# Rehashing enlarger height question

Discussion in 'Darkroom Developing and Printing' started by Ian Dodd, Aug 11, 2003.

1. ### Ian DoddGuest

Been a while since I posted on this NG. The darkroom equipment is
coming out of mothballs while a friend and I finish construction on a
new darkroom in his garage. Getting ready to build the counter top
for the enlarger and want to double check my math with you guys first.

A few years ago I posted a question regarding enlarger height, lens
focal length, and print size to determine how much vertical space was
needed (I never made any changes in my old darkroom before I sold that
house). The formula given to me then was:

distance = FL * (1/M + M + 2)

where FL = focal length and M = magnification

By my calculations, if I want to do a 16X20 from 4X5 (and figuring a
little more than 4 times magnification for true image size on the
negative and maybe a little cropping), with my 150mm lens I need about
40" from neg stage to paper:

150mm * (1/4.5 + 4.5 + 2) = 150 * (.222 + 4.5 + 2) = 150 * (6.72) =
1008mm = 39.7 in. The same formula for 20X24 yields a result of 45.4
in.

My Omega D-II measures 50" tall with the cold light installed with the
negative stage 9" below that. If we wall mount it as high as our
ceiling allows, the negative stage ends up 81" off the floor. If we
put our counter top at 35" (standard kitchen counter height), that
leaves plenty of room for 16X20 prints and just enough for 20X24 (with
the paper right on the counter top--no easel). 81" - 35" = 46"

Also, by eyeballing it, it looks like the centerline of my lens is 19"
out from the back wall when the head is at full height. Any Omega
users out there that can verify this? If that's correct, it seems
like our counter needs to be about 30-32" deep to accomodate the 16X20
easel centered under the lens.

Am I figuring this correctly? Do these numbers fit with your actual
darkroom set ups? Thanks for your help.

Ian

Ian Dodd, Aug 11, 2003

Hi Ian,

I went through the same situation several months ago. You didn't seem
to be getting any responses, so I thought I'd chime in.

I have a wall-mounted D5-XL in my basement darkroom that also uses a
custom-built countertop as the "baseboard." My setup sounds *very*
similar to what you describe--albeit with a D5 instead of a D2. My
approach was to place the enlarger base plate exactly the same
distance out from the wall as it originally was from the end of the
original baseboard. I then built the countertop to the exact same
depth from the wall (34 inches) as the depth of the original
baseboard. The enlarger and countertop have been meticulously aligned
and leveled.

Last night I inserted, adjusted and focused a 4x5 negative so that it
was exactly 39-3/4 inches above the countertop (no easel). This
matched the result of the calculation in your post for a (slightly
larger than) 16x20 enlargement. The lens is a Schneider 150mm f/5.6
Componon-S. I then locked the enlarger and measured the following:

Some of my darkroom dimensions for reference
--------------------------------------------
Floor-to-ceiling = 105"
Floor-to-countertop = 42-1/2" (I'm 6'6" tall...)
Countertop-to-enlarger-base = 6-1/4" (elev above the counter)
Enlarger-base-to-ceiling = 56-1/4"
Wall-to-countertop-edge = 34" (same as the original baseboard)

16x20+ enlargement dimensions
-----------------------------
Negative-to-countertop = 39-3/4"
Negative-to-floor = 82-1/4"
Full-frame projected image size = 16-1/2" x 21"
Centerline of the enlarging lens out from wall = 21-1/4"
Wall-to-top-of-projected-image = 13" (horizontal)
Countertop-edge-to-bottom-of-projected-image = 4-1/2" (horizontal)

Then, using the same negative raised to a height of 45-1/2 inches for
a (slightly larger than) 20x24 enlargement, I measured the following:

20x24+ enlargement dimensions
-----------------------------
Negative-to-countertop = 45-1/2"
Negative-to-floor = 88"
Full-frame projected image size = 20-1/8" x 25-5/8"
Centerline of the enlarging lens out from wall = 22-13/16"
Wall-to-top-of-projected-image = 12-3/4" (horizontal)
Countertop-edge-to-bottom-of-projected-image = 1-1/8" (horizontal)

Not all of these measurements may be useful to you. But hopefully
there are enough for you to check and cross-check your calculations
before committing to a design. When I did it, I ended up mounting the
enlarger first before installing the counters just so I could play
around with projected images, distances and easel sizes.

Hope this helps a bit,
Ken