I have my D100 set to JPEG FINE LARGE and with the SB80DX I take 6 pix in the buffer with a 28mm lens. It's in a dark room. When I press the shutter release 6 time within 4-5 seconds. Some pictures have no flash and I don't see the flash fire during the 4th, 5th, and sometimes the 6th shot.
The batteries are new too! Does it mean my SB80 has problems?
#1. "RE: SB-80DX and D100 no flash sometimes" In response to Reply # 0
I don't think there is anything wrong with the flash for it sounds to me like the flash can't recharge fast enough. Asking the flash to fire 6 times in a dark room within 4-5 seconds is expecting too much - even with fresh batteries.
In a dark room at wide angle settings the flash probably has to fire at a fairly high output and simply can't recharge fast enough. The amount of ambient light, ISO setting, aperture used, lens, and flash-to-subject distance all have an influence on flash output. Changing any one variable effects flash output.
To check how fast it can recycle in the same conditions, take a single shot and wait for the ready light to come back on. That will give you a good indication how fast a frame rate you can shoot with flash. You will find the flash can recycle faster in brighter conditions, wider apertures, higher ISO, narrower lenses, and shorter shooting distances.
#2. "RE: SB-80DX and D100 no flash sometimes" In response to Reply # 0
It sounds like you're exceeding the capacity of the flash's recharge cycle. It can't keep up with your shutter release rate. If you're looking for that kind of performance from your flash, you should consider getting an external battery pack from manufacturers such as Sunpak or Quantum.