“Of course depth of field is razor-thin when you shoot it wide open…”
So goes a well-worn “elucidation” (in one form or another) used by clickbait carpers. “Of course” likely means that they haven’t really shot the lens wide open, but are making the claim based on assumption rather than specs and experience.
Trouble is, the line most often seems to be applied to lenses with shorter focal lengths and longer minimum focus distances. Sure, if you take a longer lens—280mm f/4 APO-Telyt-R, for example—even with a fairly short minimum focus distance, you’ll have only about two tenths of an inch of depth. That’s fairly thin in my book.
But take a lens like the Summilux-SL 50mm, which has an MFD of just under two feet, open it up to f/1.4, and you’ve got almost half an inch of depth at its shallowest. Step back to head-and-shoulders portrait distance, and you’ll have enough depth to capture facial features and hairline, at the very least, in focus.
That’s hardly what I’d call “razor-thin.” But then, maybe that’s just my perception!
Now, back to worrying about how to hold all those megapixels steady . . . !