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Issue with Red Pro Primes PL Mount

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Peter Borosh

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I've been an owner of Red camera and accessories for some time now and it isn't my first rodeo either.

Previously, I'd owned a Arriflex SR1 and I still have in my possession a Arriflex 2C with a PL hard front modification.

Here is my issue with the Red Pro Primes.... they do not mount on any other Non-Red camera bodies..... Digital or Film.

The problem is that the ears on the lens are too thick. (The ears are the 4 lugs on the lens that engage with the PL mount on the camera body.) Common PL lenses ears are 2mm thick while my RPPs' are 2.3mm thick.

I've purchased the RPPs in the hope to use with my other gear (except the 18mm) but not only it doesn't work without a modification of the camera's own PL mount.

I feel a bit disappointed that these lenses cannot be used on other camera bodies as the PL lugs are of a non-standard dimension.

I am wondering if I'm the only owner of RPPs that have this issue?
 
It might be an instance of RED doing something just that little bit differently. 0.3mm I think will translate to almost a quarter-turn of the lock-ring. One might be inclined to remachine the mount on the rear of the RED lens to comply with standard. That might have some serious implications as to whether a lens fitted to another PL-Mount camera is going to fall off if the lock-ring turns too far through and the lugs are insufficiently engaged. Usually there is an end-stop on the movement of the lock-ring to prevent passing over. If a lens remains sloppy in the mount when the end-stop is reached, temptation to defeat the end-stop device may be too much. In that event, the lock-ring may pass through to the next clearance and release the lens. If this thickness is corrected for your other cameras, then the genuine RED PL-Mount ring may reach and end-stop and leave the lens sloppy in the mount or pass over and let the lens go. If the mounts are assembled to the lens bodies by attach screws from the rear, it would be relatively simple to have them taken off and the front faces NOT the flange faces, skimmed back that 0.3mm to correct thickness. If they are integrated with lens body structure then it is a different story. The likes of Matthew Duclos might be your best mentors. As a side-bet, is there a fillet radius in the rear of the mount where the flange meets the shoulder on the RED lens? The corresponding corner edge on the receiving PL-Mount you are having issues with, may have insuffient chamfer to allow the RED lens to seat fully home on the flange face. In that instance, dressing the corner to a chamfer may be enough to allow the RED lens to mount without harming the mount for other lenses. Again. a camera technician or the likes of Matthew Duclos might be your best advisors.
 
Hi Robert,

Thanks for the reply.

I've spoke to a lens technician at Ablecine LA and he suggested a similar solution to yours. The issue is that a template has to be made to: hold the mount to skim back those 0.3mm and make sure that the machining is done as flat as possible. This doesn't sound a cost effective approach to my problem.

I might have to see if others have the same issue or my set of lenses have a unique problem. I consider these lenses as a good value purchase but when I up-grade my camera, I maybe stuck to the RED camera bodies as my only choice.
 
With your other cameras, a quick and dirty trick might be to investigate what method is used to end-stop the rotation of the PL-Mount clamp ring. With the P+S Technik IMS/PL-Mount, their method was a simple countersunk-head screw in the clamp ring, threaded into the ring on a radial centre.

The screw goes right through the ring and has a tail which engages and travels in a slot in the mount itself. The slot in the earlier mount was just over 1/8th of a turn from memory.

On a later mount, I discovered the slot had been extended so that the ring could screw further before reaching end-of-travel. I don't know what the arrangement is on your receiving PL-Mounts. It may be something else entirely. However, if it is possible to defeat this limitation of movement temporarily for test purposes, you might find that by being able to unscrew the clamp ring about another 1/4 turn further anti-clockwise, you might find the RED lens will clamp.

The lugs may not be in correct registration with their matching lugs but may overlap enough to be safe. You might also discover that the lens becomes tight to remove if the fillet radius on the inner shoulder binds on the front inner corner of the receiving mount in the camera.

I am curious as to why the RED lenses have departed from what has become more or less an industry standard by 0.3mm. I wonder if the lens manufacturer has hard-chromed the piece which is screwed onto the rear of the lens. This might account for the 0.3mm difference.
 
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We used a set of RPP's on an Arri 435 just two weeks ago with zero issues. Both were rentals. Most PL mounts,especially on Arri's are manufactured to be calibrated with various shims and this may be the problem you're having with your 2c.
 
Peter,

I had a similar but unrelated issue with my RPP and bought replacement PL lens mounts from www.optitek.org. Just be careful with the 18mm on reflex cameras, I'm not sure if it will fit or crash into the mirror. I had optitek rework the rear element housing on my 18mm, the cost was reasonable, but it did take a few months.
 
FAQs- New RED Pro Prime set.

1. RPPs are "RED-centric", which means that the light path is optimized for maximum resolution and consistent illumination, with minimum breathing for the Mysterium sensor family. Patent Pending.
2. T-stop range is 1.8-22.
3. Image diagonal- > 32mm.
4. Extra low dispersion (ELD), Super Low Dispersion (SLD) and anomalous dispersion glass for maximum chromatic aberration correction.
5. Center resolution is greater than 100 (lines pairs/mm). Edge (5K) is greater than 63 (lines pairs/mm). (You will see Wed. how much greater)
6. Close focus from lens front (from sensor) is:
25mm- 4" (12")
35mm- 4" (12")
50mm- 6" (12")
85mm- 18" (24")
100mm- 24" (30")
7. High relative illumination from center to edge of field (5K).
8. Uniform Spectral correction to accommodate any light source.
9. Internal Focus and Unit Focus designs.
10. Consistent 110mm front diameter.
11. RPPs will work with film cameras.

Full Specification Matrix to be posted on Wed.

Jim

.....from 04-18-2009

I've still yet to hear a satisfactory response why my RPPs aren't within spec to be used on Non - Red camera bodies.
As you see, I've included the description that Jim Jannard gave the RPPs..... It was point 11 that tied the deal for me to go with RPPs.
Optically, they do the job. Mechanically I have found, they only work with Red cameras. Some say that have used the RPPs on an Arri 435 but if I rent an camera body, I don't expect the rental house would want to modify their camera to fit my lenses.
 
Peter,

Have you actually taken precise measurements to see if your set of RPP's are truly out of spec? I've mounted RPP's on Arri 235 and 435, Alexa, F65 and a couple others. The F35 gave us some trouble with the RPP's, but it was an issue with the PL mount on that camera.

The RPP flange ears are notoriously thick, but they are still within spec for the PL system. There are other lenses on the market which also have thick flange components or even "large" diameter flanges and fit tighter than RPP's. Schneider Xenon FF's are a crazy tight fit on the EPIC and almost feel like they need a little grease to get them on and off an Alexa. I have not encountered any RPP sets that are out of spec and construction of the lenses seems to be very uniform in my encounters, including the set I own, which was one of the first official production sets shipped from RED.

So I guess the first place to start is to take some calipers and measure the flange thickness on your RPP's. I'm betting you they're within spec, which is available to download from ARRI. In the unlikely event that they're out of spec, then I would contact RED and have it corrected. Otherwise, it's time to look at the cameras and determine why their mounts are not within spec to cooperate. If you can't mount RPP's, then you also won't be able to mount Xenons, Summilux C's, S5/i's, or Cine-Xenar III's... not in my experience.
 
I can confirm that RPPs mount to an Arri 235. Haven't shot much film after that though.
 
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