D300 with SB-400

Started Dec 8, 2007 | Discussions
MagicNikon Veteran Member • Posts: 5,445
D300 with SB-400

I seem to be getting some underexposed shots with my D300 and SB-400 combo. The odd thing is that if I use FV lock, I get a much brighter, and better exposed image than without.

I was under the impression, that a pre-flash is emitted and then bounced back and detected by the metering sensor to make a correct exposure. The FV lock shouldnt create a different exposure, should it? It just creates the pre-flash ahead of time, and keeps the pre-flash from happening at the moment of exposure.

I need to see if my SB-800 is doign the same thing, but I have definitley noticed it with my D300 and SB-400 today while at work.

Any thoughts?
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abortz Junior Member • Posts: 43
Re: D300 with SB-400

Actually, counter to expectations, FV lock does something besides just do the preflash ahead of time - in many situations it uses center frame spot metering for the flash value as opposed to matrix. While it makes FV lock less useful for eliminating preflashes, I've noticed that the preflashes are much faster and a little dimmer than older digital Nikons (i.e. D70) so I don't worry about them anymore. At the same time, FV lock is now more useful for tricky flash situations, since I can tell the flash exactly what I want exposed. Another way to think about it is that FV lock disables balanced fill. See pg. 182 in the D300 manual.

  • Andrew

OP MagicNikon Veteran Member • Posts: 5,445
Re: D300 with SB-400

Interesting...thanks Andrew.
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arachnophilia Veteran Member • Posts: 3,362
Re: D300 with SB-400

Actually, counter to expectations, FV lock does something besides
just do the preflash ahead of time - in many situations it uses
center frame spot metering for the flash value as opposed to matrix

no, it's different even in center-weighted. i think the flash just doesn't do much of anything in terms of metering until you fv-lock it. without it, it just seems to go off on the same, default setting.

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abortz Junior Member • Posts: 43
Re: D300 with SB-400

Yes of course, if you have the camera in CW metering, the flash will also meter CW on a normal shot, but still do spot metering with FV lock. I only used matrix as an example, and a good one too since matrix metered balanced fill flash is very nice. You are also right that normally, the camera doesn't do any flash metering until the shot is taken, at which point the preflashes are used to quickly meter and set the real flash output level.

Since I imagine what a lot of people are trying to do (myself included) is meter the flash well before the shot is taken, so that no blinking/lag happens. You can do this using an SB-600/800 in remote mode and the built-in flash on commander (with itself set to --) which according to the manual will make FV lock use full frame metering (hopefully that means matrix, although I guess it could mean CW as well)

  • Andrew

Gusty New Member • Posts: 2
Re: D300 with SB-400

I have had the same problem, on a D300 I just opened (for xmas!).

I have the SB-400 attached.

For those shots where the pic is black, the pre-flash fires to check the levels, but the proper flash never fires! Interestingly, for those shots where the subject is less than 1m away, the proper flash fires almost every time. Where it is 5m away, it almost never fires! (only the pre-flash fires)

When I use the internal flash, the exposure is correct EVERY time - there is no problem at all.

Another clue - when the flash is activated (both internal or external), the exposure bar shows that the pic will be very underexposed (the bars are filled all the way to the right, the underexposed side).

If anyone has any ideas, Id v much appreciate them!!
many thanks!
Gustav

Alan Brown
Alan Brown Veteran Member • Posts: 5,655
i can help with the second query.. Gusty

Gusty wrote:

I have had the same problem, on a D300 I just opened (for xmas!).

I have the SB-400 attached.

For those shots where the pic is black, the pre-flash fires to check
the levels, but the proper flash never fires! Interestingly, for
those shots where the subject is less than 1m away, the proper flash
fires almost every time. Where it is
5m away, it almost never
fires! (only the pre-flash fires)

When I use the internal flash, the exposure is correct EVERY time -
there is no problem at all.

Another clue - when the flash is activated (both internal or
external), the exposure bar shows that the pic will be very
underexposed (the bars are filled all the way to the right, the
underexposed side).

This is normal with flash because the camera sets the sysnc speed to 1/60th sec (unless you have other modes other than auto A/S/P. This speed is usually too fast for indoor lighting even at f.2.8. So a 'normal' non'flash exposure is way to dark. or underexposed as it is displaying on the LCD. However the flash becomes' the main source of light at the actaul time of exposure. so ignore this seemingly misleading situation.

PS In the opposite situation: out door in bright conditions, you have to be careful of overexposure... where the sync speed set by the camera is usually not fast enough.. causing overexposure!

If anyone has any ideas, Id v much appreciate them!!
many thanks!
Gustav

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Gusty New Member • Posts: 2
Re: i can help with the second query.. Gusty

Alan, thanks for clarifying my second point - I beleive this is a change from the D200, so I wasnt familiar with it.

But my first complaint is still bugging me.... maybe there is a problem with my camera..

Jim Kaye Senior Member • Posts: 2,792
Re: D300 with SB-400

Actually, counter to expectations, FV lock does something besides
just do the preflash ahead of time - in many situations it uses
center frame spot metering for the flash value as opposed to matrix.

Andrew,

How do you know that? Do you have some test pics that show the difference between the flash using center spot vs matrix metering when FV lock is on vs off?
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