Metering with the SB700 - Help!

W

WhiteLight

Senior Member
So just when i thought i'd learnt something about the SB700, i got stumped.
Please excuse my
I ordered a $2 diffuser from ebay :)D) & i was trying to work with it.

Now this is my setup-
D7000 with the SB700 on camera...
In the menu, i've set the flash control as TTL
I set the flash to TTL as well.
Now the meter on the camera shows the same settings with or without the flash turned on..
So if i am in a darkish setting, the shutter speed is extra long.. which either brings in camera shake and/or the image is totally washed out.
I assumed TTL meant the camera would give the right metering settings considering the flash output.
am i totally wrong with this & i would need to just not take the metering into account and adjust the aperture/shutter speed at some setting and try trial and error?
Same with Manual mode on the flash instead of TTL?

Now if the flash were placed off camera, would everything remain the same except in the camera menu i select 'commander'?

As you would probably figure, am totally confused at this stage..... :(

BTW Here's a pic of the $2 diffuser.
I hope this should be good enough?

DSC__WLP_0001-81.jpg
 
W

WayneF

Senior Member
WhiteLight said:
So just when i thought i'd learnt something about the SB700, i got stumped.
Please excuse my
I ordered a $2 diffuser from ebay :)D) & i was trying to work with it.
Click to expand...

Good luck. Magic really does not exist. :) (it is small)

Indoors, you will like bounce better, when possible.

Now this is my setup-
D7000 with the SB700 on camera...
In the menu, i've set the flash control as TTL
Click to expand...

That E3 menu only applies to the camera internal flash. If the camera flash door is shut, it simply does not matter what that E3 menu says.

The SB-700 has its own controls, which are in play if the flash is turned on.

I set the flash to TTL as well.
Click to expand...

On SB-700, this is technically TTL BL mode. Commander is always TTL BL too, FWIW.
Selecting Spot Metering will be the other TTL mode (not TTL BL). But, it is also Spot metering.

Now the meter on the camera shows the same settings with or without the flash turned on..
Click to expand...

The camera meter you see only shows ambient, never flash. For one thing, there is no flash happening right then, but there is more - mainly because the TTL flash system has its own invisible meter. TTL is automatic flash exposure (we can control it with flash compensation though).

In camera A or M mode, the flash TTL power level automation adapts to the aperture you set.

Otherwise, in brighter ambient (which can be metered, like P mode), the flash TTL power level automation adapts to whatever f/stop it discovers is in use.

In camera A or P mode (indoors), you should see shutter speed jump up to 1/60 second when you turn the flash on (Minimum Shutter Speed with flash, menu E2)


So if i am in a darkish setting, the shutter speed is extra long.. which either brings in camera shake and/or the image is totally washed out.
Click to expand...

I am assuming camera A or P mode:
You must be selecting Slow Sync or Rear Curtain Sync.
If selecting normal sync (no symbol in the the little sync icon box)
then menu E3 will apply (Minimum Shutter Speed with flash, camera A or P modes)

Slow or Rear Sync bypasses (ignores) E3, and actual metered ambient applies to shutter speed. (slow indoors)

In camera M mode (good indoors), of course you can set any shutter speed you want. The visible light meter is ONLY about ambient, not flash.

I assumed TTL meant the camera would give the right metering settings considering the flash output.
am i totally wrong with this & i would need to just not take the metering into account and adjust the aperture/shutter speed at some setting and try trial and error?
Click to expand...

The meter you see is only about ambient. TTL has its own invisible metering system.
Same with Manual mode on the flash instead of TTL?
Click to expand...

Camera M mode is good (indoors), in that it only allows you to set any shutter speed you want. You still set aperture same as camera A mode, so there is zero difference to the flash.

Outdoors, you have to deal with bright sun.
Camera P mode knows about that, and knows about maximum shutter sync speed with flash.

Whereas, if you dumbly set f/4 in bright sun, camera A mode ain't gonna work (OK, Auto FP is an option, but it is something very different).

And TTL BL is at its best for fill flash in bright ambient. However, real high ISO indoors seems imprudent with flash pictures. Turn Auto ISO off.

Now if the flash were placed off camera, would everything remain the same except in the camera menu i select 'commander'?
Click to expand...

Commander is a very different animal, but Commander/Remote generally works about the same as on hot shoe (the stuff mentioned above). There are details though.

I would suggest:

Four Flash Photography Basics we must know - Flash pictures are Double Exposures (modes)

Using the Nikon CLS Remote Wireless Flash System (commander)
 
Last edited:
W

WayneF

Senior Member
About the little diffuser... Arguably anything is better than nothing, but still tiny, and wishful thinking. IMO, you really will instead enjoy bounce flash indoors, when possible.

The little diffuser could be great up very close (when it might appear big), like for macro work. Nothing wrong with it then. :) For this reason:

Our trig can compute the angular size of a light, as seen from the subject, by
2 arc tan(radius of size / distance).

A bare 2 inch flash head at five feet: 2 arc tan(1/60 inches) = 2 degrees size.

The diffuser appears four inches, so double that, nearly 4 degrees size.

A 40 inch umbrella, 2 arc tan(20/60) = 37 degrees.

See? The light (big and close) has some light coming from subjects left, and some light from their right, etc, so that every light path fills the shadows from all the other light paths. That size is what makes light soft... big and close. Close makes it bigger.

Our Sun is 0.5 degree size (harsh shadows, not soft). 2 or 4 degrees is not all that much different. 37 degrees though, that is quite different. And 60 degrees is even better.

The rule of thumb for guaranteed soft enough for practical purposes is a light diameter more or less equal to its distance from subject.

Bounce flash makes a pretty large lighted area on the ceiling.
 
Last edited:
W

WhiteLight

Senior Member
WayneF said:
About the little diffuser... Arguably anything is better than nothing, but still tiny, and wishful thinking. IMO, you really will instead enjoy bounce flash indoors, when possible.

The little diffuser could be great up very close (when it might appear big), like for macro work. Nothing wrong with it then. :) For this reason:

Our trig can compute the angular size of a light, as seen from the subject, by
2 arc tan(radius of size / distance).

A bare 2 inch flash head at five feet: 2 arc tan(1/60 inches) = 2 degrees size.

The diffuser appears four inches, so double that, nearly 4 degrees size.

A 40 inch umbrella, 2 arc tan(20/60) = 37 degrees.

See? The light (big and close) has some light coming from subjects left, and some light from their right, etc, so that every light path fills the shadows from all the other light paths. That size is what makes light soft... big and close. Close makes it bigger.

Our Sun is 0.5 degree size (harsh shadows, not soft). 2 or 4 degrees is not all that much different. 37 degrees though, that is quite different. And 60 degrees is even better.

The rule of thumb for guaranteed soft enough for practical purposes is a light diameter more or less equal to its distance from subject.

Bounce flash makes a pretty large lighted area on the ceiling.
Click to expand...

Wow.. a lot of that zipped past my head..!
Lots to learn as you point out..
But something interesting was 'guaranteed soft enough for practical purposes is a diameter more or less equal to its distance from subject.' which means the diffuser should be useful for close up & macro...



 
Top