Both the camera and the Flash are in AUTO, so in low light it should make the flash pop up, but it does not. Instead it just seems to take a shot with longer exposure, making the photo appear with more light.

I have already tried resetting the settings but it still does this. Please help me out, I hope its not broken.


I tried to open the flash manually in P mode but it does not open. Going to take the camera to the store to see if it can be repaired and for how much. Thanks for the help.

  • \$\begingroup\$ Did it ever work how you expected, or is this a new development? \$\endgroup\$ Aug 25, 2013 at 22:22
  • \$\begingroup\$ this is new, ive had the camera for a while now and it has never done anything like this. could the flash be jammed or something? \$\endgroup\$
    – Alex_dlc
    Aug 25, 2013 at 22:35
  • \$\begingroup\$ Can you activate the flash manually? Press the flash button in the left side of the viewfinder. The flash should pop up. \$\endgroup\$
    – Unapiedra
    Aug 25, 2013 at 23:25
  • \$\begingroup\$ no, the flash does not pop up when I press it, and I dont think its supposed to. \$\endgroup\$
    – Alex_dlc
    Aug 25, 2013 at 23:33
  • \$\begingroup\$ In auto mode pressing the flash button usually doesn't do anything as the flash is forced into automatic operation only. In P mode, however, pressing the flash button to enable forced flash should work, and cause the flash to pop up. It's one thing you should try in order to troubleshoot. \$\endgroup\$ Aug 26, 2013 at 6:32

3 Answers 3


While in the Auto shooting mode it should automatically pop up. Try shifting the camera in to P mode and push the flash (lightning bolt) symbol on the side of the flash. If it still doesn't pop up when you do this, the release for the flash is damaged and you will need to get it repaired. It can often be a fairly simple repair, but involves taking the camera apart, so it's wise to have a service center do the repair, particularly if it is still in warranty.

  • \$\begingroup\$ Just tried in P mode and the flash does not open. \$\endgroup\$
    – Alex_dlc
    Aug 26, 2013 at 10:05
  • 1
    \$\begingroup\$ Going to take the camera to the store to see if it can be repaired and for how much. \$\endgroup\$
    – Alex_dlc
    Aug 26, 2013 at 13:16

In auto mode there will be a threshold in terms of light level below which it will activate the flash.

Before reaching this threshold, the camera will try to adjust exposure using other means such as increasing aperture, increasing exposure time and increasing the effective ISO of the sensor.

Only once all these other measures reach their acceptable limits (wide open for aperture, a suitable maximum ISO, and say 1/60s or 1/30s for exposure time), then the Flash will activate.

Some cameras also have the ability to detect other situations where you may want to use the Flash such as strong backlighting, but there is a limit to how intelligent this can be.

The problem with this is that you probably often want to use the Flash when the camera hasn't reached the threshold for automatically enabling it. That's why there's an ability to manually override it.

For example, it's perfectly sane to want to use a Flash even when you would otherwise be able to get a 1/60s or 1/120s exposure: this is fast enough to hand-hold the camera, but not fast enough to capture human movement without your subjects being blurred. Thus, enabling flash will help freeze the action, assuming you are comfortable with the trade-off in appearance of using flash (on-camera flash can create harsh lighting appearance). You may also decide that the camera's boosting of ISO makes the noise too harsh - ultimately, auto mode has decided on its own compromise between noise caused by boosting the ISO and the effect of flash, but since you are smarter than it, you may decide you want to override the camera's wisdom.

If you know whether you want the flash to be on, you wouldn't set it to auto - you would put your camera in a mode that lets you control the things you want to control. The most basic of these modes is P mode where, by default, everything is still controlled automatically, but it allows you to set various things, including the flash, to manual. This is usually accomplished with a button that physically flips the flash up, but it should also be confirmed with an icon in the viewfinder or on the back of the camera indicating the flash mode.

I'd encourage you to also experiment with other flash modes such as slow curtain flash, when your foreground subjects are in the dark but there are lights in the background. Experiment to find what works well.


Page 67 of the D3100 User Manual.

The flash Never pops up in modes A,S,P, or M. You open it manually if you want it to be used, and leave it closed if you don't want it used.

It does pop up automatically when it thinks needed in Auto or in some Scene modes.


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