Very interesting - is it possible to use such a speedbooster with my sigma/nikkor lenses in combination with a nikon photodiox adapter?
You can use one with most Nikon F-Mount Lenses aswell as most Canon Mount Lenses (Some other Mounts also).
Problem is Flange Focal distance, because of that no normal adapter (which is ready for purchase right now) will work.
To help you understand the Situation with Chronos Cameras and Speedboosters here some numbers:
CS-Mount, Which is the Native mount on Chronos Cameras (also the Flange Mount with the Four Screw holes on the Front of The Camera Body) Has a Flange Focal distance of 12,526mm. That means, you need to be able to Render a sharp image at that exact point behind the Lens Mount Surface of the CS-Mount with your Lens.
Now you try to use an Nikon F-Mount Lens, for example an old 50mm f/1.2 one. That one has an Flange Distance of 46,5mm, and since that is much longer than the 12,526mm of the CS-Mount, you can just put some Spacer tube in between, which happens to have both of the needed mount on both ends (Thats basically the "dumb" Empty Tube Style adapter, just a spacer tube with mounts).
Most people use Chonos Cameras with C-Mount Lenses However, because they are just SO MUCH more Common, and you got tons of Lens-Options more. for that, you only need a 5,0mm Spacer, since C-Mount Flange Distance is 17,526mm.
BUT there are no speedboosters made for C-Mount or CS-Mount.So your best bet would be to get an MFT-Mount Speedbooster. MFT has a Flange distance of 19,25mm, and since that is still a longer Flange Distance than the one of the Chronos, you can adapt it. So, you still have about 6,7mm space to fit an adapter in there. Now because the MFT-Mount also has some Bajonet parts of the Mount itself which protrude behind the actuall Mount Surface, its pretty tight, but very possible, and i allready made it work. You basically need to build an adapter which is able to mount a MFT Lens safely and also screw on those four Screws on the Chronos body, while providing the Propper Flange distance Spacing for the Lenses to produce an Sharp image on the Sensor Surface.
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What you can also do (Since the MFT-Mount is mostly just a ring of Metal screwed onto the Speedbooster itself (Most Metabones ones), but not all offbrand ones are also built this way, so look what you got on yours), is to just replace the Actuall MFT-Mount Ring on the Speedbooster with an Spacer with Flat Surfaces and holes to take The Screws to mount on the Speedbooser Body assembly instead of the original mount and onto the Chronos Camera body. But for that Methode you need to be more Carefull and measure quite a bit to get your dimensions right.
The Big Advantage of the "interchangeable MFT-Mount For the Chronos" Methode is, that you can also use anything else with MFT-Mount (As Long as your lens is no Focus By Wire or needs any other kind of Electronic communication with the Camera Body).
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To learn more about the C-Mount / CS-Mount Topic and the Flange-Distance Stuff, some Wiki-Links:
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https://en.wikipedia.org/wiki/Flange_focal_distance https://en.wikipedia.org/wiki/C_mount
