Topic: old HP5

[Volker]

hi all,

some time ago i got one box of old HP5 sheet film (13x18)
Does anybody know why this film has "a recommended meter setting" of 320 ASA instead of 400 ASA?
I always thought HP5 = 400 ASA.
Was there a difference between sheet and 35mm film emulsion? unfortunatelyi couldn't find any information or an old fact sheet online.



Thanks

[Francois]

You had me looking at my stuff.
This is the old HP5. The one they sell nowadays is HP5 Plus.

I think I have the specs for this one... I'll have to look.

Sorry... I checked an old book I got used and someone cut out the pages for it with an X-acto knife...

[gothamtomato]

320 was also the recommended setting for Tri-X as well. I don't remember if it was on the box or not, but it was the setting used by many photographers.

[jojonas~]

320 was also the recommended setting for Tri-X as well. I don't remember if it was on the box or not, but it was the setting used by many photographers.

I think it's recommended by their datasheets as well. I dunno why? maybe large format shooters are more picky so they adjust for that?

[Late Developer]

Could it be to avoid vignetting - i.e. not having a centre spot filter with a narrow aperture lens trying to cover a larger surface area?

[mcduff]

I wonder if this is related to the post I made about how ASA was adjusted in 1960 effectively doubling the rated film speed. Now HP5 (with no plus) came put after this change - it was HP3 that made the somewhat arbitrary jump (from 200 to 400 with no emulsion change). But it certainly raises the point that box speed is not cast in stone.  Perhaps someone felt the newer rating was just a bit 'too much' of a speed jump for larger formats?

[Francois]

320 was also the recommended setting for Tri-X as well. I don't remember if it was on the box or not, but it was the setting used by many photographers.

Few people know but there was actually two different tri-x films. There was tri-x pro which was rated at 320. It was available in all formats. Then there was regular tri-x that was rated at 400 and only available in 35mm.