Comparing contrast of b&w film stocks

[Xiong Chiamiov]

This may be a silly question, but I'm trying to solidify some concepts in my head. Please correct any of these building blocks if I've misunderstood them.

In the "send my film off to the lab and get back scans" world, film stocks are commonly discussed to have certain set amounts of contrast (for a given scene). For instance, hp5+ is somewhere in the middle-to-low contrast, while fomapan is high contrast.

Setting aside choice of chemicals, development technique affects among other things contrast. As an example, increasing development time for a push increases contrast as a result of the developer continuing to work on the silver in the highlights after the shadows are exhausted.

When reading analyses from people with spectrometers, they'll say that when fitted to a standard contrast curve fomapan 200 will have a true ISO of 100, for instance (https://adrianbacon.com/simple-photography-services/simple-film-lab/films/fomapan-200/). Is this saying that Foma is up-rating their boxes and providing essentially times for a +1 push as the standard box speed development?

To put it another way, if you like the cheapness of fomapan but not the contrast, would you be perfectly happy just down-rating it?

 

[Bill Burk]

My friend Adrian Bacon knows his stuff. He found 160 in the article.

 

[halfaman]

I rate Fomapan 200 in Rodinal 1+50 as ISO 125 and develop it normally. It is an interesting film with a particular look, if you want a "softer" film I think Fomapan 100 is a better choice (exposed at ISO 80 in Rodinal).

 

[koraks]

My friend Adrian Bacon knows his stuff. He found 160 in the article.

Fomapan 200 in my experience comes quite close to its box speed and certainly higher than 100 without loss of shadow detail. YMMV as always...

 

[RalphLambrecht]

This may be a silly question, but I'm trying to solidify some concepts in my head. Please correct any of these building blocks if I've misunderstood them.

In the "send my film off to the lab and get back scans" world, film stocks are commonly discussed to have certain set amounts of contrast (for a given scene). For instance, hp5+ is somewhere in the middle-to-low contrast, while fomapan is high contrast.

Setting aside choice of chemicals, development technique affects among other things contrast. As an example, increasing development time for a push increases contrast as a result of the developer continuing to work on the silver in the highlights after the shadows are exhausted.

When reading analyses from people with spectrometers, they'll say that when fitted to a standard contrast curve fomapan 200 will have a true ISO of 100, for instance (https://adrianbacon.com/simple-photography-services/simple-film-lab/films/fomapan-200/). Is this saying that Foma is up-rating their boxes and providing essentially times for a +1 push as the standard box speed development?

To put it another way, if you like the cheapness of fomapan but not the contrast, would you be perfectly happy just down-rating it?

Yes,manufacturers are commonly rating their films a bit on the optimistic side and many photographers get better results if they downrate the box speed by 2/3 stop. This often results in better shadow detail.

 

[Jonno85uk]

In XTOL, Fomapan 200 seems to be somewhere between 125 and 160. The datasheet suggests ~80-100 but I haven't felt the need to go that far. I typically rate at 125 and if I want a faster film i use Foma400 at 250.

 

[Anon Ymous]

In XTOL, Fomapan 200 seems to be somewhere between 125 and 160. The datasheet suggests ~80-100 but I haven't felt the need to go that far. I typically rate at 125 and if I want a faster film i use Foma400 at 250.

80? This is way too low contrast. For a γ of about 0,6, it reaches 160.

 

[Jonno85uk]

80? This is way too low contrast. For a γ of about 0,6, it reaches 160.

Oh, wait. Yeah, i reread that graph wrong.

 

[osella]

Giving more exposure than box speed doesn’t necessarily mean less contrast. You will get more shadow detail, but if you don’t alter you development time the highlights may come out too dense.

 

[Jonno85uk]

Giving more exposure than box speed doesn’t necessarily mean less contrast. You will get more shadow detail, but if you don’t alter you development time the highlights may come out too dense.

True. I cut development for those ratings, something I found was an absolute necessity with Ilfotec-HC (blown highlights). I don't bother for 1/3stop increase of exposure.

 

[Lachlan Young]

80? This is way too low contrast. For a γ of about 0,6, it reaches 160.

I'd need to check if it's been corrected, but the ID-11/D-76 chart in the Fomapan 200 data sheet has had the gamma transposed somewhat - 0.8 for what is actually 0.6 etc. I think the other tables are correct. Gamma 0.65 or so is usually what works out to a 0.6 CI.

 

[RalphLambrecht]

In XTOL, Fomapan 200 seems to be somewhere between 125 and 160. The datasheet suggests ~80-100 but I haven't felt the need to go that far. I typically rate at 125 and if I want a faster film i use Foma400 at 250.

interestinly enough in both cases 2/3 stop less than box speed; it works as a rule-of-thumb!

 

[john_s]

The other variable is how you use your meter. Many years ago I "upgraded" from a Nikon Centre-weighted meter camera to a matrix metered one. Then my negs were underexposed. I realised that I had, barely consciously, been pointing my old camera down a bit to bias the meter away from the bright sky and that with the be-all-and-end all super matrix meter I was unwise to trust it to know what it was supposed to be doing. So, altering my use of the meter or adjusting the film speed setting was required.

 

[Sirius Glass]

The other variable is how you use your meter. Many years ago I "upgraded" from a Nikon Centre-weighted meter camera to a matrix metered one. Then my negs were underexposed. I realised that I had, barely consciously, been pointing my old camera down a bit to bias the meter away from the bright sky and that with the be-all-and-end all super matrix meter I was unwise to trust it to know what it was supposed to be doing. So, altering my use of the meter or adjusting the film speed setting was required.

Getting the exposure right is much easier with calibrated equipment used properly. That is much easier than the cycles of unending useless testing for the mythical unicorn called "EI". When all else fails RTFM and use the meter correctly.

 

[Adrian Bacon]

This may be a silly question, but I'm trying to solidify some concepts in my head. Please correct any of these building blocks if I've misunderstood them.

In the "send my film off to the lab and get back scans" world, film stocks are commonly discussed to have certain set amounts of contrast (for a given scene). For instance, hp5+ is somewhere in the middle-to-low contrast, while fomapan is high contrast.

Setting aside choice of chemicals, development technique affects among other things contrast. As an example, increasing development time for a push increases contrast as a result of the developer continuing to work on the silver in the highlights after the shadows are exhausted.

When reading analyses from people with spectrometers, they'll say that when fitted to a standard contrast curve fomapan 200 will have a true ISO of 100, for instance (https://adrianbacon.com/simple-photography-services/simple-film-lab/films/fomapan-200/). Is this saying that Foma is up-rating their boxes and providing essentially times for a +1 push as the standard box speed development?

To put it another way, if you like the cheapness of fomapan but not the contrast, would you be perfectly happy just down-rating it?

Sigh... the downside of publicly posting information... The ISO standard does not dictate what developer the film manufacturer uses to determine film speed, only that they disclose what developer, temperature, and time, and the manufacture can round up or down up to a third of a stop to the closest even ISO rating. In the case of Foma, they use Microphen at 20C with 5500K daylight per their tech sheets and yes, they absolutely round up.

Now, all that being said. The page you linked to is actually quite old. I'm in the process of generating updated information for most of those pages I created.

 

[Ian Grant]

Sigh... the downside of publicly posting information... The ISO standard does not dictate what developer the film manufacturer uses to determine film speed, only that they disclose what developer, temperature, and time, and the manufacture can round up or down up to a third of a stop to the closest even ISO rating. In the case of Foma, they use Microphen at 20C with 5500K daylight per their tech sheets and yes, they absolutely round up.

Now, all that being said. The page you linked to is actually quite old. I'm in the process of generating updated information for most of those pages I created.

The older ASA/BS (British) standard did use a specific developer, as did the German DIN standard and ironically the ASA/BS developer actually gives a slightly higher EI compared to D76/ID-11.

Kodak had the ASA standard revised becuse Tmax 100 & 400 didn't reach the claimed box speed in the AASA/BS developer. Instead they used a Phenidone (Dimezone) Ascorbic house developer for their testing, this pre-dated Xtol, and gave a slight speed increase. There was a US Pantent issue that prevented Kodak selling a developer like Xtol until the Patent expired.

Ian.

 

[ic-racer]

film stocks are commonly discussed to have certain set amounts of contrast

Discussion about a film's contrast is like writing about the size of party balloons. It depends on how much air one puts in the balloon. It might be better to write of the tonal range of the film which might be like the stress modulus of the rubber in the balloon.

 

[Sirius Glass]

Talking about a film's contrast is like talking about the size of party balloons. It depends on how much air one puts in the balloon. It might be better to write of the tonal range of the film which might be like the stress modulus of the rubber in the balloon.

However some films are contrastier than others and that was the OP's question.

 

[ic-racer]

However some films are contrastier than others and that was the OP's question.

Not if they are developed to the same gamma.

Maybe a food analogy. Like writing turkey breast is putrid compared to bagel, because you cooked them at the same temperature.

 

[Sirius Glass]

Not if they are developed to the same gamma.

Maybe a food analogy. Like writing turkey breast is putrid compared to bagel, because you cooked them at the same temperature.

But if they are all developed with one developer following the development times specified by the film manufacturer or by the developer manufacture the films have different contrast. I am talking about straight forward processing not twisting oneself into a pretzel.

 

[Adrian Bacon]

But if they are all developed with one developer following the development times specified by the film manufacturer or by the developer manufacture the films have different contrast. I am talking about straight forward processing not twisting oneself into a pretzel.

uh.... no. They might differ a bit in the toe or shoulder, but Ilford films developed with Ilford chemistry using Ilford time and temperatures and agitation results in the same amount of contrast or close enough to it. The same goes for Kodak, Foma, etc. Where things get convoluted is each manufacturer has a different standard for what is considered “normal contrast” coupled in with the fact that they apply that to to other manufacturers films when supplying times for their developers. Throw in massive dev chart and Internet forums and the net result is a cornucopia of contrasts.

If you use one developer and come up with process times for the same contrast for each film, they all look shockingly similar, with the primary difference being grain structure and spectral response. There are exceptions, but with modern films, it’s ncredible how close to each other they are.

I’ve done this exercise with Xtol and have process times for a whole pile of films that nets the same rough contrast levels for all the films. Unless you where intimately familiar with a given emulsion, you’d have a difficult time telling them apart.

 

[Sirius Glass]

uh.... no. They might differ a bit in the toe or shoulder, but Ilford films developed with Ilford chemistry using Ilford time and temperatures and agitation results in the same amount of contrast or close enough to it. The same goes for Kodak, Foma, etc. Where things get convoluted is each manufacturer has a different standard for what is considered “normal contrast” coupled in with the fact that they apply that to to other manufacturers films when supplying times for their developers. Throw in massive dev chart and Internet forums and the net result is a cornucopia of contrasts.

If you use one developer and come up with process times for the same contrast for each film, they all look shockingly similar, with the primary difference being grain structure and spectral response. There are exceptions, but with modern films, it’s ncredible how close to each other they are.

I’ve done this exercise with Xtol and have process times for a whole pile of films that nets the same rough contrast levels for all the films. Unless you where intimately familiar with a given emulsion, you’d have a difficult time telling them apart.

I believe that is what the OP wants to know.

 

[MattKing]

The OP may be conflating contrast with a characteristic curve that favours lots of shadow separation over midtone and highlight rendition.
I see a lot of examples of people describing an image as "contrasty" when it is essentially just dark.

 

[Carter john]

Fomapan films: 100, 200, 400

I agree with Matt, I had to use an Orange filter to get blue sky. The color spectrum on their website is not right in my book. I've had over 10 years thinking I could do something with this film and also been disappointed in their IQ: last straw was a hole in the paper backing that ruined a frame because I forgot to close the red shutter on my folder during rewind. And as he says lots of highlights and lots of dark shadows on the histogram (i.e. no mid-tones). Save your money.

I won't go on but with the use of Yellow or Orange filter; shouldn't but I will because of the high red and infrared sensitivity they make your reds come out as almost white.

 

[Anon Ymous]

The spectral sensitivity charts at the Foma datasheets were made with a 2850K light source. As a result, it will show reduced sensitivity at the blue end and increased at the red. If this test had been performed with a 5500K light source, the chart would look very different, with the blue end being much more sensitive and the red less.