Why can't I take pictures in the dark in the automatic mode with a Canon Rebel?

Question

I can't seem to take a picture with a Canon T3i Rebel in the dark. I want to take a picture at night with very little light around the subject, but the camera won't allow it in automatic mode. What can I do to make it work?

Answer 1

There are several reasons your camera might not take a photo in low light.

First, it may be too dark for the autofocus system to work. Most cameras have AF systems which work down to about EV -1, which is dim ambient light. (Your eyes will adjust and be able to see relatively well, but the camera won't work.) And, in turn, many cameras will refuse to take a picture without a focus lock. There are three solutions here:

1. Buy one of the relatively-few recent higher-end cameras with support for focus down to EV -3 (moonlight). This probably isn't a practical answer, as your current options are the Canon 6D at $2000 or the Pentax K-5ii at $1100. It may be that in the future this will trickle-down to entry level cameras like the Rebel, but I expect it'll be kept as a higher-level feature for a while.
2. Use a focus-assist lamp. This feature is found on most add-on flashes (and can usually be used independently of the flash firing). Some cameras have a light built-in for this purpose, and others can strobe the built-in flash, which is very annoying but functional. Or, you could use a flashlight or laser pointer as an ad hoc solution.
3. Put the camera in manual focus mode and do it yourself.

Second, it may be too dark for the longest shutter speed allowed by your camera's auto mode. Options here are:

1. If you haven't already increased the ISO, do that. (On some cameras, auto-ISO will not go as high as setting it manually will.)
2. Use manual mode to set a very long exposure, ideally with a tripod.
3. Use the EV compensation to tell the camera you want an underexposed, dark image.
4. Add light, with a flash, by flipping a light switch, or waiting until dawn.

Answer 2

You haven't mentioned which lens you are using, but the standard kit lens, a 18-55 zoom, is very slow (small maximum aperture). It doesn't let a lot of light into the sensor system.

Both the auto-focus system and the main sensor require light to work. They dont' work in the dark. Unlike your eyes. You may simply need more light.

When I am doing low light work on a tripod, I use a small LED flashlight to help the camera focus. Press the shutter half way, use the flashlight, turn off the flashlight and press the shutter the rest of the way.

Answer 3

If I am taking pictures of something like the moon, I use spot metering and it will generally take a picture, but for the moon specifically, it will come out over-exposed, so you have to use manual mode and set the shutter-time faster or aperture smaller (larger number). It really depends on the phase of the moon, but you could try around f/11 and 1/100 and go from there. (Take a picture, see how it looks and then readjust and take another.)

On the other hand, I think I have experienced the problem you are having. To try to take a picture of the stars where you are taking a time exposure of 20, 30 seconds or more (bulb), I have had to "trick" the camera. First, set it for a long time-delayed shutter and set focus to manual (focus it to infinity, or however far your subject is). Next, to get the camera to open the shutter, I aim it at a light on some building to get it to start, then as soon as the timer light starts to blink, turn it quickly towards your subject (in my case, upwards to get the star picture), make sure the tripod is locked and let go of the camera, so the vibration of the camera and tripod has settled down by the time the shutter opens. Using this time delay method with the manual focus is the only way I can get the Rebel to take a very low light long-exposure picture. I think it is something about the way it was programmed. (Whoever programmed them did not appear to conceive that someone would want to take pictures of very low light objects like stars.)

To others who have not had this problem due to a different camera, perhaps, I will mention that it happens whether you are in one of the manual modes or an auto mode. It seems to be a glitch that we just have to work around.