WhiteWolf

Aren't those Large Format lenses? We're talking Medium Format here... 

all of which either lack usable iq at their widest aperture, and in some cases don;t even have an aperture, are completely unusable due to requiring huge outlay on bespoke remounting, are heavy, are coated and or glass selected for for b+w only, and have colour fringing issues so bad they need to be used in B+W only, or as pointed out, have ffd's too shot to permit focal reduction.  Not to mention most of those lenses lack basic function such as a focus mechanism since all are designed for infinity from high altitudes.

when we're talking medium format 'speed lenses' for focal reducer use that are adaptable, accessible and have basic featurs such as aperture and a focus mechanism on full frame cameras there are very few that will deliver the resolutions required to make the endeavour and expense worthwhile.

1. Hasselblad 110/2 - at f2 this thing matches a 135 format lens for resolution, but has a 80mm image circle.  compressing this down by 0.7x almost doubles the resolution onto a FF sensor, while still using the best area of the image circle.  this hassy could be compressed by 0.5x without running out of image circle for full frame.

2. Rollei 6000 Xenotar 80/2 - as above

 

3. a few ultra projection lenses for 70mm film.  which can be fitted to an off the shelf helicoid and are sharp wide open

 

There are no other medium format lenses that fulfil all of the basic criteria while delivering the base IQ required to make it worth going for a MF lens rather than a fast 135 format lens.

 

 

 

 

 

You can't use that last lens because it has a very short flange focal distance (as said on mflenses.com). There are a lot of fast short teles that could cover 645, but most of them have the same problem.

Surprised no one has mentioned the fastest (and cheapest) MF lens, the Mamiya 80mm f/1.9, known as the Nocilux for Medium Format. It's sharp with lovely characteristic Bokeh. I use the 110mm f/2.8 also, gorgeous glass.

 

I've shot some anamorphic footage also as a taking lens, the image is killer! 

Yes, the Hasselblads are optimal performers but I find the image less interesting on some versions but that's just me, I love that vintage look. And if we're talking bang-for-buck, nothing touches Mamiya - 200€ for the fastest MF ever made for mass production. Expect that price to go North if Kipon make a Mamiya mount, i'll be getting one for sure.

A7rII/sII with this Kipon speed booster and the 80mm f/1.9 Sekor C? *drool*