Incidentally (pardon the pun), 18% is not quite correct, nor is the K-factor explanation in The Negative...
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Incidentally (pardon the pun), 18% is not quite correct, nor is the K-factor explanation in The Negative...
… apparently nobody read the instructions that came with the Kodak gray card.
EDIT: This is, perhaps, the best demonstration of the effect of gray card angle I’ve ever seen. See post 3:
https://www.photrio.com/forum/thread...-usage.135637/
Ha! Thirty four years ago...likely guilty as charged!
I would like to state that I'd discussed this specularity "issue" prior to that class, and that students either did not understand completely or were just careless - but to be honest, I cannot remember doing this.
Edit: but there are indeed situations (incidences:rolleyes:) where being able to orient a gray card in a way which might put it at risk of exposure to some degree of specularity is otherwise advantageous. Sometimes this is not possible, in which cases an incident light meter or spot meter is always a safer bet.
I agree. The Adams books are only going to create obstacles and difficulties to someone early in learning to expose and develop film (and understand their results!). Learn to walk before you try to run - ya know?
Go back to Henry Horenstein's beginners/semi-advanced books and start there.
monochromeFan, the example given by Adams has been used by other writers, but as others here have pointed out, it seems that your eagerness to learn as much as possible about photography quickly may be outrunning you a bit. But no big deal; we all have some areas we grasp more readily than others.
I don't know if I'd discard reading the Adams books so easily; I have always found his writing to be very good, and I think you will find them valuable as you get your bearings a bit more. However, it may help you at this point to "cross-reference" that reading with a book such as David Vestal's The Craft of Photography, or some other, which you can get through the library (maybe interlibrary loan) or buy used for less than $10. Each author approaches fundamentals and advanced technical aspects in his or her own way; one may clarify for you what another doesn't quite get across.
Understanding how a light meter works does not necessarily come instantly. We think of meters as reading some kind of "absolute" level -- how many degrees hot or cold, how many decibels of sound, etc. The light meter does read levels, but it averages them out for the purpose of providing exposure suggestions that will often work well. Before there were meters and sensitivity-calibrated films, more guesswork was involved.
Imagine two thermometers reading the temps of two breakers of water, side by side: one cooled to 40 degrees F, the other heated to 100 degrees F. Each thermometer would read its own temp, but the average, you could compute, would be 70 degrees, right? Now, if you poured the two beakers into a larger one that would hold the water from both, a thermometer placed in it would read 70 degrees, all other things being equal.
That averaging is what a light meter does as it takes in whatever view it is taking in, whether it's an incident meter, a 30-degree reflected meter, or a 1-degree reflected meter. The "spot" (typically 1 degree) meter just allows you to choose a much smaller area to read, but it's still averaging whatever it sees. And what it reports to you, is a set of combinations of shutter speed and aperture, based on the sensitivity of the film (ISO number) that you have set on the meter, all of which will give you a medium gray -- an "average middle tone," you could say. This is adequate for many situations, but a scene that is primarily either dark or light (e.g., a snow scene on an overcast day) will end up gray instead of white if you simply follow the meter's suggested exposure.
I hope that helps.
I just purchased Photography by Phil Davis for my assistant to do the same drills I did some 50 years ago.
Ansel excelled as a master photographer and was highly regarded as an instructor. However, the books he authored that sit on my shelf have never appealed to me. To call them dull would be putting it mildly, but the images in them are great.
Think of it this way. Your meter loves middle gray in a very deep and very unnatural way. Say you have four tiles on a wall in direct sun; one white, one light gray, one dark gray, and one black. You stick your meter close to the white tile and take a reading. The meter says to itself, "that tile is white, but I like gray, so I will tell him to add two stops, so instead of f16 at 1/100, I'll tell him f8, and when he prints that negative the white tile will be mid-gray. Ha ha." You don't like that neg, so next time you meter the black tile. The meter knows the tile is black, but she prefers gray, so she tells you to stop down two stops, so instead of f16 at 1/100, she tells you to use f32, and laughs, because when you print, that tile will be mid gray ("Ha ha, got you again!") So, you can see where this is going:
For the white tile, f8 yields mid gray
For the light gray tile, f11 yields mid gray
For the dark gray tile, f23 yields mid gray
For the black tile, f32 yields mid gray
Since you are cunning, and jealous of your meter's affection for mid gray, you step back a bit, and get all four tiles in your meter's view, and declare victory! Now the best she can do is average the readings from each tile, and give you f16 at 1/100, which she does, but then sulks the rest of the afternoon.
So an averaging meter works well on an average scene, but will overexpose a white house in snow, and underexpose a black horse in the dark.
To get the white tile correct, take the reading, then, knowing your meter loves mid gray, stop down two stops to make the tile white in the print. Same with the black tile. Your meter wants it gray, so take your reading, then add two stops exposure to make it black.
I think that is how it works, but did have wine with lunch...