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What have I done?

Bolex Super 16mm reflex

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#1 Arthur Sanchez

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Posted 07 February 2018 - 07:40 AM


I’ve created a hybrid… combining 8mm and 16mm parts.

IMG_4545.JPG

 

I recently discover the joys of the reflex viewer up stream from the lens iris. This allows the image to stay bright, not affected by the iris. So, I took converted super16 and machined out an 8mm film block. The lens’s frame mask was converted to super16 aspect ratio.

IMG_4540.JPG

It all seems to line up… anybody see any potential problems???


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#2 Dom Jaeger

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Posted 07 February 2018 - 07:54 AM

Hi Arthur!

What have you done exactly? What 8mm parts have you used? What do you mean by "machined out an 8mm film block"?
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#3 Arthur Sanchez

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Posted 07 February 2018 - 08:39 AM

Hello Dom...

 

that's an 8mm film block and turret... I machined out the inside so the shutter could rotate freely, and dang, it seems to line up... have shot some film tests and made some minor tweaks...

 

the flange on this lens is shallower than RX lenses... make sense?


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#4 Dom Jaeger

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Posted 07 February 2018 - 09:52 AM

Isn't it a 16mm C mount zoom? No different from a 16mm Rx lens in terms of flange depth required.
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#5 Arthur Sanchez

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Posted 07 February 2018 - 10:16 AM

that lens came off a "M" camera... when I put the lens on a REX camera... focusing thru the camera's reflex system... then looking into the Zoom's reflex system... the Zoom is slightly out of focus... very slight but noticeable. and vice-versa


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#6 Jean-Louis Seguin

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Posted 07 February 2018 - 11:27 AM

I don't understand what exactly you are doing nor what you are trying to accomplish with this modification.

If the lens is out of adjustment on a H16RX, it needs to be collimated, that's all.


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#7 Arthur Sanchez

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Posted 07 February 2018 - 12:51 PM

so you are saying a zoom lens works the same on a reflex REX as an M camera... each has a different distance to the film plane...

 

and you are saying that does not matter??


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#8 tom lombard

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Posted 07 February 2018 - 01:11 PM

reflex REX as an M camera... each has a different distance to the film plane...

 

 

 

 

Is that accurate?  A lens I put on my M won't focus the same on my Rex or EL?


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#9 Arthur Sanchez

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Posted 07 February 2018 - 01:26 PM

A prime lens will be fine... it's a zoom lens in question... this particular lens on a REX will focus BUT it will loose focus as you zoom.


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#10 Dom Jaeger

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Posted 07 February 2018 - 03:59 PM

A reflex Bolex has a longer physical flange depth because the prism in the light path bends the light rays which has the effect of extending the film plane further back, but it does this to any lens. The lens itself, whether Rx or not, is still collimated to focus at the C mount standard of 17.52mm behind the mount flange.

Non-reflex lenses on a reflex Bolex can exhibit some aberrations introduced by the prism, though usually only focal lengths under 50mm at apertures wider than about f/3, but otherwise any collimated C mount lens should work on any properly adjusted 16mm Bolex.

If a zoom is not holding focus on a particular camera either the lens needs its back-focus adjusted or the cameras flange depth is out of tolerance. An auto-collimator can be used to set both of those settings accurately.
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#11 Arthur Sanchez

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Posted 07 February 2018 - 05:28 PM

Dom...

 

I think we're saying the same thing...


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#12 Dom Jaeger

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Posted 07 February 2018 - 06:10 PM

Not if you think a zoom that works on an RX camera won't work on an M because their physical flange depths are different. Their optical flange depths are the same, which is what matters. 


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#13 Arthur Sanchez

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Posted 07 February 2018 - 07:15 PM

Dom...

 

don't understand why I want to make a lens not work...


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#14 Simon Wyss

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Posted 08 February 2018 - 01:48 AM

The main mistake is to abuse a turret camera with a zoom lens. You have a turret for a set of relatively compact and lightweight primes. I do of course understand the wish for reflex viewing which was a major innovation but there is no reflex finder system free of drawbacks. Paillard chose a half-hearted solution and made a mistake with it themselves. Nobody saw that the light path from the lens to the matted surface is longer than the light path from the lens to the film. Different from the symmetric prism block in the Technicolor three-strip camera Paillard-Bolex’s is asymmetric. This causes an increasing error with decreasing subject distance, that is on macro shots.

 

You might want to go in the opposite direction with a Paillard-Bolex H camera, forget about RX. The standard models, by the way the only other makes besides Bell & Howell, offer the old rackover system based on a critical focuser behind another turret port. The refreshing thing about it is that you have nothing between lens and film but air. You can use every C- or D-mount lens. It’s possible to screw on a wide-angle lens that protrudes into the turret until it just misses the shutter.

 

The pellicle reflex viewing system has the disadvantage of fragility. The thin glass membranes are most difficult to clean, in the case of the Pathé WEBO M camera even impossible to clean on the backside without disassembly of the front. The mirror shutter reflex system after Vinik, ARRI, and all others causes slightly uneven exposure across the frame due to its angled standing. It also obstructs wide-angle lenses.

 

You have the front assembly of an H-8 RX on a body with a SUPER16 name plate. That’s not a hybrid but a chimaera.


Edited by Simon Wyss, 08 February 2018 - 01:50 AM.

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#15 Arthur Sanchez

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Posted 09 February 2018 - 08:35 AM

Well Got the Film test back and it ALL worked as expected.., Zooms stay in focus and centered...

 

what I loved best about this is that there was NO machining required other than for the shutter. it all fits fine...

 

The only misfire was the lens .... it adds vignetting on the wide end of the lens,

 

SO ALL CAME OUT AS EXPECTED, except for the lens


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#16 Dom Jaeger

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Posted 09 February 2018 - 04:03 PM

I still don't understand why you needed to replace the front with one from an 8mm camera.

I've worked on plenty of both reflex and non-reflex H16s with a dog-leg zoom fitted, there's no need to change anything (except to remove the eyelevel Finder). If a zoom doesn't hold focus it just needs its back-focus tweaked, usually only by a few hundredths of a mm. If you needed to adjust the camera flange depth there are shim plates under the gate. Why all the palaver with machining and interchanging format parts?

I think all those dog-leg zooms will vignette at the wide end on a S16 camera.
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#17 Samuel Berger

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Posted 09 February 2018 - 04:09 PM

If anyone knows where I can buy a dog-legged C-mount zoom that doesn't cost a human arm and a leg, please let me know.  Everything on eBay is beyond my means right now and I'm in love with the Filmo 70-DR, just not its lack of reflex.


Edited by Samuel Berger, 09 February 2018 - 04:10 PM.

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#18 Jean-Louis Seguin

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Posted 09 February 2018 - 04:36 PM

Samuel, I have a few Berthiot 17-85mm zoom lenses w/dogleg. If you're interested PM me.
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#19 Arthur Sanchez

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Posted 10 February 2018 - 09:30 PM

Yeah I have one TOO!


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#20 tom lombard

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Posted 11 February 2018 - 04:15 PM

If anyone knows where I can buy a dog-legged C-mount zoom that doesn't cost a human arm and a leg, please let me know.  Everything on eBay is beyond my means right now and I'm in love with the Filmo 70-DR, just not its lack of reflex.

 

if you happen to snag either a Som Berthiot Pan Cinor 16 (17.5 to 70mm) or the 85 (17 to 85mm), i have the original Instructions For Use which includes the focusing table.  i'd be happy to send you either if it will do you some good.


Edited by tom lombard, 11 February 2018 - 04:19 PM.

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