Hi,
Depth of field for any lens will be the same, for the most part, regardless of the size of the imager. A 28mm Ultra Prime on a super35 camera will have the same depth of field as a 28mm digiprime on a 2/3" 3-chip camera.
The difference between the 2 will be the resulting field of view. On a Super35 camera, the 28mm lens will have a more or less wide field of view. On the 2/3" camera it will be quite telephoto (similar to 65mm lens on S35). Both lenses are compressing/expanding the image in nearly the same way, but the digiprime is projecting a smaller slice of that onto a smaller sensor, effectively cropping the field of view by a factor of about 2.2.
The 28mm digiprime will give you the field of view of a 65mm lens, with the depth of field of a 28mm lens.
Here are how they stack up. Digiprimes on left, equivalent field of view S35 lens on the right. Nearest equivalent in Zeiss Ultra Prime is in parenthesis.
3.9mm = 9mm (close to UP 10mm)
5mm = 11mm (UP 12mm)
7mm = 16mm (UP 16mm)
10mm = 23mm (UP 24mm)
14mm = 31mm (UP 32mm)
20mm = 45mm (UP 50mm)
28mm = 64mm (UP 70mm)
40mm = 90mm (UP 100mm)
70mm = 159mm (UP 180mm)
6-24 zoom = 14-48mm zoom
17-112 zoom = 39-254mm zoom
You can use depth of field charts for identical focal length lenses to determine DOF, and use this info above to determine which equivalent DOF chart to use.
Many phone apps like pCam, etc have all of this information at the ready.
Please let me know if you have more digiprime questions, or if I didn't quite get to the answer you were looking for.
Thanks,
Randy Wedick
Technical Consultant
Band Pro Film & Digital
