Ilford HP5+ and Delta 400

[George Collier]

I'm trying Delta 100 and Delta 400 with Rodinal, with my normal films being FP4 and HP5. Using the Ilford development chart (unchanged for many years), FP4 and Delta 100, for many combinations, track fairly close in time given the same collateral settings with different developers. Similar for Delta 400 and HP5, except for Rodinal, which shows almost twice the time for Delta 400. Anyone know why, and is it true?

 

[madNbad]

The increase development is because Delta 400 is a tabular grain film. HP4 and HP5 are the older cubic grain films.
Also, are you using the Rodinal at 1:25 or 1:50?

 

[George Collier]

madNbad - I know what you mean, but Delta 100 is also a T-grain film, and it's times are very close to FP4.
My dilution is 1:50.

 

[madNbad]

Here's an old thread with a lot of information:

https://www.photrio.com/forum/threads/delta-400-in-rodinal.11236/

 

[pentaxuser]

The old thread doesn't seem to answer the OP's question which seems to be why do HP5+ and D400 track each other closely in a range of developer except for Rodinal where the difference is almost twice as much

I don't know the answer but nothing I've seen so far seems to give an answer However I have a bottle of original Rodinal that I bought in 2005 and while its time for HP5+ and D400 are not the same for the two films its times for the dilutions of 1+25 and 1+50 are consistent

pentaxuser

 

[George Collier]

pentaxuser - thanks for actually reading my question. I guess I'll try something close to what it recommends, but pull back a bit - better slightly low contrast than over the top.

 

[Andrew O'Neill]

Yes, the tabular films take a bit longer to develop, but that is a considerable difference, I'll say! Is Rodinal your only choice? Have you used Rodinal at 1+25?

 

[MattKing]

The tabular grain films are the result of relatively newer R&D, and most likely were designed with more recent commercial processing considerations in mind.
So it wouldn't be surprising if they were designed to be more suitable for 24C than the older films.
Which equates to longer times in 20C.
And Rodinal is so different from most commercial developers, it is bound to behave differently than, e.g., D-76/ID 11 or X-Tol or HC-110.

 

[George Collier]

OK, after some thought, I'm going with 7.5min at 73˚F, dilution 1:25, and thanks for the replies.

 

[titrisol]

I have no idea why, but this happened when Ilford changed de Delta400 formulation (2002 or whereabouts)
The new Delta is finer grained, have nicer tonality and responds better to Rodinal than the older one