this photo so I could get an idea of what the camera thinks is the “proper” or baseline exposure. Next, I set my focus to manual mode and then I attached my Lee Filter 10-Stop (aka the Big Stopper) ND filter.

Now I’m ready to go over to Slower Shutter and figure out what my new exposure should be.

I enter 1/80 for the exposure time and 10 for the ND strength. The new shutter speed that I need is 13 seconds.

So I go back to my camera and put it in Manual mode. I change my ISO to 100 and aperture to f/16 – just as in the original photo. The only thing I need to change at this point is the shutter speed. Making sure the ND filter is on the camera is also a good idea.

Camera set to Manual mode. 10 second exposure at f/16 and ISO 100.
Camera set to Manual mode. 10 second exposure at f/16 and ISO 100.

Now we’re getting somewhere. Interestingly enough, my camera should have been set to 13 seconds, but I accidentally set it to 10 seconds. As a result, I had to do a little increase in Exposure in Lightroom to get the photo to the right exposure.

Note how in this second photo, the texture in the water is pretty much all gone, leaving you with a glassy reflection. You might also notice that the color has shifted decidedly more blue. This is the result of the 10-stop ND (neutral density) filter that I was using. The thicker the neutral density filter, the longer your exposure will be. The longer your exposure, the more color shift you are likely to encounter in your captured image. Be sure to set your white balance ahead of time as a point of reference when you process your photos later.

So there you have it. My approach for using Slower Shutter in the field to take long exposure photos. For more tips on long exposure photography, check out Scott Wyden Kivowitz‘s ebook Time is on Your Side.