This is the sixteenth in a series of photos I took from a vehicle on a trail in South Africa. The air was very still and it was very quiet.
Up to that point the zebras had been in various states of unaware and mildly curious. Then it changed. And I think it was the sound of the shutter on the camera that put this zebra on alert with a look of ‘Oh oh, what’s going on?’
Looking back now, I wondered how far I was from the animal. And I think I have been able to work it out, more or less.
The EXIF information on the camera said that the focal length of the lens was 300mm. That’s the maximum reach of that lens. I was shooting with a Nikon D500 camera, which has a DX format sensor, meaning that it is 1:1.5 ratio compared to a full-frame sensor.
And what that means is that a 300mm focal length has a reach of 450mm in full-frame equivalent.
With that information, I looked up the angle of view tables for Nikon cameras and lenses. For a DX camera at 300mm and it said that the horizontal angle of view is 4.5°.
You can imagine two narrow lines reaching out from the lens with an angle of 4.5° between the lines. At some distance they will cover the horizontal length that is in the frame of this photograph. What is that distance?
From looking at the photo I estimated the length of the animal and the space either side at 4.25m (14 feet). Finally, I input that information into an angular size calculator and it gave me a distance of 54.5m (178 feet) from my camera to the zebra.
So, could the zebra hear the camera shutter 54.5m (178 feet) away? Oh yes, definitely.
Why Camera Shutters Make A Sound
It depends on the kind of camera. Little point and shoots are often silent. On the other hand I had a Panasonic GF1 that sounded like someone wheezing. I don’t think there was any reason it had to make a sound, just something the manufacturer built in.
But dSLRs like the Nikon D500 make a noise because of their construction. ‘SLR’ stands for single lens reflex. and dSLR stands simply for digital single lens reflex. And whether film or digital, the principle is practically the same.
SLRs are called ‘reflex’ cameras because of the mirror that diverts the light that comes through the lens. and sends it up to the viewfinder.
Looking through the viewfinder of an SLR is like looking through a periscope in a submarine; it’s just that the periscope is only a half an inch tall.
When you press the shutter to take a photo, the mirror flips up out of the way to allow the light to reach the sensor. Then it flips back down again. That’s the reflex.
And even though camera manufacturers dampen the mirror when it flicks up and down, it still makes a noise – and I think that is what the zebra heard.
Mirrorless cameras can have silent shutters. And that is one of the reasons that photographers shooting wildlife are using mirrorless cameras more and more.
There is another reason why mirrorless cameras are replacing dSLRs. That is without a mirror to flip up and out of the way and back again, the camera can fire more rapidly.
The Nikon D500 is a fast camera. It acquires focus quickly and it can fire off 10 frames in a second. But some mirrorless cameras can fire at twice that rate. And that is important to wildlife photographers.
Imagine, there is the bird ready to take off or about to dive into the water. At 20 frames per second the photographer can pick the best of a series of frames. And he or she can be pretty sure that one of the frames at least will show the bird to perfection.
A third reason why mirrorless cameras are becoming more popular for photographing wildlife is again to do with the mirror on dSLRs. Each time the shutter fires on a dSLR, the mirror flips out of the way, as we have said. And when it flips out of the way, the optical viewfinder goes black. Imagine that little periscope and the mirror moving out of the way and not letting light travel to the eye.
So Why Are dSLRs Still Popular
It’s precisely because the viewfinder in a dSLR is an optical viewfinder that keeps some photographers attached to using them. The view in the viewfinder of a mirrorless camera is a digital representation of the scene. And some photographers feel that robs them of an immediacy that is part of the reason they are photographing in the first place.