Focus on the blur
Posted 2/14/2014

I'll occasionally post shots such as the harbor seal photo above that generate questions as to how the shot was accomplished. I've talked in a previous blog post (see Give a man a fish...) about the settings I'll typically use when shooting condors, but in this post I'll concentrate on the harbor seal shot and another "misty water" shot.

One important thing to note about the shots in this post is that more or less everything in each shot is actually in focus. The reason that parts of the image (typically the water) look blurry (or misty!) is that those parts moved during the shot. The movement introduces the blur.

The longer the shutter stays open to get the shot, the more blur gets introduced into the parts of the shot that are moving.

Of course, another effect of keeping the shutter open for a long time is that more light gets in, which means you have to take steps to make sure that too much light doesn't get in and turn the whole image into an overexposed white. There are two approaches to that issue that I take, firstly I'll shoot a lot of these types of shot when it's almost dark and secondly, I have a Neutral Density (ND) filter that I can put in front of the lens to block out a lot of the light.

Finally, you need the camera to be on a tripod for these types of shot so that the camera doesn't introduce its own motion (and therefore blur) during the exposure.

Here are the examples, with details of the camera settings underneath

Camera Settings:
ISO 100
13 secs
f7.1
42mm

This image was taken about 20 minutes or so before sunrise, so I was able to use the lack of light to get the long exposure. This image is actually one wave coming in over the rocks. It was taking around 13 seconds from when it arrived at the outer rock until it finished washing around the rocks nearest to me, but the fact that the image is a 13 second exposure is based more on the amount of light at that time of day.

I don't have a great idea about what length of exposure will produce the best image, it all depends on the view, the height of the waves etc., so I'll keep taking photos as it gets brighter, shortening my shutter speed to cope with more light until I get down to around 2 seconds or so (at which time it's typically time to concentrate on the sunrise!) and then look at the images when I get home to see which ones worked the best.

Camera Settings:
ISO 400
3.2 secs
f7.1
100mm

For the harbor seal shot, I'm using my very dark ND filter (it's a 10 stop filter designed originally for taking photos of the sun or similarly bright events) in the middle of the day. It cuts out so much light that I can get 30 second exposures in the middle of the day if I use ISO 100 and a small aperture. On this day, the ocean was quite calm, so I was thinking that a 6 second exposure might be the way to go to get enough motion into the water, but the harbor seals wouldn't stay still long enough. They'd be up looking around at folks walking on the Pacific Grove Rec Trail, and when they'd do that, their motion would cause blur in the image too.

So, after watching them for a while, I figured I could get away with a 3 or so second exposure and did that. Of course, the seals continued to move while I was taking shots, so I had to take lots and eventually got some where they remained stationary (and therefore sharp) during the exposure.

Finally, I need to thank my friend Andy for the idea behind the seal shot as although I see seals all the time and like taking long exposure shots of rocks and water, it never occurred to me that these seals do good rock impressions and would lend themselves to this sort of shot until I saw him do it. Check out his work and tutorials at Photoshop Scares Me.
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