I have a Nikon D780 and a Speedlight SB-400 which I use only very occasionally. It used to work great, but today it essentially stopped working. What's strange is that everything appears normal: the "Ready" light is on, the camera recognises the flash, etc. When I take a picture, the flash goes off, but at such low power that the effect is pretty much like no flash at all. (The subject was at a distance of only about 2m at night with the ISO setting set to 1000 and a 4.5 aperture, so very well within what the flash can handle.)

I'm not sure how to even troubleshoot this since that flash is supposed to pretty much "just work". It has almost no physical UI controls and most setting adjustments are done from the camera menu.

I was seeing a "Zoom head position warning" icon, but when I played with the head, the flash would work occasionally, but only maybe 10% of the time. For example these two pictures:

example 1, well exposed

example 2, mostly dark frame

were taken with the exact same settings and the flash went off both times. Shutter speed was 1/50s.

Any ideas of what I could try?

  • \$\begingroup\$ Did you actually check the flash settings? I don't know that model, but all bar the very basic entry-level flashes have a whole swathe of settings - focal length, TTL metering, manual, etc, etc. \$\endgroup\$
    – Tetsujin
    Aug 17, 2022 at 15:59
  • 2
    \$\begingroup\$ @Tetsujin The SB-400 has no settings on the flash itself, it's all controlled by the camera. The flash settings on the camera look normal, the only thing being that the "Zoom head position warning" icon is shown. I suspect that this is because the focal length of the SB-400 is fixed at 18mm, while the lens is a zoom. (But that has never been a problem so far.) \$\endgroup\$
    – Martin
    Aug 17, 2022 at 18:42
  • \$\begingroup\$ 'normal' is still subject to much interpretation - onlinemanual.nikonimglib.com/d780/en/… gives all the varieties of "normal". \$\endgroup\$
    – Tetsujin
    Aug 17, 2022 at 18:46
  • \$\begingroup\$ @Tetsujin What I meant is that it correctly mirrors the camera settings regarding speed, aperture, ISO setting and that, besides the "Zoom head position warning", the other indicators also just show what one would expect: mode is TTL-BL, flash ready icon is on, and bounce icon is off since the flash was angled straight. \$\endgroup\$
    – Martin
    Aug 17, 2022 at 18:50
  • 1
    \$\begingroup\$ @MrUpsidown OK, so the SB-400 also doesn't work when trying it on a different body and the speedlight from the shop worked fine on my body, so it looks like the SB-400 just died... Sorry for lowering the signal-to-noise level... \$\endgroup\$
    – Martin
    Sep 21, 2022 at 16:55

1 Answer 1


Couple of things you can try:

Try another flash on the hotshoe.

It could be the flash, it could be the camera hotshoe. If you have another speedlight available to test with, putting that on the camera and seeing if it works properly might help you narrow the issue down to the camera or the flash.

Check that the flash is properly seated in the hotshoe.

This actually may not be as easy as it sounds. :) The D750 introduced a weird issue that sometimes a flash can sit too far forward in a Nikon hotshoe for all the pins on the foot of the flash to touch their respective electronic contacts on the hotshoe, so you only get partial communication and some weird behavior. Some folks built spacers for their hotshoes, but a simpler method to try would be to put the flash on the hotshoe, partially tighten the foot, and then slide it back until the locking pin engages (clicks into place).

Check that the flash has recycled.

It takes a while for a flash's capacitor to draw enough charge from the batteries to be ready to fire. Some folks assume they can burst shoot with flash or forget to check the ready light. If it's taking more than four seconds (the SB-400 is speced for a full power recycle at 4s for alkaline batteries, 2.5s for NiMh batteries), it may be the batteries.

Try new/different batteries in the flash.

Batteries deplete and the older rechargeable batteries get, the less charge they may hold. Having a specialized charger that can test capacity on a battery may be worth looking into. But failing that, just getting some brand new alkalines to try in the flash can also help eliminate if it's a battery issue.

If none of this is working, it's possible the flash has some kind of internal damage that may require servicing or replacement.

  • \$\begingroup\$ The SB-400 has a "lock" switch on the back. If the flash sits anywhere but in the right position, the lock won't lock (at least on my D750). When the lock is engaged (but not locked) the switch will stay half way between the locked and unlocked positions and when I slightly move the flash back and forth in the hotshoe, the lock switch will eventually move to the locked position. Once it is properly locked, I have never had any issues with it. \$\endgroup\$
    – MrUpsidown
    Sep 20, 2022 at 8:52
  • \$\begingroup\$ @MrUpsidown, I pretty much though I'd covered the D750 and later hotshoe fit with the second heading/paragraph. :) You may want to post your comment as a separate answer if you feel it doesn't; there's nothing wrong with short answers. \$\endgroup\$
    – inkista
    Sep 22, 2022 at 23:40
  • \$\begingroup\$ That was just my own experience with it but you are right, you had pretty much covered this. I am not going to post it as an answer as we now know this wasn't the issue. \$\endgroup\$
    – MrUpsidown
    Sep 23, 2022 at 8:47

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