Ilford FP4+ reciprocity and semi stand and pyrocat hd

[climbabout]

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

 

[gainer]

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]

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]

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

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]

I also. See the article "Reciprocity Revisited" to see how much overexposed your negs might be if you use Ilford data for reciprocity corrections.