Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

For those who can deal with someone rambling for over 13 mins, this video shows why using lower ISO and adjusting in post processing to recover the shadow detail, and how to check your camera to see if you can do it with your camera(s)

https://www.youtube.com/watch?v=udd1mkk37Gc

My D800 can deal with 2-3 stops or so underexposure. My D810 is good for about 5 stops or better. Notice how bad the Canon 5d Mk II is, btw.

Mac Loc: Pittsburgh, Philadelphia now Hernando Co. Fl.

I keep my ISO set to 100 unless the situation calls for higher.
I only use AUTO-ISO in changing light conditions when I want to maintain a specific shutter speed and aperture.

Gspeed Loc: Rhinebeck, NY

Woah! Stunning!

mwsilvers Loc: Central New Jersey

I will always use the lowest ISO I can to get the shot. But using the base is not always possible for me since I shoot indoors more than half the time, and often in very low light. In that situation my preferred lenses are my Canon EF 35mm F2 IS USM, and my Sigma 18 to 35 mm F/1.8 ART. Even with these fast lenses and shooting static subjects I often have to crank up the ISO to 1600, 3200, and more rarely 6400 and occasionally even 12800.

The base ISO range of my 7D Mark II is 100 to 16,000. I've never shot in 16000 other than as a test, and I'm not sure if I've even ever tested the extended ISO range. For those who have cameras with a much higher bass and extended range, I've often wondered under what circumstance they need to have the ISO raised to 25600, 51200, 102400 or higher.

While on my camera noise is controlled fairly well to 6400 requiring minimal amount of noise reduction, above that ISO setting, I'll need much higher amounts of noise reduction to produce acceptable images.

lamiaceae Loc: San Luis Obispo County, CA

True enough, but considering the OP'er reference to an ISO of 100, what stop do you use today to shoot a moving train with? Certainly not f/16 if you are worried about absolute sharpness; then you would want to avoid diffraction. So at f/5.6 to f/8 in daylight even at ISO 100 you would have plenty of high shutter speeds available. Say at f/5.6 around 1/800 s. Personally I usually leave my cameras at the manufacturer's suggested default of ISO 200, and shoot at f/5.6 to f/8 (I did say usually). I will use higher ISOs indoors when needed.

rehess Loc: South Bend, Indiana, USA

I used moving trains as an example of how the rules seem to have changed when we weren't looking. Digital cameras require settings different from what we could get by with using film, and that is one of the forces pushing us into higher ISO territory.

Rongnongno Loc: FL

Any ISO that influences the camera DR.

For the D500, it seems to be over ISO 200. The DR drop off is progressive and varies with cameras.

Rongnongno Loc: FL

Err, no where do I mention ISO 100 as a reference. I use 'Base ISO' which varies depending on the camera used.

Please note that the DR exploitation is available only with the new crop of cameras that use invariant sensors.

chrisg-optical Loc: New York, NY

As you can see from other posts its out of necessity rather than choice in most cases.....but you always should shoot at the lowest ISO possible when conditions allow. Lately ive been shooting with auto ISO, max 6400, manual mode to lock in desired shutter/fstop combo on my D7200.

rehess Loc: South Bend, Indiana, USA

Some time back http://www.uglyhedgehog.com/t-380030-1.html I reported on an image on-line where a professional used ISO 8000 to get the image he wanted. In certain situations, such as sports, color depth and dynamic range may have to take second place to other considerations.

Deecee

I like to take pictures of the Milky Way. A typical exposure is 30 seconds at 2500 or 3200 ISO. Any longer than this and you will get star trails, so a high ISO is necessary
I also shot an indoor wedding once. The only way to get the background light to match the flash was to use an ISO of 1600. The pictures came out really good, but it is ABSOLUTELY necessary to get the exposure right when you take the picture. Any underexposed picture will show a lot of digital noise if you try to lighten it up in Photoshop. This applies to any picture taken with an high ISO (800 or greater)

Steamboat

This is a great question of best practises.
Working professionally I stick to the base at all costs........unless you need to crank it up to insure sharpness...."get the shot'

When shooting for myself I embrace the noise. If I need to go above so be it 800 1600 are all fair gaim.....3200/6400 in a pinch.
For personal use a sharp photo with noise is better that no photo at all.

Currently 1600 3200 is most usable....I cant with for my next camera and better Hi SO
I love film...... I really love Digital. I can do things I never could before.

BebuLamar

I used to shoot only film until 2013. When I shoot film ISO 100 film like Ektar, and 160 ISO film like Porta 160 were great and so was Ektachrome 100. The are great for a lot of photographic situation but I did see so many images I liked to have but couldn't. The light was usually so beautiful but low and the color temperature was also low. The subjects didn't move quickly but not still. A tripod for many reasons not pratical. Using high ISO film like 1600 was possible but the result was so poor. What did I do? I didn't take those images and always missed them.
I stayed with film for so long because although digital offers a lot of advantages which I do like but not missing them without. I didn't want to spend quite a bit of money for a new camera. I could capture just about any kind of images that I capture using a digital now. The quality of the film image may or may not be the same as the digital but they were OK for me always. I didn't feel the need for better (that's why I stayed with 35mm and didn't move on to MF or LF).
But film is hard to find sometimes. I went into the largest photo dealer in Dallas and asked for film. The guys laughed at me. I went down the street and got a roll of Portra from the little store that specialize in used stuff and film and got a roll of Portra for like $10.
And so I decided to go digital and with digital it open up for me a whole new capability to shoot under low light. I started shooting all those images that I missed during the film days. I have no problem using ISO 12,800 when I needed. The quality suffers but not any where near like changing from an ISO 100 film to ISO 800 film.

Fotoartist Loc: Detroit, Michigan

Good post. I am reconsidering the old advice given by Tim Grey and many others to always expose to the right. Since that advice was given, camera sensors have changed quite a bit and this probably hasn't been taken into account till now. So I am re-examining my premises in this regard. Thanks.

pendennis

As others have mentioned, the particular scenic demands are how I determine which ISO. A few years ago, using my Nikon D200, I could see noise @ ISO 800. Today, my D750 and D500 are almost noiseless at ISO's up to 3200. And when the noise does get high, my image editors can fix that. Of course, with VR on the Nikkor lenses, it's much easier to obtain steady handheld shots of moving birds, etc.

I do run into problems in the other direction, though. Both the D500 and D750 run @ ISO 100 in native mode. There are times when I'd really like an ISO down around 25 or 50 for some still life images where I need a lot of depth, but not much shutter speed. It's a hassle to go through the exercise of exposure compensation to get overexposure on demand.