blog.glorious-landscape.comFine Art Photography

Who can turn down an opportunity to photography a beautiful Cardinal, Oriole, Hawk, etc? At first, probably no one. But when the prints come in, or you see it on the screen, you may recall having thought “Where’s the Bird?”, kind of like this shot of a Cardinal in the photo below. It didn’t look like that when I shot it. (or did it?) There is a bird in there somewhere.

Don’t feel bad. You’re not alone. It’s interesting and sometimes frustrating to figure out what lens you need to photograph birds in the wild. It really is about the lens. Unless your name is Dr Dolittle, most of us can’t get the birds to come close, sit still, and pose for us. Of course there is always the alternative of hiding in a Blind and waiting for the birds to come to you, but that isn’t always possible. Here’s a great video example of this. I’ve always had an interest in photographing birds, and having had the common experience described above, I also realized soon after that I would need a good telephoto lens, and a teleconverter to extend the reach of that lens. The question was what focal length do I need?

On to mistake number two. Looking at your lens budget, and thinking that surely 200mm-300mm is a long lens, you make your next purchase and head back out to capture the ellusive bird. (that’s after spending anywhere from $180 to $5000 to get to this range, depending on the quality of the lens.

Once again, you get home to see the results, and now you have something that looks like a bird, (see below) so you’re thinking Ok, I’ve got it! You crop 80 percent of the photo to get to a photo that you hope looks like the front page of some Bird watcher magazine, or National Geographic.

You end up with what looks like an out of focus bird photo taken by a cellphone. Not exactly good news. One of the added problems of not being close enough is getting the autofocus system to lock on this tiny bird rather then the twigs in front of it, which is what happened here. Manual focus doesn’t help much when the subject is this small in the viewfinder. Now this is getting expensive!

Going through this myself early on got me wondering why my perception of what focal length I needed was so far off. Or was it some kind of optical illusion?

Optical Illusion or Perception

It feels like an optical illusion, but there is no real false reality here, so it must be a problem with size perception and a misunderstanding of the camera’s resolution. This got me thinking about the idea of size perspective. For example, if a person 6 feet tall is standing fifteen feet in front of me, and I zoom to 80mm, that subject is going to fill a good amount of the frame.

Now do the same with a tiny 4 inch bird at the same distance, and see how much of the frame is filled by the bird. By the way, the person is 18 times larger than the bird, and yet it’s hard to get much closer than 15 feet to birds. At the same 80mm focal length this bird is now filling a tiny portion of the viewfinder. Can you say Crop? As you crop you are losing resolution. So you crop out 80 percent of the image, and what do you have left? With a 12 megapixel original, you now have a 2.5 megapixel photo, and whatever it is, it doesn’t look like a magazine cover. Why did we think this would work? There isn’t enough resolution left to show any fine detail.

I think the answer probably lies in how the eyes and brain work together to filter out everything except the subject that we are focused on. At that moment we lose perception of size relative to our field of view. Possibly our eyes do better than 12mp at this distance, but I’m not sure. Either that or our eyes just have less focus problems with tiny moving subjects. That’s probably more likely.

The Solution

The photo at the top solves the problem in two ways. First, the lens is a Nikon 200-400mm zoom with a 1.4x teleconverter attached. The final focal length was 550mm. Keep in mind that even at 550mm this only worked with the bird at around 20 feet away. The ideal lens is a 600mm with a 1.4x or 1.7x teleconverter, which ends up getting you to 840mm/1020mm. Nikon’s version of this lens, at over ten thousand US dollars, is very cost prohibitive. There are other brand lenses though that can be considered with some trade-offs and a lower price. However, this is what keeps most camera owners away from birds that aren’t in a zoo or a feeder.

The second factor is the camera’s resolution, but this is less important than the lens. The Nikon D3X used at the top is a 24mp camera, so it has twice the total resolution of a 12mp camera, which means it can capture more detail in the same portion of the frame, which helps. However, it’s also a very expensive camera body in its class.

[Update: Some thought I was saying here that a 24mp camera is required to photograph birds. This is not the case. The point is that higher resolution helps when you are cropping. With the right lens 12mp is more than enough resolution. In fact, top notch photographs of birds have been done with far less than 12mp.]

There is also the crop factor of a digital SLR that has an impact on the density of pixels relative to the frame, but that’s another article.

Try this next time

Ask yourself the following when photographing anything that is very small:

- How much of the frame is my subject filling?
- What percentage of the frame will I need to crop because I couldn’t get close enough?

If the subject doesn’t fill 25 percent of the frame in one direction, it’s time for a longer lens. Or there’s always the possibility of a postage stamp contest. :^}

Let me know what you think by posting a short comment.

- Mark

Nikon TC-14E II (1.4x) Teleconverter

Nikon TC-17E II (1.7x) Teleconverter

Nikon 200-400mm f/4G Zoom

Nikon D3x 24.5MP FX Digital SLR