f-stop printing calculations

Todd Barlow

Subscriber
Joined
Aug 9, 2004
Messages
494
Location
Ontario
Format
Multi Format
What is the formula that is used to calculate the times shown in the various f-stop printing sheets?

For example
If the base time is 8 sec:
+1 stop = 16 sec how do you arrive at +1/2 stop = 11.3 sec?

Todd
 

Bruce Osgood

Membership Council
Member
Joined
Sep 9, 2002
Messages
2,642
Location
Brooklyn, N.Y.
Format
Multi Format
Todd Barlow said:
What is the formula that is used to calculate the times shown in the various f-stop printing sheets?

For example
If the base time is 8 sec:
+1 stop = 16 sec how do you arrive at +1/2 stop = 11.3 sec?

Todd
Click to expand...
------------------------------------------------------------

http://unblinkingeye.com/Articles/TestExpo/testexpo.html

This should give you a good starting point.
 

Lee L

Member
Joined
Nov 17, 2004
Messages
3,281
Format
Multi Format
Todd,

I made up my own tables in a spreadsheet. If you can handle openoffice or Excel spreadsheets, the attached .zip file has both formats (done in openoffice) that produce an f-stop printing table. You can look at the formulae used in the spreadsheet to get an idea of how it works.

I just taught two 6th graders the basics of B&W, and since they'd just learned the basics of geometric progressions with camera stops and shutter speeds, f-stop printing seemed very natural and logical to them. I now use an RH Designs timer rather than these charts.

Lee
 

Attachments

  • fstopprinting.zip
    48.1 KB · Views: 343

vet173

Member
Joined
Mar 29, 2005
Messages
1,209
Location
Seattle
Format
8x10 Format
Thanks Lee, that is great. Helps us what got problems with cypherin.
 

lee

Member
Joined
Nov 23, 2002
Messages
2,911
Location
Fort Worth T
Format
8x10 Format
RH Designs Stopclock timer will do this for you and is much more accurate but the trade off is it is more expensive.

lee\c
 

Marc Leest

Member
Joined
Oct 23, 2003
Messages
504
Location
Hasselt, Bel
Format
Multi Format
Todd Barlow said:
What is the formula that is used to calculate the times shown in the various f-stop printing sheets?

For example
If the base time is 8 sec:
+1 stop = 16 sec how do you arrive at +1/2 stop = 11.3 sec?

Todd
Click to expand...

Simple

it would be T x 2^+f
(^ means to the power)
So in your example
it would be
8 x 2^ +1 = 16
8 x 2^+0.5 = 11.31

M.
 

Lee L

Member
Joined
Nov 17, 2004
Messages
3,281
Format
Multi Format
For those without a spreadsheet program, an f-stop timing table for printing is at: www.largeformatphotography.info/articles/f-stopTimingAdv.pdf
This is a .pdf file of a page from Way Beyond Monochrome.

I didn't mention it in my earlier post, but openoffice is free and very capable, and available for Windows, linux, solaris, BSD, and Mac OS-X. See openoffice.org

Lee
 

joeyk49

Member
Joined
Jan 13, 2004
Messages
1,325
Location
New Jersey,
Format
Multi Format
Todd:

Thanks for asking the question.


Posters:

Thanks very much for answering.


Joe
 

Gerald Koch

Member
Joined
Dec 14, 2004
Messages
1,662
Format
Multi Format
Do a google, there are several places on the web where you can download the images to make a calculator. Or buy a new/used copy of the Kodak Darkroom Guide which has one.
 
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…