Canon EOS REBEL T6S Instruction Manual page 166

a: Manual Exposure
Under [z2: Auto Lighting Optimizer], if the checkmark <X> for

[Disable during man expo] is removed, the Auto Lighting Optimizer can
be set even in the <a> mode (p.146).
When ISO Auto is set, you can press the <A> button to lock the ISO speed.

If you press the <A> button and recompose the shot, you can see the

exposure level difference on the exposure level indicator compared to
when the <A> button was pressed.
I Using the Built-in Flash
To obtain a correct flash exposure, the flash output will be set
automatically (autoflash exposure) to match the manually-set aperture.
The shutter speed can be set from 1/200 sec. to 30 sec or bulb.
BULB: Bulb Exposures
Elapsed exposure time
Do not point the camera toward an intense light source, such as the sun

or an intense artificial light source. Doing so may damage the image
sensor or the camera's internal components.
Since bulb exposures produce more noise than usual, the image may

look slightly grainy.
You can reduce the noise due to long exposures by setting [z3: Long

exp. noise reduction] to [Auto] or [Enable] (p.148).
For bulb exposures, using a tripod and a remote switch (sold separately,

p.367) is recommended.
You can also use a remote controller (sold separately, p.366) for bulb

shooting. When you press the remote controller's transmit button, the
bulb exposure will start immediately or 2 sec. later. Press the button
again to stop the bulb exposure.
166
A bulb exposure keeps the shutter open for
as long as you hold down the shutter button.
It can be used to shoot fireworks and other
subjects requiring long exposures.
In step 3 on the preceding page, turn the
<6> dial to the left to set <BULB>.
The elapsed exposure time will be
displayed on the LCD panel.