T8i: Let's assume I'm in Manual Auto ISO, too dark and too light exposure issues

[stevet1]

Let's assume I'm in Manual with Auto ISO.

The scene is stationary, so there's no danger of motion blur.

I meter the scene and it hits 0. I'm properly exposed, but I think the picture is a little too dark or too light for my tastes.

My focal length is around 50 or 60mm, and my shutter speed is up around 1/250, so I've got some wiggle room before I risk camera shake.

My ISO is around 320-400, so I'm not too much danger of introducing objectionable noise.

The conventional wisdom to darken or lighten my picture by 1/3 or 2/3 of a stop is to use exposure compensation, whIch In Manual plus Auto ISO is going to raise or lower my ISO.

Why should I do that instead of just slowing or speeding up my shutter speed by 1/3 or 2/3rds of a stop?

On my camera (a T8i), using exposure compensation requires two simultaneous actions - pressing the set button whiie turning the main control wheel.

Changing the shutter speed only requires the one action of turning the control wheel.

Steve Thomas

[rdominy · Accepted solution]

You can change your shutter speed, but the camera will increase or decrease the ISO in response to match its metering. That shouldn’t change what you see in the viewfinder.  If you feel the metering is off (too light or dark), you need to change the exposure compensation.  

[Waddizzle]

“ Why should I do that instead of just slowing or speeding up my shutter speed by 1/3 or 2/3rds of a stop? “

Good question. Excellent question!

I don’t think that there’s any objective answer to it. The best answer probably falls somewhere between personal preference and shooting conditions.  But, I will tell you how I resolved this situation with DSLRs. I use a different strategy with MILC bodies 

I have used several Canon DSLRs released since the late 2000s.  The Canon DSLRs seemed to have a small amount of  exposure compensation baked into the metering system.  I began to  have this suspicion once I began shooting in M mode with ISO Auto. Canon bodies seemed to slightly overexpose. This could give better performance in shadow areas, but it could also raise the risks of saturation in the highlight areas.

[EDIT] I “confirmed” that suspicion with a light meter.. At least so I thought. Always doubt your conclusions.

So, I dialed in AEC at -1/3 EV for my exposure setting. I used to compensate for this apparent bias using my LR import profiles.  I felt getting right in “in camera” gave me better results. 

MILC bodies. I have used the RO. I wound up buying the R6ii. I no longer have -1/3 EV if AEC dialed in.

[stevet1]

Waddizzle,

You wrote, "The Canon DSLRs seemed to have a small amount of  exposure compensation baked into the metering system.  I began to  have this suspicion once I began shooting in M mode with ISO Auto. Canon bodies seemed to slightly overexpose."

I've been having the same suspicion. At first I was blaming the use of Auto White Balance. Then I started blaming the use of Aperture Priority. Now I'm wondering if it's not just inherent in the system.

Steve Thomas 

[stevet1]

rdominy, 

This makes sense. My scenario would only work if my ISO were fixed.

Steve Thomas

[Waddizzle]

For numerous subjective and objective reasons, Canon DSLRs have had a reputation for not having the best performance in the shadow areas.  Upping the exposure slightly reduces that noise, but it also increases the potential for saturating the highlights. I am willing to trade under exposed shadows instead of over exposed highlights. 

[ebiggs1]

"... I'm in Manual with Auto ISO." ... "This makes sense. My scenario would only work if my ISO were fixed."

You are not really in 'Manual ' mode are you? A pseudo manual mode perhaps but not manual.

[ebiggs1]

"The Canon DSLRs seemed to have a small amount of  exposure compensation baked into the metering system."

Not buying that for a second. There are way too many variables to make a statement like that. Wide aperture lenses, exposure mode how much contrast is on the scene or how bright, WB settings, etc., and way many more. 

[Waddizzle]

“ I've been having the same suspicion. At first I was blaming the use of Auto White Balance. Then I started blaming the use of Aperture Priority. Now I'm wondering if it's not just inherent in the system. “

I am certain that books were being cooked. Test it for yourself.  Take a variety of shots with -1/3 Ev of AEC. I am not concerned about darker areas in the photo. Colors seem more true to life.

 

[Waddizzle]

“ Not buying that for a second. There are way too many variables to make a statement like that. Wide aperture lenses, exposure mode how much contrast is on the scene or how. “

It seems to be baked into the cameras. You can see signs of it in histograms. There’s even a name for it. ETTR.