[QUOTES=dancqu;448194]
"I thought that the case for some time. Actually condensers
do just that, condense the beam of light. Beyond the set of the
two usual condensers which will cover any format, additional
condensers are used to increase the level of light striking
smaller negatives. Light fall off occurs when the light is
so condensed as to not cover the negative."
To expand some on my previous post:
The above is stating the obvious. But it was Not obvious
when reading the instructions for my Omega B8, a junior D2.
The auxiliary condensers were associated with the focal lengths
of the enlarging lenses as glbeas has stated. I don't recall any
mention of the size of negative to be illuminated.
What may not be so obvious from the instructions is the use
of the two large condensers alone for any format and any focal
length enlarging lens. If small format negatives are illuminated so,
it is the same illumination any small section of a large negative
might receive. If the magnification of the small negative is not
great, print times can still be reasonable. That is the only
reason for the auxiliary condensers, shorter print times.
Well that and easier focusing for large prints.
"From my reading the focal point of the condensers is to
fall beyond the lens' placement. I've measured my pair and
found that the focal point just exceeds any useful extension
of the bellows. I've an Omega B8, junior partner of the D series."
That above with a 105mm enlarging lens which, IIRC, is 10 or
15mm greater than the instructions allow. I have not tested
with a lens whose useful extension exceeds the condenser
focal length. So like I say in the above paragraph, "From
my reading ... "
To measure the focal length of the condensers one need only
to remove the negative carrier and lens board. With the light on
observe the image of the bulb projected upon the easel or a card
and make note of the distance to the negative stage. Dan