Exposure triangle explanation please.

Started 9 months ago | Questions thread
Jeff
Veteran MemberPosts: 4,470
Like?
could also be called auto ISO ...
In reply to texinwien, 9 months ago

texinwien wrote:

Limburger wrote:

It's a matter of formulae and definitions. But photographically by whatever ISO will be replaced it will be in relation with shutterspeed and aperture just in the fashion it is now.

You need not know how the internal combustion engine works in order to drive a car.

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Cheers Mike

It's already not necessary on some cameras. On my current camera, I almost always shoot at base ISO. I ignore the ISO completely.

I focus only on the aperture and shutter speed necessary to get the desired DOF and the desired freezing of subject movement, always trying to get as much light on my sensor as possible. In low-light situations, I just choose the aperture and shutter speed I need for artistic purposes, knowing that I'll end up with a noisier image.

Later, I apply the necessary gain to my photos to make them as bright as I want them.

You see, I'm able to forget about ISO, completely. I focus only on the 3 actual variables that are a part of the exposure equation - scene luminance, shutter speed and aperture. No need to confuse the issue with the ISO, since it's just applying gain. Why should I choose the gain applied before I take the photo? There's no good reason to if you're shooting RAW and applying the gain yourself later on.

Once this is possible in-camera for JPEG shooters, the concept of ISO is simply confusing baggage that can be jettisoned.

Furthermore, my camera, the OM-D E-M5 has a function that shows me, in the live few, which highlights I'm about to blow. This allows me to quickly adjust shutter speed and aperture to get the optimal exposure (most light possible without blowing important highlights - leads to the least visible noise in the resulting exposure) in situations where light is abundant.

Add this capability to the ability to quickly adjust an exposure's gain in-camera, and ISO is simply thing of the past. Good riddance

There's a lot that agree with in this post. What you're relying on, of course, is that your camera has enough dynamic range that you can postpone the determination of {gain|ISO|image brightness} until PP. With modern sensors in larger formats that can work as you've indicated within reason. Depending on tolerance for noise in your images, you'll have 4-5 stops of head room to work with. In effect, you're working in an auto-ISO mode where gain is determined at the end to produce the final image.

I've been fooling around a lot lately with iPhone photography (don't judge, I enjoy the challenge and am having fun with it) where dynamic range is very limited. Shooting base ISO is basically forced because there is so little head room on the sensor. The f-stop is fixed, too, so effectively the only knob left to control image brightness is shutter speed. The point is that the small sensor format forces a different approach to exposure than the one you describe. At least for me, controlling {ISO|gain} at the time of exposure is still a very important aspect of creating the final image.

When the day comes that sensors -- both small and large -- have as much headroom as we encounter in typical photography situations, say 12-15 stops of headroom, then we can chuck {ISO|gain}. Until then, I'd rather hang onto the knob, or some proxy of it.

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Jeff
http://www.flickr.com/photos/jck_photos/sets/
You don't make a photograph just with a camera. You bring to the act of photography all the pictures you have seen, the books you have read, the music you have heard, the people you have loved.” -- Ansel Adams

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