Film group meeting 3-27-2017

Topic was developing time based on temperatures.
Developed 3 negatives at 1 minute, 9 minutes (recommended time) and 45 minutes. Each produced an image on the negative.

Member scanned one negative from the 9 minute developing time neg and a similar image from the 45 minute developing time neg and checked the image densities at similar locations.

Just for reference, he used Ansel Adams book “The Negative” and found the following approximate densities as desirable for a good negative

The darkest shadows (Zone I) should have a density of 0.09 – 0.11
Midtones (Zone V) should be around 0.65 – 0.75
Highlights, the brightest areas of the scene (Zone VIII) should be around 1.25 – 1.35

That would mean that the highest density in the negative (1.35) would give the brightest areas of the print (sky…white objects, etc). Any density above that means that you have extra silver developed that you have to print through (by increasing the printing time ) to produce an image. This would also mean more grain being present (more silver = more grain).

He measured the densities for various parts of the negatives. The 9 minute negative gives reasonable densities for a good print. The 45 minute negative has much higher densities overall, higher contrast which is visible in the two images and would provide a good print given enough time. He will print an image from each negative to see how the grain compares in addition to the exposure time difference.
Next meeting: Black and white slides