Dark pictures with canon 5d mark 3 and 600ex flash, night indoors in Auto Mode and flash on.

[getit]

I have purchased a new canon 5d mark 3 and speedlight 600ex-rt flash. While testing it indoor at night , the room lights are on and I was using the Auto Mode with Flash on. The pictures are Dark with the Flash on and when the flash is turned off the pictures are brighter. I am confused. How to get the AUto mode working with the Flash on.

[cicopo]

TRY Program mode

LEARN Exposure Compensation AND Flash Exposure Compensation

And then learn photographic basics to get even more out of that investment.

Your manuals are your friend & they've improved big time over the years.

[getit]

Are you saying the Auto Mode does not work well with Flash, I know I can get a better picture with P mode

[cicopo]

In my opinion Auto mode is of very little use. In most cases you need to be able to use Exposure Compensation & Flash Exposure Compensation & I don't think Auto allows that.

[getit]

That does not answer my question. I understand you want me to use advanced functions to get a better picture quality, but I want my Automode to work reasonably when I need to take a few quick shots. Anyone who have used AUtoMode with Flash, is this a problem with the camera or flash ..is there any other setting I need to change even though I am using AutoMode?

[cicopo]

Yes it does answer your question. You bought a very serious camera & you are expected to learn how to use it for the best results. Auto mode is not able to predict enough of a scene to get it right instantly. That same information applies to every Canon DSLR I've owned. 

[Skirball]

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@getit wrote:

 ..is there any other setting I need to change even though I am using AutoMode?

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I don't think there are settings that you change in automode, are there?  I can't think of any reason why the camera would act as you describe, but I don't really know much about the automodes.  You checked that you're on eTTL (on the flash)?  As Cicopo said, I'd have a look at the flash exposure compensation, but there's no way that could be dialed down enough to not light anything.  I can't really think of anything else other than a malfunction, but I can't see it only malfunctioning in automode.  Is the flash firing? What settings (speed, aperture, ISO) are the pictures being taken at both with flash and without?

[TCampbell]

Automatic mode, it it's attempt to be reasonably foolproof, is going to lock you out of having any control over the exposure.

The E-TTL metering system on your camera & flash are attempting to find the correct exposure for your subject.  

Due to laws of physics (the inverse-square law), light has "fall off".  It's not actually possible to use a single light source and expose a large room with that single light.  Either the subject is nicely lit but everything else will probably be too dark.  OR... the background is nicely lit but the subject is heavily over-exposed.  (BTW, there are two ways to get around this.)

The amount of fall-off is based on the relative distance from the light.  Every time the distance increases by a factor of 1.4 the amount of light is cut in half.  This means if you have subject 10' away, but you have a foreground object only 7' away and a background object 14' away, and the flash is exposed for the subject at 10', then the foreground object will be over-exposed (with twice as much light as needed) and the background will be under-exposed (with half as much libght as needed.)  Incidentally... if you "double" or "halve" the distance then the light difference will be 4x or 1/4 (depending on if you are getting closer or farther.)

Here's a video which both explains and then later demonstrates the concept in a way that makes it very obvious to see and easy to understand.  If it seems confusing at first... stick with it.  The video is only 12 minutes long.

In fully automatic mode the camera wont let you control anything (except how far away you stand from your subject). 

If you switch to "Program" mode, it essentially works like automatic mode EXCEPT it will actually allow you to override settings or set compensations.  

When you use a flash in a room with some ambient lighting (but otherwise dimly lit) there's a technique called 'dragging the shutter' (which the camera can actually do for you somewhat automatically).

To do that, set the camera to Tv mode (Tv = Time value... which is shutter priority mode).  Dial in a slow-ish shutter speed... say around 1/60th of a second.  Use a moderately boosted ISO (400 would probably work well... you might even go up higher).  

The camera is going to evaluate the exposure needed for the room as though you don't have a flash... and it'll set the camera settings accordingly.  However... since it knows you have a flash, it'll still perform the E-TTL II exposure metering and will use the flash anyway.  What you end up with is a shot that has a nicely exposed primary subject (because the camera used flash) AND... a nicely exposed background which was primarily illuminated with ambient light -- but looks pretty good because the camera used an exposure that was adequate for the ambient light.

The reason I suggest using Tv mode and NOT Av mode is because you can control the mixture of flash vs. ambient light by controlling the TIME that the shutter is open.  But this does NOT work if you control either the aperture or ISO.  

Here's why:  The flash is "momentary" but the ambient is constant.  If you were to adjust the aperture settings, that will increase or decrease ALL the light sources that contribute to the exposure... so it increases (or decreases) the amount of flash AND the amount of ambient light ... and it does them in the same proportions.  If you want to bright up the background lighting WITHOUT over-exposing your foreground subject, then you don't want to increase both... you only want to increase the amount of ambient light.

Since the flash is a momentary burst of light, if you leave shutter open longer you wont actually collect any more light from the flash (because the flash was providing illumination for only a tiny fraction of a second.  Extending the amount of time that the shutter remains open means the camera will _only_ collect more of the ambient light... and that helps bring up the dark backgrounds.

One way to get around the flash fall-off problem is to greatly increase the distance between flash and subject.  You still get "fall off" but now the distance you have to change to notice the fall off really increases.  But this method usually isn't very practical because you'll be standing much farther then you'd prefer to be to get the shot.

The second way (and much more practical) is to "drag the shutter" (deliberately use longer shutter times so that the camera can collect more ambient light long after the flash is done.).

[Skirball]

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@TCampbell wrote:

It's not actually possible to use a single light source and expose a large room with that single light.

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I guess it depends on what you consider a large room, but unless he’s shooting it down a huge, bare, high-ceiling hall, something is going to pick up a reflection from the flash.  He seems to be getting nothing, and I’m assuming he’s just in a normal room in a normal house.  In which case it'd be nearly impossible to fire a 600ex anywhere and not pick up some exposure off it.

I’ve lit a room with a single speedlight many times.  Shoot it just off straight-up at the ceiling.  The results aren’t as good as multiple lights with modifiers, but with some balancing with ambient it can certainly produce acceptable results.

[nmotion4]

I'm new to flash also, actually just got the 600 today, but can't you also achieve 1/60 by adjusting the ISO if you want to keep a certain aperture for dof?