Where is your threshold for ISO?

[Inkanyezi]

I think exposure compensation is not to be worked after a recipe, but by thorough understanding of what happens. When setting a negative value at the same time as higher ISO, it is an invitation to underexposure, where shadow detail is drenched in noise.

But it must also be better understood, that raising ISO will decrease dynamic range, so that not so much dynamic can be caught on the sensor before it saturates and clips highlights.

So if the dynamic range of the scene is larger than the actual dynamic range of the sensor, something will be lost, either shadow, highlight or both. It is up to the photographer to decide whether to lose anything and in what region - highlight, shadow or both. Applying a constant -0.7 exposure compensation is telling your camera that you want the image to be darker than the metering system suggests. If the reason is that ISO has been raised so much that something must be lost, it is also a choice toward losing at the shadow side, drenching the details there in noise.

ISO setting does not alter the sensitivity of the sensor. It only governs the amplification of its signal, as well as noise. Raising amplification may push highlights into clipping, when the dynamic range of the scene is greater than what the sensor can capture at a given ISO setting. Highlight detail may be saved with a high ISO setting at the price of lost shadow detail, by setting negative compensation.

[pnodrog]

....how about exposure? Is it better to exposure exact or should some EC be used? I generally set my EC to -0.7 and may adjust at touch, but generally leave it there as it seems easier to recover shadows in Post with a -0.7. Any changes in EC for High ISO?

Thanks again

On bright sunny days to protect the highlights I sometimes set -0.7 EC. However at low light levels where I am pushing the ISO I nearly always have EC at 0. (or whatever it needs to be to according to my estimate of the correct exposure) I find if you under expose at high ISO the noise in shadow areas is far more apparent. In night street scenes it sometimes results in some lights blowing out slightly but generally it is less objectionable than noise caused by underexposure.

[TheBigE]

I think exposure compensation is not to be worked after a recipe, but by thorough understanding of what happens. When setting a negative value at the same time as higher ISO, it is an invitation to underexposure, where shadow detail is drenched in noise.......

Thanks for the explanation Urban. It makes total sense and tracks very well with what I have learned in my High ISO photos. It was certainly the case in some High ISO photos that when I tried "pulling" out the shadows in PP, I pulled out a fair amount of noise and not much detail.

Really again comes down to evaluating the entire composition and making a decision on where the emphasis needs to be placed and this can help decide if EC is even needed in a High ISO environment.

[dje]

I used Auto ISO a couple of times, and it was just not for me...I know how it works and understand the concept, but I did not like not knowing exactly what my ISO was...sure maybe I lost a photo or two because of camera shake when manually setting ISO, but I enjoyed setting ISO and working other parameters to make the exposure work. This way I know exactly what I have set.

Erik it depends on the type of photography you are doing. I find Auto ISO useful for situations where I am looking for a minimum shutter speed and don't have time to fiddle with settings for every shot. eg sports action or birds that are likely to move. In these situations, I use Aperture priority mode and set the shutter speed at which Auto ISO kicks in to the minimum value I require. This means that the shutter speed I get will be at least as fast as the minimum required until the light has dropped to the point where the max ISO setting is reached. After that, for lower light again, shutter speed will get slower.

Dave

[Mike Buckley]

this can help decide if EC is even needed in a High ISO environment.

I use exposure compensation regularly but it is never needed. It's only a convenient tool to be used as an alternative to manually adjusting an exposure setting.

[James G]

I use exposure compensation regularly but it is never needed. It's only a convenient tool to be used as an alternative to manually adjusting an exposure setting.

Mike +1 for me

This tread is interesting, and has started me thinking about why I do stick to my ISO preferences... simplistically, it's habit but I'm also becoming aware of being overly wary of noise.

[Inkanyezi]

When using Auto-ISO not all cameras have exposure compensation, but will only set exposure as with Auto without compensation. Some models however have compensation also with Auto-ISO and manual settings, so you have to check with the manual of your camera whether or not.

[DanK]

You don't lose detail due to noise, never. You can lose it because the detail is under your noise threshold, which means that you did not expose well.

I know what you mean, but as written, the first sentence is misleading. One doesn't lose detail in the capture because of noise. Where you lose detail is in using software to reduce noise. That is why I avoid high ISOs when I can.

I shoot at whatever ISO is required to get the shot the way I envision it with regard to shutter speed and aperture settings. Another way of putting it is that the ISO setting is the least important one of the three settings for me.

I can't give any single general rule. For me, the most important setting(s) depend on what I am shooting.

I use exposure compensation regularly but it is never needed. It's only a convenient tool to be used as an alternative to manually adjusting an exposure setting.

Exactly. Just one tool among several. However, it can be very useful. I'll give a concrete example of the last two points. This morning, I was out shooting pictures of mist rising off a lake in early morning light. The dynamic range of the scene was large, and the appropriate exposure varied considerably depending on the image and my position in shooting it. There was plenty of light to maintain an acceptable range of shutter speeds at f/8, which is the aperture I wanted, and ISO=200, which I wanted to maintain essentially noise-free images. Finally, I had to move very fast, because the mist was dissipating quickly.

A perfect situation for Av: keep the aperture and ISO fixed and let the camera adjust the shutter speed as I quickly changed focal lengths,framing etc. However, because of the light on the surface of the lake, for a lot of the shots, an evaluative reading was fairly consistently 2 EV too dark. I dialed in EV+2 and changed that when circumstances called for it. Necessary? Not at all. But quicker (for me) than the alternatives, certainly quicker than manual (which I use a great deal), so given the rush, it seemed like the best option. Unfortunately, I ended up with a bunch of well-exposed mediocre images, but that is a different problem--the 12 inches / 30 cm behind the viewfinder.

[mgagnonlv]

My threshold is very variable.
On my old Nikon D70 (vintage 2004, I think), minimum ISO was 200 and noise could be seen at ISO 400. For low-light exposure, I rarely pushed it beyond ISO 1000. On my current D7100, I will easily go up to ISO 640 or 800 without questions. And for many subjects, I have no problems going up to ISO 2000 – 4000. ISO 2000 might not be great for flower close-ups, but it usually works perfectly for action photos.

[chauncey]

For those that have Auto-ISO...have any made the comparison between a totally manual shoot
and/or locking in your SS and f/stop with the camera determining your ISO.

What are the ISO differences...which method coughs out better exposures.

[DanK]

For those that have Auto-ISO...have any made the comparison between a totally manual shoot
and/or locking in your SS and f/stop with the camera determining your ISO.

What are the ISO differences...which method coughs out better exposures.

Shouldn't make any difference in exposure. I rarely use auto ISO, but I just did a little test. Put my camera on a tripod and took a picture in manual mode, ISO 200. I then put it on auto ISO, leaving it in manual, and made the shutter speed much shorter. The camera simply raised ISO to compensate, as it should. The resulting images had virtually identical histograms. The one with auto ISO would just be noisier, if I had looked at it on something other than the lcd. It's no different from manually increasing the ISO and manually making the shutter speed faster to compensate.