Canon EOS 80D - Manual (Page 296)

k Shooting Movies
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ISO Speed in Basic Zone Modes
 The ISO speed will be set automatically within ISO 100 - ISO 12800.
ISO Speed in the d, s, f, and F Modes
 The ISO speed will be set automatically within ISO 100 - ISO 12800.
 In [Range for movies] under [z2: ISO speed settings], if you set
[Maximum] to [H(25600)], the automatic setting range will be
expanded to H (equivalent to ISO 25600). Even if you set
[Minimum] to ISO 200 or higher and [Maximum] to ISO 3200 or
lower, the range will be set within ISO 100 - ISO 6400 automatically
(p.332).
 If [z3: Highlight tone priority] is set to [Enable] (p.174), the ISO
speed will be ISO 200 - ISO 12800.
 Under [z2: ISO speed settings], [Auto range] and [Min. shutter
spd.] cannot be set (p.152-153) for movie shooting.
 Since shooting a movie at ISO 16000 may result in much noise, it is
designated as an expanded ISO speed (displayed as “H”).
 When switching from still photo shooting to movie shooting, check the
ISO speed settings before shooting movies.