Digitaltruth Photo

The numbers don't seem to match Ilford's data sheet for HP5+ in D-76

Confused....?

http://www.ilfordphoto.com/Webfiles/2006216122447.pdf


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smpn wrote:The numbers don't seem to match Ilford's data sheet for HP5+ in D-76

Confused....?




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Sorry I don`t follow what you are asking, what numbers don`t match?

The development times of course??

HP5+ D-76 from the Ilford dev chart I posted

stock
400: 7.5
800: 9.5
1600: 12.5

1+1
400: 11
800: 13
1600: not recommended

From the massive dev chart:

stock
400: 7.5 (ok)
800: 10.5
1600: 14

1+1
400: 13
800: 16.5
1600: 18

Very different numbers.

smpn wrote:The development times of course??

HP5+ D-76 from the Ilford dev chart I posted

stock
400: 7.5
800: 9.5
1600: 12.5

1+1
400: 11
800: 13
1600: not recommended

From the massive dev chart:

stock
400: 7.5 (ok)
800: 10.5
1600: 14

1+1
400: 13
800: 16.5
1600: 18

Very different numbers.

The massive development chart appears to be using the times for Ilford ID-11 which has the same published formula as Kodak D-76. The commercial products most likely differ slightly in terms of the weight of components per litre of stock solution. I know that the Ilford patent for ID-11 uses an extra gram of borax compared to the original published formula. The replenishers are likely to differ as well if you check the replenishment recommendations for ID-11 compared to Kodak`s recommendations for replenishing D-76.
Start with what ILFORD recommend and then adjust the times if less or more contrast is required in future. It takes a while to get to know any film and developer combination well. The times given in any development chart should be considered only as a starting point. They can and should be adjusted if a different level of contrast works better for you.

OK, is the chart going to be updated?
How does that happen?

2nd issue: The iphone app doesn't have 400TX, I assume it's under Tri-X 400.
However the app shows D-76 at 1+1 as 10:00 minutes

The website database shows it correctly as 9.75

So far the database is zero for two for me.
I don't want a starting point, I want a reference that has the same values as the manufacturer's data sheet....

Reference: http://www.kodak.com/global/en/professi ... /f4017.pdf

Even what the manufacturers recommend are to be considered starting times. Even pro labs adjust the times based on what they find to be best.

--Gary

For further information please consult the FAQ in the User's Guide to the Massive Dev Chart which explains these issues:
http://www.digitaltruth.com/devchart.php?doc=faq

If you want to use the manufacturer's data, then you should be able to download the data sheet from Ilford for HP5+. I don't believe Kodak publishes a time for HP5+.

All published development times are starting points. It is incorrect to use a published time, whether from the manufacturer or any other source including the Massive Dev Chart, as an absolute value. Ilford's own data for HP5+ clearly states: "The development times are intended as a guide and may be altered if a different result is needed."

The times published by manufacturers are optimized for different gamma values / contrast indices, and are not determined by a universal system. Manufacturer's times rely on statistically average contrast values which will not always yield the desired result if the subject contrast differs from these values. Development time must also take into account the printing equipment (diffusion or condenser enlarger etc), as well as your personal taste in print contrast.

Keith is correct that there is no appreciable difference between the chemical performance of D-76 and ID-11. Although Ilford publishes times for HP5+ in D-76, the fact that the times differ from those for ID-11 suggests that Ilford did not use the identical testing procedure for the two sets of results.

The Massive Dev Chart is designed to provide the most reliable starting points, and unlike traditional published data it benefits from user submissions and feedback. While Ilford's data is generally very good, the same is not true of every manufacturer. In this case, I think you will find that either the starting point recommended by the Massive Dev Chart, or by Ilford, will work perfectly well. The only difference will be a slight increase in contrast where the time is longer.

The times in the iPhone app are identical to those in the online chart up to and including the most recent update on Sept 27th 2009. The Tri-X 400 entry lists all Tri-X times including any relevant legacy 400TX data. Although Kodak revised many times when Tri-X coating was last changed, there is an excellent article by former Kodak scientists Dick Dickerson and Silvia Zawadzki which appeared in the March/April 2003 edition of Photo Techniques proving that there was no appreciable difference in development recommendations, despite Kodak altering some times by as much as 50%.

Where the developing times given for D-76 and ID-11 differ, you could average them, but they will always remain as just a starting point what ever films you are using. You will need to experiment to find the optimum time for your own enlarging equipment and your own personal preference.
As Jon has said, there are no absolute time values for processing B&W films, whether they are given by the film manufacturer or a photo-Guru.

Thank you Jon, for the detailed response.