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# Thread: exposure adjustment for change in enlarger height

1. ## exposure adjustment for change in enlarger height

Hi, somewhere I have a table that does a quick approximation for the change in exposure when the enlarger is raised or lowered. I know the formula, but the table would make things easier. I have looked online and can't find one. Also, I assume that the measurement is made from the film plane to the top of the easel.

2. here's one from Ralph Lambrecht that I found a long time ago on his Darkroom Magic site

3. Originally Posted by samcomet
here's one from Ralph Lambrecht that I found a long time ago on his Darkroom Magic site
I can offer this;hope it helps a bit.

4. ooopppss Ralph beat me to it before I could upload the same image. Thanks mate!!!!

5. There was once a very useful table here on APUG given to us by a APUGer as a link You simply entered the before and after column heights and the original exposure and it produced the new exposure.

I bookmarked it but the site has gone, alas. Maybe the originator would consider resurrecting it, assuming he still participates here?

pentaxuser

6. Originally Posted by samcomet
ooopppss Ralph beat me to it before I could upload the same image. Thanks mate!!!!
I guess no one reads before they post these days. I posted a link to the same chart. Yeah, the pdf is better.

7. sorryBill

8. A bit of mental arithmetic can achieve the same result. Suppose that you have a test filling 5x7" and want to make a print on 16" paper, the new image area is measured to be about 11 1/2"x16" (ignoring small borders). So the increase in exposure is (11 1/2x16) divided by (5x7), (184/35), which works out to 5,26 and therefore 5,26 times the original exposure time, as a starting point.

Given the large change in size you might also want an increase in contrast, and probably to change the exposure by a few tenths of a stop from the test - but the different print areas are illuminated by the same light-source, so the starting-point increase (or reduction, if making a smaller print) in time works like this.

If you make 'minimum-time-for-maximum black' style contact-sheets, and use an enlarger as the light-source, then you can also estimate a starting point for any size print from the time used for your contact-sheet.

9. Originally Posted by RalphLambrecht
I can offer this;hope it helps a bit.
Many thanks. It does indeed help.

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