Reciprocity for Delta 100

[Joanna Carter]

Having been an Acros addict for a while now, I need to start using Ilford's Delta 100 to extend the life of my Quickload stock :-)

Now, those of us who use Acros will know of its amazing reciprocity characteristics but, looking at the curve that Ilford supply for Delta 100, it would appear that all Ilford have done is to copy the same curve for all their emulsions. I'm sorry but, I refuse to believe that a 50 ISO film has exactly the same reciprocity as a 3200 ISO film.

Does anyone have any real world experience of long exposures and reciprocity with Delta 100?

[percepts]

As with all HD curves, reciprocity curve is subject to processing conditions. i.e. which developer, time and temp etc. Therefore you can not rely on any published curve.
However, assume that the Ilford curve is for reciprocity of the highlight values.

What I mean by that is that a night time image or indoor image may have areas in bright light and some in areas of very deep shadow thereby creating a scene with a very large subject range. Base you exposure on the highlight value and there may be no reciprocity. Base it on the shadow and it will tell you there is reciprocity. Which is correct? Using the highlight value will work better than using the shadow. For black and white use development for a 10 stop range. In most circumstances that will give you very good results using Ilfords chart. Use the shadows for setting exposure and the chart will cause you massive over exposure to highlights.
I have found the Ilford chart good for HP5 using exposure as I have suggested. I see no reason why it won't work just as well for Delta.

[Keith Tapscott.]

Does anyone have any real world experience of long exposures and reciprocity with Delta 100?

Not personally, but you might find this useful.

[Marko]

Having been an Acros addict for a while now, I need to start using Ilford's Delta 100 to extend the life of my Quickload stock :-)

Now, those of us who use Acros will know of its amazing reciprocity characteristics but, looking at the curve that Ilford supply for Delta 100, it would appear that all Ilford have done is to copy the same curve for all their emulsions. I'm sorry but, I refuse to believe that a 50 ISO film has exactly the same reciprocity as a 3200 ISO film.

Does anyone have any real world experience of long exposures and reciprocity with Delta 100?

Since you are now manually loading Delta 100 sheets, why not manually load Acros and stay with the emulsion you like and are used to?

They are still making Acros, they just stopped producing the Quickload....

[Joanna Carter]

Since you are now manually loading Delta 100 sheets, why not manually load Acros and stay with the emulsion you like and are used to?

Because, as yet, nobody in the UK is selling the sheet film

[Marko]

Because, as yet, nobody in the UK is selling the sheet film

If you can purchase across The Pond from eBay, why not from Badger?

[Joanna Carter]

If you can purchase across The Pond from eBay, why not from Badger?

The way that Fuji UK behave, that may well be the only way to get hold of it

[DJGainer]

freestyle has it too, for slightly less than badger. still waiting on b&h's price point before I make a decision whether or not to try the loose sheets.

[Michael Rosenberg]

Joanna,

I have found the reciprocity behavior of Delta 100 (exposed at ASA 100), developed in Xtol 1+2, to be excellent. I do not do any correction up to 2 min, and add 5 sec every 15 sec increment up to 4 min. Fine grain in Xtol, but not as fine as TMY2. I process in a Jobo 3010 tank at 22C for N=9:00 min.

[Lenny Eiger]

Not personally, but you might find this useful.

Not useful. Incorrect.

Joanna, try this: we just tested this earlier this year. They are an approximation based on shooting outside and reading with densitometer, and as always, where one points the meter controls a lot of things... It's been working well over a series of trips...

Meter Shoot at
1 1
4 5
8 11
15 26
30 50
1 min 2 min
2 min 5:15 min

Give it a whirl - it works for me....

Lenny