1999, Darryl C. Nicholas, All Rights Reserved
Enlarger lenses are generally
grouped into three price categories: hobby (inexpensive), regular "professional"
(moderately priced), and Apochromatic (APO) professional (very expensive).
APO lenses are designed mostly for use in precise color separation work,
where all three primary colors must be focused at precisely the same
plane simultaneously. They are also used for printing large magnification
images where there is a need to work the lens at wider open apertures.
Non-APO lenses tend to produce a slight scattering of light at the edges
of the image when their aperture is wide open, requiring that they be
stopped down by at least one f/stop to produce acceptable images. While
APO lenses also scatter the light at the edges of the image when wide
open, the effect is usually mild enough to allow for the production
of acceptable prints.
There are three companies currently making most of the enlarger lenses
being sold in America: Rodenstock, Schneider, and Nikon. All three make
several different price ranges of lenses. Beseler sells a family of
lenses that are made for them--and to their specifications--by Rodenstock.
Both Rodenstock and Schneider make "APO" enlarger lenses.
EL Nikkor does not offer an APO enlarger lens.
A 4x5 negative will require a lens of at least 135mm focal length. If
you are going to be using a medium format camera and shooting 6x7cm
format, you will need an enlarger lens of 90mm (or longer) to print
those images. Negatives of 6x6cm or 6x4.5cm require a lens that is at
least 75mm long. If you are going to use a 35mm camera, you'll
need an enlarger lens of 50mm (or longer) to print that format.
Yes, you can use a 90mm enlarger lens to print 35mm negatives but, because
of its longer focal length, you will have to have the head of the enlarger
raised much higher in order to make the same size print that a 50mm
enlarger lens would make with the head much lower. When you use a very
long lens it is possible that you might not be able to raise the enlarger
head high enough to make the size of print that you might want to make.
Thus, most folks use the shortest lens that will work with a given negative
format, allowing them to make the largest possible print with their
If you only have a 90mm enlarger lens, it is possible that you might
not be able to make wallet-size prints from your 6x7cm negatives because
the head of the enlarger might not be able to be moved low enough to
accommodate the 90mm lens. You might need a 135mm lens in order to make
wallet-size prints from 6x7cm negatives. It all depends on your specific
enlarger and how low toward the easel you can move the negative plane.
A 90mm lens would commonly be used to make wallet-size prints from 35mm
negatives for the same reasons. Most enlargers will not allow the head
to be lowered enough for a 50mm lens to produce wallet-size images from
If you think that you might want to blowup a small portion of a negative,
you might want a very short focal length lens--like a 25mm. But, remember,
such a short lens can only be used on a very small portion of a negative.
It cannot "see" an area much larger than the size of a disc
negative (smaller than a 110 negative). Such a short lens will usually
require a "recessed" lensboard.
You might want to use an "extended" lensboard with your
longer focal length lenses like the 90mm or the 135mm. An extended lensboard
(while not absolutely necessary for routine work) can be helpful when
you are trying to make small prints or prints that are actually smaller
than the negative (less than 1:1). Use a regular, flat lensboard with
a 50mm lens.
Beseler offers a line of "professional" lenses that are
made for them by Rodenstock in Germany. They are called "Beseler
HD lenses." They are comparable in quality to Rodenstock's
Rogonar-S brand. They are available from most photographic dealers,
and are perfectly great lenses.
Making Small Images. All lenses are capable of focusing at a magnification
factor of 1.0, provided that the enlarger is capable of moving the negative
plane low enough, and providing that the bellows is capable of extending
the lens far enough from the negative. For a magnification factor of
1.0 to be reached, the negative plane must be exactly "four times
the focal length of the lens" above the easel surface.
Most enlargers will only allow the negative plane to be lowered to about
12-14" above the easel surface. This is not quite close enough
for short lenses, like 50mm, to produce 1.0 magnification factors.
Remember, a lens cannot be focused if the negative plane is any closer
to the easel than four times the focal length of the lens. For example,
a 90mm lens will not focus if the negative plane is any closer than
14.04" from the easel surface. A 135mm lens will not focus if
the negative plane is any closer than 21.04" from the easel.
Making Prints Smaller Than The Negative. When making prints that are
smaller than the original negative, the negative plane is actually further
from the easel than the magical distance of "four times the focal
length of the lens," but the lens is closer to the easel than
it would be at the 1.0 magnification point. At no time--regardless of
the size of the print being produced--can the negative plane of the
enlarger ever be closer to the easel than four times the focal length
of the lens being used. See the accompanying sketches for a fuller understanding
To make a print that is smaller than the negative, first be sure that
you have selected a lens with a focal length that equals or exceeds
the diagonal measurement of the negative.
Next, be sure that your enlarger is capable of focusing the lens to
a 1:1 magnification. That is, be sure the enlarger head can be lowered
far enough down toward the easel so that the distance from the negative
plane to the easel is equal to or less than four times the focal length
of the lens.
Next, even though the negative plane of the enlarger can be lowered
far enough, be sure that the lens bellows will extend far enough to
allow the lens to be focused. For a lens to focus for a 1:1 magnification,
the lens must move away from the negative a distance equal to two times
the focal length of the lens. If you intend to go on and make a print
that is smaller than 1:1, the lens will have to move even further from
the negative plane. Many enlarger bellows are not long enough to accommodate
the longer focal length lenses, thus, longer focal length lenses are
frequently mounted on extended lensboards to help the bellows extension
by providing a couple of extra inches of distance. See the accompanying
sketches for the required bellows-extension dimensions (in inches) for
typical enlarger lenses.
Finally, move the negative plane to the point where the lens produces
a 1:1 size image on the easel, and focus the image. Be sure that you
are really at the 1:1 position and not slightly larger (or slightly
smaller). A lens cannot be focused if the negative plane is below the
point where a 1:1 image is created. However, if the lens has been stopped
down a little, it will appear to be focusing. So, be sure that you are
doing this with the lens wide open.
Then, raise the negative plane slightly--maybe a 1/4". And refocus
the lens by moving the lens further toward the easel and away from the
negative. It will focus. Do not refocus by moving the lens back toward
the negative. That will only produce a larger image, not a smaller image.
Continue to raise the negative plane in tiny increments (maybe 1/4"),
and continue to refocus the lens by continuing to lower the lens toward
the easel. The projected image will get smaller and smaller. But, you
must move in tiny increments or you will easily overshoot the limits
of the lens, and reach a point where the lens can no longer be focused
because the image has become "0" in size. As you continue
to make the image smaller and smaller you will probably reach a point
where the bellows isn't long enough to allow you to continue to
refocus the image. At that point you might want to use an extended lensboard
in order to gain an extra few inches of distance, and get a slightly
Using these techniques it is possible to make some very tiny images.
These are the techniques that are used for making photographic images
that can later be put in tiny lockets, pendants, and bracelets that
men and women sometimes wear.
As the image gets smaller and smaller the depth of focus for a given
lens and f/stop gets greater and greater, making it a little difficult
to know where the exact focusing point really is. Almost everything
will appear to be in focus. Do the focusing with the lens wide open.
It will be a lot easier to know exactly where the focusing point really
is. Then, stop the lens back down to make the print.
I usually focus the enlarger by holding a strong magnifying glass down
close to the projected image. You'll have to get down and hold
your eye very close to the magnifying glass, but then you can focus
the enlarger fairly accurately.
There is no easy way to mathematically calculate the correct exposure
level for images that are smaller than 1:1. I just do a series of bracketed
If you'd like more help with selecting the best lens for your
enlarger or how to use it, you can contact me at: firstname.lastname@example.org.