Please help me understand the built in flash on the Nikon D3100

Revet

Senior Member
I have owned a D3100 for 3 years now but over the last year I have spent a lot of time getting to know everything about the camera. There is one thing I just don't quite get. I normally use a speed light for flash photography but occasionally I don't have it with me and I am forced to use the on-camera flash. I rarely shoot on auto anymore. I mostly use the semi-automatic or manual mode. The problem I am having is getting the built in flash to fire. For example, this morning I was taking some practice shots to mess with them with Adobe Lightroom to improve my post-processing skills. I was in Aperture mode, using an f8 setting with the flash up and ready to fire (ISO 400). When I take the shot, I just get a long shutter speed with no flash. In fact I rarely can get the flash to fire when I use the manual mode or semi-automatic modes (aperture, shutter priority) but sometimes it does. I have tried using matrix metering instead of spot and still get the same result. If I put my speedlight on, it will always fire in those modes (probably because it is TTL). Why is this and how can I force my built in flash to fire if I want it??
 
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WayneF

Senior Member
I was in Aperature mode, using an f8 setting with the flash up and ready to fire (ISO 400). When I take the shot, I just get a long shudder speed with no flash. In fact I rarely can get the flash to fire when I use the manual mode or semi-automatic modes (aperature, shudder priority) but sometimes it does. I have tried using matrix metering instead of spot and still get the same result. If I put my speedlight on, it will always fire in those modes (probably because it is TTL). Why is this and how can I force my built in flash to fire if I want it??

This does not sound good for the internal flash. The internal flash should ALWAYS fire if a) the door is open and ready, AND b) the camera is in A, S, P, or M modes. Metering mode is not a factor, flashing only depends on the flash door being open.

In the various Auto or Scene modes, then the flash is more dependent on the light level metered (door opens automatically), but camera A, S, P, or M modes will trigger it if the door is open, regardless.

So possibly it could be door switch problem, simply not recognizing the door is open? Such issue is not unheard of. If it sometimes fires, it would NOT be a bad flash tube.

Moot point, does not help, but I was curious if it worked any better in the Auto or Scene modes? If those do open the door automatically, but the flash does not fire, that sounds like a door switch issue. But I am guessing, the actual logic the software does in those modes is not known to me.
 

Revet

Senior Member
Thanks Wayne, That makes sense. I'm going to try it in Auto and Scene mode when I get home. I'll get back to the forum with the results of the test.
 

Revet

Senior Member
I got it figured out. When I put a charged battery in, it works like it is supposed to. I have noticed in the last 1/2 year that my batteries show they are fully charged until they are almost dead (like this morning). The batteries are what came with the camera so it might be time to get new ones. As I remember though, they are VERY VERY expensive or better yet, not stocked anymore!! I guess I just have to bite the bullet and upgrade to a better Nikon body, maybe even a full frame model. My reasoning makes sense to me, how about everyone else?? How about my wife??
 

WayneF

Senior Member
Well, it is good news if there is nothing wrong with the flash. :) The flash is a pretty strong load on the battery. Possibly with a low battery, the flash capacitor was not able to charge enough so that the Ready light comes on (the lightning symbol at right end in the view finder). If that Ready light were not on, that would explain a lot.
 

Bob Blaylock

Senior Member
I got it figured out. When I put a charged battery in, it works like it is supposed to. I have noticed in the last 1/2 year that my batteries show they are fully charged until they are almost dead (like this morning). The batteries are what came with the camera so it might be time to get new ones. As I remember though, they are VERY VERY expensive or better yet, not stocked anymore!! I guess I just have to bite the bullet and upgrade to a better Nikon body, maybe even a full frame model. My reasoning makes sense to me, how about everyone else?? How about my wife??

I believe that all the D3?00, D5?00, and D7?00 cameras all use the same battery, the EN-EL14.

I also believe that the genuine Nikon EN-EL14 has an MSRP of around $40 or so—well short of “VERY VERY expensive”.

On deciding that I ought to have a spare for my D3200, I ended up getting this via Amazon. For $25—significantly less than the cost of the genuine Nikon battery—I got not one, but two batteries. And on top of that, they claim a capacity of 1800 mAh, which is about 80% higher than the genuine Nikon battery's claimed 1030 mAh.
 

Bob Blaylock

Senior Member
This does not sound good for the internal flash. The internal flash should ALWAYS fire if a) the door is open and ready, AND b) the camera is in A, S, P, or M modes. Metering mode is not a factor, flashing only depends on the flash door being open.

I was going to respond that I thought that the flash probably wouldn't fire if the selected shutter speed was faster than the X-sync limit (1/200 of a second for my D3200, and I presume the same for the D3100); but then I decide to try an experiment, wherein I learned that if the shutter was set to a faster speed than 1/200, that opening the flash drops it to 1/200.
 

Revet

Senior Member
The problem has returned and it is not a battery issue as I first thought. It happens mostly I try to shoot in low light conditions (but sometimes it works in low light) I am getting the auto-focus lock beep telling me I'm ok to shoot (I do have AF assist on). Once it malfunctions, it will not work again until I switch to Auto, put the pop-up down, fire it (will always work in this situation, but it won't if I don't first close it), then switch back to Manual mode. Any ideas or is it time for service (which scares me because it is an intermittent problem which can be more difficult to diagnose). I also see that other D3100 users have had problems with the pop-up not firing when it should.
 
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