5D Mk III LCD auto-exposure compensation?!

[billium99]

Hi - I have the 5D Mk III and I'm confounded by one thing the camera does that I can't seem to prevent. No matter what setting I try in M mode, if I manually open or close my lens aperture, my LCD preview compensates to give me some kind of neutral exposure, but this is completely inaccurate from the final photo taken. 

Why does the camera do this by default? I get that LCD preview is not a great, accurate way to guage how the photo will look, but I'm just looking for a ballpark estimation of exposure, and instead, I basically have to snap photos, adjust, snap more photos, etc because the LCD preview doesn't help me.

Am I missing an obvious setting somewhere? I've tried WRENCH > LCD Brightness and set to manual, but this doesn't nothing to help with this exposure compensation.

Any suggestions?

Thanks

Bill

[ebiggs1]

Bill as you stop down the lens it will get darker.  That is where it is getting it's light from.  It is not meant to be a light meter, however.  Even the view finder will get darker and it isn't a lightmeter either.

[RobertTheFat]

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@ebiggs1 wrote:

Bill as you stop down the lens it will get darker.  That is where it is getting it's light from.  It is not meant to be a light meter, however.  Even the view finder will get darker and it isn't a lightmeter either.

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That doesn't sound right to me. Bill is undoubtedly using a preset lens, which doesn't stop down until you push the shutter button. So everything looks as it would at full aperture. To see the actual intensity of hte light (at least to the extent that the LCD preserves it), you'd have to push the preview button. Or am I missing something obvious?

[ebiggs1]

You may have a point and be right.  I assumed he was using a lens that actually stopped down in manual.  I don't know what else would cause the LCD to darken as you stop it down.

[billium99]

Hi Guys,

Thanks for the time!

Yes I'm actually using some Zeiss zf primes with de-clicked apertures, so I'm manually stopping down.

But...what I'm saying is - my LCD get's darker momentarily, then compensates and "normalizes" the exposure shown in the LCD window. If I open it up, the LCD gets brighter momentarily, reflecting my change, but then lowers the exposure in the preview. 

This does not affect the final image. But that's the problem. I can't get an accurate preview or anything even close to accurate, in the LCD screen if I'm experimenting with exposure parameters.

Does that make more sense?

Bill

[ebiggs1]

Yes it does make more sense and it is normal.  The LCD is not a light meter and the camera is adjusting it for your ease of use.

It is totally electronic and not meant to be an actual result of the picture.  It is like a TV or computer monitor.

[billium99]

Well I agree that appears to be their design intent - I don't agree that it should be the case that a "preview" should look completely different from the actual result. I'm not using it as a light meter. I'm using it as a preview approximation. And in this context, it fails for me.

Thanks again for your time.

Bill

[PhillRoath]

I can only speak for the T3i, but mine does what you are asking for.  It does it in M mode with the ISO set to a value (not automatic).    I can sit here at my computer in live view and see the image on the LCD lighten or darken as I change settings, (e.g. chane the shutter speed).

As soon as I switch to Av it only does a small amount due to the limited f/stop range of the lens.  With Tv mode, from a normal viewed picture on the LCD increasing the shutter speed darkens the image.  At 1/1250th, the LCD is so dark I can barely make out the image.

Again, this is with my T3i.  YMMV

Is this what you were asking?

Phill

[billium99]

Hi Phill - yeah precisely.

And the 5D Mk III, in M mode, isn't doing what your T3i is. Or rather, it does appear to show a "fixed" adjustment if I change shutter speed or even if I radically change ISO.

But if I manually move my lens aperture, it "fights" the adjustments in the preview window, and gets further and further away from an accurate preview.

Not very helpful, imo

Bill

[PhillRoath · Accepted solution]

One more thing.  I just downloaded the 5D Mk III manual and on page 203 it speaks of Final Image Simulation (page 202 speaks of Exposure Simulation). On page 203 down below it says "Exposure (with [Expo. simulation: Enable]) and page 207 shows how to enable.  Perhaps this is not on?

My T3i does not allow me to change this, it is always on.

Phill