|
Depth of field for various formats and lenses
May 30, 2012
|
It is common to discuss DOF for various formats and lenses. There are two statements commonly made:
1) Small format means more DOF
2) Longer lens means shallower DOF
I wanted to verify this by doing actual DOF calculations. I used http://www.dofmaster.com/dofjs.html to do these calculations.
Methodology:
I set the standard to compare with as using a full frame camera with an 85mm f/1.4 lens, standing 2.5 metres from the subject - an acceptable distance for head and shoulder portrait I guess. Then, for a given format and lens spec, I calculated the 35mm equivalent focal length and adjusted the subject distance. For e.g., if I am using a 50mm f/1.4 lens on Nikon D7000, the subject distance would be 75/85 * 2.5m = 2.2m.
The overall assumption is that the framing of the subject is the single most important factor and has to remain constant.
Following are the results for some common format/portrait lens combos.
(focal length, aperture setting, subject distance - DOF in metres).
Full frame:
85mm, f/1.2, 2.5m - 0.06m
85mm, f/1.4, 2.5m - 0.07m
50mm, f/1.4, 1.47m - 0.07m
50mm, f/1.0, 1.47m - 0.05m
100mm, f/2, 2.94m - 0.1m
APS-C (Nikon size):
50mm f/1.4, 2.2m - 0.11m
60mm f/2.2, 2.65m - 0.17m
85mm f/1.4, 3.75m - 0.11m
100m f/2, 4.4m - 0.15m
MFT:
45mm, f/1.8, 2.65m - 0.18m
75mm, f/1.8, 4.4m - 0.18m
25mm, f/1.4, 1.47m - 0.14m
(I chose 60mm f/2.2 with APS-C because that is the combo I have right now using the Tamron 60mm f/2 SP Macro lens with Nikon D40)
What I found:
1) Small format means more DOF - TRUE. Mainly because for the same lens focal length, subject distance increases, increasing the DOF.
2) Longer lens means shallower DOF - FALSE. As the focal length increases, so does the subject distance and the eventual DOF remains constant.
I hope I've not made a mistake above. What do you think?
| Post (hide subjects) | Posted by | When | |
|---|---|---|---|
| May 30, 2012 | |||
| May 30, 2012 | |||
| May 30, 2012 | |||
| May 30, 2012 | |||
| May 30, 2012 | |||
| May 30, 2012 | |||
| May 30, 2012 | |||
| May 30, 2012 | |||
| May 30, 2012 | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| May 31, 2012 | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| 11 months ago | |||
| 11 months ago | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| 11 months ago | |||
| May 31, 2012 | |||
| May 31, 2012 | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago | |||
| 11 months ago |