D600 flash compensation modes

godsakes

godsakes

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Simon
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quick question, my nikon D600 has 2 options for flash compensation:

1) entire frame
2) background only

1) entire frame
0 ev
dsc4104d.jpg

+3 ev
dsc4105d.jpg

-3 ev
dsc4106t.jpg


2) background only

0 ev
dsc4107bp.jpg

+3 ev
dsc4108.jpg

-3 ev
dsc4109bs.jpg


Okay I'm confused shouldn't the ambient light (background) exposure be varying in the 2) settings??
 
jacob12_1993 said:
How close is your flash to the BG? it is probably lighting it too
Click to expand...

the flash is to the side of the prop and over 1m away from the background, granted there's likely some reflected off the wall to the left straying back into the rear wall but if that's the case it's going to be pretty hard to use this mode indoors unless you have a huge studio
 
godsakes said:
quick question, my nikon D600 has 2 options for flash compensation:

1) entire frame
2) background only
Click to expand...

We can think this one through from first principles, surely.

The camera will be assuming that the foreground is illuminated by the flash, but the background isn't. (How else can it define "background"?)

So to achieve 1) it simply has to change the exposure, which will affect the whole frame.
And to achieve 2) it has to change the exposure, then apply an equal and opposite change to the flash output.

Does that make sense?

Of course, if the fundamental assumption (that the foreground is illuminated by the flash, but the background isn't) isn't true, then it won't necessarily work very well. In your case it looks like your background is so close that it's also being illuminated by the flash. In other words it's really foreground, and you don't really have a background, so 2) can't work.
 
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Hi Stewart

The point about the flashgun possibly lighting both the subject & background makes perfect sense, but I've just tried another shot this time narrowing/snooting the beam to minimise any spill (the background now is certainly very dark) but again playing around with just background compensation just keeps giving me the same exposure

there's supposed to be a 3ev difference between these 2 shots (I'm fairly certain I've eliminated spill from the flash)

dsc4162o.jpg

dsc4161x.jpg
 
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Was that room dark, and the flash the only real light source? If so, then you're expecting the impossible. If the flash is the only light source in that room, then background compensation will not work at all.

Try using flash in daylight... you'll see it works. It's designed to help people balance flash with a continuous light source. It looks like your flash is the only light source in a dark room. If that;'s the case, the camera will not be able to compensate for anything... because there isn't any continuous ambient light in the background. Being the only light source in the room, adjusting the flash will adjust the entire exposure. Think about it.

All background exposure comp will be doing is adjusting shutter speed to allow more ambient in, while maintaining the aperture and flash brightness/duration to maintain the flash exposure. If there is no, or very little ambient light, then it can't can it?
 
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Pookeyhead said:
Was that room dark? If so, then you're expecting the impossible. If the flash is the only light source in that room, then background compensation will not work at all.

Try using flash in daylight... you'll see it works. It's designed to help people balance flash with a continuous light source. It looks like your flash is the only light source in a dark room. If that;'s the case, the camera will not be able to compensate for anything... because there isn't any continuous ambient light in the background.
Click to expand...

Agree totally.
 
Sorry... edited some more in after you quoted me. :)
 
Even if the room was light enough for you to see, the differences in light levels between the flash (which looks very close to the subject) and the light levels in the room, would be MUCH more than 3EV.

If the room is very dark, forget exp comp... just do it manually. Switch your flash off, put the camera into manual, and get a light reading (shutter speed) for the aperture you wish to use. Test it... take a shot... ambient light OK? Good... now adjust nothing on the camera, switch the flash on, and put the flash into a TTL mode, and take the shot.

You haven't told us what kind of flash you are using however. I'm assuming a TTL Nikon Speedlight of some sort?

If not.... if it's manual studio flash then the flash exposure comp will not work anyway.


[edit]

If using a TTL remote cord, Pocket Wizard, a second SB speedlight in commander mode, or the inbuilt flash in commander mode, you will have to enable slow sync flash first if using a semi automatic mode.


Balancing flash and ambient is really easy with TTL flashguns. Just get a shutter speed and aperture for the ambient light... no matter even if it's 20 seconds or something....(hence needing slow sync flash enabled) and then just switch the flash on and make sure it's in a TTL mode. If you are in manual mode, then all is well (assuming the flash is not too close to your subject). In auto modes, the shutter speed may default to whatever the flash shutter speed is set to... by default, probably 1/60th. (Do not confuse flash shutter speed with flash sync speed). Flash shutter speed is the shutter speed the camera will default to when a dedicated TTL flash gun is connected (or in-built flash popped up) and switched on while in an auto exposure mode.


Edit]



Mods... shouldn't this be in Technical or a lighting forum?
 
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Pookeyhead said:
Try using flash in daylight... you'll see it works. It's designed to help people balance flash with a continuous light source.
Click to expand...

Yes just tried a few shots with the window behind the subject and it worked


Pookeyhead said:
You haven't told us what kind of flash you are using however. I'm assuming a TTL Nikon Speedlight of some sort?
Click to expand...
sb910

thanks for the replies, I'll get me D-hat on
 
Glad you've got it all sorted out :)
 
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