Canon EOS 250D Advanced User's Manual page 468

I cannot lock the focus and recompose the shot.
Set the AF operation to One-Shot AF. Focus lock is not possible in the
z
AI Servo AF mode or when servo takes effect in AI Focus AF mode
(= 195).
Horizontal stripes appear, or the exposure or color tone look
strange.
Horizontal stripes (noise) or irregular exposures can be caused
z
by fluorescent lighting, LED lighting, or other light sources during
viewfinder or Live View shooting. Also, the exposure or color tone may
not come out right. A slow shutter speed may reduce the problem.
The standard exposure cannot be obtained or the exposure is
irregular.
During viewfinder shooting or Live View shooting, if you use a TS-E
z
lens (except the TS-E17mm f/4L or TS-E24mm f/3.5L II) and shift or tilt
the lens or use an extension tube, the standard exposure may not be
obtained or the exposure may be irregular.
The continuous shooting speed is slow.
The maximum continuous shooting speed may become slower
z
depending on the shutter speed, aperture, subject conditions,
brightness, lens, flash use, temperature, battery type, remaining battery
level, shooting function settings, etc. For details, see page 112.
The maximum burst during continuous shooting is lower.
Shooting a subject with fine detail, such as a field of grass, increases
z
the file size per image, which may lower the actual maximum burst.
ISO 100 cannot be set.
ISO 100 is not available when [z: Highlight tone priority] is set
z
to [Enable] or [Enhanced]. If [Disable] is set, ISO 100 can be set
(= 137). This also applies to movie shooting (= 222).
468