Summary
The sensor in some Phase One backs is smaller than the medium format film that lens angle of views calculations have traditionally been based on. Also known as lens conversion or magnification factor.
To calculate the digital angle of view simply multiply the medium format film focal length by the Lens factor resulting in the approximate digital angle of view. For example if shooting on a 645 camera with the H20 and a 105mm lens, the digital angle of view will be approximately (1.3 x 105mm)=147mm. If shooting with a zoom lens, 50-110mm, you would have a decrease in the wide digital angle of view but an increase in the telephoto end.
In-Depth
Full frame 645 camera backs
IQ280, IQ260, IQ180, IQ160, P65+ Lens factor 1.0
49mm camera backs
P45+, P45, P25+, P25 Lens factor: 1.1
44mm camera backs
IQ250, IQ140, P40+, P30+, P30, P21+, P21 Lens factor: 1.3
36mmx36mm square camea backs
P20+, P20, H20 Lens factor: 1.4
36mm camera backs
H10 11MP, H10 6MP, H101, H5, Lightphase Lens factor: 1.6
To calculate the "magnification factor" or the "digital angle of view" the following formula can be used. Divide the film diagonal by the sensor diagonal to create the lens factor.
| Film Sizes: | Diagonal |
| 645 = 56mm x 42mm | 70mm |
| 6x6 = 56mm x 56mm | 79.196mm |
| 6x7 = 56mm x 67mm | 87.3212mm |
| 6x8= 56mm x 76mm | 94.4034mm |
| 4" x 5" = 100.16mm x 127mm | 161.707mm |
| CCD sizes: | Diagonal |
| Fullframe=53.9mm x 40.4mm | 67.36mm |
| P45/+= 49.1mm x 36.8mm | 61.36mm |
| P25/+= 48.9mm x 36.7mm | 61.14mm |
| P30/+= 44.2mm x 33.1mm | 55.22mm |
| P40+=43.9mm x 32.9mm | 54.86 |
| P21/+= 44.2mm x 33.1mm | -55.22mm |
| P20/+= 36.9mm x 36.9mm | 52.1845mm |