# How good is the cameras decision?



## imagesliveon (Jul 17, 2014)

I consider myself to have enough experience to move away from the Automatic setting on my cameras however I feel it's still a good idea sometimes to base my settings on the cameras choice, then work from there. For a couple of years I went from my little Canon 400D to a Canon 7D and now a 5D3. My question relates to how the cameras computer thinks. For example if I'm shooting in Low light with a say a 50mm 1.2 with the camera switched to auto will it take more advantage of the wide aperture or will the camera choose to hike the ISO or both?

Regards.

Simon


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## Overread (Jul 17, 2014)

Try it and find out.

That's really the best answer, in some of the scene modes like you'd have on the 400D the camera has some specific weighting - eg sports mode it tries for a wide aperture and fast shutter speed - landscape it will try for a smaller aperture and will assume you've got the camera on a tripod/short lens used (ergo slower shutter speeds). 

For full auto its mostly just running on some pre-set conditions. I've heard that Nikon pre-load their cameras with a host of situations and scenes that the camera cycles through; comparing them to what it sees through the lens to try and get a little bit more accuracy on where to weight the important setting for the scene. However even then whilst its a "smart" approach it might not be the right approach.

In short the camera can't mind read. It can't see a scene and know what you want from the shot. It can tell you the light based on how you've set the meter to read it and it can balance all 3 settings; but it can't know what you want artistically speaking from a shot. This is where learning how aperture, ISO and shutter speed each affect your photo and contribute to the final exposure along with experience shooting in a wider variety of scenes and situations slowly teaches you how to pre-conceive a shot. 

How to go into a situation and quickly think "Ok I want "this" and to get it I do "this"" .

I would try to ween yourself using the cameras auto mode to do that thinking for you as it will stunt your ability to be creative with the camera if you're always letting it define your starting position. It's also slower because you've got auto where you test the exposure; then you've got to jump into manual or semi-manual (aperture/shutter priority) to actually set those settings - change them if you want and then take the shot.


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## lambertpix (Jul 17, 2014)

You can almost certainly count on the camera to do better than an iPhone would.  ;-)

All kidding aside, considering the camera knows absolutely nothing at all about your intent in "auto" mode, it's probably doing a pretty remarkable job of guessing.  With just a little more input from you, though, it can do even better.  If you move off full-auto onto something like Av (aperture-priority) or Tv (time, or shutter-priority) modes, you can control one part of the camera's exposure and let it meter for the rest.

As you indicated, you're trying to understand how the camera "thinks" -- this is a great way to give the camera a nudge in the right direction by indicating the one part of the exposure computation that's most important to you.


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## bratkinson (Jul 18, 2014)

One of the things I've discovered about Auto capabilities of my digital camera 'progression' the past 10 years or so is that Auto keeps getting 'smarter'. I sometimes put my 5D Mark iii in Auto when I'm under some really screwy, mixed indoor lighting such as LED, florescent and sunlight all lighting the scene and I have been amazed at the good results. 

The algorithms used by the camera manufacturers are likely 'top secret' within the company and I'm sure they continually adjust the Auto programming to handle a little bit different than xxx situation, or whatever. But the wizards in Japan don't 'see' the desired photograph as I 'see' it. Nor do 'they' recognize when I want to shoot 'wide open' for a thin DoF, or stopped down a bit to get a group shot, or a slow shutter speed to intentionally cause some blur, etc. The automated decision logic used is based on the most common types of photographs...people pictures, scenery, tourist-type shots, baby pictures, and perhaps even some concert-type situations with flashing lights or from the back of the room. The cameras probably recognize sunrise/sunset pictures as well. But put a subject or two looking at the camera with their backs to the sun...the subjects will be underexposed as the camera is exposing for the bright sun. In low light situations, the camera will likely use a larger aperture and/or slower shutter speed and/or higher ISO speed, to get the 'best' exposure with the least amount of moving-subject blur. But it has 'limits' of how far to automatically go on each setting without getting too much noise, or too much blur, or too under exposed, etc.

Perhaps the easiest way to start shooting beyond Auto mode is to use either Av (aperture priority) or Tv (time priority (shutter-speed) where you select one of the priorities and let the camera do the rest. I was at an outdoor car show a couple of months ago and shot everything in Av...f8...to get a good depth of field (DoF) of the individual cars. Zoomed in, zoomed out, sun behind me, to the side, or even in front of me, I always got most or all of each car in focus (DoF) and an accurate exposure. At other times, such as taking pictures of trains or moving cars, I've gone to Tv and set my shutter speed high enough to stop action, and let the camera do the rest. It comes down to -recognizing- when Auto won't give the results you want and then determining how to handle it fully- or semi-manually. 

But it would appear that as you've been using Auto more or less exclusively, you really need to learn about the basics of photography...the exposure triangle, in particular.  Here's a site with some great tutorials...
Cambridge in Colour - Photography Tutorials & Learning Community


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## Braineack (Jul 18, 2014)

imagesliveon said:


> For example if I'm shooting in Low light with a say a 50mm 1.2 with the camera switched to auto will it take more advantage of the wide aperture or will the camera choose to hike the ISO or both?



it'll probably just fire the flash.

I personally dont like how the camera handles fast glass.  I tend to notice, unless it's bright out, it pegs the aperture wide open. And I don't like to shoot wide open, especially when I care about focus/usable dof.

and even with the flash, you'll probably end up with 1/60sec, f/1.2, ISO 400.


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