STOPPING BIRDS IN FLIGHT MOVEMENT BY BUMPING ISO - PART 1
In a conversation recently the question came up about what settings are needed for fully stopping movement, what to use to show some movement, how far do you go with an increase in ISO to get a fast shutter speed and when you increase the ISO for getting a fast shutter speed what changes in the image occur and are there settings available in the newer cameras that will correct this?
Regarding the first part of this with stopping movement in a subject my answer today is different than it was a couple of years ago. For quite a while, I would tell people on workshops and when doing a program or critique that my preferred shutter speed for shooting birds in flight and other fast moving wildlife was 1/1000th of a second. That has changed with being able to bump the ISO up a bit while still maintaining image quality. If a subject is moving at a moderate rate 1/1000th is fine, but my preferred speed now is 1/2000th with 1/1600th being adequate. If I'm able to get even faster than that I'll take it. I even have some shots that were shot at 1/4000th and faster. As light fades in the evening if the shutter speed drops below 1/1000th the subject needs to have very little movement to it and once your shutter speed gets below 1/640th of a second it's close to time to calling it an evening.
While some shots taken at the slower shutter speeds may be more than adequate for some photographers, when images are selected to be shown to others those at the slower shutter speeds tend not to be included in the best shots of the day. That is unless you intend for the image to show a little bit of movement which can be a great shot if handled properly.
Sometimes, even 1/1000th will work to accomplish either of these settings depending on how fast the subject is moving. The first shot below of the snow goose flapping its wings was taken at 1/1000th of a second but there's a nice bit of blur to show movement in the wings (intended) but you see sharpness in the splashing of the water and the gooses head. The sandhill crane was also shot at 1/1000th but because its movements were not as fast the the gooses wing flaps a sharper image resulted. With a bird in flight, part of the sharpness can be attributed to how good you are at maintaining a steady pan with the subject as well as if it's soraing or flapping its wings. It takes time and practice, but keeping the subject in the same place in the viewfinder is key for getting a sharp image as this means the camera is panning at the same rate as the subject is moving across your plane of view.
Subject size also comes into play with stopping movement. The larger the subject the slower its movements will be, thus a slower shutter speed will be fine for stopping the action. Conversely, the smaller the subject the faster and more erratic the movement. Even with a larger subject, a very fast shutter speed might be desired if lots of detail is desired, especially in the primary wing feathers of a bird or water splashing.
Showing that an extremely fast shutter speed can be used is the example with the roseate spoonbill. It was taken at 1/8000th of a second with an ISO of 500. We were on a small boat so to make sure all flight shots were sharp, the ISO was increased. More often than not, I'll only suggest going to 500 for the ISO but there are times going higher has to be called for. The shot of the snowy egret was taken at 800 ISO because of how dark the setting was and a fast shutter speed was needed because of the need to freeze any movement, in this case raising its crest. The resulting shutter speed with the 800 ISO was 1/2000th.
Some images are easier to expose for than others. If there is a good bit of contrast or colors, such as the image below of fall color and snow, you have to get it right the first time. Pick and area of the image that has everything in it - colorful trees, blue sky, white snow - and find the exposure that works best for this section and use it for all of the images in the sequence. You can take a second or third series with bracketing but more than likely the best one will be the original one. Slight temperature and saturation adjustments can be made once the images is put together.
The less light there is and the sharper you want the image, some experimenting can take place, especially if you have a newer camera body that's capable of handling very high ISO. Wanting to see what my 5D Mark III body could really do at extreme ISO, I went as high as 6400 while in Bosque and the shot below shows that it does quite well at that high level. I could have gone a bit lower as the shutter speed was 1/5000th but the detail that resulted showed it was more than worth the extra shutter speed. Lots of birds in flight techniques will be discussed during my two workshops to Bosque del Apache later that year. There are still a couple of spots available if you're interested in seeing what you can do with birds. The Florida trip in late March also has space as well.
As you can see, there is no perfect answer for for the first part of the conversation, but with what cameras can do now, I would say it's safe to use most any camera at around 400 or 500 ISO in order to get as fast of shutter speed as possible, preferably at least 1/2000th of a seccond. You can never have too fast a shutter speed when it comes to freezing the movement of wildlife. Part 2 will talk about any resulting noise that comes with using a higher ISO and how to get rid of it. Detailed step instructrions will be covered.
12 image panorama - exposure set for gold trees in foreground