Thread: UM PRO Speedbooster INTEREST GROUP

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  1. #41  
    For interest, here are some grabs from a quick test I did this afternoon with the speedbooster optical cell in place and removed with a Sigma-for-Nikon 20mm f1.8 lens. I did not alter exposure. The framing was slightly different between shots but the distance of the camera from subjects remained the same. In one frame, the chair is moved. That is because when I sat on it to remove the speedbooster, I moved it and forget to shift it back again. I left the iris setting untouched. There is a light gain with the speedbooster but it is very subtle. There is a noticeable shallowing of depth-of-field in the interior shot which I cannot account for except that my rough mounting of the speedbooster optical cell is most likely not square-on to the optical axis.URSA PLUS SPEEDBOOSTER TEST1.jpgURSA PLUS SPEEDBOOSTER TEST2.jpgURSA PLUS SPEEDBOOSTER TEST3.jpgURSA PLUS SPEEDBOOSTER TEST4.jpg
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  2. #42  
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    Awesome. Send this to metabones and blackmagic. So they create a production version of this.
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  3. #43  
    Metabones has not replied to any queries I have sent. It might be a lean operation with no time available for much else other than maintaining its own R and D and the storefront.

    In regard to BM, it may be pretty much the same thing, lean and to the point with not much resource to waste on distractions. A focal reducer which works might also generate customer resistance to moving on from 4K cameras up to the 4.6K products so there is probably not much incentive for BM to do a Speedbooster.

    It will be up to enough owner-users letting both outfits know there is a market worthwhile serving and making a committment to buy. It would not be worthwhile anybody tooling up to make and sell just a hundred or so examples.
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  4. #44  
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    Amazing work guys, especially Robert.

    Need same stuff for URSA Mini Pro...Paul Ross ?
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  5. #45  
    Quote Originally Posted by Rayzen View Post
    Amazing work guys, especially Robert.

    Need same stuff for URSA Mini Pro...Paul Ross ?

    I have given up on Blackmagic. Sold my ursa mini 4.6 and am looking for my next system. If someone could make a speed booster for the Ursamini pro then I would buy that (as I still have all my accessories like the evf ).
    I am considering the c200 and the fs5/ atoms raw setups. Or even a used alexa classic (they are cheap at the moment!) so I won't be trying to make a speed booster.

    Paul
    Paul Ross Jones


    -------------------------
    www.paulrossjones.com
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  6. #46  
    Rayzen.


    QUOTE: Need same stuff for URSA Mini Pro.

    Unfortunately, the URSA Mini Pro has hardware in the throat of the camera in the form of the inbuilt IRND filter system. There remains insufficient workspace to accommodate a speedbooster "Ultra" 0.71 optical cell. The URSA Mini Pro has the larger 4.6K sensor area which is larger than the image circle of the Speedbooster optic. Therefore there most likely will be corner vignetting and corner distortions.

    The speedbooster is only a solution for the smaller BM4K sensors of similar size to the sensors for which it is designed.

    The big URSA 4K, the URSA Mini 4k and the original 4K cinema camera would each require an individual design for one of the two metal components required. That is the front piece which carries the lens mount.

    Whilst there appears to be workspace in the camera throat to accommodate the speedbooster optical cell, there may not be a solution for the original B4K camera. The EF-Mount and PL-Mount bodies do not appear to have any intermediate adaptor to steal workspace from. The mounts appear to fit directly to the front of the camera body.

    Workspace for the 4.2mm rearwards repositioning of the lens mounts has to come from somewhere and that might only be available by machining part of the front body extension rearwards. The only lens system which might be accommodated on the original BM4K might be older Nikon AI/AIS manual lenses with a modified Pro-Lock PL style clamp ring arrangement at additional cost.

    Whilst the internal carrier for the optical cell would be a direct replacement of the anti-reflection cone, there would need to be three unique parts created for the big URSA 4K, the URSA Mini 4K and the original BM4K. I doubt that there would occur sufficient marketplace economies of scale to make the cost of each variation realistic.

    Metabones offers 26 variations on the Speedboosters built around the "Ultra" 0.71 optical cell, so it is not an impossible proposition to consider. The populations of already sold BM cameras which would three variations of a speedbooster, are a lot smaller than the other camera types. Depending on the complexity and if the Speedbooster body itself can be common across enough lens/camera combinations, prices vary from US$449 to US$719 for the more complex PL-Mount to Sony E-Mount version for Zeiss CP Cine lenses.

    There is a risk of being stuck with unsold product from the sort of production run which would create economy of scale and keep price down. Unless there was a group buy deal with deposit commitments made RED-style to offset the loss risk, I doubt neither BM or Metabones will bother to get out of the morning bed for this one but who knows?

    The whole Speedbooster product range is a niche market which could evaporate with the onset of some new tech as the old 35mm groundglass based adaptor market did when RED came upon the scene and tipped it on its head.

    There might be a saviour in the wings in the form of Wooden Camera, an outfit which made accessories for the RED cams and also modified the BM cinema cameras to carry the RED DSMC1 PL-Mount. Having come out of a legal stoush with RED, Wooden camera may not too keen to run the same gauntlet with BM's registered designs.
    Last edited by Robert Hart; 07-17-2017 at 01:03 AM. Reason: errors
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  7. #47  
    I am in the process of making a special insert for the BM URSA 4KV1 PL camera to accommodate a 0.71 "Ultra" optical cell from a Metabones Speedbooster.

    Does anyone by chance know what the pitch of the threaded section of the optical cell is. It is very fine and likely to be a nightmare for a backyard engineer like me to reproduce. I could machine a piece of Delrin and use its inherent compliance to screw the optical cell into without having to cut an actual thread. I would prefer to do the job properly.

    Metabones simply does not reply to messages so there is not much point to trying for info from them forever.

    I would like also to get hold of a spare anti-reflection cone for the URSA. I may go the nolathane casting route for mounting the speedbooster optical cell within a spare cone. With care and use of a suitable separation material, I should be able to preserve the functionailty of the thread for fine backfocus adjustments. Does anyone know how best to go about getting hold of BM spares.
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  8. #48  
    How's this for a bit of fortuitous coincidence. It seems from calculations and from offer-up tests that the front face of the big URSA PL's intermediate adaptor is exactly spot-on for the rear mounting face of the Nikon 5-screw mount with a Speedbooster optical cell in the throat of the camera. The internal diameter is too wide for the Nikon F-Mount to be directly attached by screws. However for test purposes the mount can be clamped with a thin hard spring-steel grade washer arrangement with screwholes in the PL-Mount pattern.

    The washer has to be thin enough that the 1.2mm rear overhangs on the Nikon iris ring clear the washer. The Nikon mount ring also need so have the 2mm deep AI clearance of the FM2n style mount. The later mounts have a shallower clearance. For a substitute intermediate adaptor with correct internal diameter for a Nikon mount, there is a space required behind for the small 1.5mm deep rear shoulder of the Nikon mount ring and the corrugated spring, which requires some clearance channels to work properly.

    I also offered up an old Angenieux T3.9 25-250mm zoom lens. It is not viable for a speedbooster because its image circle is too small and vignettes to the big URSA's 4K sensor. It would be sort-of okay with a faux-cinemascope top and bottom of frame crop but it appears there would remain a subtle side edge darkening of an apparent half-stop.

    Interestingly, the Sony FS7 sensor is quoted as 25.5mm wide and the BM4K sensor as 25.34mm wide. I have been advised of anecdotal accounts of the Speedbooster "Ultra" EF-Mount to Sony E-Mount version, conferring a full image to the sensor of the Sony FS7 camera. I think the lenses used were Nikons via adaptors and Zeiss CP2. I have not seen it working myself.

    Depending upon the intermediate adaptor arrangement of the BM URSA Mini 4.6K, it may be possible for this camera to also provide a useful image with a 0.71 Speedbooster but the chances of corner and side edge image softness may be greater with some lenses.

    I have not yet been able to get my greasy hands on a URSA Mini 4.6K.

    NOTE: The URSA Mini Pro 4.6K is not viable for a speedbooster optic being installed in the camera throat because the workspace is occupied by the inbuilt ND filter system.
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  9. #49  
    The making of the mount was an easier go than I thought it would be. It was possible to use my original Nikon adapter mount with just a mere 2.5mm shaved off the rear locator shoulder which fits inside of the intermediate adaptor when that is in its normal place and the speedbooster optic not installed. Drilling and countersinking six new holes to match the fastener pattern of the intermediate adaptor and it was done.

    In the images, you will observe that the face of the Nikon adaptor piece is now recessed into the body of the camera and the front face is now coincident with the normal face position of the intermediate adaptor. I shaved the rear face a whisker more than the 2.5mm to give me some shim space if I need it. It remains a prototype. Some time when I am not lazy, I will remake the piece as two separate adaptors, one for the speedbooster, one without.

    This will enable me to maintain best accuracy in keeping the optical axes of the lens and speedbooster optical cell coincident.
    Attached Images
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  10. #50  
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    Awesome, Too bad this cant be used on the pro..
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