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S16mm camera + 35mm lenses (Speed booster)?


Boris Kalaidjiev
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Hi everyone, 

Is there a way to use 35mm lenses on a S16 camera (with a PL mount) and have some sort of a speed booster that shrinks the S35 lenses to correctly cover the S16 camera (416, SR2/3, Aaton XTR). I know that if you add a convertor to a PL camera and you want to attach PL lenses you wont have the correct flange lens flange distance anymore, but is there a way around this?

 

If there is, wouldn't this open up a huge number of lenses to be correctly used for S16 and also you will probably gain 1 stop of light which would be very useful for film.

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I mean I don't see a market for this. The center of lenses is always the sharpest. So using 35mm style lenses on 16mm is totally fine. Just look at all the FF coverage lenses being used on 35mm imager cameras? It's a non-issue. 

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1 hour ago, Tyler Purcell said:

I mean I don't see a market for this. The center of lenses is always the sharpest. So using 35mm style lenses on 16mm is totally fine. Just look at all the FF coverage lenses being used on 35mm imager cameras? It's a non-issue. 

It’s not about center sharpness, it’s about crop factor, s16 is ~3x so a speed booster would open up wide range of new wide angle lenses to be used with an extra stop of light. Just because you don’t see the market doesn’t mean there isn’t one.

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I 100% see the market for this—would be the first customer for such a speed booster if it were to exist. Unfortunately it does not.

Just look at how desired the Cooke 10-30mm T1.6 is. I believe it’s the fastest cine zoom in the world, and it’s only possible via adapting the back element of a 20-60mm T3.1.

Using 35mm style lenses on super-16 isn’t the same thing. Most 35mm prime sets only go as wide as 18mm-ish, and often times those tend to be the least sharp of the bunch. Plus super-16 is way more demanding when it comes to lens resolution. Compare MTF charts for high quality full frame or S35 lenses versus m4/3 lenses. Even when restricting the image area to the center, the cheap m4/3 lenses are a lot sharper. At least how I understand it, a speed booster would help bridge this gap in resolving power.

Imagine such an adapter on something like a Zeiss LWZ 15.5-45mm T2.6. It’d be perhaps a 7.5-22.5mm T1.3. I’d buy that in two seconds.

I see it as much more of a value for zooms rather than primes. There are plenty of fast wide angle primes for super-16 out there. Optex, Elite, Century, Zeiss all have/had primes that are wider than 8mm at T1.8 or faster 

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I think for sure there would be a market, for all the reasons outlined above. Unfortunately it would require a completely new optical design to overcome the lack of flange depth space. The reason Speedboosters hit the market when they did was because of the space afforded by mirrorless camera flange depths. A focal reducer actually brings the image plane closer to the lens, so you end up having even less room for the reducing optics than the nominal difference in flange depths between lens mount and camera mount. 

There would be a market, but it would be fairly niche, limited to S16 PL cameras. So I suspect any manufacturer would baulk at the R&D costs to bring something like this to market, plus it would cost more than the current crop of speedboosters due to the extra optics required. 

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Make sure you have appropriate hard mattes for your mattebox for different focal lengths to cut down the excess light from hitting the gate area to prevent ghosting, flares etc.

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I think the challenges come with creating a one-size-fits-all/most solution that can clear a mirror, but also get close enough to the film plane, and also be deep enough to allow PL lenses with bulkier rear elements to mount close enough to the focal reducing optics. Speed boosters are one thing when you don’t have a mirror i.e. m4/3s/Sony E, but with Super16 film cameras? 
One could probably be formulated for an Eclair ACL, but that’s already a niche user group. 
 

I would love to be proven otherwise! 

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From vague memory, you would need at least 16mm of workspace between the film plane and the rear of a focal reducer aka speedbooster. You will not find that 16mm of workspace inside a rotating mirror-shutter reflex camera.

That workspace is for the Caldwell 0.71x Ultra optical cell which is not ideal for the Super16mm frame. You might just shoehorn it in with a custom assembly replacing the lens turret on a C-Mount Bolex H16RX5. There may be a C-Mount to M4/3 adaptor but the only versions I have found on eBay mount C-Mount lenses into a M4/3 camera, not the other way about so you have to get one made so that a Metabones PL to M4/3 Ultra 0.71x speedbooster could be mounted.

The Speedbooster for the original BMPCC would better suit the Super16mm frame optically but has to be even closer to the film plane (6mm) and would not fit in the available workspace of any Bolex as you will interfere with even the upright shutter disk path.

The RX5 Bolex has another wrinkle in that the prism path for the viewfinder changes the flange to focal plane distance compared to the Bolex non-reflex older H16 cameras. The in-air flange to focal plane distance may be shorter than when the prism splitter is in the optical path. 

A 0.71x focal reducer may be most easily fitted if a custom C-Mount tail with M4/3-Mount front adaptor could be made. Otherwise it would come down to a custom rear tail for the 0.71x speedbooster. This is doable but introduces other difficulties including some very fine internal 0.5mm thread cutting.



 

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I looked into this some years ago before I found some ultra 16s. I dont have the details handy, but the issue was basically that any semi-off the shelf solutions would not clear the mirror on a rotary mirror film camera. You'd have to go down a very expensive road to solve that issue. I bet there'd be a market for it if one could be made and sold for $500, but I dont believe thats remotely possible.

Honestly one is better off finding a set of Elite or Optar lenses (maybe with a panther 35mm t1.3) to have a better range of focal lengths than the zeiss super speeds. IIRC you can use Digiprimes on a super16 film camera with the optex B4 to PL adapter as well. 

Its also worth noting that zeiss now sells a very nice set of new c mount lenses that cover super 16 (they're advertised as M4/3rds) if what you're after is a modern solution to wider lenses. https://www.zeiss.com/consumer-products/us/industrial-lenses/dimension-lenses.html

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25 minutes ago, Robin Phillips said:

I bet there'd be a market for it if one could be made and sold for $500, but I dont believe thats remotely possible.

I believe there would be a market up to $3k, but I don’t know if it is possible to manufacture such an object. Really, I was thinking the achievable objective is permanently (or maybe semi-permanently) converting the back element of a S35 lens to S16. You could convert a modern cheap zoom like the cine Sigma 17-35 T2 to something that is impossible otherwise (9-18mm T1), for instance. As I said, there’s plenty of S16 primes available at all speeds, so I was thinking of converting primes. Elite has a 35mm T1.3 btw.

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3 hours ago, Raymond Zrike said:

As I said, there’s plenty of S16 primes available at all speeds, so I was thinking of converting primes.

Oops, I meant “I wasn’t thinking of converting primes.” I probably should stop texting and walking.

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FOOTENOTE: I did a rough and ready offer up of a 0.71x focal reducer to the Bolex RX5. Without some severe modification which would replace the front swinging turret, I doubt you have enough real estate for the 0.71x to work to infinity focus.

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