Strange SB-800 Flash Results - Help & suggestions needed please.
I have two SB-800's and they seem to perform differently from each other, I'm wondering if anyone can suggest what I might be doing wrong, or any recommendations.
I have a D800E and a D200 and two SB-800's. The D800E has flash setting E1 set to 1/320 with AutoFP, the D200 has it set at 1/250th with AutoFP. I set manual exposure to 1/250 F4, ISO 400.
With Flash unit A and B on either camera if the flash unit is hot shoe mounted and facing forwards I get very similar exposures between TTL/FP and TTL/BL/FP settings on the flash. It seems that TTL/BL/FP is about 1/6th EV less bright, but it's very close, and boosting by 1/3 EV results in a slightly brighter value than using +0 with TTL/FP mode, hence I think about 1/6 EV dimmer in BL mode. I get the same results with both flash guns on both cameras. This doesn't worry me and is presumably normal.
However, here's the weird part, if I then use all the same settings but point the flash unit directly up, flash unit A again shows an exposure about 1/6 EV dimmer in TTL/BL/FP versus TTL/FP mode on both cameras - this is perfectly fine.
But, with flash unit B pointed straight up, the TTL/BL/FP mode results in an exposure 2 1/3 stops less on the D800E, and 1 2/3 stops less on the D200. Note that when I am in TTL/FP mode pointing straight up both flash guns work the same on both cameras. So the odd combination is only exposed with Flash unit B, only when pointing directly up, and only when in Balanced-FillFlash (BL) mode.
Given Flash B works the same as Flash A when facing forwards and both are the same (other than an ignorable 1/6 EV difference) irrespective of whether BL mode is or not not. It seems extremely odd that Flash B would be so dramatically different when pointing upwards. I think the difference between results on the D800E vs D200 is probably explained by DX vs FX, and focal length changes.
What on earth could be causing this, could I have some odd setting set on the flash? Or is Flash B obviously defective and needs servicing?
Gallery at http://www.rolandwooster.com
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|Nov 20, 2012|
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