Smaug01
Veteran Member
This is why I went back to film for B&W. I actually seek out the film that has more grain, as I think it adds a certain something to a candid people picture.
The digital filters I've seen don't quite do it for me.
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Noise and ISO, One more thread
- Thread starter Chato
- Start date
The digital filters I've seen don't quite do it for me.
knickerhawk
Veteran Member
Your test scenario is the same one DPR uses to test ISO invariance. If you were using the Nikon D7100 for your testing, here's the relevant results from DPR's ISO invariance test for that camera (note visible banding and noise in the shadows only really breaks through at a 5 ev difference in ISO. The D7100, while not completely ISO invariant, is close enough to invariant in most real world use cases that the DR benefits of keeping ISO low will generally outweigh the noise benefits of upping the ISO. YMMV.
Irrelevant to your misunderstanding of raw files.
Not at all. I'm referring to metadata fields nicknamed raw exposure bias for Fujifilm, and, as a colleague here advises me, sensor calibration for Olympus. Adobe calls it baseline exposure.
Irrelevant here.
You were looking for the word "applied", not "determined". Not always, raw multishots and some other cases form exceptions.
You are missing the point.
Being an advocate for incorrect explanations is your long-term stance.
I completely agree that exposing for maximum quality raw images might change the calculus a bit. I should have been more clear that I was talking about interpreting ISO and EC properly for jpeg shooting.
Michael Fryd
Forum Pro
You have mischaracterized my position, and that is not helpful. Let's try to stick to the topic at hand, as opposed to discussing the people participating in the discussion.
bobn2
Forum Pro
It's not really a misnomer. ISO does have a standard for exposure indices for digital, and the standard even mandates how it should be reported, as 'ISO'. To work out the confusing terminology you have to go back in history. What these things are actually is the term I use above, an 'Exposure Index', that is, a number you use to set your exposure meter in order for it to give an exposure which meets certain standardised criteria which the authors of the standard deemed to make good use of the available medium. There is really anything hard and fast about these numbers. For instance, in 1960 the ASA (American Standards Association) changed its exposure index standards so all films became a stop faster overnight with no change in their formulation.
Anyway, in those days camera controls were not labelled. You didn't have a label saying 'shutter' next to the shutter control, or one saying 'aperture' on the aperture ring. Similarly, you didn't have a label saying 'Exposure Index' on the exposure index control, but that is what it is. However, given that there were several competing Exposure Index standards, you did have a label saying which standard the control operated according to, the most common ones being 'ASA' (the standard defined by the American Standards Association) or 'DIN' (the standard defined by the Deutsches Institut für Normung). Unsurprisingly, American cameras would have their Exposure Index set according to the ASA standard and German ones according to the DIN standard. Japanese ones hedged their bet and provided both, labelling the control 'ASA/DIN' and putting both numbers on it.
So, whilst what it was, was an 'Exposure Index' control, photographers started calling it an 'ASA control', because that was how it was labeled. Later the competing standards were unified into an international ISO standard, and the control started being labelled 'ISO'. Photographers started calling it an 'ISO control', though in reality it was still an 'Exposure Index' control, though now set according to the unified ISO standard. These days, many photographers don't even know what 'Exposure Index' means.
No, it's my informed opinion, nothing personal, just something your readers may want to know and take into account.
Advocating explanations based on light amplifications is crossing the line.
Yes, I misspoke. When a photon hits the sensor, it produces and electric charge and it is that charge which gets amplified.
While I own a 7100, I used a 7000, which seems to handle light about the same.
What I FOUND is that while I COULD get the same image results whether the ISO was 100 or 1600, it required a LOT more work in PP for the 100 setting to do that. So, in future, using either of these Nikon's I intend to shoot with the ISO that is most convenient for the light AND if the subject is in motion. So, for example if I'm using a tripod on a stationary target, I would use the Lowest ISO and control the light by aperture, shutter, or both.
Michael Fryd
Forum Pro
I don't believe I have used that phrase or advocated any such explanations. If that's your basis for the personal attack, you may wish to issue a correction.
Well, I've finally learned that ISO in digital is a misnomer. There is no such thing...
I believe it to be a "misnomer." With my last film camera, A Minolta 212, I could set the ASA via a dial, and I could set the aperture manually, and the shutter speed via a dial.
Since the "sensor" on film ACTUALLY was more sensitive to light, it was a real benefit to shoot with a higher speed film in dim light. "Pushing" the exposure on a lower ASA film never produced the same results as simply USING the more light sensitive film.
So, the example I gave in my first post could never be matched with film. Pushing ASA 100 film would NEVER match the results of shooting in ASA 800 film.
mamallama
Forum Pro
As you keep saying, "sometimes words have two meanings". And I say "context matters".
bobn2
Forum Pro
That's sort of true, but not in the way that has anything to do with the operation of the ISO control. The first stage of the read chain is a MOSFET source follower which would normally be said to be a current amplifier. However, since it's driving a MOSFET gate with essentially infinite impedance, no 'current' flows, so it can be viewed as a charge amplifier (which is how Eric Fossum describes it). The 'dual gain' feature found in some mode sensors effectively changes the charge gain in one step somewhere in the ISO range, by changing the capacitance of the input of that charge amplifier. For cameras without the dual gain feature the charge gain does not change at all with the ISO setting. The output from that stage is a voltage (properly and electrical potential), the magnitude of which represents the amount of charge measured by the pixel. It is that voltage which maybe subjected to variable gain set by the ISO control, so it's not the 'charge' which gets amplified, it's the output voltage of the pixel. The charge is proportional to the number of photons collected. The reason for applying variable gain to the output voltage is to provide a better match with the ADC over a wide range of exposures. The ISO control is taken as an indicator of the likely exposure, and therefor is used to control the gain.
Your response to Googling brings a lot of links saying something like "ISO - How much the available light is amplified" was exactly this:
One might also say that pressing in a car's gas pedal makes the engine turn faster. Actually, pressing on the pedal can cause the engine to slow down as it shifts into a higher gear.
The simplified explanations given to a novices are not always factually correct.
M
Marek M
Guest
That this is a real thread.
Does anyone really now what they're arguing about?
Semantics of taking photos?
Does anyone really now what they're arguing about?
Semantics of taking photos?
For the purposes of an explanation to a lay person, and their knowledge of photography, it's all that someone like me has to know.
No offense Bob, but when I explain to lay people how a boiler works, I don't have to describe how heat is absorbed by water, to create steam. It's enough for me to tell people the heat source causes water to boil.
Michael Fryd
Forum Pro
Yes. It is factually incorrect to say to a novice: "ISO - How much the available light is amplified."
I don't consider factually incorrect explanations to be a good thing. Perhaps I was mistaken in assuming that this did not need to be explicitly stated.
bobn2
Forum Pro
It's a line from a song, and needs to be remebered.
Yes, I quite agree. But I don't think that in this case context helps decipher what 'light signal' means. Or that the use of the word 'signal' helps clarify what was meant, especially since the quote has trimmed a bit of context off which makes it very clear that what was meant was precisely that light was being amplified. As was pointed out, the full sentence is: "The job of ISO is merely to amplify the light signal that the camera receives."
Add the trimmed context and it's clear that what is being talked about is the input to the camera, which is light. The word 'signal' is actually redundant to the meaning of the sentence. It means just the same whether the word 'signal' is there or not.
And in any case the whole discussion is redundant. This quote was raised (not by me) to counter Porky's spurious suggestion that 'no-one in their right mind' thinks that light is being amplified. Even if you want to count that example out, several others have been produced which show very clearly that several supposedly authoritative photography websites are indeed saying that in unambiguous terms.
Seriously, I'm more than tired of your constant attacks and barracking. If you have some sensible constructive criticism I'm more than happy to take that on board, since if you can help me say things more clearly, that is to everyone's benefit. But your criticism is not constructive - precisely the opposite. It serves no useful purpose, or at least none that I can see.
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...because you know, sometimes words have two meanings.
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