I was astounded to discover (apparently) that there is no "low key" thread on these forums! Yes, low key often ends up black and white but it *doesn't have to be*. More often than not, low key involves one (or more) OCF ("Off Camera Flash") light source but natural light works too and even on-camera flash can do the trick. What is "low key"? "Usually one main light, or ‘key’ light, falls on your subject and the background fades to black. It’s all about the highlights and shadows and how they define the shapes in your composition." (taken from
this intro article). Want to learn Manual mode? This will get you there!
Here are a few examples I've taken myself, mostly in a room FULL of mid day, sunny spring time, ambient light! It's a great way to keep ISO low (for best IQ), and still end up with something contrasty and dramatic.
Shot with K3 ii + 18-135 WR, handheld (ISO 100, 1/160th, f11 or so) and a single Yongnuo YN585EX on my only tripod, fired with a cheap FM trigger pair I bought off of amazon:
This was probably the most challenging of this set. My dining room table, awash in mid-day sunlight, and a lit, black, oil lamp.
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One of my "local super model" shot with natural light (no flash), in a brightly lit room. ("Spot" metering is your friend!)
K-70 + Sigma 30mm f1.4:
One of my work boots, bouncing a flash (on camera) off the closest wall. K3 ii + 18-135 WR (some heavy PP in Darktable):