Ilford HPS plates.

[alexvaras]

Hi all,

Another box opened, this time old HPS from Ilford, rated at those times (195x) as ASA800!!


Ilford HPS plate.

My guess in these test shots were ASA25 and ASA10 respectively.


Shot as ASA25.


Shot as ASA10.

Histogram at scanner showed first photo about the 2/3 line right, overexposed by 1? and the second more than 2/3 of the histogram to the right so overexposed by 2?
First plate shows emulsion failure and second looks better so now Im a bit lost... keep ASA10 or try ASA50...
Developed both of them 12 minutes D-76 1+1.

All comments and help are welcome
Alex

[Julio1fer]

Hard to tell from scans, you'd better look at the plates, especially the detail in shadows, maybe with a loupe. If it is satisfactory at 25, so it is.

When in doubt, overexpose.

These plates must be really old - in this chronology there is an image of a box similar to yours, apparently launched in 1952. Fastest plate in the world at the time.

[PFMcFarland]

Could it be it has emulsion damage because it was the first plate out of the box? Maybe its proximity to the packaging or elements caused it.

PF

[Brazile]

While there is a more formal approach to testing plate speed, what I generally do when testing an unknown set of plates is that I make my best guess at exposure, then expose the plate in a sequence of 5 by pulling the dark slide in a graduated fashion. Usually -2 stops, -1 stop, my guess, +1 stop, +2 stops. That often answers the question for me adequately, and if not, refining my guess and doing one more plate always gets me close enough.

As for the subject...a step wedge of sufficient size is your best bet, because the step relationships will help guide you; otherwise, perhaps a test pattern plus gray card. High quality large step wedges are expensive, but you can also print one with an inkjet printer onto transparency film (Pictorico, Fixxons, etc.) that will work well enough. I have a file somewhere I can send you if you need one.

Robert

[Brazile]

In an ideal world, of course, you've tested for Dmax already and have an optimal development time for the plates. But looks like you're close enough already...

[alexvaras]

While there is a more formal approach to testing plate speed, what I generally do when testing an unknown set of plates is that I make my best guess at exposure, then expose the plate in a sequence of 5 by pulling the dark slide in a graduated fashion. Usually -2 stops, -1 stop, my guess, +1 stop, +2 stops. That often answers the question for me adequately, and if not, refining my guess and doing one more plate always gets me close enough.

As for the subject...a step wedge of sufficient size is your best bet, because the step relationships will help guide you; otherwise, perhaps a test pattern plus gray card. High quality large step wedges are expensive, but you can also print one with an inkjet printer onto transparency film (Pictorico, Fixxons, etc.) that will work well enough. I have a file somewhere I can send you if you need one.

Robert

Good idea, Robert, thank you! Yes please semd me the file and I will print it for my next batches.