As regular readers will know, for the past several months I have been focused on photographing birds as part of my field work for an upcoming eBook on hand-held bird photography. Part of that field work has involved experimenting with various frame rates when photographing birds in motion. This, in turn, has been generating a good number of personal emails from readers asking about ‘the best’ frame rate to use. This article discusses some of the considerations when selecting a frame rate when photographing birds in motion.
NOTE: Click on images to enlarge.
Let me begin this article by stating that the answer to the question about what frame rate to choose depends on a number of interdependent factors. There is no single ‘best’ frame rate to use on a universal basis.
Camera Auto-Focus Performance
When it comes to auto-focus performance, cameras are not created equal. Many folks concentrate on sensor size and related performance measurements such as dynamic range, colour depth and low light performance when buying gear. While important, sensor size and performance is only part of the story and may not be the most important factor to consider when it comes to photographing birds in motion.
For example, about three years ago, after selling my Nikon D800 and F-mount lenses, I had a brief flirtation with M4/3 through buying a Panasonic GH4 and some ‘pro’ Panasonic f/2.8 zoom lenses. My flirtation shooting with M4/3 gear didn’t last long for a number of reasons. One of the most significant of which was the comparatively poor auto-focus performance of the Panasonic GH4 when compared to my Nikon 1 V2. The GH4 was simply frustrating to use because of the high number of photographs of perched birds that I was missing due to its weak auto-focus performance, especially in lower light conditions.
In an earlier article I made note of the auto-focus performance differences between the Nikon 1 V2 and V3 cameras, especially under lower light conditions. My judgement was that the V2 was the superior camera of the two in terms of both acquiring focus quickly, and holding it more consistently throughout an AF-C run when photographing birds-in-flight.
The key takeaway from this consideration is the importance of understanding the capabilities of your camera gear, both its strengths and weaknesses when it comes to auto-focus performance. Obviously this has a direct impact on the frame rate that one chooses to use when photographing birds in motion. For example if you know that your camera acquires focus quicker and holds it better at 10 frames per second than it does at 20 frames per second, you’ll likely choose the slower frame rate more frequently as you’ll have a better chance of getting more usable images.
Frame Rate Availability Provided by the Camera
Whether you use a DSLR, an interchangeable lens mirrorless camera, or a fixed lens bridge camera, your make and model of camera will come with its own frame rate capabilities. It is critical to understand the capabilities offered by your specific camera and experiment with how best to utilize them. Combining your knowledge of frame rates and auto-focus performance will allow you to determine where and when to use your camera gear to its best effect.
For example, the image below captures a Great Blue Heron fishing, with its catch seen in mid-air inside its mouth. This photograph was no accident or lucky capture.
I shot this particular photograph at a frame rate of 60 frames per second, specifically to capture the bird doing this behaviour. I learned from earlier frame rate experiments that it is actually quite common for a Great Blue Heron to adjust its hold on a fish by doing slight tosses like this one.
In fact, this particular heron tossed its catch twice during the same 40 image run that lasted only 2/3 of a second. It only took 5 frames to show the heron opening its beak, tossing the fish, then closing its beak again. At 60 frames-per-second that’s only 1/12th of a second and would make the action barely perceptible to the human eye.
Knowing the particular strengths of your camera gear allows you to capture images that other people who use different gear may not be able to replicate. Here is the second toss which occurred 23 frames later in the run…
When shooting at 60 frames-per-second with Nikon 1 gear, the first image locks the focus for the balance of the run that follows. I had no hesitation using this fast frame rate and filling my buffer from an auto-focus standpoint since my subject bird was not moving quickly away from, or closer to, my camera. Knowing that it is possible to replicate this type of image on a consistent basis allows a photographer to pursue image opportunities that may not even be recognized by other people. Again, understanding the capabilities of our camera gear is critical.
In situations where a bird is flying directly at me, I still may shoot at 60 frames-per-second. An example is the image above of a gull with a fish in its beak. The difference is I will only take a very short burst of images rather than letting my buffer fill as I know the bird will go out of focus as it continues to approach me. The photograph above was the 6th frame in a run of 14 images. The gull was starting to go out of focus by about the 11th frame.
It doesn’t matter which camera make and model you choose – buy what best suits your specific photographic needs. The most important things to understand are the frame rates your camera offers and how effective your camera’s auto-focus is at those various frame rates…then use its capabilities in specific situations where you can best leverage its strengths.
Camera Buffer Size and Clearing Speed
If your camera has a deep buffer that clears quickly you will have the luxury of using the fastest frame rate your camera has available with little fear of the buffer filling before you have finished shooting your image run. If, on the other hand, your camera has a very shallow buffer you will likely be more discerning in terms of the timing of your shutter release.
For example, a number of years ago I shot with a Nikon D7000. This camera was capable of shooting at 6 frames-per-second in full auto-focus. The buffer was limited to 15 RAW images which meant I would fill the buffer capacity in 2.5 seconds. By comparison my Nikon 1 V3 can shoot in full auto focus at 10 frames-per-second and has a buffer capacity of 40 RAW images. I can shoot 1.5 seconds longer with my AF-C burst and capture 166% more images before the buffer in the V3 fills when compared to the D7000 that I shot with in the past. This means I can start an AF-C run earlier and hold it longer when shooting with my Nikon 1 V3, than I could when shooting with a Nikon D7000.
I appreciate that we all want to get the best value for our money when buying camera gear and accessories. If you plan on photographing birds in motion one of the things that you shouldn’t do is buy inexpensive memory cards that have slow write speeds.
Think of it as pre-buying some frustration if you make that choice. If you choose to use slow writing cards, there’s no doubt at some point you will miss some photographs of birds in motion because your card hasn’t cleared in time.
This is the primary reason that I use different cards in my Nikon 1 J5 bodies compared to my Nikon 1 V3 bodies. Since I very seldom shoot AF-C bursts with my J5 bodies I use 32 GB SanDisk Extreme micro SD cards in them. I use 32 GB SanDisk Extreme PLUS micro SD cards in my V3s since these cards have a maximum write speed 50% faster than the Extreme cards do.
When faced with a camera with a shallow buffer that clears slowly, people will typically use a slower frame rate so they don’t fill their buffer too quickly and miss other potential image opportunities.
Size and Behaviour of the Subject Bird
If you are photographing large, slower moving birds you can likely shoot using single frames and still get a good selection of different wing positions etc. in your images. For example, the photograph below of a Great Blue Heron with a catfish in its mouth was one of a number of single frame captures that I took. There was no point in shooting at a fast frame rate as the bird was sauntering in front of me, giving me plenty of time to compose and take my images. Plus, I didn’t want to fill up my buffer needlessly in case other birds in the area presented more photographic opportunities.
In many cases using single frame captures of large slower flying birds such as pelicans, yields a better selection of wing positions. This can be especially true when a camera has a shallow buffer.
The speed and direction of the subject bird is also an important consideration. Most cameras will struggle, at least to some degree, achieving good, consistent continuous auto-focus on a bird that is flying directly at it. Generally speaking a slower frame rate would be used in these situations.
When photographing smaller birds with faster wing movements a faster frame rate would typically be used, except where the impact of rhythmic motion is a problem.
The Potential Impact of Rhythmic Motion
One of my earlier articles discussed the potential impact of rhythmic motion and frame rate and how we may not get as many different wing positions as we expect when shooting at faster frame rates. This happens when the wing beat speed of a bird is similar to the frame rate speed of our camera.
The results that come from photographing specific bird behaviours at different frame rates really comes down to experimentation and experience. For example, I used a 60 frame-per-second rate when I captured the image below of a duck in the water beating its wings. This yielded a repeating wing position every 10 frames.
In the series of images of a Great Blue Heron flying photographed at 60 frames per second, a repeating wing position occurred every 23 frames.
The hummingbird shown in the photograph below was also captured at 60 frames-per-second which yielded a repeating wing position every 5th or 6th frame.
While it is easy to assume that a faster frame rate will generate a wider selection of wing positions in a run of images, this is not necessarily the case.
Some photographers find that their cameras only offer a limited selection of frame rates and when shooting a particular species in flight the resulting AF-C run yields almost identical wing positions in each frame. This is the ultimate negative result of a bird’s rhythmic wing motion and the camera’s frame rate being unintentionally synchronized. In this situation all a photographer can do is revert to taking a quick succession of individual frames, or taking a number of short AF-C bursts rather than just one long run.
Photographer Skill Level
The skill you bring to your camera gear has a direct impact on the frame rate you choose when photographing birds in motion. While using a very fast frame rate such as 60 frames-per-second may be tempting, unless the photographer is able to precisely time their shutter release, using this very fast frame rate may be frustrating and result in many missed image opportunities.
It is important to continually practice eye-hand coordination when tracking and photographing birds in motion to develop a good skill level. If we are unable to effectively track a bird when shooting single frames, there is no point in increasing our frame rate and capturing more poorly composed images that we’ll just have to delete later. After a good level of eye-hand coordination has been achieved, increased frame rate speeds will then have the potential of yielding positive results, and show more varied wing and body positions.
Objective of the Photographer
Generally speaking, the more precise the motion capture desired by the photographer, the more a very fast frame rate will come into play. This is especially true with birds taking off, landing, or fishing/hunting.
Hopefully this article has provided some information on factors that can be considered when choosing a frame rate when photographing birds in motion.
All photographs were captured hand-held in available light using Nikon 1 gear as per the EXIF data. All images were produced from RAW files using my standard process of DxO PhotoLab, CS6 and the Nik Collection.
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