Canon EOS 250D Advanced User's Manual page 166

Do not point the camera toward an intense light source, such as the sun or an
z
intense artificial light source. Doing so may damage the image sensor or the
camera's internal components.
In very bright light, such as at the beach or a ski slope on a sunny day, take
z
the picture promptly after mirror lockup is stabilized.
When shooting with mirror lockup, if you use both the self-timer and bulb
z
exposures, keep pressing the shutter button completely (for self-timer delay
time + bulb exposure time). If you let go of the shutter button during the self-
timer countdown, there will be a shutter-release sound, but no picture will be
taken.
During mirror lockup, shooting function settings, menu operations, etc. are
z
disabled.
Even if you set the drive mode to <i>, <M>, or <q>, the camera will still
z
shoot in single shooting mode.
When [z: High ISO speed NR] is set to [Multi Shot Noise Reduction],
z
four consecutive shots will be taken for a single picture regardless of the
[Mirror lockup] setting.
If approx. 30 sec. elapse after the mirror has locked up, it will go back down
z
automatically. Pressing the shutter button completely locks up the mirror
again.
When shooting with mirror lockup, using a tripod and Wireless Remote
z
Control BR-E1 (sold separately, = 463) or Remote Switch RS-60E3 (sold
separately, = 463) is recommended.
166