Developing Times

On my Ilford DD-X developer it shows a time of 7:00 at 75deg for HP5+. On the Ilford Compensation Chart it shows 6:15. Which should I use as a reference?

The Ilford compensation chart agrees with the one in Ralph's Lambrecht's book. Both clearly indicate that 9 mins at 68 which is what the DDX dev times info shows is 6:15 at 75 and not 7 mins but of course you know this as you have told us above.

There is an inconsistency here which maybe you want to tell Ilford about. As I am based in the U.K.( much colder climate than Texas) I always use the 68 temp and have always used the Ilford times as per the developer tech sheet so 9 mins.

9 mins always gave me reasonable negs which suggests that at 75 degrees 6:15 mins should give the same.

Take your pick. 45 secs less should only make a small difference to the neg development.

If the film can be cut without destroying anything vital then cut in two( one neg lost only) and develop at both times( 7 mins and 6:15) and then see which set of negs look better and more importantly print better/easier.

pentaxuser

Test your film, and find the developing time that fits the SBR of your scene. Sans testing, you might end up with a good negative, and then again, you might not. You can test your film using the temperature that you are most likely to use in YOUR darkroom using YOUR conditions. The testing procedure is easy, inexpensive, and in the long run will save you lots of time and money spent on negatives that are not as you might have wished. Such testing can be done by following protocols outlined on APUG, in multiple photography books, or by contacting ( amongst others ) Fred Newman at the View Camera Store. Please feel free to contact me by PM if more details are needed.