Sidwalkastronomy Loc: New Jersey Shore

I see people using auto ISO and wondering WHY?
I shot as low as I can 100 to 200 and sometimes 400. I realize it's only one third of the triangle and modern sensors can do a lot more. Most cameras have limit sensors for high and low but curious if there is a reason for auto that I'm missing

I use Canon rebels crop sensor 77D and T7i. I'm happy with my cameras and can't justify expense of upgrading, too many other hobbies.

lamiaceae Loc: San Luis Obispo County, CA

I am sure you will get many answers. And I know there are lots of Auto ISO fans on the UHH.
Personally I have no use for Auto ISO. I have tried it a few times and just end up with a confused mess. I usually set my ISO to 200 or 400 and shoot in either Aperture Priority mode or Manual. And occasionally Shutter Priority for action.

Longshadow Loc: Audubon, PA, United States

If one wants a particular ƒ-stop and shutter speed, auto ISO will adjust the exposure as required (within its limits).

I myself never use Auto ISO. I just leave my camera set to the native ISO (100).
But I can adjust in low light conditions if desired.

Everyone does things differently.
(Now we'll get a bunch of replies stating why I should use Auto ISO...)

Longshadow Loc: Audubon, PA, United States

Scruples Loc: Brooklyn, New York

Most photographers, including myself, “Grab” the camera and take a shot. I will attribute this to my own laziness. After one or two ‘chimp’ shots, I will dial on the Aperture Priority or Manual Mode. Here I will float the shutter, aperture and ISO. While this may seem wasteful, I have several exposures that I can play with and if need be, jury-rig.
I have shot RAW and wasn’t delighted by my results. Perhaps, other Hoggers have better success. Needless to say, after so many years, I am still learning.

DaveJ Loc: NE Missouri

I use manual with auto ISO almost 100% of the time. With modern cameras, ISO is my least important setting. I use EC to adjust for backlit or other tricky light. For me, the wrong shutter or aperture can ruin a photo. I can work with some fairly high ISO if shutter and aperture is where I want or need it. YMMV.

JD750 Loc: SoCal

Auto-ISO is an auto-exposure mode. You can set boundaries for high and low ISO. It can be used in conjunction with other auto-exposure modes, such as aperture priority.

And now I ask you, could there be any conditions, scenes, events, where using auto exposure modes make sense? if yes, what are they?

leftj Loc: Texas

If you don't have a reason for auto don't worry what others are doing.

Indiana Loc: Huntington, Indiana

I am photographing covered bridges in Indiana. I have my D850 16x35 lens set on auto ISO. Why? Because I shoot the inside and outside of the bridges, in shade and sunlight, and don't have to concern myself with shutter speed with auto ISO. Inside of covered bridges is very dark. I only concern myself with composition and subject matter. I leave the rest to the camera and lens. Works for me. My photos look great even in unprocessed RAW.

larryepage Loc: North Texas area

Cameras today have many capabilities. Photographers today have many capabilities (or not). There are also many fads and trends. Auto ISO has been available for a number of years. It's been a fad for at least four years that I can remember. I think that started along with another current fad...don't dare use anything more than the two middle f/ stops on your lenses. Diffraction will kill you if you stop down below f/8 and the evil spirits will get you if you open up beyond f/5.6. So those folks really don't have an exposure triangle, they only balance shutter speed against ISO. They end up using auto-exposure with shutter and aperture priority and calling it Manual (because that's how they lock aperture and pick their shutter speed.

My choice is not to use Auto ISO. It goes back to years of using a D200 and D300, where changing ISO was a big consideration. Changing the ISO changed the entire characteristic of the image, and since a lot of what I was doing precluded post processing, it was a big deal. I refuse to allow fear of diffraction or of large apertures control me, so selection of Program mode usually moderates any likelihood of wild shutter speed/aperture combinations. Newer cameras have reduced the image impact of higher ISOs, but they have not eliminated the loss of dynamic range as ISO increases. And remember...that loss is on raw images just as much (or more) than with JPEGs. For me, there is just no reason or justification for floating the ISO.

Now keep in mind that if you post process everything, you are essentially using your initial exposure to create a coloring book page which can then be resaturated, recontrasted, and even recolored in the computer. All that loss doesn't matter. So it would seem that the post-processing fad also contributed to the floating ISO fad.

Before you post processing folks jump all over me, let me be clear. I post process my images WHEN IT IS APPROPRIATE. But not all the time. I have posted images here (before I stopped posting images) that have been significantly processed. And they have done fairly well in contests. But I expose with care, and most are not.

williejoha

I use auto ISO when shooting BIF’s. I put the shutter at /3200 and the f stop at 5,6 or 8. This way, with the constant change in light there is no worry when using auto ISO.
Normally I shoot as close to native ISO (100) the rest of the time.
WJH

kpmac Loc: Ragley, La

I can say that it works for birds in flight as the light changes drastically while one pans. I use auto ISO with manual and find I get more keepers than when I use any other setting. Your shooting style is probably different than mine. Do what works for you.

R.G. Loc: Scotland

It's taking away a potential distraction, leaving you to concentrate on more important stuff like composition, timing, lighting etc.

There are various ways to implement auto ISO. I would recommend M+AutoISO. It gives you direct control over shutter speed and aperture which, for most people most of the time, are the two most important exposure variables to control. Putting it another way, ISO is the most compromisable variable so it's the best choice for a floating variable.

Don't let the terms "auto" and "floating" mislead you. In M+AutoISO you control the ISO through your choice of shutter speed. And if you include exposure compensation you have full control over the exposure, despite the fact that you're using the camera's metering to determine what the "correct" exposure should be - EC allows you to override the camera's assessment if you think it's necessary to do so.

In fully manual mode (no AutoISO) you have to keep a close eye on the camera's meter scale, especially if you're using it to implement exposure compensation. Using M+AutoISO removes that distraction from you because you can leave the camera to keep the exposure on target.

lamiaceae Loc: San Luis Obispo County, CA

You are NOT WRONG.

(Oh, in my initial post I forgot to say Native ISO for Pentax Cameras is ISO 200, though you can set it as low as 100 or even 80 [on some models])

lamiaceae Loc: San Luis Obispo County, CA

Agree.