In article <3123B0D4.2455@cc.ntnu.edu.tw>, s22107@cc.ntnu.edu.tw says...

>I recently bought a Nikon SB-26 speedlight to go with my F90X.
>After shooting a few test rolls,I found that most of the faces
>in my portrait photos were too harsh,so I decided to try bouncing
>the flash off the ceiling and correct the problem.But I realized
>that the SB-26's distance calculation switches off if I tilt or pan
>flash head,thus disabling me to get accurate calculations for how
>much compensation I should increase.As a result,most of my pictures
>came out underexposed.I wonder if any of you guys using SB-26 has
>come across the same problem?If so,how do you calculate compensation?

If you are using the flash in TTL or Auto modes, there is no
calculation needed for the bounce, since flash shut-down occurs when
there has been enough flash exposure on the film. (The calculator does switch off, since there is no way of knowing what, or how far away,
the reflective surface is.) If you are getting underexposure in these modes, it is for other reasons, like a light-skinned subject/light
toned clothes. Like the ambient light meter, the flash meter can only tell you how to render what is in front of it middle grey - it doesn't know what's out there, so if it is unusually light or dark, you need
to compensate for that (not for the bounce light, unless there isn't enough, in which case the ready light will blink after the exposure). There is one other possibility. The 8008 - SB-24 combination underexposes black and white film one stop in TTL mode (color is
exposed correctly). If this is true for your camera, add + 1 stop compensation when using black and white film with TTL mode. You can check this by first shooting a subject in Auto mode with everything
set correctly. Then switch to TTL mode, with no compensations, and
shoot the identical photo. Then shoot the same subject again in TTL mode, but add + 1 stop compensation. (Be sure that all photos are well within the normal minimum and maximum distances for the flash for the ASA and aperture used.) Contact print the three negatives together,
and see which matches the first frame (BTW, Nikon Auto modes seem to
be very consistently accurate). Oh, and disable the "auto-fill" mode
on the flash (it is better to dial up your TTL compensations manually, anyway), and use Manual mode on the camera and select a shutter speed - aperture combination that will underexpose the ambient light at least three stops for this test.
Hope This Helps