Ive been asked a couple of times to do a tutorial on macro photography, and Ive given a few "quick and dirty" explanations on various forums. But its easier to write about it formally in an article and just point someone to a link. So here goes :)
Disclaimer: I am not the last word, nor in my humble opinion is anyone the last word, on any photographic discipline! There are many different ways to take a photo, and I really dont think that any technique is inherently wrong -just different. In this article Im going to explain how I shoot macro and hopefully there will be something that you can use. The important thing to remember is that my technique was developed based on my experience with a camera -and the things that I do may be detrimental to you! So take my techniques, experiment with them, and adapt them to your own style of shooting. Dont let anyone tell you that you have to have a certain piece of equipment for a particular type of photography -think outside the box! If I listened to the conventional wisdom concerning macro photography Id be chasing fast moving insects with a camera on a tripod and only have a handful of usable images...
In this article Im only going to cover using a flash as the primary light source. In another article Ill go over using natural light with the flash as fill.
Now lets get into the nuts and bolts of shooting macro :)
When Im shooting at life size I usually have my camera set to manual mode, F11 for the aperture, 1/250 of a second for the shutter, and the ISO set to 100. At those settings Im shooting a full two stops below the ambient exposure for the scene and thats on a bright sunny day. So the flash is going to be my primary light source and if it doesnt fire then the scene will be completely black -and thats a good thing since I want to use the short duration of the flash to freeze motion.
Even though the shutter is open for 1/250 of a second there isnt enough natural light (ambient) to be registered by the cameras sensor. The photo receptors (or the photo sensitive grains in film) act like buckets for photons: If the buckets dont get full enough youll get an under exposed image and if they get too full the scene will be over exposed. So the flash becomes a virtual shutter since its the only light that is registered by the camera. Remember that the intensity of the light from your flash does not change from exposure to exposure, but the flash duration does. One of the tricks to getting sharp hand held macro images is to get that virtual shutter as fast as possible and the easiest way to do that is to get the flash as close to the subject as possible. Flash duration increases with the distance from the flash to the subject, so increasing the distance between the flash and the subject will cause more glare and decrease your ability to freeze motion.
You can use any flash to shoot macro, you dont have to use a dedicated macro flash unit. I think that its easier to use a macro flash though and if you take a lot of macro photos then getting one is a good investment. The MR-14EX ring flash is easy to use right out of the box just remember to set the ratio control to make one flash head brighter than the other so your images wont look flat (Ive used from a 2:1 to a 4:1 ratio). I currently use the MT-24EX without ratio control (I place the flash heads on the flash mount at a 90 degree angle to each other to get dynamic lighting) and I diffused the heads with a set of Gary Fong Puffer diffusers amazing what you can do with a hot glue gun ;)
Why hand held?
I shoot a lot of fast moving insects critters that just wont sit still long enough for me to set up a tripod. Plus a tripod, at best, will only eliminate my movement but it cant stop the subject. So I diffuse my flash and get it as close as possible to what Im photographing and I rely on the short duration of the light from the flash to freeze all the motion in the scene. I do look for ways to brace myself and the camera, and I look for subjects that will put me at an advantage (I never shoot anything thats above eye level).
I think one of the big misconceptions with using a flash for macro photography is that no matter what the duration of the flash is it will always be fast enough to freeze motion -and Im convinced that it just isnt true. The amount of information in a macro scene is a lot higher than a shot of the beach at sunset so small movements, of less than a pixel or two, during the exposure of a macro shot can result in a blurred image. It wont look like motion blur, youll think that you missed the focus or that diffraction was a problem.
One of the other big misconceptions is that you have to use a tripod for macro photography. Even if the critters didnt move, the wind blowing across the legs of the tripod or the mirror slapping up into the mirror chamber when you take a photo could cause enough vibration to ruin an image. I can get just as much stability with resting my elbow on my knee as I can with a tripod and the knee pod is a lot faster to set up and take down ;)
I often get asked how I get so much depth of field in my photos. There isnt any magic to it really, its just technique. Dont be afraid to stop the lens down. Diffraction can be a problem, but its a minor player in effecting overall image quality nailing the focus, keeping the flash duration low, and bracing yourself are far more important. I shoot at F11 with an MPE-65mm macro lens all the way up to 5x and Ill take the lens all the way to F14 if I have to. I avoid F16 above 2x with the MPE-65mm because I think the lens performs poorly at F16 at high magnification (but I dont think the problem is diffraction). Sometimes getting more depth in a scene is more important that getting an image thats razor sharp
Remember that the plane of sharp focus is perpendicular to your lens and although its flat it has some thickness to it. If you move in toward a critter until its eyes are in focus, and then press the shutter release, then the plane of sharp focus starts at the eyes and ends somewhere between the critter and your lens possibly out in the middle of nowhere in an area that you dont need it! Often I move in toward an insect until the eyes are in focus and I keep moving in until they go out of focus again, and then I move away from it until the eyes are sharp and then take the shot. That way the area of sharp focus starts at the critters eyes and extends into its body where I need the extra detail
Look for magic angles. Since the plane of sharp focus is perpendicular to the lens you can lay it over your subject so that it covers the critter like a blanket. You can make a scene look like there is more depth of field than what is really there. If you are shooting an insect from the side its a good idea to make sure the lens is perpendicular to the plane of its body so that the entire length of critter is in sharp focus but its not necessary to do it all the time. You can use a shallow depth of field to draw the viewers attention to a particular area in a scene, so going for maximum depth of field all the time might be a mistake..
I take multiple frames of each composition and I refocus for each frame. Sometimes what looks good in the viewfinder doesnt look good when I see it on my computer but as long as I refocus for every shot Im sure to get at least one frame that has the area of sharp where I want it. I focus the lens by moving my body there is no focus ring on the MPE-65. When Im shooting with Canons 100mm macro I sometimes use the focus ring as a course adjustment and use my body for the fine tuning.
I always shoot RAW because of the JPG compression penalty: When you take an image in high quality JPG mode the camera is compressing the data, and since JPG is a lossy form of compression data is thrown out to make the file smaller than a RAW image. Im going to have to edit the shot even if I nail the exposure, since I can never get away from dust spots showing up in an image no matter how often I clean the sensor in my camera. After getting rid of the dust and doing the other minor post processing Id have to save the file as a JPG and even more information gets tossed out during the compression. But by shooting in RAW I only pay the JPG compression penalty one time when I save my RAW file edits. The end result is sharp images without having to use Unsharp Mask.
Last but not least no matter how you shoot macro have fun! Find ways to make taking high magnification images enjoyable for you and youll keep doing it