Reciprocity for Delta 100

[seabird]

Lenny, thank you for posting your Delta data. I dont mean to hi-jack the thread, but did you also test FP4+? If so, can you share your results? Thanks.

[Lenny Eiger]

Lenny, thank you for posting your Delta data. I dont mean to hi-jack the thread, but did you also test FP4+? If so, can you share your results? Thanks.

I didn't specifically re-test this in the last round. I have always used the old standby.

time add
1 sec 1 stop
10 secs 2 stops
100 sec 3 stops

Or, to remember, if the number has 1 digit, then its 1 stop, 2 digits, 2 stops, etc. I did interpolate for 5 secs (1.5 stops to add). I don't know if its perfectly accurate, but it gets you in the ballpark with most traditional film....

Efke is the most difficult. The shorter amounts work fine in that scenario, but as the time gets longer, even more time is needed.

I hope this helps,

Lenny

[tgtaylor]

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?

Hi Joanna,

Like you, I have been an Acros addict for several years now. Starting with QL's, I switched to sheets a couple of years back to save $ + weight and bulk on backpacking trips. Frankly, I've come to enjoy the "holder experience." Somehow it is more "photographic experience" to me when using holders and there is no envelope hanging out in the wind to pick up vibrations.

To answer your questions, last winter I shot a box (25 sheets) of Delta 100 in Yosemite with the last 3 sheets taken indoors in Mariposa. Two sheets were exposed in an old upstairs courtroom in the Mariposa County Courthouse. Working with a 90mm f4.5 Grandagon my meter indicated a normal exposure of 15 seconds which translate to 55 seconds on the Ilford curve. Both negatives came out superb with normal development @ 68F. The third sheet was shot inside St Joseph's Church. It also came out superb using the Ilford’s curve.

[willwilson]

I use Howard Bond's numbers mostly, but there are so many different variables when shooting in low light that experience will really be your best guide. Development has a lot to do with low light exposure as well. I often will move a shot into reciprocity with a neutral density filter for the increase in contrast.

Sometimes the meter says 30s and the chart says to give it 41s but you know that it really needs 1m just because of the way the light is hitting the scene. I have yet to make a negative that is too dense to work with but I've got a few that I wish had some more density.

I usually count anything under 20s and use a watch for longer times, so with the shorter exposures I lean towards a little extra time with a slow verbal count, a little quicker if I am going to do N+/N++ and a little slower for N-/N--. I recalculate exposure totally if I am going to do some type of compensating development. I use the first 5 or 6 spots on my chart all the time and they work great. I typically rate Delta 100 at 75 or so. I use Xtol and rotary development.

I think if you are doing anything longer than a few minutes then you are mostly making an educated guess. I know my meter doesn't work well in that kind of light (Soligor Spot II).

Here's the chart I use (It's taped to my meter along with some other junk):
2s - 3s (I usually shot these at a long verbal counted 2s)
4s - 5s (this says 8s on the chart taped to my meter instead of 5s. I keep meaning to change it but I haven't. I have shot lots of things that metered at 4s and should of gotten 5s but they were shot with an 8s exposure by mistake and they are always fine or at least I haven't been able to tell!)
8s - 9s
15s - 19s
30s - 41s
1m - 1m 33s
2m - 3m 50s
2m 40s - 5m 13s
3m 20s - 7m
4m - 9m 20s
8m - 20m

[Hans Berkhout]

A reciprocity failure situation becomes more complicated if the illumination is not constant during the exposure time. How to deal with sun rising or setting?- deviation from the correction tables may be necessary. I must admit that I haven't tested for this!

[spiky247]

another complication to consider is how contrasty the scene is. if you are shooting a city scape at night with a lot of contrast, the exposure compensation may vary greatly depending on where you want to put your mid tone.