KIPONs “Baveyes M645-LPL 0.7x” focal reducer is designed to use medium format Mamiya 645 Sekor C glass on full frame cinema cameras. The LPL mount allows it to natively be used on Arri Alexa LF/Mini LF and Alexa 35, as well as Sony Venice/Venice 2 and RED DSMC2/3 with third party LPL lens mounts.
According to KIPONs website, “the 0.7x optic adapter gets rid of crop factor, and increases the aperture.”
In theory this would be a wonderful design to get the most out of the medium format glass on a full frame sensor. The Mamiya 80mm would be close to a 55mm and the Mamiya 35mm would be close to a 24mm, while at the same time increasing the lens speed.
Oddly, every time I’d see a lens test, the speedboosted shots never looked right. The Mamiya with focal reducer always seemed significantly tighter.
Here are some examples from other lens tests that I’ve found on the internet. The images below are from Framed’s ‘Agony of Choice’, as well as a ‘Mamiya 645 + Kippon 0.7x Speedbooster VS Zeiss OTUS Cinemod’ by Blake Kotrla:
Recently I had the chance to test the focal reducer together with my Mamiya Sekor C lenses. The camera used for the test is a Sony Venice 2 in Open Gate (3:2) 8.6K. As a reference I am using the Kipon PL to LPL adapter with GL Optics Canon FDs.
TEST 1 - Mamiya 35mm vs Canon FD 24mm
In this first test I am comparing the Canon FD 24mm 1.5 with the Mamiya Sekor C 35mm 3.5 and KIPON Baveyes focal reducer. As you can see, the combo does not at all match. The 35mm Mamiya is significantly tighter.
In a second comparison, I am comparing the same lens with a 28mm FD and this is a much better match.
TEST 2 - Mamiya 80mm vs Canon FD 55mm
For the second test I am comparing Canon FD 55mm 1.3 and Mamiya Sekor C 80mm 1.9. Again, the 80mm with KIPON 0.7x focal reducer is not even a close match.
CONCLUSION:
The Kipon Baveyes focal reducer does not seem to deliver on the advertised 0.7x crop factor. Instead it seems like its close to a 0.8x crop factor.
In my first test the 35mm nearly identically matched the 28mm FD. If we calculate the crop factor with 0.8x we get the following: 35mm x 0.8 = 28mm
In the second test the 80mm Mamiya would have matched a 64mm, as I don’t have a 65mm reference lens, I added another lens to the test. The 70mm Mamiya with the Kipon focal reducer and our new crop factor should look like the following: 70mm x 0.8 = 56mm
Indeed the 70mm is a near identical match with the 55mm FD.
I’ve asked KIPON for a response to my findings but they have yet to respond.
Let me know what you think about this and happy shooting!