Why are there two different zone systems?

ChristopherCoy · Jan 23, 2021

Ok, I guess I'll put the question back then.

Why are there two different implied zone systems - film, and digital?

Sirius Glass · Jan 23, 2021

A guess: Color and black & white film use the shadow detail for the Zone System. Slides and digital use the highlight detail for the Zone System because the range of subject to brightness ratio is so narrow.

ChristopherCoy · Jan 23, 2021

Sirius Glass said:
A guess: Color and black & white film use the shadow detail for the Zone System. Slides and digital use the highlight detail for the Zone System because the range of subject to brightness ratio is so narrow.

I thought maybe it was because modern digital cameras have more tonality than film. i.e. 6 stops on film, and up to a reported 14 on digital.

Ariston · Jan 23, 2021

ChristopherCoy said:
I thought maybe it was because modern digital cameras have more tonality than film. i.e. 6 stops on film, and up to a reported 14 on digital.

I don't know... these guys got 15 stops of range out of negative film. It definitely is way more than 6 for negative film. Most of the perceived advantage of digital is due to the limitations of film scanning, I think. And scanning limitations are digital limitations:

https://petapixel.com/2014/12/18/comparing-image-quality-film-digital/

.

Sirius Glass · Jan 23, 2021

ChristopherCoy said:
I thought maybe it was because modern digital cameras have more tonality than film. i.e. 6 stops on film, and up to a reported 14 on digital.

Exactly the opposite: 14 f/stops for film and 6 f/stops or less for digital.

Adrian Bacon · Jan 23, 2021

ChristopherCoy said:
Ok, I guess I'll put the question back then.

Why are there two different implied zone systems - film, and digital?

They have different zone systems because how exposure is measured between the two is different. With BW film, exposure is based on the minimum amount of light you need to get density off of film base plus fog. With digital, exposure is based on the maximum amount of light needed to get the sensor and ADC to clip to white, per the CIPA exposure standards, hence, two different standards.

DonW · Jan 23, 2021

Sirius Glass said:
Exactly the opposite: 14 f/stops for film and 6 f/stops or less for digital.

You're joking,,,,, right?

Adrian Bacon · Jan 23, 2021

Sirius Glass said:
Exactly the opposite: 14 f/stops for film and 6 f/stops or less for digital.

Digital has a lot more than 6 stops. You might only get 6 stops if shooting jpeg and expose like you're exposing film, but if you shoot raw and expose for digital, there's *a lot* more than 6 stops to work with.

Sirius Glass · Jan 23, 2021

DonW said:
You joking,,,,, right?

Absolutely not. I get 14 to 15 f/stops on film regularly, the problem is putting it on paper which has only 7 at best. As for slides and digital, the exposure can get blown out highlights if the exposure is off by much. There is lots of documentation on that, but none the other way for slides.

revdoc · Jan 24, 2021

My understanding (and experience) is that digital has a lot of latitude for underexposure, but blocks up fast with overexposure; film is the opposite, more or less (but obviously this depends on the film).

Nothing much to do with the original question!

Adrian Bacon · Jan 24, 2021

revdoc said:
My understanding (and experience) is that digital has a lot of latitude for underexposure, but blocks up fast with overexposure; film is the opposite, more or less (but obviously this depends on the film).

Nothing much to do with the original question!

exactly, with film you expose for the shadows because the worse thing you can do is not give enough exposure. With digital, it’s the exact opposite, you expose for the highlights because the worst thing you can do is give too much exposure. If shooting raw, digital has a lot of dynamic range, if you know how to expose for it and post process it. Heck, even the little Canon EOS RP, which by modern sensor tech standards has atrocious dynamic range easily clears 11+ stops of usable dynamic range, and pretty much every other modern sensor bests it by at least 2 or 3 stops for a total of 13-14+. Again, if you shoot jpeg and insist on exposing like you would film, it’s easy to be disappointed and claim that digital has very little dynamic range, or is like slide film. This is why it has a different zone system. Zone 10 is sensor clip, which puts zone five 5 stops down, which if using the camera meter, is not actually where the camera meters for, believe it or not. And people wonder why it’s confusing.

Ariston · Jan 24, 2021

michael_r said:
I’m not a digital expert but if used carefully and wisely, at this point can’t we say exposure stacking effectively gives the digital shooter the ability to bypass whatever limited exposure range the sensor/software has? Granted since it means combining more than one exposure it of course doesn’t define the actual latitude of the device.

I am not a fan of HDR, but it is, as you say, more than one shot.

Digital has plenty of latitude, as does negative film. I don't think anything has only six steps of dynamic range (the OP actually said "tonality") except slide film. As has been said, you have to treat digital like slide film.

In fact, if you shoot digital in RAW and underexpose it dramatically, you can still crank up the gain in post processing and recover a photo. By the same token, you will have to try pretty hard to overexpose negative film beyond usability.

SrMi · Mar 7, 2021

With digital, once the sensor is saturated, all data is lost (aka highlight clipping). Therefore the main exposure rule is not to clip the relevant highlights while saturating the sensor as much as possible to reduce the noise in the shadows (aka ETTR). The zone system is typically not used in digital, AFAIK. The histogram and clipping warnings are the main tools to determine the best exposure.

AnselMortensen · Apr 4, 2021

Well, there's the Zone System...
There's Dean Collins' ChromaZone System...
And there were a few zones Ansel kept for himself.

Why are there two different zone systems?

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