I posted the following message to rec.photo.equipment.35mm Since two people had the same question, there are likely readers on this list who also have the same question. (From: [EMAIL PROTECTED] (David Elfstrom) (Subject: Re: Nikon SB-28 questions (Date: Sun, 27 Dec 1998 01:01:24 GMT In article <[EMAIL PROTECTED]>, [EMAIL PROTECTED] (Brian C.W.) wrote: >I have the N70 and SB-28 combo and I get the same thing. I take >reading w/the flash on and mark down the combo (shutter aperture) then >I switch to M mode and set those settings I have marked down. The >resulting meter says underexposed... why? > >On 26 Dec 1998 15:51:30 GMT, [EMAIL PROTECTED] (Hybwolf) wrote: > >>With my N90s and SB-28 combo, when I have the camera set to aperture priority >>and the flash set to Auto fill. The camera will show a UNDEREXSPOSURE reading >>in the veiw finder.Say a shutter speed of 1/60 at f/4 >>When I change the camera mode to P. The camera will show a correct exposure at >>1/60 @ f/4. >> Why does the camera do this. There is no difference in exposure when the >>camera is in P mode or Aperture priority when the shutter speed and aperture >>are set to the same values. It's all in the manual. I must admit it's not very clear. Nikon F90X Manual, page 117: o When flash turned on in P mode: *** if shutter speed shows 60 ***, background may be underexposed. To extend the automatically controlled shutter speed range set the camera to slow sync mode or switch to another P mode that will choose a slower shutter speed and/or a wider aperature. In slow sync or rear curtain mode, LO may appear in the viewfinder if background will be underexposed. o When flash turned on in Aperture priority mode: if electronic analog display indicates minus value, the background may be underexposed. To give background correct exposure, switch to Slow Sync or set a wider aperture. To simplify the above: Both of the readings you observed (the 60 in P mode and the minus in A, M or S modes) mean that the background lit by ambient light will be underexposed at the current standard sync speed (1/60 sec). It means that your flash will cease to be a fill light and instead become the main source of light for the photograph. If you want to have a properly exposed background from the ambient light, you will have to use a tripod and force a slow sync speed, say 1/4 of a second, which returns your flash to a secondary source of light. DavidE.
