ISO is in a lot of ways the third wheel to exposure. It isn't so fun to play with creatively and mostly you just want to keep it low and forget about it. But ISO can be a friend and can be really useful. Think of it as the friend you always call to get you out of trouble.
All things photography come down to light, and how we manipulate it. There are many ways we can manipulate light with our cameras but there are 3 essential ways. 90% of what photographers need to know is these three settings and how to balance them for the effect they want. So it is worth getting used to thinking about them as you take pictures and troubleshoot your way through your photoshoots.
Shutter Speed, Aperture, ISO are the 3 core settings required for all photography.
We have covered how shutter speed is like a curtain opening and closing over the camera sensor, controlling the time given for light to enter the camera. Aperture we said was the size of the opening the lens which allowed more or less light in. Both of these also effect how the picture is captured. Shutter speed determines how movement is captured and aperture efects how depth is captured. So what is ISO?
ISO is the way we process the light that has entered the camera. We can use every last piece of light or we can only process some of the light that has entered the camera to formulate the final image. The downside of using too much light is it can introduce a reduction in quality in the image which we refer to as noise or grain.
While this can be intentional to create an aesthetic, it is mostly an undesirable side effect which we want to avoid as much as possible. So the advice of keeping it low is really solid advice. However some people take it so far and say you should never bump your ISO to get a good exposure and only alter the aperture and shutter speed.
Common (mostly good) advice: Keep your ISO low and never bump it up.
But when we have determined our ideal aperture and shutter speed we may find we have too much or too little light coming in. This is when it is ISO time to shine.
It can be our get out of jail free card. That friend we call, when we are in a jam and need a dig out. By boosting/lowering the ISO we can push our aperture/shutter speed settings to maintain the creative effects of these settings while still using the appropriate amount of light.
My advice: Keep your ISO as low as possible but don't be afraid to adjust it when needed. Just keep an eye on the resulting images and check for quality.
ISO is measured in whole numbers starting at 100 and going up in 100s so 100, 200, 300, etc up to insane numbers such as 25600 or more. When I brought my first dSLR camera 6400 was seen as the highest and was exceptionally excessive. Now no one bats an eyelid at 6400. Camera manufactures love to push this boundary with every new camera launch, much like back in the day or film cameras Mexapixls was the marker of advancment in camera development. Yes it is nice to have rnage in ISO but it will be so rare you need an ISO value of 25600 or anything even close to it for product photography I really wouldn't invest a lot of money in a camera based on the ISO range.
So there you have it. Assuming you have read the other two blogs on Shutter Speed & Aperture you have just covered 90% of what you need to know about capturing a well exposed image and having creative influence over the image as well. The only thing left now is for you to go out but put this new knowledge into practice.
I gave some tips on how to use shutter speed and aperture to up level your product photography but with ISO I would just remember my advice. Keep it low as possible but bump it as necessary once your Shutter speed and aperture are set!.
And never forget to to keep an eye on the grain of your images.