Nikon D3300 Auto exposure

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B_Tank

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Hi all,

I'm a beginner and was experimenting with my camera yesterday.

It was in the evening in my room with warm white LED ceiling lights. I was trying different modes taking pictures of random stuff, and what I noticed is when I let the camera deal with the exposure on S mode, the exposure shows up on the histogram as in the second quadrant of the graph, so slightly under exposed. The camera says the exposure is correct though by looking at the exposure meter before you snap. You look at the resulting picture and it is a little dim. To correct this I would have to do +0.3 on exposure compensation, then it looks good. I haven't tried the same in other environments yet just in the same room for now but it looked odd to me.

Is there something wrong with the camera's auto exposure?
 
Probably not a problem. In shutter priority the camera opens and closes the lens aperture to control the exposure. But the camera may have difficulty opening up the aperture sufficiently to make an adequate exposure, particularly if you're using a fairly slow lens such as the kit lens.
 
I also remember trying in M mode, with the aperture fully open as it would go, on auto ISO with a high limit something like 12000, and me controlling the shutter speed. The camera had plenty of room to correct exposure with the full open aperture coupled with the high ISO limit. It still gave similar results.
 
Ok, give us some specifics in that case; what shutter speed, aperture and ISO were you using [or did the camera choose] and what was the lighting [indoor, outdoor, bright etc].
 
Ok one example:

1/125
f5.6 - I was zoomed in to max
ISO Auto 5000
Indoor dim lighting.

1/60
f5.6 - I was zoomed in to max
ISO Auto (unsure exactly what this one was but was lower as the camera compensated for shutter speed)
Same Indoor dim lighting

The point I'm trying to understand is, the camera had plenty of room to play with on the ISO, but it always seemed to calculate exposure a notch lower than ideal as shown by histogram and the slightly dim snap. It was clearly capable to doing it at the correct level as shown when I do EC to +0.3 or +0.7. I haven't noticed it do this before, I don't know if camera EC react differently to different lighting conditions. I'll keep an eye on it tomorrow when I take pictures at Duxford Air Show.
 
Well they're dim environments at slow aperture and not long exposures. I guess the question is why didn't auto ISO go up further to compensate? How is configured in your camera? It's a long time since I looked at it on mine. It might be Nikon's algorithm that tries to keep high ISO noise low at the cost of under exposure.
 
Deckard said:
Well they're dim environments at slow aperture and not long exposures. I guess the question is why didn't auto ISO go up further to compensate? How is configured in your camera? It's a long time since I looked at it on mine. It might be Nikon's algorithm that tries to keep high ISO noise low at the cost of under exposure.
Click to expand...

Yeah your question about the ISO is the same question I have. There's room for a higher exposure that can be chosen by the camera, but it doesn't for some reason. ISO is configured as auto, with a maximum of 12000. So, the camera can go up to 12000 if it feels it's needed, but didn't go nowhere near when it had to do something, to get it correct on the histogram. Note though, the built in exposure meter was aligned properly. So it seems the camera thought it had calculated the exposure correctly. The histogram didn't show that though. I would have thought the noise can be controlled by the limit of auto ISO you can put on the camera so it shouldn't be holding back the ISO.

Orangecroc said:
You will probably find it overexpose slightly in very bright conditions and is heavier on the right side of the histogram. That is what the exposure compensation is for, to allow you to adjust to the processors short comings.
Click to expand...

If that's the case then it answer's my question, but why does that happen?
 
I believe it was spot or centre.
 
B_Tank said:
So it seems the camera thought it had calculated the exposure correctly. The histogram didn't show that though.
Click to expand...
You can't readily judge whether the exposure is correct by looking at a histogram.

Here are a couple of photos I took the other day. The histograms are quite different.
I don't think you could just look at the histograms and say whether the exposures were correct.

19088-1506081647-a0707c53228796acfc8fa353e18954ca.jpg
 
B_Tank said:
Ok one example:

1/125
f5.6 - I was zoomed in to max
ISO Auto 5000
Indoor dim lighting.
Click to expand...
There's a good reason why the camera might think it had calculated the exposure correctly, but then the picture turns out a bit dark. That's because the indoor lighting is effectively pulsing at 100Hz (twice the mains frequency) and your shutter speed isn't an exact multiple of the pulse interval. When you're shooting under indoor lights, you should always set your shutter speed to be 1/100th, or 1/50th. or 1/25th, etc. to avoid unwelcome effects with regard to exposure and white balance.

I'm not saying this has caused your problems - without seeing your images I can't possibly know - but it can't have helped.
 
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