How to properly use Auto.... Or, "How I set up my camera".

[sk66]

There is a lot of "hate" on auto modes out there, and I just don't get it.
In photography exposure is almost always a compromise and yes, YOU should be choosing what to give and when. But if you set up your camera correctly it can make exactly the same decisions you would but much more quickly/accurately. Setting your camera up "correctly" can free you up from focusing on exposure to focusing on composition and the creative part of photography.
I will explain the various ways I set up my camera for various situations. I already know there will be those who find it "confusing" or "complicated" and complain that they can do exactly the same thing in manual mode. The reality is they are not incorrect, but once my camera is set up I seldom have to do anything other than occasionally verify that the camera is doing what I want it to.

This is not really beginner level stuff.
First, you have to understand the exposure triangle and how each setting affects the others. Then you have to know your gear in order to know what you want to give up for a certain situation. In order to get to this point you need to have learned quite a bit already, and maybe using manual mode will help you get here if you're not already. But once you understand all of that, at least in basic principles, it's now appropriate to "give up control". Using an "auto mode" is NOT letting the camera do what it wants. It is setting the camera to do what I want it to do, and if I disagree with the camera I simply override it.

I'm a Nikon user so I will be using Nikon terms, but there are Canon equivalents for almost everything. Also, not everything I may mention is available in every camera model nor will every camera model perform as well when set up a certain way. I have extensive experience with the D200/D300/D7000/D3 and they all behave/perform a little differently and my settings need tweaked for each one. That's part of knowing your equipment.

So, now on to the settings.
As I said, exposure is almost always a compromise. You don't get to "choose" all three, ISO/Aperture/Shutter Speed. You get to choose two of them and you have to accept the third which gives you a proper exposure.

Different subjects require different "thought processes". For fast moving subjects SS may be the critical setting, For stationary subjects aperture may be the critical setting. It is important to understand how your camera "thinks" and behaves in the various settings in order to set the camera to the correct "thought process" in order to get the desired results.

In manual mode with auto ISO off the camera does not "think" or do anything...it just meters/focuses. When I use manual mode, which is very seldom, I have the ISO set to auto. With the camera set this way when I change Aperture or SS (or both) the camera will automatically select the ISO for correct exposure. You use exposure compensation to adjust for various subjects where the meter will be fooled. Now exposure compensation is a 2 finger adjustment on Nikons, a button and a dial. That's a little more complicated than it needs to be. Plus, Nikons tend to underexpose so I almost always have a default +.3-.7 EC set. Therefore I seldom use Manual mode.

In all of the auto modes if auto ISO is turned off you balance the SS/Aperture for correct exposure and change ISO when necessary. However, this is almost as involved as full manual and really no different than using variable program mode with auto ISO off.... Works fine; I'm still in complete control. But it's not making my life much easier. ISO changes and EC are two finger adjustments or even worse; menu items.

Now for auto ISO...if auto ISO is enabled with the limit for minimum SS set to the lowest available and the max ISO setting set to max available the camera does very weird things...I have no idea what it's thinking and the camera doesn't know what I want because I haven't set real any limitations for it's behavior. For auto ISO to be of benefit I need to set the minimum SS, usually to 1/focal length, but subject depending. And I need to set the maximum ISO, usually 1600 for the D7000 as that's where noise and dynamic range are starting to be compromised too much.

In SS priority with auto ISO turned off the camera will change the Aperture to achieve correct exposure. Once the aperture has reached the limits the exposure will fail. If Auto ISO is also enabled once the aperture limits have been reached the ISO will then be changed to achieve proper exposure, otherwise it stays at base ISO. I seldom want to give up aperture before ISO. However, my D7000 has a feature called "easy ISO" which can be enabled. If SS were the ONLY factor I really cared about (almost never happens) I can use SS priority and enable easy ISO. WIth these settings I can set SS for the subject/lens and this would remain basically "locked". I will have my general +.3 EC set in. So now I meter a scene..the camera is going to use the locked SS and the set ISO and automatically adjust the aperture for correct exposure. If it chooses an aperture I don't like I simply turn the dial for easy ISO to change the ISO and thus change the aperture. I am still in complete control. Still, when things are happening quickly I may not have time to "correct" the camera and I may end up with an aperture setting I wouldn't have chosen...Not ideal. So I seldom use SS priority.

In Aperture Priority with auto ISO disabled the camera will only change the SS for correct exposure. If it can't get a correct exposure you have to do the 2 finger ISO change or the exposure will fail. If auto ISO enabled the camera will change the ISO first within the set limits and then change the SS. It will stay at minimum SS set until it reaches maximum ISO set and then it will reduce the SS below the minimum setting.

Aperture priority is the mode I am in 99% of the time.
With the D3/D300 I would also have "easy exposure compensation" enabled. Set in this manner I choose the Aperture the SS remains at the minimum set in the auto ISO menu and ISO is changed from base to the max set in the menu to achieve correct exposure. Once ISO reaches the max setting the SS will drop below the minimum set and I can give on aperture if I need to in order to regain my SS. With Easy exposure comp enabled a simple turn of the thumbwheel will change the ISO/SS settings for various subjects/lighting and the changes occur exactly as the Auto ISO settings behaves.

With my D7000 I have another option...I can enable "easy ISO" instead of "easy exposure compensations". Set in this way the camera behaves the same as before but when the auto ISO hits the limits of it's settings I can drive the iso above or below the menu settings just by turning the thumbwheel. This is useful in more "constant" situations and I'll have the ISO limits set very tight in the menu to something like 100-400 or turned off.

So that's all of the complicated how the camera "thinks" and behaves in various settings.

[sk66]

So this is me and how I think. I "always" care about aperture first, either for maximum sharpness or DOF control. Second, I always have to have a minimum SS for the subject/lens. Third, I need an ISO to match with those other two settings.
I think about exposures in "Aperture Priority".

ISO is *always* the thing I give first because, up to about ISO 1600 (D7000), the biggest sacrifice I'm making is some dynamic range and color sensitivity and I can regain much of that in post. I'd much rather loose a little dynamic range (which I might not even have use for) than have a blurry image due to too low a SS or too shallow DOF/lack of sharpness due to too wide an aperture.

Now, there are three scenarios. One where things are changing rapidly. One where things are changing, but not time/reaction critical. And one where things are fairly constant.

For any environment where things are changing frequently I am in Aperture priority with minimum SS and Max ISO settings set and enabled in auto ISO. I also have easy exposure compensation activated. With these settings the I set the Aperture, SS stays at the minimum setting and the camera changes the ISO to get me the correct exposure. Once ISO has hit the limits set the SS will then change above/below the minimum I set and I can affect that with one dial aperture changes. I can adjust the exposure at any time with one dial adjustments of easy EC....works great. Most of the time it's a simple "one dial adjustment" and often I don't have to do anything.

For a relatively constant or time/reaction non-critical environment I may be in Manual mode with auto ISO enabled. I choose the specific Aperture/SS and ISO follows for correct exposure. I tend to do this because it's a simple switch of the mode dial as opposed to staying in Aperture priority, disabling auto ISO, and enabling easy ISO (which gives the same level of control). But often I will just stay in Aperture priority as above.

For a very constant environment..meaning I'm not moving much, the lighting direction is not changing, and the lighting levels are not varying much (i.e. no rolling clouds or lit/unlit areas) I may go to full manual mode because then it's just "set it and forget it". But usually I will stay in Aperture priority and just turn off auto ISO. The result is the same and it's just one setting change as opposed to two.

[RichardTaylor]

Thanks for the post Steve.

Never looked at auto ISO before (it is on my Canon 40D).
It doesn't work the same way as it appears for the Nikons and doesn't look like an attractive option.

I shoot in shutter priority with the shutter speed set to what I want and ISO set to give me an aperture around F8-F11 normally.
Or
I shoot aperture priority with the aperture I want and the ISO set to give me a shutter speed so that camera shake will not be a problem.
Or
I shoot manual in difficult lighting conditions, with the ISO set to give me the shutter speed and/or aperture I want, but low as possible.
I use exposure compensation where needed.

The only time I let the camera take a lot more control is when shooting wide or near wide open. In good light - daylight outdoors the ISO will be fairly low, and it doesn't really worry me what shutter speed is used so long as it is high enough.

For action in real low light I will be shooting wide open, with the ISO at or near maximum and take what ever shutter speed i can get,

[sk66]

Your 40D is the first model where Canon implemented auto ISO and they didn't do that good a job of it from what I understand. The newer/higher end models do much better and more like the Nikons.

[RLucas]

Thank you so much for this Steve! If there were a tip jar, there would be some cash in it!

[Gwenise]

Hey Steve...your post is extreamly informative but I have 1 question I am shooting with a Nikon d3000 and I cant set my ISO to Auto ...how do I do it?

[RichardTaylor]

See page 120 of the English instruction manual.

Also point #3 on page 62 may be helpful as well..

[Hill Country Hack]

Thanks for taking the time for putting this together. I have learned something today.

[brianxlt]

Nice write-up, I do almost the same thing with my 7D, but never put that much thought in it. I shoot in A mode most of the time and adjust ISO to get the desired SS. I almost always have ISO set at 100, but I do mostly landscapes so a fast SS is almost never needed. Back when film was the only media I would on occasion push the ISO above the film rating to get the setting I needed then pull the PP in the darkroom. With digital you can't push the censer, but you can pull the PP as long as you don't lose too much detail in the original, but then there is always HDR if needed.

[STB]

Thank you for this post. I'm a newbie and just using a bridge camera as I learned but this made me feel better about some of the choices I'm making and explained a few more things.

I appreciate you sharing the knowledge.