Is there such a thing as medium format fast glass, ie f1.4 primes?
If not, why?
Good question.
I assume it's due to size, weight and cost considerations.
Here is a summary of MF lenses
at f2.8 or faster. I'm making this up as I go along so don't rely on it 100%.
The Contax 645: 80mm f2, 45mm f2.8, 140mm f2.8
Bronica ETR (645) has a 50mm f2.8, 60mm f2.8, 75mm f2.8.
Bronica SQ series (6x6): 80mm f2.8
Hasselblad V: f/2.8 80 mm 'C' lens. The rest of the C series is slower. The F lenses were faster: f/2 110 mm, f/2.8 50 mm, f/2.8 80 mm and f/2.8 150 mm
Hasselblad H: HC f/2.8 80 mm and HC f/2.2 100 mm
Rollei PQ/S: 50mm f2.8, 80mm f2, 80mm f2.8, 110 f2, 180mm f2.8
Mamiya 645: 80mm f1.9, 80mm f2.8, 45mm f/2.8, 55mm f/2.8, 150mm f2.8, 200mm f2.8, 300mm f2.8
Mamiya 67: 110mm f2.8
Pentax 67: 75 mm f2.8, 90mm f2.8, 105 mm f2.4, 165mm f2.8
Pentax 645: 45mm f2.8, 75mm f2.8, 150mm f2.8
Result: the fastest lenses are: Mamiya 645 80mm f1.9, Contax 80mm f2, Hass V 110mm f2 (F), Rollei 110 f2, Rollei 80mm f2
Did I miss any?