If you
have any questions concerning box cameras or related matters, this website is a
good place to share your doubts, and if you are lucky enough, get an answer
that gives you the details you are looking for. As you can see, this website is
designed for a person with more than a passing interest in the subject. If you
are a casual hobbyist, we are sure this website will help you, but our aim is
to present material for the person who really wishes to delve beneath the
surface and find out the why behind
the operation of things.
To begin
with Question No. 1, we often come up against a query of the sort :
I bought a Kodak, and when I opened it, I found that the film guides were curved so that when I load a roll of film, it is going to lie in a curve over the picture area. I just wondered if there is any particular reason for this; why make the film lie in a curve when it could be laid flat as you find on so many other camera makes?
I bought a Kodak, and when I opened it, I found that the film guides were curved so that when I load a roll of film, it is going to lie in a curve over the picture area. I just wondered if there is any particular reason for this; why make the film lie in a curve when it could be laid flat as you find on so many other camera makes?
Answer: Your Kodak box camera was designed by one of
the best brains in camera technology. When the camera was put on the market,
the manufacturers used every means at their disposal to see that this simple
piece of equipment did not give disappointing pictures. Try out your camera and
you will find it will give you beautifully sharp results.
Like many
other box cameras of its class, the Kodak comes equipped with a meniscus lens.
If you find this term confusing, I would suggest you drop into an optician’s
shop and ask the dealer to show you a +5 Dioptre or higher power spherical
lens. Study the lens carefully; you will find it is thicker at the centre that
at the edges, and it bulges out on one side and is cupped on the other. A
perfect example of what they call a meniscus lens.
As every
high school student of physics knows, a meniscus lens is also known as a concavo-convex
lens. It is a versatile bit of glass; it is used on spectacles in different
powers to correct eyesight, and it can be made to serve as a magnifying glass
too. When used on a camera like your Kodak, it projects on the film an upside
down image of the scene that confronts you.
Now the
meniscus lens has the distressing property that when used on a camera it
projects an image that lies on a curved surface, an effect known as ‘curvature
of field’ amongst optical designers. No matter how hard the designer tries, he
cannot do away with this effect, so the best he can do is keep the film itself
on a curve that partly confirms to the curved image thrown by the lens. On more
expensive cameras, this shortcoming is corrected to a high degree, along with
various other aberrations inherent in a lens, by proper choice of lens elements
with mathematically computed surfaces.
The curved
film plane on your box camera is therefore an expedient adopted by the
manufacturer to ensure the sharpest possible picture on the negative.