Choosing the right interval for shooting HDR

What we need to determine now is the proper interval for shooting. Now, there's lots of factors with intervals. If I had a lot of clouds up there, I'd go with a shorter interval, so they looked more smooth. In this case, I don't. However, we are going to be coming up with a change in lighting conditions tied to the sun moving, and it's going to get a bit darker here. So I'm going to go with a relatively shorter interval. But remember, there are so many factors that impact this. Essentially with the interval, you need to think about how you're going to cover out the entire scene.

What this means, pretty easily, is that you need to cover the time. I want to shoot for about an hour's worth of coverage. And, the end result is going to be an animation, or time-lapse movie, that lasts about 30 seconds. Well, if it's 30 seconds long and I'm delivering at 30 frames a second, I'm going to need about 900 frames to cover that, give or take. We can speed things up or slow it down. I'm going to shoot for about an hour. So, if it's an hour, that's 60 minutes times 60 seconds in a minute.

I've got 3,600 opportunities to shoot, and I need 900. Well, that's pretty easy. 3,600 divided by 900 is 4. So my interval is going to be one series every four seconds. Now, the tough part is, is that since I'm shooting HDR, that type of interval is too tight. We can't actually pull that off. But, it's okay. With this more advanced intervalometer, what's going to go on, is that it's going to measure the time between the series.

If I was using a traditional intervalometer, I'd have to estimate how long that HDR series was going to take, and the problem with that is it could be very difficult to get the right time. What would happen is that it would eventually, as the lighting levels changed, take longer to shoot the HDR image, and the intervalometer could get out of sync. But because we're using an advanced intervalometer, one that's essentially controlling this through the data port, it's a computer running the camera, and the IPad has got more processing power than the computer in the DSOR.

So it could take more precise control, and it's basically going to be a master relationship to the camera. So, with that in mind, I could dial in my exposure, and my times, and let it rip.