New fangled technology ruins everything!

[unpopular]

THAT SAID. I do reject the scene luminance parameter. I do not think that scene luminance has anything to do with this (and certainly not if we're excluding sensitivity), as I've said already, exposure is cumulative. Scene luminance determines time and aperture. It's the amount of light at the medium that determines exposure, not the amount of light in the scene.

 

[Gary A.]

I say yes. Camera makers, vis-a-vis Matrix/Evaluative meter modes and Live View/EVF's, are attempting to remove the importance of knowing the basics of exposure. For old timers like myself, the lack of understanding exposure and how a meter works, is a significant deficiency for a photographer. I shoot Fuji and adjust my settings to what the scene that is reflected in my EVF sans active metering. Between Live/EVF and ultra sensitive/ISO-less sensors, I see a future where meters become vestigial.

Has your student heard of the Sunny 16 rule?

 

[Ysarex]

No. You certainly don't. Naturally, ISO is a set it and forget it parameter as far as I'm concerned. In fact, I don't even like calling it "ISO" with digital, because it's not the same thing as in film at all; in fact, last I knew the ISO hasn't even set standards for digital photography. Maybe they have by now?

They have but there are multiple options and you get to pick the one you like. Most camera manufacturers are going with a definition based on a brightness value measured in the camera generated JPEG -- in other words what they want.

I suppose it makes some degree of sense to exclude sensitivity. For one, we really don't have that much control over it (and in the case of digital, we don't have any control at all). But the term "exposure" kind of sets me back a bit, this implies that there is some kind of reaction happening or at least, a state in which that reaction occurs.

This latter bit might be the solution: according to Google Dictionary, exposure is defined as "the state of being exposed to contact with something", and the fact that contact is made says nothing of the effect that this contact makes. My first clue should have been that "exposure" is a noun, not a verb.

Exposure is a noun and I was careful to write "photographic exposure" -- the noun as we use it in the discipline.

Joe

Exposure to a sensor is the same regardless of how sensitive, or even if the material is capable of making direct measurement at all for that matter; like you said, the light doesn't change.

So really, encoding could be defined as a function of exposure and quantum yield/efficiency (i.e. sensitivity), whilst decoding could be defined as a function of processing.

 

[Ysarex]

THAT SAID. I do reject the scene luminance parameter. I do not think that scene luminance has anything to do with this (and certainly not if we're excluding sensitivity), as I've said already, exposure is cumulative. Scene luminance determines time and aperture. It's the amount of light at the medium that determines exposure, not the amount of light in the scene.

Illumination outside the camera is a necessary condition for an "amount of light at the medium" and as the scene illumination changes so does "the amount of light at the medium" -- exposure. That's the key to the definition; what can cause a change in "amount of light at the medium."

I've seen definitions that identify only shutter speed and f/stop as exposure determinants, the scene illumination being assumed in the definition. The definition that includes all three is the most common, widely accepted, and long standing and as I noted it long predates both of us.

Joe

 

[BananaRepublic]

Ok. Not really. I'll never go back to the darkroom. Like ever.

But I am talking with a third year cinematography student pal of mine, and he doesn't seem to understand a grey card is used for exposure, and not just white balance.

Has automation, such as AE and AF disrupted how we learn about photography to the point that the craft of photography risks being lost forever?

Isn't a grey card what you get when you turn 65.

 

[unpopular]

The definition that includes all three is the most common, widely accepted, and long standing and as I noted it long predates both of us.

This doesn't really concern me much, honestly. For the majority of film's history we had very little understanding about how it worked, atomic theory wasn't even discovered until 1914. So a historic definition really doesn't hold much weight IMO.

The scene illuminance should not be considered a part of exposure because it only determines the *maximum* amount of energy available over any arbitrary time, not the actual accumulation of light at the medium over the duration of the time specified. Because time and attenuation are arbitrary variables not dependent on illumination, and if sensitivity is a factor of serviceable exposure, then likewise illuminations must be considered separately.

 

[vintagesnaps]

Is there going to be a test??!!?

Good thing I learned this young so now it seems second nature and I don't seem to have to think about it much, I just do it. What's so hard about getting the needle lined up where it needs to be?

I think it seems like exposure is often the thing that people don't understand and prevents them from getting decent pictures. And seems to be the reason they might be editing a lot because the exposure was off.

And I don't think the craft of photography is totally lost, there are some of us using early photography technology; but I do think the 'newfangled technology' can be great sometimes but isn't always the most effective way to do something. Not just in photography - relying too much on a device to do whatever for you without keeping tabs on what said device is doing, isn't necessarily the best way to go about something.

 

[Ysarex]

The definition that includes all three is the most common, widely accepted, and long standing and as I noted it long predates both of us.

This doesn't really concern me much, honestly. For the majority of film's history we had very little understanding about how it worked, atomic theory wasn't even discovered until 1914. So a historic definition really doesn't hold much weight IMO.

The scene illuminance should not be considered a part of exposure because it only determines the *maximum* amount of energy available over any arbitrary time, not the actual accumulation of light at the medium over the duration of the time specified. Because time and attenuation are arbitrary variables not dependent on illumination, and if sensitivity is a factor of serviceable exposure, then likewise illuminations must be considered separately.

Without illuminance no exposure is possible. Consider this definition from the Ilford Manual of Photography which bares an original publication date of 1890, although this is copied from the 6th (1970) edition:

"Exposure

When a photograph is taken, light from the various areas of the subject falls on corresponding areas of the film for a set time. The effect produced on the emulsion is, within limits, proportional to the product of the illuminance E and the exposure time t. We express this by the equation

H = Et

Before international standardization of symbols, the equation was E = It (E was exposure, I was illuminance) and this usage is sometimes still found. The SI unit for illuminance is the lux (lx). Hence the exposure is measured in lux seconds (lxs)."

They don't mention attenuation through the lens in their definition: Exposure is accumulated illuminance over time. They're not concerned in the definition with the camera control factors. So we have this distinction between the hard definition (lxs) and then the functions when taking a photo that produce exposure.

Back to the Wiki definition: "In photography, exposure is the amount of light per unit area (the image plane illuminance times the exposure time) reaching a photographic film or electronic image sensor, as determined by shutter speed, lens aperture and scene luminance."

Parse the sentence carefully and you get exposure defined as amount of light per unit area (illuminance times the exposure time). That's the same as the Ilford Photo Manual definition. In the second half of the sentence the Wiki definition provides a list of the three practical functions that can control or alter exposure -- a subtle distinction.

I think we're just dancing around a lack of clarity over that distinction. I'm guilty for mixing the term "definition" up with the practical control functions. My original question did ask for those control functions as opposed to the hard definition:

"Fill in the blanks:
Photographic exposure is a function of _________________, ____________________, ________________"

The hard definition requires illuminance.

In any case it's all good as long as we keep this guy from mucking it up:

Medium sensitivity does not belong to either the hard definition or the list of practical control functions that determine exposure.

Joe

 

[unpopular]

The issue though is that there is no unit of area without an image plane. Illumination is always that of the image plane, not that of the scene; and the image plane illumination is always attenuated. Attenuation must be considered, otherwise exposure has no meaning at all.

It does not matter what the illumination of the scene is, provided that illumination exists. Specifically, how bright the scene is plays no role in the measured value. All we can say definitively is that a brighter scene will have a greater effect on the exposed than a darker one in any specific time period at any specific aperture. But we cannot say that a brighter scene will yield any specific effect, greater or less, at any arbitrary aperture and time period.

As for Peterson, I'm glad I'm not alone. His advocacy of "correct" exposure masquerading as "artistic control" is super bothersome. To add technical fault on top is only insult to injury at this point.

 

[Deleted member 215987]

I think the main problem with digital is that people feel they don't need to learn the basics because, "I can fix it in Photoshop"!

 

[unpopular]

Yes. I think there is a misplaced sense of the roll of post processing, though on the other hand, negatives, in particular b/w negatives were probably even more forgiving than digital, only that most people didn't have a darkroom. This is especially so when you start taking into account reducers, toners, etc.

I think that this might be an initial attitude, but it is quickly realized to be a faulty one (just as the darkroom techniques are).