|Nikon D7000, 300mm f/4 lens, f/6.3, 1/640s, ISO 500.|
Like I mentioned the other day, this is one of many that were roosting in the top of a small copse of spruce trees. We were driving down the road on the edge of Nehalem Bay in Oregon when I noticed that one had landed in a tree. My car handles better than expected on soft gravelly shoulders, and in no time I was faced with my first dilemma in making images: which lens should I use?
Naturally, I wanted a long lens, lots of magnification, big number followed by mm. I had two choices: a 28-300mm f/3.5-5.6 VR lens or a 300mm f/4 lens. The f/4 is an older generation lens, but is pretty incredible in many situations--as most prime lenses are--but it's long and kinda heavy which means it gets wobbly sticking off the end of the camera. The 28-300mm if just about the same length, and only slightly lighter, but it's hot off the production line, and the new iteration of vibration reduction Nikon has created is pretty darn good at stopping that wiggle by countering the operators' movements with micro motors gyro-ing around inside it. That means that even though I'm giddy as a school girl at the chance to shoot some huge birds in an interesting location, the pictures are much more likely to come out sharp.
So, you're thinking, "Duh, take the new lens!" But, there's one more consideration: sharpness. I'm not talking about focus, but rather how much detail there is in the stuff that's in focus. The rule of thumb is that most lenses produce their sharpest images when the aperture is closed down from wide open about two full stops (this is called stopping the lens down). That means that the 28-300mm, which has a maximum aperture of f/5.6 at 300mm, is sharpest at f/11, whereas the 300mm f/4 is sharpest at f/8; and what that means is that there is twice as much light available at f/8 than there is at f/11 (it's an area of a circle equation with an exponent...) and on a cloudy day that leads to the next consideration.
Big birds make fast movements when lifting off and landing and in order to freeze those movements, a fast shutter speed is required, and that depends on the amount of light coming into the lens. The fast shutter speed not only freezes the bird's movement, but it also freezes your movement as you balance this howitzer off the front of your face. The VR can compensate for your movement and help get a sharp picture of something holding still, which mean I can hand hold a slower shutter speed than I could with the antique 300mm. However, when the subject is moving, VR just doesn't cut it: you gotta have raw shutter speed. From the specs above you can see that I shot this one at 1/640 of a second at f/6.3. See, I know that the 300mm is sharper at all apertures than the fancy new zoom, so I wasn't scared to open up the aperture a little. But let's say I used the zoom at f/11 for a sharp picture: my shutter speed would only have been 1/125 of a second! When I'm dancing that slow, my wife is the only bird in my sights. There's no way to freeze action at that speed.
So, all this ran through my mind as I changed lenses and jumped out of the car, dodged a logging truck, and hopped the guard rail to make a few frames. I should have taken my thoughts a step further, however, and considered more carefully my camera choice. I grabbed the D7000 with a smaller sensor because it captures an apparently larger image of the subject at a given distance than my D700. However, the D7000 is a little grainy, and the herons were far enough away that I had to crop considerably to make this picture fill the frame so the detail isn't what it could be if I could have gotten closer with the better body. Haste makes waste, as they say.
Of course, if I actually took my wife slow dancing I may be able to convince her of the need for a 600mm f/4 VR lens, thus combing all the best features of both lenses and the best body!
Anybody know any dance halls?
The picture above was shot as a color jpeg, allowing me a faster rate of firing on the camera. I then processed the picture as a black and white image. While I was considering my next move to finish this image off, I recalled my high school photography classes when I spent one rainy week hand tinting a mediocre black and white print of a mountain stream with some colored pencils. The result was far better than the original image had been. So, I thought I'd give it a shot here, and I rather like the effect.