Macro with the Olympus C-730 Digital Camera
The Olympus C-730 digital camera with the 10x optical zoom comes with a
Macro and Super Macro capability in the menus. The Macro ability from the
button allows slightly closer focussing than usual and the Super Macro
mode accessed via the menus allows very close focussing but at a very close
distance from lens front to subject. There are alternative ways to get
better macro and at a better working distance (lens front to subject).
The simplest way to get a better result is to add the Olympus CLA-4
adapter tube that allows 55mm thread accessories to be mounted in front
of the lens. Raynox (www.raynox.com) makes a similar adapter that has a
probably more useful 52mm thread that suits their range of wide angle and
tele adapters. Either way, add a close-up lens to the adapter and things
improve dramatically. Better of course is to use the more expensive 2 element
design of close-up lens. Hoya, Canon and Nikon make these in various dioptre
strengths and various filter sizes. I started out using a Nikon 6T which
happens to be +2.9 dioptre and 62mm thread size, but I intend changing
over to all 52mm size accessories to make life simpler and lighter.
Experimenting with various ordinary quality single element close-up
lenses in various strengths I came up with the following chart. The measurements
are shown in millimetres and inches in brackets. Numbers have been rounded
somewhat as it is not a precise science. I just observed a metric ruler
through the viewfinder and then measured the distance from the lens front
to the subject with a tailor's tape. Rough enough.
|
Combination
|
Manual Focus to
|
Width of Image Seen
|
Working Distance
|
| +1 |
Infinity
|
100mm (3.9in)
|
1020mm (40in) |
| +1 |
Closest (1m approx)
|
58mm (2.3in) |
500mm (20in) |
| +2 |
Infinity
|
49mm (1.9in) |
530mm (21in) |
| +2 |
Closest (1m approx)
|
38mm (1.5in) |
340mm (13in) |
| +2.9 Nikon 6T or 4T |
Infinity
|
34mm (1.3in) |
350mm (14in) |
| +2.9 Nikon 6T or 4T |
Closest (1m approx)
|
31mm (1.2in) |
250mm (10in) |
| +4 |
Infinity
|
24mm (0.9in) |
260mm (10in) |
| +4 |
Closest (1m approx)
|
23.5mm (0.9in) |
200mm (8in) |
| +5 |
Infinity |
20.5mm (0.8in) |
200mm (8in) |
| +5 |
Closest (1m approx) |
20mm (0.8in) |
170mm (7in) |
| +10 |
Infinity
|
10mm (0.4in) |
100mm (4in) |
| +10 |
Closest (1m approx)
|
11mm (0.4in) |
85mm (3.3in) |
| Super Macro Mode |
Closest 4 cm indicated
|
44mm (1.7in) |
40mm (1.6in) |
All the above results came from using the lens at the 59mm end which
is equivalent to 380mm in the 35mm film world, except of course the Super
Macro mode which sets the lens to the equivalent of 63mm focal length in
35mm film. If you zoom back from the tele end of course the subject image
width seen will be larger, ie less macro. To get the equivalent image of
the 1:1 macro lens in 35mm world then around +3 dioptre is needed at full
tele. To get the rather unheard of 3:1 image size (3 times enlargement)
in 35mm world equivalent then the +10 dioptre delivers.
From my experience if photographing insects a working distance of greater
than about 200mm (8in) is desirable, that makes the +5 dioptre as about
the strongest close-up to use on the C-730 for living insect subjects.
Not tested but the C-700, C-720, C-740 and C-750 would all deliver
very similar results due to their large optical zoom range.
I used manual focus as it involves less fiddling and delays. Auto focus
can be used within the distance ranges shown in the working distance column
but it is painful as sometimes it takes a few tries to focus correctly
on macro subjects. It is far better to always manual focus and shift the
camera or the subject to and fro. I tend to leave the manual focus always
at infinity to get the better working distance and then change image size
by zooming.
Hoya list their AC (Achromatic) range of filters in their filter handbook
and the strengths are +3, +4, +5 and +10. The size range is 49mm, 52mm
and 55mm for the +10 Macro Close-up. The size range is 49mm, 52mm, 55mm
and 58mm for the AC Type Close-up with the +3, +4, +5 strengths. Nikon
make a 4T close-up which is +2.9 and 52mm size, and also the 6T close-up
which is +2.9 and 62mm size. Nikon also make some +1.5 close-ups but don't
bother with the lesser strength. Canon make some two element close-ups
in various sizes, best to consult B&H lists to see what is there, www.bhphotovideo.com
The main thing to make sure of is that they are TWO ELEMENT close-up
lenses, the ordinary cheaper single element ones will work but the image
quality suffers somewhat.
Another option not tried yet is the Raynox Explorer set of two close-up
lenses. Some say the image quality is a bit dreadful, but I have yet to
find out for myself if I can manage to borrow a set from a friendly store
to test.
This is the result of using the C-730 with manual infinity focus at
maximum tele and the Nikon +2.9 dioptre close-up added (working distance
from subject to front of lens about 350mm or 14 inches). Slight image quality
was lost due to jpegging down to a suitable size for the web. The top edge
of the rule shows about 33 and a bit millimetres, so is a bit better than
the 35mm world of 1:1 macro image which would come out to about a whisker
under 36mm across. I used f/8 and about 1.6 sec exposure as that is how
the light happened to be on my kitchen table at the time. Took the picture
in 640x480 mode so no downsizing or cropping was done. I used a decent
tripod of course. |