Ilford FP4+ reciprocity and semi stand and pyrocat hd

climbabout

Member
Joined
Aug 11, 2005
Messages
225
Location
Fairfield Co
Format
8x10 Format
Hello all - have any of you done any scientific testing regarding reciprocity failure using FP4+ (sheet film 4-5 through 8x10)and semi stand development in pyrocat hd? My initial tests using Ilfords charts as well as a similar table a friend of mine uses indicates I am substantially overexposed - anyone else have a similar experience? Also would you think a reduction in development would be in order as well - would like to hear your experiences. My current semi stand dilution is on the order of 1.5/1/175, 36min and initial agitation of 1min with 2 adition agitations at 12min intervals in a tube in vertical orientation.
Thanks
Climbabout
Tim Jones
 
Last edited by a moderator:

gainer

Subscriber
Joined
Sep 20, 2002
Messages
3,699
Some time ago Howard Bond did extensive (and intensive) testing of reciprocity characteristics of a number of films, including FP4+. His results were quite diferent from the tables presented by Ilford. I analyzed his results using a slightly different approach than usual, and the results are in www.unblinkingeye.com under the title "LIRF is Lurking at your F-stop". My curve fits Ilford data, but with different coefficients than Bonds data. Bond's data show that you would indeed be overexposed if you use Ilford's data.
 

Flauvius

Member
Joined
Jul 8, 2004
Messages
63
Format
8x10 Format
My EI is a function of SBR and development. That being said, with a SBR of 5 and my use of Pyrocat-HD semi-stand, my EI is 100.

However, from the data you have supplied it seems that your developer is quite strong. As such, I suspect your negatives are overdeveloped, and not overexposed. Although my ratios are .7:.6:100, and my times and agitation patterns are the same as yours, and my developing temperature is 70 degrees; the diameter of my adigation rod my result in our having difference highlight densities.

Flauvius
 

sanking

Member
Joined
Mar 26, 2003
Messages
5,437
Location
Greenville,
Format
Large Format

My own tests with FP4+ using Pyrocat-HD with stand development with dilution similar to yours shows a speed gain of about 1/4 stop over continuous agitiation. However, 1/4 stop does not amount to "substantially overexposed" so I am inclined to believe that your film may have been well over-exposed.

Sandy
 

gainer

Subscriber
Joined
Sep 20, 2002
Messages
3,699
I also. See the article "Reciprocity Revisited" to see how much overexposed your negs might be if you use Ilford data for reciprocity corrections.
 
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…