MACRO - HOW TO ACHIEVE IT !

There are a number of ways to achieve macro photography. First, a
couple of points should be made. Fixed lens cameras and those that do
not have through the lens viewing are not suitable for macro work in
general. A 35 mm. SLR is the ideal tool. Medium format cameras, whilst
the necessary equipment is available, are rather large and unweildly
for such use. Due to their larger image size, a greater than 1:1
enlargement is needed to `fill the frame` with smaller subjects.

1. CLOSE UP LENS - A screw in simple supplementary lens, much like a
filter, can be bought in several strengths, known as `dioptres`. These 
do not really reach macro enlargements in the  more  common sizes - 1
to 4 dioptres, but are quite useful to have in the bag. They can be
bought for the `Cokin` type systems too, making them capable of fitting
many filter sizes, but they have a number of disadvantages.

The lens focal range is changed so that it no longer focuses on
infinity.

Only the glass versions have sufficient quality and then it may not be
good enough. Small apertures MUST be used to ensure only the central
part of the supplementary lens is used as well as for depth of field.


2.  REVERSING THE STANDARD LENS - For most SLR systems a lens reversing
ring is available. This fits to the camera lens mount and allows the
camera standard lens to be fitted IN REVERSE. This feature allows
direct high quality close ups in excess of 1:1, but virtually no
ability to focus at other distances at all.

The major problem here is that all automatic functions are lost which
is  hardly acceptable. Many modern lenses do not have auto/manual
switches so could not be used. In some cases a piece of gear called a
`Z` ring is available. This fits to the back of the lens and, via a
double cable release, allows the camera shutter and lens aperture to
work together.

The system is not very practical.


TELECONVERTERS - MACROCONVERTERS

Units are available that fit between the lens and camera body, and by
means of lenses built into that unit, increase the apparent focal
length of the prime lens. Some of these are specially designed for use
with certain lenses, such as the 1.4X convertor from Canon for use with
their 300 mm f2,8 lenses. Those are, of course, very good indeed and
very  expensive. The more general types, in my experience, ALWAYS cause
loss of image quality. There are some special versions with close
focusing tubes to allow up to 1:1 magnification. I have tried one and,
whilst adequate for colour enprints, was not critically sharp when it
mattered. The same applied to the other 2X converters in almost every
case.

Converters, then, are also to be used when nothing else is available.


BELLOWS - Are the modern equivalent of the units fitted to all old
plate cameras. They fit between the camera and lens and allow
continuous extensions from a few millimeters to, possibly, in excess of
150 mm. The magnification can be more than 3X.

Bellows tend to be very expensive and slow to use. They are best for
static subjects, and are often fully manual, although electronics have
helped change that.


EXTENSION TUBES - Probably the best bet all round. They are quite
cheap, especially if you buy some from an independent maker, and retain
the automatic functions. My 'Jessop' tubes for the Canon FD mount were
well under 1/2 the price of genuine Canon ones and do the same job.
They usually come in sets of three, giving 7 possible permutations of
extension. This is quite adequate for most purposes, and consistent
extension lends itself to standardised results.

As there are only 7 possible combinations of magnification for each
lens, then a chart of fixed standard conditions can be built up and
carried at all times.

Tubes work with almost all lenses, but there are exceptions and you
should try them in the shop before you buy. For example, my tubes cause
cut off in the image corners with my Tamron 90 mm macro lens, and I had
to buy it's own dedicated tube - at a further cost of over £40.

Take care with zooms too. You can achieve huge magnifications at the
wider end of standard zooms, but they are not designed to be used so
close and quality can suffer. It is also possible to get so close to a
subject that it gets squashed on the lens front element.  This IS a
fact, not a joke !!!!

Sets of three tubes exist for medium format SLR's, but are usually sold
singly as they are so expensive - they really shouldn't be, but it's
supply and demand. I use the small tube for my Mamiya regularly with
the 150 mm. lens as it allows it to focus that little bit closer for
big head and shoulder shots. The exposure correction with a small tube,
especially on a longer lens is so small that it can usually be ignored.

It is interesting that, as focal length increases, the exposure
correction required for any degree of extension reduces. This is
related to magnification, which also reduces. Try the 'CALC' program on
this disk - it will illustrate this point.


MACRO LENSES - If you are really interested, you will buy a proper
macro lens. They are prime lenses, not zooms, and are not cheap. They
come in three general focal lengths - about 50 mm, about 90 mm. and
about 200 mm. All major camera manufacturers have them, but the
independents are usually just as good, but cost less. My TAMRON was
still nearly £200 quite a few years ago, plus the cost of it's tube !

Some macro lenses achieve full 1:1 without further assistance. Very
nice, but they tend to be rather big and heavy. I chose the 90 mm.
Tamron because it is small, but only reaches 1/2 life size - adequate
for most purposes. If I need 1:1 I fit the tube but loose infinity
focusing. The Tamron, with it's interchangeable mount system, also
means that I can use it on both Canon FD and EOS camera systems by just
changing the mount.

Macro lenses focus over the full range in their prime state. They have
extra small minimum apertures - f32 - for depth of field and are
designed to be at their best at close distances and small apertures.
They are good in any condition of use, hence the cost. ( More normal
lenses often perform less well at tiny apertures and close distances. )

The focal length to choose ? The 90 mm. type is a good bet. 200 mm. is
a bit specialist and 50 mm gets a bit too close. For 1:1 with a 50 mm.
it may be only 6 inches from the subject and will frighten off timid
insects. A 90 mm. will be nearer 12 inches from the subject. The 90 mm.
also doubles as a very high quality portrait lens - this focal length
is recognised as being about ideal on 35 mm. cameras for portraits
without distortion of features.