Steve
When the BIOGON lens was designed , no one knew what a digital back would be . The BIOGON is a very good , if not the best wide angle lens and ideal for film . Therefore , the SWC is a fantastic WA camera for MF photography .
That is valid for film .
If you use the SWC + CFV-16 , you will receive a slight color cast , which in many cases is easily corrected in PHOCUS , when you readjust the color temperature , but perfectly , when you use the scene calibration tool .
Using the calibration tool of course makes only sense , if you have the corresponding WB shot . I use an EXPO DISC 95mm for the WB shot .
The restriction here is , that it is very difficult and inconvenient (in most cases impossible) to shoot handheld .
Working with the SWC + CFV-39 , you will definitely get a magenta cast on the right side and a cyan cast on the left . This is normal when shooting with a BIOGON type wide angle lens and a sensor size of 37x49 mm .
This cast is (almost) not seen when you work with the crop to square
function .
I my testing I could not fully remove this cast using a WB shot and the
scene calibration tool in PHOCUS .
I must admit , that my testing was under extreme circumstances (a snow landscape , where there is about 90% white) , but here you can see the slightest color cast .
If you have an image with many different colors , you might not always see the casts.
My conclusion : I will use the 905SWC with the CFV-16 or with the centered square part of the CFV-39 only but not with the full size of the CFV-39 sensor .
A very good lens for digital WA shooting with the CFV-39 is the
CZ DISTAGON CFE 4/40 T* IF .
Here you have a V-SYSTEM lens correction parameter in PHOCUS .
Jürgen