Christian Flemm

Hi all, I've seen in written that the RX Kerns are in fact 1/3 a stop faster than the aperture markings on the barrel. ("The RX lens is calibrated to pass 1/2 to 1/3 more light than the aperture markings on the barrel"). This, because the lenses were manufactured with a light loss of 1/3 a stop from the reflex prism in mind. In other words, due to the light loss, I'm effectively at f1.4 on the 25mm, despite the lens actually being 1/3 a stop faster than that. Ignoring the issues that come alongside using those lenses on any other camera, does it follow that the 25mm f1.4 would, on a non-reflex camera, come out to f1.2? Now, at f1.1, the 26mm is quite fast; so, imagining I adapted mine to the BMPCC4K as many others have (again, ignoring the focusing and sharpness issues that come along with doing so), and imagining that I'm shooting wide open, with no reflex prism diverting 1/3 a stop of light, am I not truly at f1.0 (or f.95, if it's passing 1/2 instead of 1/3 more light than the number on the barrel)? Anxious to hear what folks have to say about this... Christian

Hey Daniel! Sorry to have left you hanging. Indeed I've been looking at the 18.5mm lens quite a bit as of late, 'specially since I can't seem to adapt the one I bought 😄 Dom noted that, prior to my purchase, due to the retrofocus architecture, attempting to adapt the 18.5mm BNC mount lens using a BNC-R to MFT/EF might prove difficult (due to it having a "straight cylindrical rear protrusion rather than a tapered or bevelled one"). So I wrote to the buyer who provided measurements of the rear element that seemed to put me in the clear; however, upon receiving the lens I discovered that the rear element was too large to fit through the back of the adapter (which, to a certain point, is bevelled - this beveling being the chief obstacle). Given that you've adapted several of these lenses, I wonder if you might be able to offer up a BNC to MFT solution for the 18.5mm lens? I'd love nothing more than to adapt it, and I'm sure I'd have a hard time selling it with that mount. Geoffrey Berliner at the Penumbra Foundation suggested I find a Mitchell that's been torn apart and ask that the mount be drilled out so that I could machine my own adapter...sounds nice but highly unlikely! It should go without saying that the Zero Optik rehousing, while ideal, is absolutely out of my price range. Here's to hoping that something'll come of this... Best, C

Dom, you are a godsend! And thanks for the history lesson – I needed it! Angenieux introduced the 18.5mm in (I believe) 1951. I've read that the lens wouldn't cover the full frame sensor of (say) my 5D were I to adapt it, and that it'd be much like equipping an APS-C lens. Any idea if this is true? If the lens was manufactured for a Mitchell camera, for Academy ratio, how could it be the case that the vignetting would be as severe as with an APS-C lens on a full frame camera?

Hi everyone – long time reader, first time poster! I'm considering purchasing an Angenieux 18.5mm Type R2, and was previously under the assumption that the mount was Mitchell BNCR. The lens' owner, however, has just informed me it's not a BNCR mount but BNC. Apparently, these mounts are slightly different. As I don't know my way around a Mitchell (or anything Mitchell, for that matter), and as I've not got the budget to rehouse the lens, I'm wondering whether a BNC lens (in particular this Angenieux) would fit an EF to BNCR mount adapter. I've been unable to source an EF to BNC adapter, so if I'm out of luck with the BNCR adapter I'm wondering if there might be other solutions to the problem. Happy New Year, Christian