Low light (400D)

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leezer3

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Please bear with me a tad; I'm reasonably conversant with manual functions (If not always happy to use them all!), but this has got me confused.

Recently, I tried some low-light shooting with my 400D, at approx 8:10AM, so shortly after dawn. No bright lights & a relatively evenly lit scene, so the metering mode was set to evaluative.
The 'issue' is that I basically found that it was consistently under-reading by approximately 2 stops. Whilst I've noticed under-reading in the past, I've always assumed that these were situations that I should have been using partial metering in.

Trying again in a dim room, I've again observed the camera under-reading by approx 2-stops. I suppose I can automatically correct in my head for this, but I'm sure I'm doing something wrong.....
I've also tried with both an 28-135 IS lens and a 28-105 standard lens in case the IS was effecting matters.

Is this something I'm (not) doing, the camera or something else?
I don't think I ought to be in one of the other metering modes, for low-light, although I'm not certain :s
 
I've always found in-camera metering to underexpose in low-light situations - you can dial in some exposure compensation, but I've always found the best way is going to manual mode. Takes some practice, but worth it in the long run.
 
Is this something that just started happening or is this normal when shooting? The one thing I can say with certainty is that the camera doesn't always meter correctly. It does a pretty good job but it is our job to monitor it and keep the exposure correct. Even when it is correctly exposed I may adjust it for my personal preference, to set a mood or other reasons. Truthfully I wouldn't be to concerned if you can correct it with exposure compensation. Like the other op said, I would use manual and take control of all the power your dslr has to offer.
 
Long shot...

Have you accidentally left 2 stops of exposure compensation dialled in?
 
In either scene, was there a bright area? Thinking room light, sun?
 
Nope, no bright lights anywhere.
I'm reasonably certain there's no exposure compensation dialed in (I certainly haven't done it intentionally, not that it means anything....), but I'll have to check to be 100% certain.

I'm not sure if it's normal, that's why I'm asking :p
To be honest, from the sounds of things I need to go and try something else in low light that's not indoors and try fiddling with the RAWs in lightroom a bit.
 
In short, I've never had a camera where the meter was 2 stops out, in low light or not. The only thing that throws the meter is a bright or dark subject.
 
What were the other camera settings?

If you were in Tv with a fixed ISO it might be that the lens hit its maximum aperture before it could correctly expose - e.g if you needed f/1.4 to correctly expose but the lens only goes to f/2.8 you'd see a 2 stop underexposure in the resulting images.
 
An example or three with full intact EXIF is needed here, just to see what the scene looks like.
 
There is a chance that your sensor is metering correctly. Don't forget that your camera sensor doesn't have the dynamic range of the human eye and brain. Your eye/brain combination is constantly adjusting to light levels thousands of times a second for your entire life and post processing in real time. It's the organic equivalent of HDR photography.

I may be wrong here, but I'm sure I read that the human eye can see a few stops below and a few stops above a modern camera sensor can record!

Camera sensors have still got a long way to go before they cover the dynamic range of our eyes.
 
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Very true. I need to try something else with true low light (I get the nasty suspicion that a small room probably isn't the best test of metering) and post the results, not something I'm probably going to manage just at the moment :S

IIRC the initial issue was in P, IS on & a fixed ISO of 800.
The attempted test was in full manual, and with both ISO400 & ISO800.
 
It shouldn't make much difference what the room size is - the camera meter should just deal with it.

Try using evaluative metering, and just take a couple of shots again to see if the problem still happens. If not, without the problem photos to look at again, don't worry about it :)
 
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You weren't trying to take a picture of a flat white wall were you? That would cause what you are seeing (as alluded to by Richard in post 6).

Please post some of your test images, it will help a lot.
 
leezer3 said:
Very true. I need to try something else with true low light (I get the nasty suspicion that a small room probably isn't the best test of metering) and post the results, not something I'm probably going to manage just at the moment :confused:

IIRC the initial issue was in P, IS on & a fixed ISO of 800.
The attempted test was in full manual, and with both ISO400 & ISO800.
Click to expand...
My 400d, was somewhat similar. The noise at 800 or 400 ISO was quite dreadful, and the images 'felt' dark if they were attempted in low-light (my current Canon 'feels' better, but without a scientific test I couldn't say). Mine didn't do auto-ISO (don't know whether that is a new feature from the firmware).Double-check the exposure compensation, I didn't ever use P, but in the modes I was in I found it 'easy' to accidentally knock the dial which drags down the exposure.
As another has said, it could be that the room is darker than you really expect, your eyes adjust quite quickly to dim situations. It can be quite difficult to judge. Only last week I thought there was some strange light going on and off in a remote room I could see, because my eyes were adjusting so much to the light cast only by a television.

I also found that the 28-135 IS became dissappointing when compared with other lenses. It was a good walkaround lens which did me for a long time, but it struggled at f/5.6 at zoomed in with any decent quality. Certainly the colour quality dropped unless in bright sunlight (or at least that was the perception from this lens).

The thing to do, is take a shot, if it doesn't look how you want, change something (i.e. dial in compensation) and shoot again.
 
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