The Hasselblad SWC with the amazing Zeiss Biogon 38mm f/4.5 on 6x6cm is one of my all-time favorite cameras ... I've somewhere got a chart of all the focal length to format setups that net the same/similar FoV on square format. I think I remember that for 35mm and FF digital, cropped square, it's a 16mm lens needed. Ah, here it is:
6x6
Width = 56 mm, Length = 56 mm, Diagonal = 79.196 mm
f Hor Vert Diag H/V
38.0 72.7687 72.7687 92.3595 1.0000
35mm FF :: 24x24
Width = 24 mm, Length = 24 mm, Diagonal = 33.9411 mm
f Hor Vert Diag H/V
16.0 73.7398 73.7398 93.3723 1.0000
APS-C :: 16x16
Width = 16 mm, Length = 16 mm, Diagonal = 22.6274 mm
f Hor Vert Diag H/V
11.0 72.0547 72.0547 91.6109 1.0000
FourThirds :: 13x13
Width = 13 mm, Length = 13 mm, Diagonal = 18.3848 mm
f Hor Vert Diag H/V
9.0 71.6753 71.6753 91.2118 1.0000
I sold my last SWC to help fund buying the Hasselblad 907x ... and bought the XCD21mm lens with that camera so I could get the SWC FoV on its 33x33 square crop format. 🙂
G