 Close-ups
The other day I was asked to take some pictures of snails which got me
thinking about the perils of close-up photography in general.
The first problem we need to look at is, how close the lens will focus.
Lenses have a minimum focus distance which varies considerably from lens
to lens, some longer zoom lenses have a 'macro' setting and will focus
quite close but most lenses will not focus close enough to take the picture
on the right.
Extension Tubes
If the lens you are using will not focus close enough there are a couple
of ways to make it do so. If the lens is detachable from the camera, you
can use 'extension tubes'. These usually come in a set of three which
can be used separately or together. They fit between the lens and the
camera body and, as the name suggests, there is no glass in them, they
merely serve to move the lens further away from the film plane (or CCD
on a digital camera). The lens will now focus on closer objects than it
would before but will no longer focus on infinity.
Extension tubes are a good solution as you are still using the quality
lens that you paid so much money for and so the picture quality
will be the same as for any other shot. The downside (there's
always a downside, you never get anything for nothing) is that
you need more light (the inverse
square law works just as well behind the lens as it does in
front), either a longer shutter time or a wider aperture.
Your meter will automatically compensate for this but it can lead
to severe depth of field problems which we will discuss in a couple
of paragraphs.
 Close-up
Lenses
Close-up lenses are a bit like reading glasses, they are attached to
the front of the lens and their strength is measured in diopters. So a
+2 diopter lens will focus closer than a +1 etc. Using close-up lenses
solves the problem of needing extra light but now you have something on
the front of your lens. The front element of your lens and the beautiful
multi coating on it, that you paid a fortune for and have lovingly looked
after, are not being used. The quality of your photo is now, to some extent
at least, in the hands of your close-up lens. So make sure you buy a decent
make, they are not expensive so there is no need to buy the cheapest.
Depth of Field
Whichever method you choose to get your close-up, the mere act
of focusing on close objects narrows the depth of field down to
problematic levels (for an explanation of depth
of field click here). Any kind of wide aperture setting
becomes out of the question if you hope to get the whole object
in focus. If your subject is static and you have a tripod you
have the option of shooting at a slow shutter speed and therefore
a small aperture, but if not, you need a lot of light. Either
sunlight or flashlight will do (I used a small studio flash for
the snails), but you must get the aperture ring closed down to
f22 or whatever your smallest aperture setting is. Even then you
will find that sometimes this is not enough and part of your subject
is still out of focus. Well, if that's the case, then it's time
to make a decision about which parts of the subject most need
to be in focus.
All other things being equal, I would almost always choose to have the
parts nearest to the camera in focus and let the background and parts
furthest from the camera go out of focus. This to me looks less like a
mistake than a picture where the foreground is out of focus. There are
always exceptions and one I can think of is an extreme close-up of a face,
if I had to choose between the eye(s) being in focus or the nose, I would
always choose the eyes because they are a more important part of the face.
 There
are times of course when a shallow depth of field can be very
effective. I'm quite fond of this flower shot because the stamens
really stand out against the out of focus petal. I also like the
area of sharp focus on the right. It is usually considered to
be a bad thing to have two focal points in a picture but in this
instance I think it works quite well. To me, the main centre of
interest is the right hand side with the lovely crisp water droplets.
This was a very dull day just after the rain, I had no tripod and so
could only manage 1/60th at f8. I must admit that if I could, I would
have tried to render the whole flower in focus but I like this the way
it is.
It is also a good illustration of photography in muted lighting conditions.
I am usually an advocate of strong sunlight but here it would
have caused problems with too much contrast, making these beautiful
colours difficult to render.
Try this book about close
up photography
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