1Dx M2 Sensor Resolution - Back of envelop estimate
- Thread starter RGF
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And let's assume the lighting hasn't changed at all and I collected the same number of photons.
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I'm guessing we arrived at the issue of if I keep the same number of photons collected, and vary ISO, does noise change? I would argue it has to, with higher ISO's being noisier. No?
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filluppa said:
We understand how it works, but you have over trolled this to the point you have made all of Neuro's earlier points about you. He doesn't need to answer your question because he has won the victory.
When you first posted I thought you were just trolling and you knew you were trolling to get at Neuro.
But you didn't stop when a good troll would and you had the best of him.
Instead you beat the incorrect portions of your claim to the point it appears that others may be right about you and your a half a slice short having a full loaf of bread. You may not even know you are trolling.
Take that lesson with you. Had you stopped earlier you would have had the troll's victory.
At this point your posts are just silly and pointless.
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filluppa said:
Filluppa....I'll ask again.
Why does my 1dx have a "High ISO Noise REDUCTION" setting? Key words...HIGH ISO, NOISE, and especially - REDUCTION.
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filluppa said:
Hey buddy, I think you're the one that's confused with the noise to signal ratio.
Forget the wording, forget the physics behind it, forget the charts and the stats...
Watch the following video: https://vimeo.com/10473734
After watching that video, you should agree that in that video -> light is not changing and the image is not changing, the only thing that is changing is ISO... with escalating ISO values -> noises is added to the image.
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filluppa said:
READ noise is lower because less is being read. Who cares? That's trivial.
What is impactful is that noise is a more significant component in high ISO photography than low ISO. Whether you want to call it noisier (like a normal person) or "less signally" isn't particularly important.
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3kramd5 said:
Just for reference, the actual read noise generated by the electronics does not change with ISO; what's listed in that table is called the input referred noise which basically tells you how many photons/electrons the read noise is equivalent to at the current gain setting. Filluppa doesn't understand the difference between input and output referred noise though so he keeps posting that like it proves his point.
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Are you sure? The component coming from the ADC itself does not change, but the amplification adds some more noise and I would also count that as read noise. It's no great contribution at low ISO values but becomes more important at higher ISO values. Also in the table which filluppa has now posted about twenty times the input referred noise does not decrease inversely proportional with ISO (it's almost constant at high ISO), so the output referred noise increases (although slower than proportional to ISO).raptor3x said:
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midluk said:
Yeah I'm sure, what's happening is that you can break the read noise down into two components: upstream of the amplifier and downstream of the amplifier (it should also be noted that some cameras use 2-stage amplifiers but the same approach is easily extensible to those as well). The resulting output referred noise becomes something like
No^2 = C*(N_us)^2 + (N_ds)^2
Where No is the output referred noise, N_us is the actual read noise of the upstream components, N_ds is the contribution of the downstream components, and C is the gain. To get the input referred noise we simply use the relationship*
Ni = (1/C)*No
where Ni is the input referred noise, which gives us
Ni^2 = (N_us)^2 + (1/C)*(N_ds)^2
Looking at both of these forms, you can see that as the gain becomes large, the relative contribution of the downstream noise becomes small; however, looking at the input referred noise should make it clear why you get an essentially constant read noise at high ISO in that table. The noise coming from the electronics doesn't change at all with ISO, but both their relative and absolute contributions to the final image absolutely changes.
*There's a little bit more to it than this but I honestly don't remember all the details; the scaling holds up though.
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raptor3x said:
The C in equations 1 and 3 has to be squared. But then it is pretty much what I said, when we identify my "noise coming from the ADC itself" with N_ds and " the amplification adds some more noise" with C*N_us. And because this amplification is done by electronics, I would definitely see C*N_us as increasing "read noise generated by the electronics", but that is mainly a question of definition.
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