Canon EOS 1300D - Manual (Page 290)

Troubleshooting Guide
290
 Under [53: Custom Functions (C.Fn)], if [6: Highlight tone priority]
is set to [1: Enable], ISO 100 cannot be set. If [0: Disable] is set, ISO
100 can be set (p.263). This also applies to movie shooting (p.177).
 Under [53: Custom Functions (C.Fn)], if [6: Highlight tone priority]
is set to [1: Enable], the [H] ISO speed (equivalent to ISO 12800)
cannot be selected even when [2: ISO expansion] is set to [1: On]. If
[0: Disable] is set for [6: Highlight tone priority], [H] can be set
(p.263).
 Under [53: Custom Functions (C.Fn)], if [6: Highlight tone priority]
is set to [1: Enable], the Auto Lighting Optimizer cannot be set. If [0:
Disable] is set, the Auto Lighting Optimizer can be set (p.263).
 Set [z2: Auto Lighting Optimizer] to [Disable]. When [Low],
[Standard], or [High] is set, even if you set a decreased exposure
compensation or flash exposure compensation, the image may come
out bright (p.123).
ISO 100 cannot be set.
ISO speed [H] (equivalent to ISO 12800) cannot be set.
The Auto Lighting Optimizer cannot be set.
Even though I set a decreased exposure compensation,
the image comes out bright.