newbie enlarger Q

[ezwriter]

Why is there aperture settings on an enlarger when exposure is set by time? On a camera apereture is for depth of field/shutter but you're shooting
flat paper.
Sorry, havent found a Beseler 23dga manual yet so just starting darkroom work!

 

[Steve Smith]

Your not shooting flat paper, your shooting a negative which can often be anything but flat.

An enlarger is really a macro camera with the negative as a subject and the paper in place of the film.
as with most macro shots, the depth of field at the subject (in this case, the negative) is very small.

By stopping down a bit (usually a couple of stops) you get a bit more depth of field which can compensate for a bit of curl or bowing of the negative.

At the paper, the aperture controls the depth of focus. This is not as critical as it is at the negative stage but again, a bit of stopping down allows for some non-flatness in the paper (quite a lot actually).


Steve.

 

[derwent]

Also if you want a bit
More time for dodging and burning then stopping down will
Make the exposure longer...

 

[Ian C]

Part or your question is discussed here along with related ideas.

(there was a url link here which no longer exists)

 

[mdarnton]

When I was much younger I worked in a series of professional B&W labs. I ran exposures by keeping the timer set to 5 seconds, and stopping down until the image on the baseboard looked a certain darkness. In the same situation (unchanging darkroom illumination), it becomes a bit like judging the density of the final prints in room light. Eventually it got to the point where I could run hundreds of prints without a remake. It's a lot easier than test strips, and I don't think it was that difficult of a skill to acquire, but you won't ever get there if you keep changing the timer all the time.