Keith and a couple of other people have asked me to share some tips for photographing plants. It's taken me a while to get it together, but I've got a plan now: I'll write up a series of "lessons and exercises" you can participate in, if you wish. Here's the first one, and I hope that it is neither too basic, nor overly technical. (I doubt it's either) feedback welcome, of course.
I've been thinking about how I can share some ideas with people to help improve their skills when photographing their carnivorous plants. Don't get me wrong, there are plenty of great photos posted every day on the forums, but the odds are some technique or trick will come up in this discussion that brings something useful to your "tool kit". I don't want to write an entire book on the subject, but neither do I want to treat important concepts so lightly as to fall short of actually delivering useful information. With that in mind, I have decided the way to do this is to break things up into smaller pieces, each discussion topic taking the form of an exercise that people can participate in if they wish. I hope you find some of this useful.
Before I outline the first exercise I want to say something about cameras. Everything I am going to talk about presumes that you know your camera controls and features well enough to say that you can operate it with confidence. If you don't think your skill level fits this description, then I urge you to take some time to study your device's manual in some depth. After all, you can't make an omelette until you know how to work the stove. (and find the eggs!)
Exercise 1: Isolate The Subject
I think the most common "error" photographers make when planning and executing their photo is the failure to isolate the subject from its surroundings (background and/or foreground). I'm sure you know what I mean; that photo of a beautiful Nepenthes pitcher that can barely compete with all the visual noise going on behind and around it. Its easy to look through your lens and be seduced by the beauty of the subject, forgetting to study everything in the viewfinder and decide what to emphasize, and perhaps more importantly, what to de-emphasize! Well, this isn't a difficult issue to address, and there are some easy ways to deal with this:
* control the background: use a backdrop! (fabric, construction paper, etc.)
* use a shallow depth of field: it blurs everything that isn't the focal subject.
* related to the previous: increase the distance between the subject and the background; the greater the distance between subject and background, the less of a distraction it will be.
Something I will save for later discussion is post-processing of your photos. (image adjustments done after the photo is taken: Photoshop, Lightroom, Picasa, iPhoto, etc) If your image still needs help creating the right emphasis on the main subject matter, some post-processing tools can help; blurring the background, tilt-shift effects, etc. Most photos need at least a bit of contrast adjustment to optimize them, or maybe a bit of sharpening or a nice vignette. However, first we need to have a photo to work with. I want to talk about a couple of simple ideas to help us plan and take the photo, so let's start with depth of field.
Many people don't really know what depth of field means.http://en.wikipedia.org/wiki/Depth_of_field It's a very simple concept: it refers to how much of what the camera sees is going to be sharply in focus, from foreground to background. The aperture setting you choose determines how much of your foreground/background is going to be in focus. For the purposes of this exercise, we want to use as little depth of field as possible. That way, you will be emphasizing only the primary subject.
Here is where your camera manual may need to be consulted: you need to know how to set the camera to aperture priority mode. This mode let's you manually select the aperture size and the camera will choose an appropriate shutter speed for the correct exposure. For this exercise I'm going to ask you to do at least some of your photos with the lens wide open, (the largest aperture, indicated by the smallest F-stop number. On my most often used lens, that is F 4.4) and some photos with the lens stopped down only two stops from wide open. The concept of the exercise is to discover how valuable a wide lens aperture can be in helping isolate specific objects in your image.
Moving along, here are two photos to illustrate depth-of-field in application. The first image was taken with the camera aperture open to F 4.4, its widest setting. (the maximum aperture size will vary from lens to lens) The Nepenthes pitcher is the only thing in the image that has any sharp features, and the rear of the peristome (lip) is no longer in sharp focus since it has fallen outside the range of the depth of field. (This is N. briggsiana, by the way)
The second image was taken with the aperture closed down to F 22, the smallest aperture this lens allows. (ironically, the smaller the aperture size, the larger the number used to designate it! This is counter-intuitive, I know, but it is how lenses have worked for over a hundred years) In this version of the photo, much more of the scene is in focus, except the most distant objects, but they are sufficiently sharp that they become visual "noise" that distracts the viewer from the main subject! The photo literally contains Too Much Information!
So, both photos have their merits and their shortcomings, but the point of this exercise is to create a pleasant background by limiting the depth of field, significantly blurring everything but the focal object. So, I urge you to resist using any aperture other than your lens's largest. As you see, a wide open lens (large aperture: small F number) delivers a soft, blurry background, but it can come at the expense of losing some sharp focus where you want it, as in the case of the first photo, where the rear of the peristome which has fallen out of focus. In practice, you will likely want to choose a smaller aperture that allows you to compromise: sharpness where you want it, but not so much that the background objects come too clearly into focus. (I'm not going to illustrate this third option here, I want you to try shooting with the lens wide open for this exercise)
So, give this a try and see how you do. Feel free to post your results here, and don't worry, this isn't a competition, it's just a learning exercise. Just be aware that only a very limited "slice" of your chosen subject will be sharp, so choose carefully what you focus on; the rest will quickly fade into blur. If you have specific questions about anything I've described here, ask. (if its a technical question about a specific camera model, or things like that, its unlikely I can provide help: review your manual!)
Note: for the example photos shown, I was photographing in the greenhouse in the early evening, when here was no direct light on the greenhouse. And so, the shutter speeds were slow, especially when I shot the F 22 version: almost half a second. This made it mandatory that I use my tripod, because (and I'm sure most of you know this about shutter speeds) there was no way to avoid motion blur if I tried to hand-hold the camera. So, when you shoot in soft, indirect, or late day light, be aware that you may need a tripod to get the best results. Watch what your camera is doing and make note of what shutter speeds it is using when you take your shots. A good rule of thumb is this: if the focal length of your lens is (for example) 250mm, then no matter how steady your hand, a shutter speed slower than 1/250th of a second is unlikely to be sharp unless you are using a tripod. If your lens focal length is 50mm, then you might be safe to shoot hand-held with shutter speeds as slow as 1/60th of a second (round up to the nearest shutter speed for your camera model) For my favored lens, (a 28 - 105mm zoom) I usually shoot at 105mm, so I avoid hand-held shooting if I have to use 1/125th of a second shutter speeds or slower, to be safe.
Have fun with it, and be open-minded about the results. I'll write up another exercise in a week or two. Good thing we don't have to buy film anymore, huh?! :-)