reciprocity failure: B&W versus colour

[kraker]

I've just made my first steps into pinhole photography. Reciprocity failure (or Schwarzschild effect) is something you don't encounter every day in "normal" photography, but it's omnipresent in pinhole photography.

So, I started comparing some data sheets of the films I use most and I found that for black and white film (which is 90-95% of what I shoot), the reciprocity law breaks much sooner than for colour (neg or slide) film.

Case in point: Ilford HP5+, start compensating from 1/2 second; at 5 seconds, it's already more than 1 stop. Delta 100, same story.
On the colour side there's Fuji Provia 100F (slide): no compensation up to 128 seconds; Agfa Optima 100 (neg): +1/2 stop after 10 seconds, +3/2 stop after 100 seconds.

My question is: why does B&W film require more & earlier compensation for reciprocity law failure than colour film? :confused:

My first guess was that things would be the other way around: colour film will need more compensation, there's 3 different layers, they all react differently to light, you'll not only need to compensate for reciprocity failure, but also for difference in reciprocity failure for the different colour layers. In B&W, there's only one layer, no difficulty to get and keep the colour right, etc.

I'm just curious... Can anybody shed some light on this? (PE, maybe?)

 

[kraker]

Nobody?

Anyway, I've mentioned this to a fellow photographer who happens to be a Fuji-fan. Maybe it's just my "limited selection" of films that leads me to believe that reciprocity failure occurs sooner in B&W than in colour emulsions.

"Look at Fuji Acros 100", he said. No correction below 120 seconds, +1/2 stop between 120 and 1000 seconds.

Okay, so maybe I was seeing ghosts. But I want to use Ilford film! Fuji Acros 100 seems less of a hassle, though, for long exposures...

Didn't look at Kodak or Rollei or Adox or what-have-you-not yet, though.

It also seems a bit strange that the reciprocity curve for the "classic" Ilford films and the Delta range is exactly the same (Simon?). Maybe I shouldn't take these curves as the truth, and just do some experiments.

 

[Mick Fagan]

I first noticed that there was a real difference with colour film when Kodak Ektar 25 professional came out, this was a colour negative film.

IIRC there was no change required down to 10 seconds.

The Fuji Reala that I have used since it came out, has a change required from 1 second (I think)

Currently I have Tmax 100 4x5 film which is a 1991 expiry, it has no problems until you get to 1 second when you need to allow for reciprocity.

The FP4+ 4x5 film that I opened two weeks ago has virtually identical reciprocity requirements of the Tmax 100.

I too noted that Ilford films, both the conventional and modern flat technology, were similar in their reciprocity characteristics.

However Kodak's Tmax and TRI-X have virtually identical reciprocity requirements to the Ilford film, so I don't see anything problematic with the Ilford films.

I have recently metered a moonlit scene that suggested 120 minutes at f/11 for the Tmax film. With reciprocity allowances of about 3 stops required, I juggled a hat over the lens whenever a car came along, I got the shot, then went to bed.

Generally I have found that you lose shadow detail, no matter what you do. In a nocturnal exposure, this takes on a real interesting meaning.

Mick.

 

[kraker]

Hi Mick, thanks for sharing your findings;

(...)

I have recently metered a moonlit scene that suggested 120 minutes at f/11 for the Tmax film. With reciprocity allowances of about 3 stops required, I juggled a hat over the lens whenever a car came along, I got the shot, then went to bed.

So *that's* why a photographer needs a hat!

Generally I have found that you lose shadow detail, no matter what you do. In a nocturnal exposure, this takes on a real interesting meaning.

Mick.

That's is a valuable remark: look at it artistically, not too scientifically.

 

[Lee Shively]

With color film you also can get a color shift which needs filtration to correct, so color can be more complicated in reciprocity compensation than black and white. I haven't shot large format color in years, but I remember using Ektachrome 64 in 4x5 and having to filter the hell out of it with different strengths of magenta, depending on the length of the exposure. I presume the current color transparency films have improved in the respect.

With black and white, I generally trust the film's latitude and just bracket in half stops up to two stops over the meter reading. That always gets at least one good printable negative.

 

[eddie gunks]

i can not explain why this is but i like it. i too shoot pinhole. i have since moved from foma100 to tmax100 becuase tmax is so much "faster" than foma. what took me about 3-5 min takes the tmax like 40 sec! thats fast! acros and tmax seem to be the fastest. i find FP4 to be much much slower than tmax. i shoot fp4 the same as i do the foma and it comes out perfect.

i enjoy shooting color neg and slide film with the poinhole because it is so fast. i mostly shoot NPS 160 rate it at 50 and do no further compensation. works great everytime.

FYI check out http://www.pinhole.cz/en/pinholedesigner/ it give great reciprocity calc for most B&W films. as well as lots of great pinhole related info.


eddie

 

[eddie gunks]

some pinhole photos below. slide, neg, and B&W

 

[Rich Ullsmith]

Eddie, I agree about the FP4, I didn't notice much difference between it and Delta 100 in adjusting. I loved the Acros 100; with a red 25 filter out in the sun, exposures were around 90s. However, I have yet to find an Acros 100 source (4X5) that is not in the quick-load packs, which cost about two and a half clams apiece! Now I got a box of tmax100 but the sun hasn't shown here in about four months, so I've yet to try it.

 

[Michel Hardy-Vallée]

Case in point: Ilford HP5+, start compensating from 1/2 second; at 5 seconds, it's already more than 1 stop. Delta 100, same story.
On the colour side there's Fuji Provia 100F (slide): no compensation up to 128 seconds; Agfa Optima 100 (neg): +1/2 stop after 10 seconds, +3/2 stop after 100 seconds.

My question is: why does B&W film require more & earlier compensation for reciprocity law failure than colour film? :confused:

Your sample is too limited for the conclusion you draw: Ilford films are not renowned for their reciprocity behaviour, even the modern Deltas. In comparison, the Kodak T-Max and Fuji Neopan films have way better reciprocity. Fuji claims no adjustement below 120s for Acros 100!

With B&W films, you have to bear in mind that the current market is split between "classic" and "new" technology. Classic films like FP4+, HP5+, Tri-X, Plus-X, do not in general have as good a reciprocity as New tech films like T-MAX etc.

Now, most color films currently in production (with the exception of Kodachrome) use grains similar or identical to the New Tech films. Ektachrome uses t-grains, like t-max does. Provia uses sigma-grains, like Acros. As these grains have better reciprocity characteristics, so do the color films using them. Provia has about the same reciprocity characteristics than Acros does.

 

[kraker]

Your sample is too limited for the conclusion you draw: Ilford films are not renowned for their reciprocity behaviour, even the modern Deltas. In comparison, the Kodak T-Max and Fuji Neopan films have way better reciprocity. Fuji claims no adjustement below 120s for Acros 100!

Yes, I noticed that already, Acros 100 sounds very nice in that respect

Still, I had expected more of the Ilford Delta line, which is also "New tech".

With B&W films, you have to bear in mind that the current market is split between "classic" and "new" technology. Classic films like FP4+, HP5+, Tri-X, Plus-X, do not in general have as good a reciprocity as New tech films like T-MAX etc.

Now, most color films currently in production (with the exception of Kodachrome) use grains similar or identical to the New Tech films. Ektachrome uses t-grains, like t-max does. Provia uses sigma-grains, like Acros. As these grains have better reciprocity characteristics, so do the color films using them. Provia has about the same reciprocity characteristics than Acros does.

Thanks for this clarification.

 

[Michel Hardy-Vallée]

My pleasure. I too am wondering why Ilford did not try to cash in on reciprocity with the Deltas.

 

[colrehogan]

Eddie, I agree about the FP4, I didn't notice much difference between it and Delta 100 in adjusting. I loved the Acros 100; with a red 25 filter out in the sun, exposures were around 90s. However, I have yet to find an Acros 100 source (4X5) that is not in the quick-load packs, which cost about two and a half clams apiece! Now I got a box of tmax100 but the sun hasn't shown here in about four months, so I've yet to try it.

Rich,
For LF non-Quick Load Acros 100, go here:
Dead Link Removed

Yes, it's in Japan, but as far as I know, it's the only place you'll get it in loose sheets.

Regards,
Diane