Ilford Delta 100 Recipricol failure

[an1uk]

This shows different values from the apps for Ilford Delta

 

[ChrisR]

Looks like this on my phone. Before it shows the time there's a note saying to hit calculate. Maybe send a note to the developer via Google Play. There's another app but that seems to make a guess based on extrapolating values.
View attachment 95980

OK, the tick box line is at the very bottom of the screen on my phone, and there's no way to move the screen down. Looks like the developer wrote it for a larger screen resolution and missed something out...

EDIT: FWIW the note that @steveo_mcg sent me had "actual" times of 3:50 for Delta 100 based on a 120 second exposure, so much closer to the Reciprocity app than the Exposure Assistant values!

EDIT again: I have now emailed the developer, also giving him a link to this thread. It's a free app so we have no right to expect anything, but it would be nice!

 

[ChrisR]

I've got that as well Chris and I really don't understand it at all. Where's @steveo_mcg when you need him?

What sort of phone do you have, Andy?

 

[Andysnap]

What sort of phone do you have, Andy?

I have a Geordie phone... An Huawei something or other, but its one of the bigger phones so everything fits.

 

[ChrisR]

The developer emailed back "Thank you for your feedback, I will be addressing this issue soon and make it work for smaller screens too. I will email you an email update when it is done."

 

[ChrisR]

Been looking at the data sheet for Tri-X. It says:

"1 sec +1 stop 2 secs -10% dev time
10 secs +2 stops 50 secs -20% dev time
100 secs +3 stops 1200 secs -30% dev time"

So, how do I deal with this if I have some low light shots in the middle of a roll? And what are the implications of suggesting those reduced dev times?

 

[ChrisR]

I asked this question on twitter to @filmdevelop and got several answers. @PanamStyle suggested that if I devved it as per normal, "highlights may be blocked; accentuated grain; depends on several variables". @tripcodeuser said '"less dev, more light" is same as pulling film. datasheet is rephrasing ansel adams' and went on to recommend stand or semi-stand dev to handle varying EI on the same roll, which is fine except it won't work with a Rondinax tank. @LBWheaton said "Sounds like they assume low light would be a high contrast night shot (like under street lamp) so the 'pull' to tame contrast?", to which I replied "that actually makes a lot of sense. Guess I’ll have to try taming contrast in pp. Thanks for the thought."

Quite an interesting experiment, I thought. However, the RF for Tri-X is so bad, I don't think I will try night time exposures unless I really have to. There could be a use for day time long exposures when you don't have big stopper, I guess. (I have 3 NDs: a SRB ND1000, a SRB ND1.2, and a Kood ND4! Trust me to get all the variations, but I have to think really hard to work out how many stops they each are!)

EDIT from Wikipedia it appears they are a 10 stop, 4 stop and 2 stop respectively, and there are apparently yet more variations than I've got...

 

[steveo_mcg]

I've got that as well Chris and I really don't understand it at all. Where's @steveo_mcg when you need him?

alright dudes, whats going down in groove town.

 

[Asha]

alright dudes, whats going down in groove town.

you have magical answers (evidently ) in reciricol failure times

I will be holding you more than one hundred percent responsible if I stuff a sheet of delta due to your incorrect info, so be warned

 

[steveo_mcg]

reciricol failure

reciricol I am a published expert, I know nothing about taking film photographs at night though..

 

[Asha]

reciricol I am a published expert, I know nothing about taking film photographs at night though..

Oh that's OK cos the shot I have in mind will be taken in the middle of the day .......


It's just that it's gunna be in a building with shadows like one finds in a coal cellar

 

[steveo_mcg]

Oh that's OK cos the shot I have in mind will be taken in the middle of the day .......


It's just that it's gunna be in a building with shadows like one finds in a coal cellar

Ah, I can only help with coal cellers when there is a black cat involved, I've specialised in wild life photography.

 

[Asha]

Ah, I can only help with coal cellers when there is a black cat involved, I've specialised in wild life photography.

I have a black cat!!!!

She's not very accommodating though and is unlikely to want to show any involvement

 

[steveo_mcg]

This shows different values from the apps for Ilford Delta

View attachment 95982View attachment 95983

I've only just seen this. The one one right uses the official Illford reciprocity formula which works great for their "conventional" grained films but is way off for their more modern emulsions.

OK, the tick box line is at the very bottom of the screen on my phone, and there's no way to move the screen down. Looks like the developer wrote it for a larger screen resolution and missed something out...

EDIT: FWIW the note that @steveo_mcg sent me had "actual" times of 3:50 for Delta 100 based on a 120 second exposure, so much closer to the Reciprocity app than the Exposure Assistant values!

EDIT again: I have now emailed the developer, also giving him a link to this thread. It's a free app so we have no right to expect anything, but it would be nice!

Did you ever make up that crib sheet you were thinking about? @Nomad Z was asking for my data and I can't find the stuff I sent on to you. I'm sure it would be neater than my tables.

 

[ChrisR]

Did you ever make up that crib sheet you were thinking about? @Nomad Z was asking for my data and I can't find the stuff I sent on to you. I'm sure it would be neater than my tables.

I did combine your observations with some data I extracted from datasheets, and colour coded it to make it a bit more obvious where you've got worry (red cells where it's more than half a stop from metered, IIRC). At this moment I can't work out how to display it here in readable form, but I'm sure it'll be possible at a better hour!

 

[ChrisR]

Did you ever make up that crib sheet you were thinking about?

So, the diagram below is based on something Steven sent me a while back. The first part is sort-of a downward extension of Sunny 16, ie a way to characterise the (low) light levels by just looking, based on his experience of night shots in Edinburgh. The remaining blocks are data for the exposure of various films, although the very first is the "ideal" case with no reciprocity failure. The blocks for Delta 100 and Delta 400 are based on Steven's actual data from tests, or at least from real exposures. The remaining blocks are based on manufacturers' supplied data sheets. The Vista 400 data sheet doesn't supply data for longer than 120 seconds. I only did the films I was interested in at the time; I would probably add FP4 and the two current Portras at some time.

One thing I have added is to colour-code the data: green for where it follows the "ideal" reciprocity case, orange for where it's a bit off, red where it's a stop or more off. Not sure how well it's going to turn out putting it up by the method I have in mind. Just to remind y'all, this is basically Steven's work I'm reporting in different form.

 

[Asha]

Reviving this thread to update on my findings.

Having exposed two frames of Delta 100 for metered exposure times of 4 seconds and 32 seconds respectively using the recipocracy adjustment described below, I have two perfectly exposed shots!


Adding a half stop compensation for every doubling of metered exposure time required. For example :

Metered exposure time / Additional compensation / Actual exposure time

1 second / 0.5 stop / 1.5 seconds

2 seconds / 1 stop / 4 seconds

4 seconds / 1.5 stops / 12 seconds

8 seconds / 2 stops / 32 seconds

16 seconds / 2.5 stops / 96 seconds

32 seconds / 3 stops / 256 seconds

Wether this method continues to work efficiently at longer exposure times will only be found out by experimentation.


The sheets were devd in HC-110 (B) solution for 5mins 6 seconds.

The 15% reduced duration from 6 full minutes as stated in the Massive dev chart to 5 mins 6 secs was to compensate for continual gentle agitation with the Orbital processor.

Hopefully this info will help others to get their long exposures somewhere close to correct.

 

[excalibur2]

Well I don't do B\W but some of those compensation times are amazing

 

[Peter B]

Good news 1: Ilford have a 2017 pdf that deals with the new factors, and the factor for Delta 100 is 1.26. This is the same as FP4+

https://www.ilfordphoto.com/wp/wp-content/.../Reciprocity-Failure-Compensation.pdf

Good news 2: @Kevin Allan has very helpfully worked out a table of compensated times for FP4+ which you can either print out, take a photo on your phone, or both!

https://filmphotography.blog/2017/09/24/ilford-fp4-updated-reciprocity-information/

 

[ChrisR]

I must admit I'm very surprised that the reciprocity effects for Delta and FP4 are supposedly the same, given they are supposed to be such different films!

It's also interesting that Asha's exposures metered at 4 and 32 seconds (presumably shot at 12 and 256 seconds) came out properly exposed, given that Kevin suggests the "old" values would have been 9 and (maybe) 170 seconds, and the "new" exposures would be 6 and (maybe) 80 seconds (the maybes are because Kevin gives values for 30 rather than 32 seconds, and I'm not good at extrapolating in a power space!). I'm guessing this shows that Delta is an extremely flexible film as far as exposure goes.

 

[excalibur2]

I must admit I'm very surprised that the reciprocity effects for Delta and FP4 are supposedly the same, given they are supposed to be such different films!

It's also interesting that Asha's exposures metered at 4 and 32 seconds (presumably shot at 12 and 256 seconds) came out properly exposed, given that Kevin suggests the "old" values would have been 9 and (maybe) 170 seconds, and the "new" exposures would be 6 and (maybe) 80 seconds (the maybes are because Kevin gives values for 30 rather than 32 seconds, and I'm not good at extrapolating in a power space!). I'm guessing this shows that Delta is an extremely flexible film as far as exposure goes.

h'mm easily solved by someone exposing a subject with Asha's times and others to see the difference on the neg.

 

[StephenM]

I asked this question on twitter to @filmdevelop and got several answers. @PanamStyle suggested that if I devved it as per normal, "highlights may be blocked; accentuated grain; depends on several variables". @tripcodeuser said '"less dev, more light" is same as pulling film. datasheet is rephrasing ansel adams' and went on to recommend stand or semi-stand dev to handle varying EI on the same roll, which is fine except it won't work with a Rondinax tank. @LBWheaton said "Sounds like they assume low light would be a high contrast night shot (like under street lamp) so the 'pull' to tame contrast?", to which I replied "that actually makes a lot of sense. Guess I’ll have to try taming contrast in pp. Thanks for the thought."

Reciprocity failure affects both effective sensitivy and contrast; at times longer than "normal" contrast rises; at times shorter than "normal" (usually assumed to be be 1/1000th sec but in my day only encountered with high speed flash) contrast drops. Hence advice to extend or cut developing times depending on the end of the scale you were. Colour balance would also be affected (presumably different reciprocity effects in the different emulsion layers).

 

[Asha]

Revival of this thread following an exposure taken today.

Ilford Delta 100

Metered exposure time 3 mins 30 seconds

Actual exposure time 13 minutes………….. the resulting negative is correctly exposed!

The most info i had available was for 60 seconds metered required an exposure time of 173 seconds ( almost 3 mins)
Using a calculated guess, I multiplied that time by 3.5 ( minutes metered) then added 35% of the result giving a total exposure time of 13.5 mins.

Like with most things with me, I didn't time it precisely to the second knowing that at that length of exposure time, a half minute more or less wasn't going to make a lot of difference.

Anyway it gives some idea to help others if doing extra long exposures.

Also don't forget that the reciricol failure is the same for FP4 although without experimentation I don't know if that film will behave in the same manner as Delta.

 

[ChrisR]

Also don't forget that the reciricol failure is the same for FP4 although without experimentation I don't know if that film will behave in the same manner as Delta.

While the Ilford figures are now the same, this seems really odd to me as presumably the physical chemistry (*) of the films are very different?

* If that's the right term for the crystal structure/gelatine mix etc...

 

[Asha]

While the Ilford figures are now the same, this seems really odd to me as presumably the physical chemistry (*) of the films are very different?

* If that's the right term for the crystal structure/gelatine mix etc...

Time for you to load up a sheet of FP4 and shoot a scene ( using ND filters if necessary) with a metered exposure time of 3.5 mins then let us know the results.

I would post the resulting Delta negative for you all to see but it's potentially an entry for one of the FPOTY categories later in the year so I aint sharing ….Yet!

 

[ChrisR]

Don't think I have any FP4 sheet film, sadly.

 

[mkhardy]

Hi,

I also shoot Delta 100 (4x5), and shoot with a center-filter (2-stop) and a polarizer (1.5 stops). I meter with an incident meter.

Got fed-up trying to calculate the appropriate exposure time whilst stood in the cold, so I made a spread-sheet with all the filter-factors across the top against measured exposure down the side (adjusted for D100 reciprocity factor 1.26). Print and carry in your bag.

Hope this helps.

 

[Woodsy]

Hi,

I also shoot Delta 100 (4x5), and shoot with a center-filter (2-stop) and a polarizer (1.5 stops). I meter with an incident meter.

Got fed-up trying to calculate the appropriate exposure time whilst stood in the cold, so I made a spread-sheet with all the filter-factors across the top against measured exposure down the side (adjusted for D100 reciprocity factor 1.26). Print and carry in your bag.

Hope this helps.

View attachment 270354

That's excellent, many thanks!