 |
Ever want to take a picture
of a really small subject? I mean a REALLY small subject. You might be
able to do so with the equipment you already own or by adding just an item or
two (and what photographer doesnt want more equipment). But before I can
discuss how to take that picture, let me define some terms so that we all agree
on just what were doing. We need a mutual vocabulary to establish the
concepts parameters.
The best way to talk about
any sort of closeup photographyand indeed about the only consistent wayis in
terms of the magnification on the film. This provides a constant so we can
make comparisons, independent of the lenses or film formats in use.
Magnification on the film is the ratio between the physical size of the image
recorded on film and the physical size of the actual object being
photographed. Let me be absolutely clear about this point: when I say
"the image on the film" Im talking about the actual measurable size
of the image on the actual piece of film you use to take the picture.
A magnification rate is how
this ratio is commonly expressed, and is usually written as a power. Fractional
rates such as 1/4X, 1/8X, 1/10X mean that the film image is smaller than the
actual size of the subject. At any fractional rate a one-inch long subject will
appear smaller if its image is measured on the film. At 1X, the image and the
subject will be identical in size; the 1 inch object will measure 1 inch. At
rates over 1X, such as 2X or 3X or 4X, the image size is actually larger than
the subject. In other words, you are starting to magnify on film.
So a magnification rate of
1X is a major dividing line. Sometimes it is written as 1 to 1 or
1:1 but most often you will see it referred to as life-size
since the image on film is the exact same size as the subject is in real life.
At life-size whatever you photograph has the same dimensions as whatever film
format you happen to be using. If youre shooting 35mm the image area of the
film is 24mm x 36mm, roughly 1 x 1.5 inches, so at 1X this dimension is the
area youre photographing. Working at life-size is basically the same as
taking a slide mount, holding it flush against your subject, then photographing
what you see within the rectangular opening of the mount.
In passing Ill mention the
physical measurements of a life-size image depends on the film format used.
For 35mm its 1 x 1.5 inches, for a 6 x 7cm medium format camera its 6 x 7 cm,
for a 4 x 5 camera its 4 x 5 inches. Life-size is another way of saying youre
photographing a subject the size of the film format. But on all formats,
regardless of what you use, at life-size a one-inch long subject will appear as
a one-inch long image on the film. Think about this fact, and youll understand
why its much simpler to shoot high magnification pictures with a 35mm outfit
than any other. A "full frame" photo of a honey bee might be 1X on
35mm, but to get that same "full frame" image using a 4 x 5 camera
means youve had to magnify the image a lot more.
If you know the
magnification rate you can easily figure out the subject size youre
photographing or vice versa. Divide each dimension of the 35mm frame by the
magnification rate and youll get the size of the subject covered at that
rate. For example, a magnification rate of 1/8X covers a subject that is 8 x
12 inches, 1/4X is 4 x 6 inches and 1/2X is 2 x 3 inches. Past 1X (life-size,
that is) the subject area is, of course, smaller than the format. At 2X youre
photographing an area 1/2 x 3/4 inch; at 3X its 1/3 x 1/2 inch; at 4X its 1/4
x 3/8 inch, and so on. To find the magnification rate when you know the size
of the subject you want to photograph, divide the dimensions of the frame by
the dimensions of the subject.
All by themselves most
current camera lenses used at minimum focus yield an image thats about 1/10X
(10 x 15 inches). So what do you do when you want to photograph something
really minute, something in the "ultra itty-bitty" range? If youre
a Canon user you could purchase their 65mm f/2.8 MP-E lens, made just for 1X to
5X photography. This is a special purpose lens to be sure and has a special
price to go along. If you can justify the purchase, by all means go ahead. But
for the rest of us...well, there are still ways to achieve the desired photo.
What you need to do is try
out all the combinations of equipment that you own. We all fall into the trap
of assuming that certain pieces of gear can only be used in one fashion. Trust
me on this: there is no one correct way to shoot at magnifications greater than
1X. My first suggestion is to disregard all the information the camera
manufacturers tell you; instead shoot some test film with various combinations
of equipment and look at the results.
Lets assume you own a few
items: a teleconverter, some extension tubes, a couple of the Nikon T series
close-up lenses, and a TTL flash and off-camera cord (of course, this
flash/cord combo means you also have a newer camera body capable of TTL flash
metering). If you have a macro lens, particularly one in the 100mm range, add
it to this collection of gear. How many ways can you possibly put these items
together? Sit down on the floor with all these items spread around you, and
simply play. Try different combinations of gear, stick a camera on, and look
at a subject with fine detail such as the side of a film box. Note the working
distance, how bright the viewfinder image appears, and if all the
mechanical/electronic connections work as they should.
Extension tubes by
themselves allow whatever lens you put them on to focus closer. The more tubes
you add, the more magnification. A rough formula is that magnification on the
film equals total extension divided by focal length. Add a teleconverter to
the system and you gain magnification. Use any system that gets you to
life-size, add a 2X teleconverter, and you can double the magnification. But
wait a minute, exactly where do you place that converter? Consider this: the
converter will magnify whatever you put in front of it. For example, to get to
life-size with extension tubes you need to add roughly the focal length of the
lens youre using. A 100mm lens needs about 100mm of extension added to hit
1:1. Add a 2X converter behind the extension and you have effectively doubled
the amount of extension, ending up at two magnifications on the film. But if
you put the converter directly behind the lens you have now doubled the focal
length (this is how we normally use a teleconverter with a long focal length
lens to make it effectively an even longer focal length). Put that 2X
teleconverter directly behind a 100mm lens and you have now created a 200mm
lens. Now you would need even more extension, about 200mm, to get to
life-size, and a total of 400mm to get to two magnifications. Right away the
best sequence of equipment for high magnifications becomes apparent: camera
body, teleconverter, extension tubes, lens. Your working distancethe distance
between the end of the lens and your subjectwill depend on the focal length of
your lens. The longer the focal length, the longer the working distance, but
of course this also means you might need some additional extension tubes.
You can add Nikon T-series
close-up lenses (if they will fit on your lens) to gain even more
magnification. These are relatively inexpensive, screw on any lens just like a
filter, and yield great quality. They come in 52mm and 62mm filter sizes and
in both 1.5 and 3 diopter powers. Get one of each power and you can stack them
together for even greater magnification, adding the stronger one to your lens
first.
For example, suppose I have
a 105mm macro lens that goes to life-size all by itself which indeed most
macros of this focal length do. Add a 2X teleconverter and I end up at 2X
magnification. Place about 2530mm of extension between the converter and lens
and Ill have roughly 3X magnification. Screw on a Nikon 4T close-up lens,
increase the extension slightly, and Im at 4X magnification. Remember that 4X
magnification means Im photographing a subject that is 1/4 inch by 3/8 inch.
Thats a mosquitos portrait! By the way, at these magnifications dont even
attempt to focus by turning the focusing mount on the lens or by using
autofocus. Set your system for the subject you want to photograph then move in
and out until the viewfinder images pops into focus. Your working distance at
these higher magnifications will be just a few inches so dont expect to take a
full frame shot of an ant from four feet away. Think four inches instead.
You wont have much success
if you try to work with natural light. Use TTL flash instead. Both Nikon and
Canon suggest that their flashes cannot be positioned closer that about 2 feet
from the subject for TTL to work. What they should say is that you need to
keep the flashes back from the subject if you want to work with the lens wide
open. Why would you do a close-up with no depth of field? You want to have
your lens set in the f/11f/16 ballpark. Shoot a couple of frames to see what
aperture yields the best results. Ive used TTL positioned quite close to my
subjects with no problem at all. Youll actually get better lighting results
by having your flash close to your subject, as now it will act as a giant
bounced light source compared to the subject. Back the flash away and youll
get harsher light. Youll need to get the flash out of the hot shoe by using a
TTL flash cord; you can either just hold the flash and point it at the subject
or make some sort of bracket, a third hand if you will, to position the flash. Since
youre running TTL, the exact location of the flash is not critical at all.
Aim it at your subject and fire away.
Youll discover that
photographically youre in a whole different world when you start working past
1X. All sorts of subjects will appear. Your backyard? Well, its a jungle
out there waiting for you to explore.
|
