Nikon D850 User Manual page 113

Image quality is set by pressing the T button and rotating
the main command dial until the desired setting is displayed in
the control panel.
T button
A
JPEG Compression
Image quality options with a star ("★") use compression intended to
ensure maximum quality; the size of the files varies with the scene.
Options without a star use a type of compression designed to produce
smaller files; files tend to be roughly the same size regardless of the
scene recorded.
A
NEF+JPEG
When photographs taken at settings of NEF (RAW) + JPEG are viewed
on the camera with only one memory card inserted, only the JPEG
image will be displayed. If both copies are recorded to the same
memory card, both copies will be erased when the photo is deleted. If
the JPEG copy is recorded to a separate memory card using the
Secondary slot function > RAW primary - JPEG secondary option,
each copy must be deleted separately.
A
The Image Quality Menu
Image quality can also be adjusted using the Image quality option in
the photo shooting menu (0 251).
Main command
dial
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