gvarner Loc: Central Oregon Coast

The difference is in how your sensor handles grain that comes with high ISO's. A review of the specs on your cameras will give you a sense of that. If in doubt about how high to go, keep your ISO below 3200. My sense is that most sensors can do OK up to that level.

rmalarz Loc: Tempe, Arizona

The answer is simple. When the ISO you're using isn't sufficient to provide proper exposure, raise it a bit until it does. As with film, the higher the ISO more grain will be present. With digital that is in the form of noise. That is an unfortunate nomenclature carry over from the electrical engineering field. Don't obsess over it.
--Bob

burkphoto Loc: High Point, NC

Every equipment situation is slightly different. Run tests to determine what you like.

I would expect most folks would find that the MAXIMUM likable/acceptable/usable ISO for their cameras falls with in ranges of:

Full Frame: between 6400 and 12,800

APS-C or DX: between 3200 and 6400

Micro 4/3: between 1600 and 3200

Your camera may do a bit worse or a bit better than that, so testing is CRITICAL to knowing what you can do with specific cameras. Start your testing a stop below to a stop above those ranges I listed, and see what you think.

Your taste, talent using noise reduction software during post production of raw files, and experience play huge roles as well.

Saigon Loc: Atlanta, GA

Overthehill ,

Another application of high ISO setting is indoor flash shooting such as social event, wedding, party, family gathering,....The flash only helps lighting a small area closer to the camera or from the walls which you bounced your flash into - You also need to raise your ISO to serve two purposes:

1) Helps out your flash: more a natural look, flash power limitation
2) Blending between ambient light around the subject - Slow shuttle speed only helps you to a certain point. You don't want to see the only subjects is being exposed properly while the room is totally in dark. You could raise ISO to 3200 or higher w/o any issues for certain camera.

Regards

Grey Ghost

I recommend using whatever it takes to get the shot. If high ISO is what it takes then go for it!

TriX Loc: Raleigh, NC

👍👍 Good guidelines Bill. I think many users obsess over anything above base ISO, but consider that a blurry shot from an insufficient shutter speed is unusable as is often the case with insufficient DOF, but a little noise can often be addressed in PP. I often shoot in auto ISO, choosing the SS to freeze movement and aperture for the required DOF and let the ISO fall where it may. My FF Canon is good to 12,800 and my crop Fuji is very usable to 6400.

burkphoto Loc: High Point, NC

One more note: Film grain and electronic noise are NOT the same. Noise is spurious signal not coming from the source of the image (or sound you want, in audio). Sources of electronic noise include background radiation from space or radioactive materials, stray electrical fields, radio sources, and the circuit design and construction. ALL AV and photo electronics can record unwanted noise with desired signal.

The higher you crank the ISO (to a point), the more amplification is needed to boost the analog signal from the sensor before it is digitized. This lowers dynamic range. The less dynamic range you record (the difference between the brightest tones and deepest shadows), the greater the proportion of noise in the signal.

I liken high ISO to the effects of automatic gain control in an AM radio receiver. As you move away from an AM radio station, the signal decreases (according to the inverse/square law, radiation dissipates as the inverse of the square of the distance from the source). Eventually, the signal is so weak that the AGC amplifies all the static from nearby car ignition, hum from AC power lines, more distant radio stations using the same frequency, lightning crackles... and it sounds terrible.

OTOH, film grain is the size of the individual grains of silver used to form the image. The more sensitive the film, the more silver it contains, and the larger the grains. (In color film, the silver is coupled to color dyes in three layers, then removed during processing by the bleach/fix or blix solution and wash water.)

NOISE from radiation contributes to film fog. Over time, X-rays, heat, microwaves, radio signals, etc. penetrate unexposed film containers and randomly expose the film. Development reveals this a an overall fog that reduces contrast and adds grain. This is why film has a shelf life, generally less than three years for optimal speed and image quality. Expired film generally exhibits increased fog, reduced effective film speed, and may reveal ghost images of whatever was in the way of stray radiation as it penetrated the protective packaging.

If you scan film, or copy it with a digital camera, careful use of noise reduction software can remove some of the effect of film grain, revealing an image that would appear far grainier if printed optically.

petrochemist Loc: UK

For reasonably modern cameras those ranges are about right, but my first APSC camera maxed out at 1600, and tended to be seriously noisy above 400. (It's base was 200!)
As you say in addition to the major factor from camera body, & under exposure there is also a degree of influence from subject & post processing...

Running tests is certainly the best way to hone into what works best for you, but even after that don't be afraid to try shots at ISO above your threshold if circumstances demand. Noise can spoil images but it's often better than unintended motion blur, or insufficient DOF.

Having shot 1000 ASA film back in the 1980s I find I can tolerate quite a bit of noise & still see merit in the image. :)

wapiti Loc: round rock, texas

AND AUTO ISO

burkphoto Loc: High Point, NC

I concur! I had a Nikon D70 and Canon EOS 20D, in 2005. Both of them were quite noisy above ISO 640 or so.

In high school in the 1970s, I was the yearbook candid photographer. Quite often, I pushed Tri-X film to ISO 1280 in Acufine developer, just to work at reasonable shutter speeds in low light. So digital noise does not bother me until it gets pretty bad.

CPR Loc: Nature Coast of Florida

With my background in photojournalism I have to chuckle at the concern about upping the ISO. In my mind it's about "Getting the shot!!" You know your gear and set it for the best capture, say ISO 100,f8, 200 .
Then on the fly you ramp up until you can get the best capture of your goal be it DOF, stop motion or just plain documentation.
You need to understand the whole process and choose the setting based on that understanding. If someone says "Always use..." I stop reading because they don't understand the process.

DirtFarmer Loc: Escaped from the NYC area, back to MA

Low noise is overrated.
Unless you're selling large prints of an image, family shots can tolerate a lot of noise. If the noise is too much, you can always downsample.
In my opinion, images with noise are preferable to images with motion blur.

petrochemist Loc: UK

Used creatively motion blur can add a lot to a shot, but where this isn't the case noise is certainly preferable.

burkphoto Loc: High Point, NC

Yeah, in photojournalism, it's all about bringing back an image. You do what is needed to record the moment, and if noise intrudes, or color depth is less than ideal, or the image is a little flat, so be it. If the image is newsworthy, or for historical purposes, use whatever setting you can to grab it.

Many folks here, though, are interested in finding the best compromise between image technical quality and practical camera handling. There's a high percentage of UHH'ers who do landscapes, birds in flight, and grand kid chasing. Then there is the equipment distribution... everything from bridge cameras to medium format. Then there's film...

That's why I always suggest testing. Are you using a larger format sensor? In-body image stabilization? In-lens image stabilization? Dual IS of some sort? How big do you print, IF you print? Do you need to crop? Are you working in mid-day full sun, outdoor overcast conditions, golden hour direct sun, indoors with overhead fluorescents, indoors with stage lights, indoors with direct flash, a studio, a party lit with black lights, or...? The answers guide the application.

But all that said, there's usually a range of tolerance each of us finds for using specific equipment.

I use auto ISO for some things, but my camera lets me set a maximum ISO ceiling. Above that ceiling, I want to make a conscious decision about the settings I use. So I nearly always USE the ceiling feature. It keeps me from falling below the quality floor I want to stay above, until I NEED to fall through that floor.

When I'm recording video, I can't use auto-anything when trying to match the results with my son's camera. In that case, I set BOTH identical cameras to exactly the same "full manual" parameters. It makes color grading during the editing process MUCH easier. We both white balance and set exposure off the same target, every time the lighting changes.

BebuLamar

When should you use high ISO setting? Quick answer, when you have to.
You would use the lowest ISO and adjust the exposure via the aperture and shutter speed. When the light is dark, you will have to open to larger aperture and/or longer shutter speed. To a certain point you can't open the aperture any wider (or even if you can the depth of field is too narrow) and the shutter speed becomes too slow to prevent camera shake and you can't use a tripod. Then in that case you have a couple of choice, to increase the ISO or to not take the picture.