this post was submitted on 24 Oct 2023
1 points (100.0% liked)
Photography
1 readers
1 users here now
A place to politely discuss the tools, technique and culture of photography.
This is not a good place to simply share cool photos/videos or promote your own work and projects, but rather a place to discuss photography as an art and post things that would be of interest to other photographers.
founded 11 months ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
This is a myth that hammers way too many new shooters.
The correct ISO is the best to shoot at, regardless of what that ISO might be.
Dual ISO is not so much about noise as it is about dynamic range. It's important, but it's about maximizing details in your shadows when taking poorly/dimly lit photos.
Base ISO is an arbitrary number. If it's 200 or 100 it means the same thing: "I have all the light I need, boss!"
It should be as low as possible, but not for the reasons you're thinking.
In and of itself ISO has no adverse effect on your shot. (Heads are exploding everywhere right now)
ISO does not cause noise. The noise is because you did not have enough light and had to raise the ISO... but the noise was already there because you were not capturing enough light. Raising the ISO just lets you see that noise.
Assuming ISO 100 is the correct ISO for a shot the reason it is better is because your sensor is being completely saturated with light - more than enough light to hide the noise that's there - and you therefor do not need more ISO.
ISO is the alarm bell that tells you that you are not saturating your sensor with enough light, and so you will have visible noise in your shot. ISO 800 is telling you that you're missing 3 stops worth of light.
tl;dr -- If you do not have enough light you will have noise. It is just that simple. If you have to raise the ISO, do it, because you're not hurting anything by doing so. A better option when doing portraiture however is to gather enough light that you do not need to do that in the first place. A longer shutter speed, a wider aperture, or add light via flash/reflector (or some combination of these) is what is needed... but if all else fails, raise that ISO without fear - and deal with the noise you're going to have in post.
Iso causes noise. Stop spewing the Bs northrup Invents.
Ultra bright outdoors, shoot at 1/4000 f22 iso 26000 it will be noisy. And don't give me the "1/4000 f22 makes little light hit the sensor, it's lack of light"
Lack of light makes you use high iso to expose correctly, therefore noise. Of course.
From an electrical engineering perspective, you’re both right.
ISO in digital sensors is an amplification of the analog signal output by the photovoltaic sensor before it is converted to digital. Amplifiers indiscriminately amplify both noise and your signal of interest. In that sense, he’s right that a high quality sensor with little inherent noise will produce a less noisy image at high ISO than a low quality sensor with a lot of inherent noise. A high ISO (amplification) will serve to amplify noise existing in your signal.
However, amplifiers also have a quality known as “noise figure”, in that all non-ideal amplifiers will add some noise to a signal. So you are also right in that there is some amplifier added noise that is possibly more visible when you increase your ISO, because amplification tends to reduce your maximum theoretical dynamic range through the additive noise, not increase it.
All that being said, this is all semantics and in practice I think the comment you’re replying to is correct, but is a bit loose with some technical concepts that don’t really matter in practice.