D40x Internal Flash question

[gabrielh]

Hello,
I have got a question about the internal flash of the D40x—but could be on any camera— (have been reading some things about flashes recently but still have a problem): if you take a picture, say, in Program mode, will the light meter be influenced if the flash is on or off? I have read that the light meter of the camera and the light meter of the flash are two different things, but is this only for external flashes? If the (internal) flash mode is on TTL (and not on Manual), then, does the camera choose the flash intensity or is it always the same and it adjusts the aperture/shutter speed?
I have started reading Strobist, but I think Lightning 101 is only for external flashes (if I am not reading something over there...)...
Thanks everyone for your answers!!

 

[Big Mike]

I'm not exactly sure how Nikon does it...but this is how I understand it anyway.

It depends on what mode you are in...and how bright it is.
For example, if you are in Auto (P) mode, when it is dark enough for the flash, the camera will probably give you the largest aperture and a preset shutter speed, 1/60 for example. The camera will use a pre-flash to determine how much flash power to use. This can work well, but when it's darker, this will probably underexpose the background quite a bit, making it look like your subjects are in a cave.

If you are in Shutter or Aperture Priority modes, the camera won't default to presets, it will give you exposure settings as if the flash wasn't turned on (wide open aperture and slow shutter speed when it's dark). The flash is still metered via a pre-flash, but it might only give you enough light for 'fill'...or that's how it may look because of the ambient exposure. This can make for more natural looking photos, but you might run into blur problems with slow shutter speeds.

What I do, is use flash with the camera in manual mode. This way, I can choose a happy medium between looking like a cave and motion blur from ambient light.

This should all hold true, whether you are using the built-in flash or an accessory flash...as long as you are in TTL mode with the flash.

 

[gabrielh]

Thanks, Big Mike! I have just checked my camera, and there is something "odd"/"funny". Here is how I understand with this Nikon:

If I set the camera on P mode and then use the flash, then the camera puts indeed "preset" shutter speed of 1/60 and the meter will say everything is way to underexposed.

This is precisely the same in A mode.

But in S and M mode, as I set manually the shutter speed, the camera cannot change it to its preset flash shutter speed. So I would think the camera would say something about the fact that it is overexposed (say, I set the shutter speed to 1/3). But no, the camera metering system seems to not care about the flash in these two cases...

Help..?
Thanks
Flash photography is cool, but really is a bit "woohooow" at the start!

 

[Mike_E]

Gabriel, check that your exposure compensation is at 0. If it is set to a negative number then the camera will intentionally underexpose that amount. (and vise-versa)

In P mode the camera should go to a preset Aperture and Shutter speed for correct exposure Within range of the flash. If your subject is further away than the flash is capable of properly exposing then you will have underexposure.

In A mode the camera should adjust the flash to expose for that aperture and have the shutter speed compensate for the ambient exposure.

In S mode the camera should default the flash to P mode as shutter speed has no bearing on the correct exposure of your subject only the background.

M mode is self explanatory.

As to the in camera meter, it's showing the scene as a whole unless you have it on spot meter (which only meters the spot in the middle of the view finder) which should show a lack of light. The preflash is what determines the amount of flash needed in P, S and A.