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Why is exposure so confusing?
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Jan 21, 2019 19:45:49   #
Curmudgeon Loc: SE Arizona
 
[quote=Cany143]If I were trying to understand exposure based on things I read today, I probably wouldn't get close to a reasonably exposed shot.

I agree when I started to use a DSLR I had exposure figured out from my film days. Then I started to read, You Tube, UHH, various books and now I am like the centipede who was asked by the ant "how do you coordinate all those legs. The centipede thought about the question all night and by morning he was so confused he could never walk again.

First pick one reliable source and don't listen to any other advice ever. DSLR's give instant gratification. Take that advice and go out and shoot. Take notes, look at the previews, consult a medium (just kidding) and keep shooting until you get it right and understand why it's right.

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Jan 21, 2019 19:46:37   #
Curmudgeon Loc: SE Arizona
 
Cany143 wrote:
If I were trying to understand exposure based on things I read today, I probably wouldn't get close to a reasonably exposed shot. Exposure --and the shutter speed, aperture, ISO/ASA/EI values that determine it-- is not the stuff of convoluted analogies, computational mathematics, or lengthy confabulations. Its the stuff of go-out-and-shoot-it while paying freaking attention to what you aimed the camera at, and what settings you used that worked or the settings you used that didn't work. Jeez!
If I were trying to understand exposure based on t... (show quote)

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Jan 21, 2019 19:55:50   #
Bipod
 
sloscheider wrote:
When you get the above common sense changes to take place your next assignment is to get us Yanks to move on over to the metric system! I’ll support your political party, just say the word. It’s only the US, Burma and Liberia left to go metric...

True enough. Just imagine the cost of everyone in the USA -- mechanics, auto shops wholesalers and
retail stores -- having to keep two sets of every type of wrench (spanner) they use or sell.

It's even worse when you consider photometry. The following units of measure are used in the USA:

Luminance stibs (CGS system), apostibs, lamberts, foot-lambert, lumens per steridion-square meter,
candelas per square foot, candela per-square meter (metric, SI)

Illuminance: phots (CGS), foot-candles, lux (SI), lumens per square meter (metric, equivalent to lux)

Moreover, luminance units are often used for illuminance, and vice versa. Are we having fun yet?
Welcome to the Land of the Fee...

BTW, sloscheider, how's that Brexit thing working out for you?

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Jan 21, 2019 20:00:15   #
Bipod
 
Curmudgeon wrote:
DSLR's give instant gratification..

And that's what photography is all about....today.

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Jan 21, 2019 20:11:19   #
boberic Loc: Quiet Corner, Connecticut. Ex long Islander
 
For some of us, it depends upon how you learned exposure. In ancient times ALL cameras were totally manual. You either learned what ASA, Shutter speed and F-Stop to use or you didn't make a picture and you wasted a lot of money in the process .. So the $ was the main reason to leaqrn the basisc of exposure.And as above, with so many using auto, point and shoot cameras and cell phones the "art" of exposure is falling out of favor. These days EVERYbODy is a photographer. And fewer and fewer of us use Real cameras

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Jan 21, 2019 20:12:06   #
Bipod
 
So why do the light measurement mess and the exposure mess exist?

Because the scientific and engineering disciplines most related to measuring light and to
photographic exposure are photometry and sensiometry, respectively.

And photometrists and sensiometrists are few and far between (the latter especially so since
the switch to digital).

Moreover, neither discipline has a powerful professional organziation, such as the Instittue of
Electrical and Electronic Engineers (IEEE) or the Society of Automative Enegineers (SAE).
If the IEEE or SAE cared about it, it would have been fixed long ago.

Lastly, there is the inherent inertia of culture. Once people learn something one way--no matter
how messy--they don't want to change. So eventually digital camera global shipments decline
by over 70% since 2011.... and still no change in the photographic dogma.

Smart phones are a lot simpler: only one or two f/stops.

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Jan 21, 2019 20:31:40   #
IDguy Loc: Idaho
 
Bipod wrote:
Log base 2 of 2, 4, 8, 16, 32, 64.....
= 1, 2, 3, 4, 5, 6....


Yes, which has nothing to do with exposure.

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Jan 21, 2019 20:38:32   #
Timmers Loc: San Antonio Texas.
 
There is a certain something being left out and the beginners and possibly the advanced workers would like to know. George Eastman had two cards up his sleeve when he was being the MAN in photography.

The first was he guaranteed his product. If it was bad he would replace it with a like quantity, course his product needed to be of decent quality in the first place. It was, o better or worse than the other guys, just a bit better than the poor quality makers of film.

The real question is why did George kick ass on his major rival Edward Anthony? George introduced a certain item to his film when there were no standards. George and the Kodak gave a relative value of sensitivity to the box of film. The first step to the emergence of the ASA value.

Think. if you are doing film and you don't know how fast it is all the Water House stops (the precursor to the f stop) or a shutter speed were of no real value. It was not George the businessman, it was Edwin Mees the science AND engineering behind the company.

They were on the East Coast, so off to the sea side the engineers went with their family. Sea level and it was summer, these are two of the critical items that are the corner stones of the later Rule of 16 (a smaller issue was in the sun with no more than 20 percent cloud cover, but that came later). Daddy boys went to a beach location while mom and any kiddos went to play.

The boys set up THE TEST camera with what we call a set f stop and took photos of themselves at different shutter speeds, with one film batch. When they had the exposure worked out with a 'standard' development they went back to Rochester. This film base was calibrated on the ONE FOOT CANDEL device and from this came a value for Eastman's film speed system. That testing of speed against the calibrated testing device later became the early system for film speed.

Eastman Kodak NOW had what no other film maker had, a relative film speed for each batch. So if an advanced worker, like a portrait photographer (businessman) you knew how fast the film speed was relative to other batches of film you had used. You did not need to waste product and time to KNOW the speed of the film.

Yes but Tim...ok, so cover up your ISO and then don't look at your screen to see if the exposure was right, talk about frustration and lost photographs.

If you think you know the history try this, what is the standard speed of a Kodak film product?

The answer is 1/50 second.

ALL Kodak films (B&W or Color) assume you will be using their standard of 1/50 second. (the exception to the rule is/was always stated). As example Kodak Ektachrome Professional was to be exposed for 1/50 second, EXCEPT Kodak Ektachrome Professional Tungsten films, these films (35mm to large sheet films) had the standard exposure speed of five (5) seconds.

Thinking in practical terms, business terms, why shoot a test? If I know the 'reciprocity' speed of my film is 5 seconds and Kodak has told me that THIS batch of Ektachrome Tungsten 50 has an EI of 60, plus .5 yellow correction (yes, the film info sheet did say these things), BUT I will be using an exposure of 1/4 of a second then I will gain 1/3 stop speed. Thus I can expose a perfect roll of film under Tungsten lights. Hello, not 'bracket' my exposures because I do not know what the hell I'm doing. Try doing hundreds of flat art work, no 'bracketing' that is a waste of time and resources. Try taking exposures at 1/60 second where the speed rises to gain 2/3 stop increase (the tech term here is not really reciprocity failure, the technical subject is Reverse Swatchchild Effect) Or flat try doing a portrait session where the best image is lost to poor exposure!

Now add to the above that Kodak films that are from the period of PRE T-Grain Technology, the above is true. With T-Grain Technology films the entire upper paragraph fails because T-Grain based technology does not follow the old film technology standards. T Grain film are in a way like a digital RAW file with the older technology films being akin to jpegs. With T-Grain one can choose to target in the stage of film processing for different out comes! Perhaps you might think that digital evolved in some vacuum, then you would be wrong. There is not right or wrong, better or worse, there is just some who have been exposed to what has happened and can see the forest for the trees.

That is what the OP has missed, there is history, there are reasons for what happened and what we do and why. Do not be myopic in your understanding of your chosen little slice of heaven! Be that heaven!

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Jan 21, 2019 20:43:34   #
Kozan Loc: Trenton Tennessee
 
Timmers wrote:
I can easily answer your question with a simple response. There are two types of people in the world of photography, one group likes to talk about photography, while the other group wants to make photographs. I'm in the latter category, I make photographs.

F stops are quite simple, learn two neighboring f stops and you will have all f stops. Say f4 and f 5.6 as example. You then simply half or double either to reveal the other f stops. Of course one does not get anal about being 'precise' (double 5.6, that is 5.6+5.6 =11.2, round to f 11). I know, BUT! There is no BUT in the field of practical photography, or just steal that cute phrase, "Just Do It!" We are NOT doing math, we are making images.

Shutter speeds are the same but simpler (along with imaging speed/sensitivity), basic doubling (just like ISO, or the old ASA) 1/2, 1/4. 1/8, 1/15 (Don't be anal, no 1/16).

Yes, you can make it complicated, and loose the image, or make the image and put the camera away and study the math. In the latter I will just wonder away because I'm not here to do math, I'm here to make photographs, that is why people keep thinking that I'm a photographer, silly fools that they are!

Go ahead and ask Bubble about it (he is the guy in the photograph).
I can easily answer your question with a simple re... (show quote)



"You then simply half or double either to reveal the other f stops. Of course one does not get anal about being 'precise' (double 5.6, that is 5.6+5.6 =11.2, round to f 11)."

That's fine if you want to jump 2 stops. But what if you want to go one stop up or down. You multiply or divide your F-stop by 1.4. F/4 times 1.4 is F/5.6.

Interesting way to look at a change of 2 F-stops, though.

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Jan 21, 2019 20:46:22   #
Kozan Loc: Trenton Tennessee
 
sloscheider wrote:
When you get the above common sense changes to take place your next assignment is to get us Yanks to move on over to the metric system! I’ll support your political party, just say the word. It’s only the US, Burma and Liberia left to go metric...


As far as engineering goes, the US is already on the metric system. Electrical Engineering goes by the ISO standard.

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Jan 21, 2019 21:03:19   #
Timmers Loc: San Antonio Texas.
 
Kozan wrote:
"You then simply half or double either to reveal the other f stops. Of course one does not get anal about being 'precise' (double 5.6, that is 5.6+5.6 =11.2, round to f 11)."

That's fine if you want to jump 2 stops. But what if you want to go one stop up or down. You multiply or divide your F-stop by 1.4. F/4 times 1.4 is F/5.6.

Interesting way to look at a change of 2 F-stops, though.


You are making it complicated, we don't do math, we take halving and doubling. f4 doubled is f8 yes it is logs yes it is math, thumb your nose at complication.

f4 doubled to f8 with the knowledge that there is an f stop in between called f5.6.

Or for the math simpleton like me Tim, f8, then f 16 with an f 11 in between, so then f11 has an f 22 with that f16 between f11 and f22.

DO NOT get sucked into math. I know, language, loose the language and all the 'think' crap that one does, KISS (Keep It Simple Stupid!). In the world of practical working photography you need to be able to ignore math I do, and stay on task to staying in the zone, the zone of image making.

F stops are NOT numbers or math, they are simply these things. When showing first graders I have been know to ask them to call them by size if they were animals (dinosaurs are all ways kool with 1st graders). WHY, because we ain't doing math, we are making photographs, so get on with doing the making of a photograph.

But, I know that the math wiz kids will scoff, so play all you want in the garden of math, makes me no never mind, I'm making photographs and don't care about math one fig.

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Jan 21, 2019 21:10:38   #
rmalarz Loc: Tempe, Arizona
 
No, I own more than three, but never a Gossen. The primary ones I use are a Sekonic L758DR, a Pentax Spotmatic (which also serves as a reflective print densitometer), and an S.E.I. Photometer. The last is probably the most accurate of them all. All of them are calibrated and checked regularly. So, I've no problem with them reading a test card and producing the same reading. Yes, exposure is quite simple.
--Bob

Bipod wrote:
Say you own three light meters, Bob: a Nikon, a Pentax and a Gossen.
All are factory calibrated and working perfectly.
The Nikon meter says the EV is 14.
What does the Pentax meter read?
What does the Gossen meter read?

If they are different, can you explain why?
And which one is correct?

Remember: exposure is simple!

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Jan 21, 2019 21:15:34   #
Timmers Loc: San Antonio Texas.
 
Bipod wrote:
For a "strong, silent type" who only takes photographs and doesn't talk about photography,
you just posted four paragraphs, Timmers.

On a photography discussion forum. Ahem.


No my friend, I posted a butt long book, pointing to T-grain films, the early history of exposure (did not bring up the Schneider System), and I did punch in reciprocity but mentioned that reciprocity was actual Reverse Swartchild Effect, but I did not point to liquid nitrogen and reduction of temperature in the negation of Swartschild effect.

As you say, it is a photography form, but it is not void or should not be void of an image or a photograph as you really must agree that those photographs speak a thousand words, each, thats plus 4,000 more words! LOL!!! "Be happy in your posts" Paraphrase of that line in the film, Bridge Over the River Kwai.

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Jan 21, 2019 21:33:40   #
BebuLamar
 
Bipod wrote:
True enough. Just imagine the cost of everyone in the USA -- mechanics, auto shops wholesalers and
retail stores -- having to keep two sets of every type of wrench (spanner) they use or sell.

It's even worse when you consider photometry. The following units of measure are used in the USA:

Luminance stibs (CGS system), apostibs, lamberts, foot-lambert, lumens per steridion-square meter,
candelas per square foot, candela per-square meter (metric, SI)

Illuminance: phots (CGS), foot-candles, lux (SI), lumens per square meter (metric, equivalent to lux)

Moreover, luminance units are often used for illuminance, and vice versa. Are we having fun yet?
Welcome to the Land of the Fee...

BTW, sloscheider, how's that Brexit thing working out for you?
True enough. Just imagine the cost of everyone ... (show quote)


Yup when Ansel Adams said Foot Candles he really meant Candela per squared foot.

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Jan 21, 2019 22:09:49   #
n3eg Loc: West coast USA
 
The "exposure triangle", the "ohm's law pie", and other relationships have never caused me a problem. I'm sure there's one for gas/fluid pressure/volume too. it's just light and math you can do in your head. Even your technical dissertations cannot fool me.

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