Monday, December 6, 2010
Photography: Long Exposure
My sister commented with the following request:
...your moving water photos are so awesome. Feel free to explain how you did that.
Since I enjoy training and explaining, I'll use her question as my first blog photo lesson. Let me know if you enjoy this because I wouldn't mind doing more of it, but only if I know it's helpful and not boring or annoying.
[DISCLAIMER: I am an amateur and don't always know the terms or best ways to approach different photos. There are plenty of more qualified people online who can explain these things, I'm just offering up my personal experiences and thoughts in case it is helpful for you.]
It's popular to take moving water photos with a long exposure time in order to give the water a smooth, soft appearance. When I say "long exposure time," I am referring to the shutter speed, which is the length of time the shutter is open. The long exposure allows the camera to capture the motion of the water from one point to another, which translates to a silky, matte appearance in many cases.
One thing about long exposure times is that there's more opportunity for shaking the camera and making the entire photo out of focus. This is why a tripod, or at least a level and steady surface, is useful (and often essential) for these types of photos.
You might also know that the longer the shutter stays open, the more light is allowed in. If you slow down your shutter speed without changing other settings on your camera, your resulting photo may become overexposed. To compensate, you will probably need to adjust the ISO and the aperture.
For starters, I always put the ISO (light sensitivity) down to the lowest setting (100 on my camera). Lower ISOs are more desirable anyway, so this is a perfect opportunity to use one. Then I adjust the aperture (by setting the f-stop to a higher number, meaning a smaller opening) to what works best with the shutter speed for correct exposure. Take some practice shots and see how it goes.
Here's an example. The above photo's settings are as follows:
ISO = 100
Aperture/F-stop = f/22
Shutter speed = 1 second
You can use this technique to soften moving water of any kind. I'd like to try it on the ocean sometime, but haven't had the opportunity.
The settings for the above photo are:
ISO = 100
Aperture/F-stop = f/11 (it had gotten darker by now so I didn't need it as high)
Shutter speed = 3.2 seconds
If it's too bright outside, sometimes it's just not possible to use a very slow shutter speed, even when the other two settings are adjusted. It's better to take waterfall photos in the shade or while it's dim outside. Low light was on my side on this trip to Silver Falls since it's winter and was approaching sunset.
Okay, I hope this wasn't too boring and maybe even helpful. Let me know if you try it!