Less then 30€ and only 84 grams.
Macro photo always forces you to choose between size and depth of field. On one side you want a restricted depth
of field to get rid of disturbing objects in the background but you also want enough depth of field to keep most of your
object as sharp as possible. If you try to use a small aperture like f22, the exposure vill likely be too long to give you a
stable shot or the bug , spider or what you ame at, vill move to much to give a sharp image. On the other hand if you
try to increse the ISO-value, 400 or 800.. then the noise become most noticable.
One or more rings of modern high intensity LEDs around the front of your macro lens does a good job for flowers and
other objects that don't move very much but most spiders and bugs don't wait to check out why there suddenly was
another sun lighten up in the neighbourhood, they probably choose to hide at lightning speed. An other problem with
LEDs is the batteries you have to carry around an keep charged. 50 - 100 high intensity LEDs wants a lot of current!
The built in "pop-up" flash certainly can deliver a lot of light but it's not designed to do a good job in that short distance
we normaly use for macro photo, that is from 5 - 50 cm, you also risk a shadow from the lens in the image.
There are special macro flashes, ring flashes and they certainly do a good job, but they normaly have a weight of abt
500 grams and use batterys you have to carry and charge. On the other side they make your wallet lighter.
On the Internet I found some smart experiments with different methodes for lightning in the area of macro photography.
http://fuzzcraft.fuzzphoto.eu/ringlights.html.
The variants using optical plastic fibres looked very interesting.
At the time I took up this project, there where no macro flashes with p-ttl metering for my Pentax K10D. I decided
to modify the design and adopt it to my favorite macro configuration K10D an Sigma 3.5 180 and here is a short
description of my attempts with some clues for those who want to build their own variant.
My variant .
How I made it:
1. measure the area the light output of the built in flash as accurate as possible. For K10D it was 8 x 22 mm. 2 . Choose a suitable optical fibre. There are diameters from .5mm up to 2.5 or more. That is singel strand uncoated plastic fibre. I bought my stock from a US company "Fiber Optics Store" ( recommended!) In theory the fibers can fill the frame in two different ways shown in the pictures to the right: |
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A frame size of 8 x 22 mm can contain up to 194 fibers of 1.0mm diameter. There must also
be some space för glue and the whole thing shall be handeled without elaborate equipment
on the tabletop at home.
I chose the variant with 176 fibers.
Fibers with small diameter are more flexible and more easy to work with. If you intend to build for
a lens that has not a fixed physical length when focusing, a flexible design is crucial. My Signa 180
has inner focusing and fixed length and I chose to stay with a fiber diameter of 1.0mm.
One drawback of using small diameter fiber is that you need more fibers and there will be more fibers
to cut and more fiber endings to polish. On the other hand the smaller the diameter the less of the usable
area is lost between the fibers. Small diameter can also, at least theoreticaly, give us more loss due to
larger total length and larger surface where light can leak out. There are also more cuts to polish to get
a "perfect smooth surface".
3 Calculate the needed fiberlength. Take into account that the fibers probably need to be kept
bundeled at the sides of the lens, to make space for manual focusing. Use the longest fiber times
the total number to get the amount of fiber you will need. Add some footage to make up for not
so good cuts or other bad luck in the handeling. To cut the fiber avoid scissors or tools of that
type. I had no luck with the "warm knife" method described in some places on the net. Perhaps I
had the knife at the wrong temperature. I drilled a 1.0mm hole through a metal profile to support
the fiber and cut the fibers along the surface.
I used the type of tool shown in the picture with the monting jig.
4 Inspect and polish the fiber ends that will be located at the front of your design.
I used a small piece of brass with a 1.0 mm hole drilled at right angle to the surface to support the
fiber during adjustment and polishing of the cut ends. Some enlargement may be necessary to see the
tiny scratches.
5 . The front ring .
I chose a plastic material often used for industrial design models because I had a few pieces around
and it's a good material to work with. There is no reason why other materials can be used, like wood I kept the center of the ring to be able to keep it in place during the fiber mounting process. I built a kind of jig for that purpose. you don't want to use the lens and camera for that, with glue and other hostile things around. I also used the center hole as a fixed pivot point for drilling the holes for the fibers.
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A dremel or other minidrill on a stand is very helpful. As you can see on the picture I left two areas free
from holes for fibers for the monting where I used 3mm threaded rod coweed with crimping plastic sleaving.
This monting is only usable with a lens that keeps its length fixed during focus adjustments.
Beneath you can see an intermidiate picture with about 1/3 of the fibers mounted.
6 . The camera side.
Here you have to design the fiber adapter to suite your camera model. I started with a piece of material with about
correct thickness but a little too large, then I cut the rectangular hole for the fibers as exactly positioned as posible.
With the opening for the fibers as a guide, I trimmed the piece to correct shape. you have to arrange to keep the
design in place when you use it. My variant is secured to the camera body with a smal helix under the pop up flash
head to the rear part of the hot shoe.
7. Painting
I used a permanent fibertip marking pen to apply the black finish. Of course there are more exclusive methodes,
including air brush etc.
8 . Gluing
The Dutch author of the original article I read used a special poly uheretan glue and I could not find that in Sweden.
I tested a glue named LiquiSol but had no luck with that. I ended up with fast attack CyanoAcrylat which may damage
the surface of the fiber. I have no perfect soulotion for what to choose. With the experience of the first model I would
recommend to start with the front end. Get the fiber ends at right angle, polished and glued in place. Then with one
end fixed and the fibers prothruding a few mm at the camera end, glue this part an when fixed, grind / polish the bunch
of fibers to a flat surface matching the flash head.
9. In use.
My variant has worked rather good. f 11 - 13 gives most often a good exposure. I had hoped for f 22. It's possible
that my fast and dirty gluing has to some degree damaged the fiber surface in those areas, which may give more leekage?
I don't know. Anyhow it works rather good. In some cases with "big" eyes of a jumping spider or on shiny
bugs I got rather sharp reflexes but most of that can be solved in PhotoShop, PSP, Gimp or what you use for photo editing.
Most of the photos where flash is used in my album is exposured with this flashadapter.
10. Development
This simple and very lightweighted design inspired me to try another model. This time with 1.5 mm fibers and two light openings. The picture shows a 3D-model. In the picture only 2 fibers on each side are mounted. |
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S. Hjeltman