-EV and when to use it

[littleted]

Guys I'm still learning and rarely use Exposure compensation yet, but i wanted to ask some questions.

If I'm shooting in a Church for instance and my ISO creeps to 6400, will using -1 EV lower the effective ISO the camera uses, or does the ISO stay constant.
SO my questions

Do any of you always shoot with a -1/3 or negative EV ?
Do any of you lower your EV to lower the ISO ( if my question is true about ISO ) and then you claw it back in POST ? any advantages ?

thanks in advance..

 

[Phil V]

Exposure compensation is for when you can see that the inbuilt meter will be fooled by the scene you're shooting*, or you want to expose for a subject in tricky lighting conditions**.

Deliberately underexposing and then correcting in post will usually increase the amount of noise in an image. It's actually often better to overexpose and pull back in post (providing you don't blow the highlights.)***

More detail
* for instance a snow scene or at night, your camera generally assumes your subject will average out to mid grey, so you'd overexpose in bright conditions and underexpose in the dark.

**common with backlit portraits where the metered shot would give a nice BG with underexposed subject.

*** commonly a technique known as exposing to the right ETTR

 

[Carl Hall]

If you're dialing in one stop of negative exposure compensation then the camera will juggle the settings around to give you one stop less (half as much) light. What settings it changes depend what mode you're in. If you're in aperture priority mode with a fixed ISO of 6400, then the shutter speed will half. Likewise if you're in shutter speed priority then the aperture will close by one stop. I'm not sure how it works with auto ISO as I've not used it, but I would assume if you have a fixed shutter and fixed aperture then it would half the ISO. The problem is that you'll make the image much darker.

I definitely wouldn't use -EV just to reduce the ISO, as any gain you'd get from doing so would be wiped out by the huge increase in noise you'd get by upping exposure in post. You'd use the exposure compensation to make your image brighter or darker. If for instance in a church you found that the white in the windows clipped so there was no detail, then you'd dial in negative compensation to darken the whole image and retain the highlights, but that would likely lose the shadows.

The point of exposure compensation is to adjust the exposure of the image as whole, to make the whole thing brighter or darker. If you want to reduce your ISO down from 6400 to 3200 but keep the same overall exposure, you'd have to either use a longer shutter speed or a wider aperture.

 

[littleted]

thanks guys that helps. appreciated.