Quote Originally Posted by DannL View Post
38 second exposure is too dark, and a 37.5 second exposure would be just right...
That's about 1/50th of a stop difference.

Just for grins - the effect of a 1 second change in exposure:

Base
Seconds --- difference in stops for adding one more second

1.0 -------- 1.00
2.0 -------- 0.58
4.0 -------- 0.32
8.0 -------- 0.17
16. -------- 0.09
32. -------- 0.04
64. -------- 0.02

Information for converting stops<->seconds is available here, and at other locations on the web.

http://www.darkroomautomation.com/su...stopstable.pdf
http://www.darkroomautomation.com/support/grastops.pdf