Seedling
Depth of Field
#camera#lens#depth-of-field#bokeh
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The range of distance that appears sharp. Narrow = "shallow DoF" (background blurred); wide = "deep DoF" (everything from foreground to background sharp).
Aperture isn't the only one.
| Variable | Direction that shallows DoF |
|---|---|
| Aperture | Open (smaller F-number) |
| Focal length | Long (telephoto) |
| Subject distance | Close |
| Sensor size | Big (full-frame and up) |
The opposite is true. Going telephoto shallows DoF.
This is why portrait lenses (85mm, 135mm, 200mm) separate the subject so strongly from the background. Compare a 24-70 at 70mm and a 70-200 at 200mm at the same f/2.8 — the difference is obvious.
Even at the same angle of view and same F-number, full-frame yields shallower DoF than smaller sensors. Two ways to see why:
Rough conversion:
APS-C f/1.4 ≈ full-frame f/2.0 in background blur
If you've shot only full-frame, this is what you've been benefiting from.
Three of the four variables are favorable at once:
Add a full-frame sensor and it's 4 for 4. That's why short tele primes are the portrait standard.
Shallow DoF gives you the amount of blur. Bokeh quality is separate.
The 70-200 GM2 produces lovely bokeh at the long end not just because of shallow DoF but because the optics are designed for it.