Why are you so adamant on being wrong? :))
April 10, 2023
638
-
-
Iliah,
I was thinking this might deserve a separate thread, but is there a functional significance to the method used? Would the last three "digital" methods be different from the first two?
Thanks
Sherm -
Scaling in post has the huge advantage that highlight clipping is under the control of the photographer. IMHO, it should be the default once the ISOless region is reached.
-
There are lots of ISO implementations, but I am not aware of any where the variable gain function is performed in the ADC.
-
I think the 20 years ago part is correct; I think we had all the options that Iliah mentioned in one or another camera then. The " it just amplifies the pixel signal before the adc" is incorrect in that it says that only one of the available options was and is employed. The fact that that option is used sometimes doesn't make the statement correct.
-
The analogue part of the design has its goal, and that goal isn't about ISO. Acceptable signal-to-noise ratio through a wide range of exposures (latitude) is, given the cost, complexity, parts / sections availability.
As Jim explained, leaving ISO "implementation" to digital allows to avoid unnecessary highlight clipping.
One of the promising new design directions that uses a comparator on every pixel allows to avoid variable / programmable gain amplifiers and highlight clipping caused by raising gain there.
One of the reasons of the success of phone cameras is that they progressively less and less rely on the "it's just like film" sort of ideas.
-
Or any combination of the above...
Tags are better than multiplies, because multiplies that do not give a widened result cause non-linear distortion in the deep shadows. On a PC, we can use high precision for intermediate values.
We've talked about Nikon's baked-in RAW white-balance prescaling before. That should be done with tags too.
-
My position is that any processing that can be done at least as well in postproduction should be done there, not in the camera. That includes gain in the ISOless regions, lens vignetting correction, lowpass filtering and median filtering, PDAF pixel correction, PDAF striping fixes, etc.
-
he wanted a simple answer and he got it. same as what does the accelerator pedal actually do on my car. who cares if its by wire or cable 🙄 or even what the fuel/air mixture is. it makes the car go faster and slower, simple.
-
If you are unconcerned with accuracy, it's easy to come up with simple answers. The truth is that the way it works depends on the camera. I have a GFX 50S. I have a GFX 100S. The ISO settings work differently. Therefore I set the ISO on the two cameras differently.
-
No, that is not even close to an accurate answer for all situations to the question "...what does the iso dial actually do?"
A much more accurate answer is Michael Fryd's post in the ISO For Beginners thread.
-
Sorry, but unless you don’t take the Planck constant into account this is all just wishy-washy talk and doesn’t really explain what exposure is and how the ISO dial works.
-
It appears you are the one that is confused because if you raise ISO and leave aperture and shutter speed the same, as you suggest, then the exposure* will not change which is clearly not the scenario I was talking about if you read my posts.
In my posts I was talking about the resultant lower exposure*, and not a constant exposure*, if ISO was raised; a big difference.
* exposure - amount of light striking the sensor per unit area while the shutter is open
** optimal exposure - the maximum exposure* within dof and motion blur requirements without clipping important highlights.
*** under exposed - more exposure* could have been added with the DOF and blur constraints still being met without clipping important highlights. -
"a complete digital still camera." outputting a JPG.
Don
-
The photographic triangle is simply a mistake in maths. Three independent variables don't make a triangle, they make a three-axis cube.
Don
-
😕😕😕 ???? Not sure who you are replying to or what you are saying ???? 😕😕😕
-
They might not be independent depending on the goal. If you want to maintain a constant image lightness, not constant exposure*, then there is an inverse relationship between any two of them.
* exposure - amount of light striking the sensor per unit area while the shutter is open
** optimal exposure - the maximum exposure* within dof and motion blur requirements without clipping important highlights.
*** under exposed - more exposure* could have been added with the DOF and blur constraints still being met without clipping important highlights. -
Danno,
I agree. After way too many arguments with Bob, I agree that ISO is not part of the exposure.BUT… How should the photographer apply this knowledge when shooting?