Thread: UM PRO Speedbooster INTEREST GROUP

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  1. #31  
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    Very true, but I wan'r referring just about the focus or lens sharpness, the cover glass fifference (thickness) or lack of one, can cause other optical issues, see the reference I posted. And yes, the Sigma zoom is too sharp, almost clinical, squeaky clean, and can be harsh. Like the Hobit 4k. That is why I got a Olympus 14-35 f/2.0 FT lens over the Sigma 18-35 zoom, very cinematic looking IQ, along with the Angie 17.5-70 S16 zoom.
    Cheers
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  2. #32  
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    Quote Originally Posted by Howie Roll View Post
    I'm all for choice and an extra stop is great but at the end of the day the "look" is really just 1 stop. Less for camera's that have an open gate greater than s35 like the UM4.6 or Alexa which is APS H sized. I'm sure the move to larger sensors is much more about pixel density and efficiency than any VV aesthetic. The "Full Frame" look was a much bigger deal when comparing the 5D to a 1/3 or 2/3 sensor, now that s35 is ubiquitous the difference is just not that drastic, it's about a 25% reduction in DOF for a given composition. Indeed it is a good time to be a filmmaker.
    I agree with you, but only for "standard" (small wide angle or small telephoto) lenses. Not for the two lenses I mentionned.

    a) The fastest affordable 10mm lens for S35 is 2.8, and I don't even know the optical quality of it. If you want faster, it's ultra Prime at $10K+, and it's only T2.1.(http://www.photocinerent.com/fr/opti...rime-10mm-t2-1). What an Sigma ART 14mm with SB offers you is SHARP 10mm f1.3. So very big difference between 1.3 & 2.8 in term of DOF with a 10mm.

    b) The fastest affordable 14mm lens for S35 is a Sigma Art f1.8 FF Art. If you want faster, it's master prime at 20k$+, and it's only T1.3. What an Sigma ART 20mm FF with SB offers you is SHARP 15mm f1 (!). So a significant difference between F1 & F1.8 in term of DOF with a 14mm.

    However, if we compare with a 85/50/35mm FF 1.4, the difference won't be so obvious (f1 on SB S35 vs f1.4 with wider focals to compensate dof) but still exists.

    Regards,

    Hugues.
    Last edited by Rayzen; 06-17-2017 at 05:59 PM.
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  3. #33  
    The filter/cover glass in the throat of the BM big URSA is situated too close to the front of the camera body for a Speedbooster optical cell to be located within the throat of the camera without this filter having to be relocated rearwards. That may introduce other optical and colour issues. As with the RED camera experiments thus far, the filter glass would have to be remade to a smaller diameter and installed closer to the sensor on the rear of the redesigned Speedbooster optical cell.

    Unlike the RED experiment in which the optical elements themselves had to be ground flat on the edges to permit fitment within the throat of the RED camera, there is generous workroom within the big URSA's throat to fit the optics. With the aggressive BMPCC Speedbooster optical cell installed within the throat of the big URSA and the filter glass removed, Nikon lenses can be offered up and achieve infinity focus.

    There is as I expected, a significant corner vignette from the BMPCC Speedbooster optical cell along with significant edge distortion. The optical cell from the 0.71 "Ultra" Speedbooster series may yield a wider image circle and maybe less edge distortion. It may not need to protrude so far back in the throat of the camera as the BMPCC optical cell which is about 13.25mm rearwards of the M/43 flange, therefore about 4mm from the sensor itself.

    If the 0.71 optical cell can perform to the 21mm V1 URSA 4K sensor without a vignette, then it would be a relatively simple matter to remake the anti-reflection cone to carry the optical cell or the elements themselves in a custom assembly, to screw straight into the throat of the big URSA camera and shim between the rear shoulder of the BM throat and the rear face of the cell barrel for collimation.

    As for removing the filter glass, I do NOT recommend that people tackle this. This element is surface-coated and could be easily damaged. The neoprene "O" ring retainer is a challenge to re-install correctly.

    I have enquired with the folk who make and sell the Speedboosters to see if they will sell me a 0.71 optical cell. As a kitchen-table engineer, I do not like my chances but who knows.

    There is probably not a lot of point to this exercise except as an option for folk who retain the big URSA and intend to use it in controlled lighting environments alongside the URSA Mini 4.6K or Pro, for a 4K or HD finish. Then the images conferred by the lenses may be a better match.

    Due to the fitment of the ND filters in the UMP cam, there is no workspace remaining to install a Speedboster optical cell. Due to the size of the 4.6K sensor, there is no need to.
    Last edited by Robert Hart; 07-15-2017 at 12:13 PM. Reason: errors
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  4. #34  
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    And the UM Pro will have less room than the big Ursa Robert was testing with Nikon lens mounts. A EF mount will have less room yet.
    Cheers
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  5. #35  
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    Yeah It would have been great if BM had thought about this before releasing the UMP. As Kinefinity already has been doing this for 2 years I think.
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  6. #36  
    Denny. Thanks for pointing that out. Also the URSA Mini Pro has two sets of ND filters inside there as well. No Speedbooster possible for that camera and with its 4.6k sensor it should not need one. A Speedbooster is valid, assuming it works to enable some field-of-view catch-up by the 4K cams with their smaller sensor areas.
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  7. #37  
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    Quote Originally Posted by Robert Hart View Post
    Denny. Thanks for pointing that out. Also the URSA Mini Pro has two sets of ND filters inside there as well. No Speedbooster possible for that camera and with its 4.6k sensor it should not need one. A Speedbooster is valid, assuming it works to enable some field-of-view catch-up by the 4K cams with their smaller sensor areas.
    It "needs" one if one wants to get a specific aesthetic, like the two I mentionned in my previous posts. But "need" is a wrong term. S8 doesn't "need" a SB, nor S16, nor m43, nor S35, nor FF, nor Imax. Let's just say "we want".

    But you answered to my original question...It seems not possible to put a SB.

    So why did BMD didn't do like Kinefinity and their KineEnhancer ?

    I guess they prefer us to buy their hypothetic URSA VistaVision at NAB '18.
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  8. #38  
    For what it is worth. initial offer up of the Metabones speedbooster "Ultra" 0.71 optical cell appears to convey a near-perfect image to the sensor WITHOUT need to interfere with the blue filter in front of the sensor which is an unexpected bonus. The optical cell has to be rearwards in the throat of the camera almost to the blue filter disk.

    I have offered up two Nikon F-Mount wide-angle lenses, the Nikon DX 12-24mm zoom which only "just" covers the sensor and 14mm Sigma-for Nikon.

    The bad news is that a PL-Mount option is unlikely. Certainly old Cooke Speed Panchro lenses penetrate too deeply rearwards. The PL-Mount shoulder is also going to create workspace problems at my skill level. Although more competent optical engineers might find a solution, many PL-Mount lenses with rearwards penetration into the throat of the camera may clash with the Speedbooster optical cell.

    The Speedbooster version I have borrowed the optical cell from is the Canon EF version. It would be theoretically possible for an EF-Mount Speedbooster for the URSA PL 4KV1 to be made. A limitation will be the physical width of the rear of the EF mount lens which might interfere with the body of the camera. There would be risk with the Xeen lens series with wide rear bodies.

    The EF-Mount Zeiss CP2 series with EF-Mount may be more forgiving but there is a small metal assembly on the rear of the lens bodies which may interfere with the camera casework at the 4.2mm approx setback rearwards required for the Speedbooster optic to focus correctly on the sensor. This metal structure appears to be a lens support attached with two small screws. It may be remvable without affecting the function of the lens in which case, the CP2 series may work. The EF-Mount ring also partially covers the intermediate adaptor attach screws.

    As with my Nikon adaptor for the big URSA, there is no practical workspace to enable the pin latch to be fitted and corrugated spring friction alone will resist the tendency for the lens to turn in its mount during focus movements. This would preclude usage of motorised focus as the focus motor will hit stop points and turn the lens out of its mount during calibration.

    There is only 1mm of workspace in front of the intermediate adaptor disk which fits within the URSA body, so this would have to be remade slightly thinner to enable a genuine Nikon F-Mount and corrugated spring to be fitted.

    A professional engineering approach would be to remake the intermediate adaptor with a shoulder penetrating inside, replacing the anti-reflection cone entirely and containing the Speedbooster optical cell.

    Due to the fitment of the ND filters in the UMP cam, there is no workspace remaining to install a Speedboster optical cell. Due to the size of the 4.6K sensor, there is no need to.

    PLEASE NOTE THAT THIS EXPERIMENT HAS ONLY BEEN CONDUCTED WITH THE PL-MOUNT TURRET VERSION OF THE BIG URSA CAMERA. IT MAY NOT BE WORKABLE WITH THE EF-MOUNT TURRET VERSION. CERTAINLY, THE PASSTHOUGH CONDUCTORS AND ASSOCATED INTERNAL STRUCTURES FOR POWERING AND CONTROLLING THE ELECTRONIC LENSES MAY INTERFERE WITH ANY SPEEDBOOSTER INSTALLATION AND COMPLICATE THE ENGINEERING.

    My approach will be to remake the anti-reflection cone as a support for the Speedbooster optical cell and remake the intermediate adaptor as two separate components, purely because of my incompetence at fine engineering.URSA 4KV1 SPEEDBOOSTER.jpg
    Last edited by Robert Hart; 07-15-2017 at 01:12 PM. Reason: error
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  9. #39  
    Quote Originally Posted by Robert Hart View Post
    For what it is worth. initial offer up of the Metabones speedbooster "Ultra" 0.71 optical cell appears to convey a near-perfect image to the sensor WITHOUT need to interfere with the blue filter in front of the sensor which is an unexpected bonus. The optical cell has to be rearwards in the throat of the camera almost to the blue filter disk.

    I have offered up two Nikon F-Mount wide-angle lenses, the Nikon DX 12-24mm zoom which only "just" covers the sensor and 14mm Sigma-for Nikon.

    The bad news is that a PL-Mount option is unlikely. Certainly old Cooke Speed Panchro lenses penetrate too deeply rearwards. The PL-Mount shoulder is also going to create workspace problems at my skill level. Although more competent optical engineers might find a solution, many PL-Mount lenses with rearwards penetration into the throat of the camera may clash with the Speedbooster optical cell.

    The Speedbooster version I have borrowed the optical cell from is the Canon EF version. It would be theoretically possible for an EF-Mount Speedbooster for the URSA PL 4KV1 to be made. A limitation will be the physical width of the rear of the EF mount lens which might interfere with the body of the camera. There would be risk with the Xeen lens series with wide rear bodies.

    The EF-Mount Zeiss CP2 series with EF-Mount may be more forgiving but there is a small metal assembly on the rear of the lens bodies which may interfere with the camera casework at the 4.2mm approx setback rearwards required for the Speedbooster optic to focus correctly on the sensor. This metal structure appears to be a lens support attached with two small screws. It may be remvable without affecting the function of the lens in which case, the CP2 series may work. The EF-Mount ring also partially covers the intermediate adaptor attach screws.

    As with my Nikon adaptor for the big URSA, there is no practical workspace to enable the pin latch to be fitted and corrugated spring friction alone will resist the tendency for the lens to turn in its mount during focus movements. This would preclude usage of motorised focus as the focus motor will hit stop points and turn the lens out of its mount during calibration.

    There is only 1mm of workspace in front of the intermediate adaptor disk which fits within the URSA body, so this would have to be remade slightly thinner to enable a genuine Nikon F-Mount and corrugated spring to be fitted.

    A professional engineering approach would be to remake the intermediate adaptor with a shoulder penetrating inside, replacing the anti-reflection cone entirely and containing the Speedbooster optical cell.

    Due to the fitment of the ND filters in the UMP cam, there is no workspace remaining to install a Speedboster optical cell. Due to the size of the 4.6K sensor, there is no need to.

    PLEASE NOTE THAT THIS EXPERIMENT HAS ONLY BEEN CONDUCTED WITH THE PL-MOUNT TURRET VERSION OF THE BIG URSA CAMERA. IT MAY NOT BE WORKABLE WITH THE EF-MOUNT TURRET VERSION. CERTAINLY, THE PASSTHOUGH CONDUCTORS AND ASSOCATED INTERNAL STRUCTURES FOR POWERING AND CONTROLLING THE ELECTRONIC LENSES MAY INTERFERE WITH ANY SPEEDBOOSTER INSTALLATION AND COMPLICATE THE ENGINEERING.

    My approach will be to remake the anti-reflection cone as a support for the Speedbooster optical cell and remake the intermediate adaptor as two separate components, purely because of my incompetence at fine engineering.URSA 4KV1 SPEEDBOOSTER.jpg
    great work robert.

    I have tried a speed booster element inside the barrel of my ursa mini 4.6k using a machined spare "baffle" I got as a spare from blackmagic. But I couldn't get the element close enough to the sensor with the filter in there. I wasn't gutsy enough to remove the filter. I could only get close focus with it.

    I have also noticed the e-mount speed booster is ~4-5mm shorter that the non-speedbooster e-mount adaptor when you compare them. I wish someone would try and make something work- I m sure a change in the lenses would fix this.

    Paul
    Paul Ross Jones


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    www.paulrossjones.com
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  10. #40  
    Paul.


    I was using Nikon stills lenses for my test. If you were using Canon EF lenses you might not have been able to get back far enough if you left the intermediate adaptor in place. It may be that my placement of the optical cell is too far forward although I seem to be getting close-to the correct focus according to the witness marks on the lenses. Lens focus and the position of the speedbooster optical cell seem to interact to obtain focus but if they are not the correct match then you may find corner softness in the image.

    I assume you were using the "Ultra" optical cell which is 0.71 power of magnification ( maybe that's the wrong definition ). If you were not, then the smaller optical cell may need to be furthur rearwards as you describe. With the "Ultra" the measured setback for the lens flange is about 4.2mm.
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