Robert Hart

If your local hock shop or eBay has a Nikon f2.8 45mm prime like this one, maybe give it a try. It is near enough to being a normal lens field-of-view on a 35mm motion picture sized frame. It confers a different "look" to other Nikons. I am not clever enough to analyse that look or what the lens does. It is sometimes referred to as a "pancake" lens. http://www.ebay.com/itm/Nikon-45mm-f2-8-GN-Nikkor-Lens-w-Nikkor-Bubble-EXC-/162622320949?hash=item25dd0bb135:g:pMUAAOSw4GVYSBNT

Your camera spring drive may be disengaged from the transport. This is selectable "on" or "off" and enables the film transport to be hand-cranked or rewound for multiple exposure of the film. Alex. There may be other issues with your camera, so don;t take too much heed of my comment. The Bolex H16 camera family button never starts or stops "cleanly" It is a rather crude mechanical interrupt so you have to be "decisive" when pressing the run button and releasing it, fast not slowly. To avoid shock-loading the transport when re-engaging the spring drive, best practice is to not switch from "O" to "MOT" with a fully wound spring. The spring rewind crank should be swung open and engaged with the drive, then the tension of the spring taken up very slightly. Then move the nearby lever from "O" to "MOT". If it does not swing entirely to position, allow the spring rewind lever to unwind just a trace and the drive will engage. You can then release the spring rewind lever and stow it. Pay heed to better qualified people than myself who may comment here. If amateurs have visited inside the camera mechanism or sprayed WD40 in through the gaps in the case, the mechanical governor may have become contaminated. It is an old-school centrifugal governor consisting of a brass bell and three small articulated arms with leather shoes. If these shoes have become soaked in WD40 and the light fractions have gassed off, the shoes may have stuck in storage.

For interest of anyone who would like to have a speedbooster in their URSA, I have obtained some numbers from a local machinist. Costs thus far :- For both the internal support for the speedbooster optical cell and Nikon F-Mount base only = AU$460-00, plus material. GST if in Australia = AU$46-00. Nikon F-Mount supplied separately by camera owner. = Cost unknown. Cost $AU Zero if the Speedbooster is Nikon Mount type. "Ultra" 0.71 Speedbooster optical cell supplied by camera owner. = AU$610-89. With used big URSA cams going inexpensively on eBay, a cost of about AU$1010-89, plus AU$102-00 GST, probably represents over-capitalisation for the benefit of near-to full stills frame fields-of-view and being wedlocked to Nikon F-Mount lenses. I have not been able to obtain any information regarding permission related to fitments designed to match registered design and separate supply of the 0.71 "Ultra" optical cell from either Metabones or Caldwell. Each entity seems unwilling or incapable of replying to email queries.

I have been asked by a SI2K owner to obtain a quote from a local precision engineer and machinist to reproduce a copy of a speedbooster mod I made about three years ago for my SI2K. If he is willing and able, I shall post contact details for folk who might want to have their Speedbooster parts made, to contact him direct. He does stuff in CAD these days so the machine drawings are kept in computer files. Owners would need to supply their own BMPCC Speedbooster for the necessary machine work to be done on it and the IMS-Mount to be made and fitted. The mod does not prevent the original m4/3 mount from being refitted. In this clip shot on the SI2K with the BMPCC Speedbooster, ND and IR filters were used. The lenses were Voigtlander 40mm f2 and Nikon 85mm f1.4.

Subsequent edit of the above responsive post. I took too long editing and was locked out. It will depend upon what flavour of EF-Mount camera you intend to use the Cookes on. I know the rearwards penetration of the lens body will impinge on the lens pin block and other structures within the throat of a Canon 7D and likely other DSLR cameras too. Some EF-Mount to PL-Mount adaptors have an EF-Mount lens profile machined into the rear to engage into the EF-Mount like a lens. These have little rearwards space for the PL-Mount shoulder to penetrate. Another style attaches over the EF-Mount using the EF-Mount screws. This style enables a little more rearwards space but most industry PL-Mount shoulder will foul the lugs on the EF-Mount and ride high preventing the clamp ring from being turned to lock. I know that on the Blackmagic 4K EF-Mount digital cinema camera, the rearwards penetration will impinge on the lens pin block and other structures too. These will need protection against short circuiting. You may not be able to move the lens focus rearwards enough to achieve infinity focus before the inner lens body emerges from the outer cylinder and makes contact. I did not examine for this. The closeness to the lens pins was enough to put me off. There is some material which you might be able to dress off from the rear of the outer housing and off the rear of the moving barrel within to establish a working clearance. I would not recommend this for you will destroy the originality of the lens. This is a consideration for re-selling. The work would also require dismantlement of the lens to avoid metal fragments getting into the square-cut helicoid thread which is exposed on the rear. It is really only a task for folk who have an above average facility for fine metal work, suitable tools and a knowledge of lens construction. There are ARRI Standard/B-Mount to PL-Mount adaptors. The better ones either use a round circlip and a threaded tapered collar to attach to the ARRI mount shank. Unfortunately, these types have too much rearwards extension of the shoulder and will impinge on the lugs of the EF-Mount before the lens will seat home to the PL-Mount flange. There are thinner and simpler PL-Mount adaptors. These consist of a simple ring with PL-Mount pattern and a shallower rear shoulder. These may clear the lugs on the EF-Mount. The downside of these is they are secured by three or four small grubs screws which bind on the shank of the ARRI mount. There is not much wall-thickness in the shank structure. It will deform and trap the focus helicoid of the Cooke lens from free movement. In this arrangement, the entire body of the Cooke lens forward of a narrow knurled section closest the mount face turns for focus. It is absolutely important NOT to grab the iris ring when turning the lens barrel for focus movement. It is not well defined. Best practice is to grasp the very front edge of the lens and rotate from there. If you try to force the focus movement in a full natural grip of the lens body, you will likely over-extend the iris mechanism and ruin the iris. For old Cine-Xenons of this vintage, typically the 28mm, the opposite is true. The very front edge of the lens body carries the iris ring. The iris in these lenses is more easily damaged by over-extension than the old Cookes. Some aftermarket EF-Mount to PL-Mount adaptors have a sharp corner at the inner front where the tail of the PL-Mount enters. Most PL-Mounts and adaptors which attach to the rear of lenses have a fillet in the inner corner. The radius of this fillet varies and some will ride short on the sharp corner inside of the mount. The clamp ring cannot be turned to lock because the lugs remain a fraction high off the flange face. The cure is to skim a 3/32" chamfer on that inner front edge. This provides clearance for most if not all fillets and allow the mount to rest fully home.

It will depend upon what flavour of EF-Mount camera you intend to use the Cookes on. I know the rearwards penetration of the lens body will impinge on the lens pin block and other structures within the throat of a Canon 7D and likely other DSLR cameras too. I know that on the Blackmagic 4K EF-Mount digital cinema camera, the rearwards penetration will impinge on the lens pin block and other structures too. These will need protection against short circuiting. You may not be able to move the lens focus rearwards enough to achieve infinity focus before the inner lens body emerges from the outer cylinder and makes contact. I did not examine for this. The closeness to the lens pins was enough to put me off. There is some material which you might be able to dress off from the rear of the outer housing and off the rear of the moving barrel within to establish a working clearance. I would not recommend this for you will destroy the originality of the lens. This is a consideration for re-selling. The work would also require dismantlement of the lens to avoid metal fragments getting into the square-cut helicoid thread which is exposed on the rear. It is really only a task for folk who have an above average facility for fine metal work, suitable tools and a knowledge of lens construction.

I had no plans for making any sort of a business out of it. I put in hand-building, seven hours just to set up the thread-cutting gears and machining the internal assembly, plus about the same for the combined Nikon F-Mount adaptor which doubles as the Speedbooster's Nikon mount as well. Add the cost of buying in a whole Speedbooster just to use the internal optical cell, having to cover product liability, packing, shipping and Australia's overvalued dollar, I could not put them out there for a cost that folk would be prepared to pay. I think the original 4K URSA Mini PL may have the same screw pattern because the URSA Mini B4-Mount fits the big URSA PL just fine. If I can find a knackered 4K URSA Mini PL cam and 4.6K URSA Mini PL cam to study and take measurements from, likely I could find some way to make it work. BM may have a sea container of rejected parts and non-repairable camera returns by now. I might do the begging bowl on them but I don't rate my chances. Whilst BM does not discourage folk from designing and making accessories to fit BM products, something which invades the camera like the inbuilt speedbooster is unlikely to be assisted as the chances of owner-warranty being voided are too great.

Here is an image of the Speedbooster assembly fitted. Yeah I know, I am slack because I have not yet matte-blacked the shiny bits.

It might possible to make it work on the URSA Mini4.6K PL if the throat of the camera body and the anti-reflection cone are identical to the big URSA 4K PL. The intermediate adaptor in the front of the URSA Mini4.6K may be different and may have a different pattern of the mount attach screws. There may not even be an intermediate adaptor like there is on the big URSA. I have had no opportunity to study an URSA Mini 4K PL closely. I had hoped I might find one which was totalled but substantially intact around the region of the mount but no luck thus far. I did get it to within a whisker of working in the original BM4K EF-Mount camera body. I think this may have a shorter "snout" on the front of the camera body compared to the PL version but I am by no means sure. The rear of several Nikon lenses interfered with fittings just inside the throat of the BM4K EF, which is narrower but still accommodates the Speedbooster optics with about a half-millimetre clearance radially. Fitment within this camera would probably have to be via press fit into a soft cylindrical cuff as there is insufficient workspace to cut a 0.05mm pitch internal thread and an external 0.10mm external thread on a metal cylinder of only 0.5mm wall thickness. Given that the Speedbooster optic seems to pull in about 32mm of the 36mm stills image frame width to the 4K sensor, there may be a vignette of the corners on the 4.6K sensor with the wide lenses. I guess I could draw the 4.6K sensor area onto a piece of groundglass to do some image-circle tests but my old experimental pieces of surface-ground microscope slides are buried deep in the shed somewhere. A Speedbooster can never work on the latest URSA Mini Pro because the ND filter system occupies conflicting space within the throat of the Pro camera.

For curiosity only. The accompanying diagrams are not engineering drawings and measurements have not been meticulously checked. The diagram on the right is an estimation of the section of a replacement mount for the speedbooster which would replace the anti-reflection cone in the URSA 4K PL camera turret. A reminder. This is most definitely not a BM approved adventure into the working of the camera. Any such adventure by you into your camera will void your warranty.

I suspect as you describe that the optical cell of the speedbooster is not correct. The image from the 14mm rectilinear lens shows a ring of sharp focus which travels to the centre with focus trims. This lens is a little soft in its corners but not as much as is seen in the image. I have yet to make an adjustable support for it as soon as I can find out what the thread pitch for the optical cell is. I also need to find out what the pitch of the thread on the back of the BM cam's anti-reflection cone is. Then I can make the internal adjustable fitting.

This is my arrangement. It is a custom intermediate adaptor with Nikon F-Mount attached on front. It replaces both the PL-Mount and the silver-coloured metal do-nut within the URSA PL cam's body to which the PL-Mount attaches. You will observe that the front of the intermediate piece made of bronze is recessed significantly within the camera body compared with the normal intermedate adaptor because the speedbooster optic shortens the flange to focal plane distance. You will observe a few extra holes in the bronze piece. this is because it is multipurposed to function as a Nikon mount adaptor to be attached to the front of the normal silver-coloured intermediate adaptor "do-nut" by using the PL-Mount screws which secure through another set of differently arranged holes.

AJ Young. You are correct. My URSA is the PL-Mount version. Many PL-Mount lenses are not suitable for the image circle being small. Some PL-Mount lenses are not suitable because lens structure physically will overlap the front element of the speedbooster optical cell. Because I am using my old Nikon F-Mount stills lens set, the image circle is not a problem for me. My mount is the four-screw Nikon F-Mount as fitted to the FM2n stills camera. The later five-screw mounts require approx 1mm to be machined off to extend the small shoulder around the flange face rearwards to allow overhangs on the aperture control ring of older AI-AIS lenses to have clearance. Metabones specifies that in their own PL-Mount flavour of their 0.71 "Ultra" Speedbooster, the only PL-Mount lens system which is approved to work with the PL-model for Sony E-Mount is the Zeiss CP2 family defined below. The limitations are defined "opto-mechanical". On other flavours of the 0.71 "Ultra" family of adaptors, a wider range of stills lenses can be attached. Except for achieving a closer match perspectively between the BM4K and BM4.6K sensor images and about a stop of light gain, there is probably not a lot of point to using a Speedbooster in the URSA 4K cameras. The quality of the wider lens images appears to be compromised though that may be remediable with better trimming of the position of the speedbooster optic. http://www.metabones.com/products/details/MB_SPPL-E-BT1 Due to the rearwards set-back of the PL-Flange, there are mechanical reasons why a PL-Mount is not practical although it could probably be made to work with a unique thinner clamp ring arrangement. I offered up to my arrangement an old 25-250mm Angeniuex zoom. It does vignette and exhibit darker areas in the edge of the image. The Peleng 8mm fisheye lens is intended to confer a circular image within the standard stills image full frame. I understand these were modified for PL-Mount for motion picture application and the image circle covered the standard 35mm motion picture frame. In this linked vision clip, the last lens image from an 8mm Peleng fisheye is signficantly cropped and thus illustrates your point.

Better you found it out from a reliable source with all the warnings rather than venture in blindly as you may have otherwise done. - Please take incredible care and PLEASE do not ignore the use of personal protective equipment, particularly head and eye protection. - A lifetime of disability is not worth the saving of a few dollars.

The most expensive part for me will be the raw metal stock as it is a DIY project and I already have the tooling. Hollow-cast gunmetal bronze stock is not the cheapest stuff to buy but is friendly stuff to work with and has good strength. The modified intermediate adaptor should be easier than the custom Nikon F-Mount adaptor to fit the PL-Mount fastener pattern. It is basically a modified copy of the existing intermediate adaptor. It will have a narrower throat, a shallow wider clearance bore at the rear so no pressure goes on the front of the anti-reflection cone, fewer holes drilled in it and a small relief in the front to accommodate the small rear locating shoulder of the F-Mount. There is a lot less detail involved although the dimensions of course have to spot-on. To accommodate the speedbooster optical cell, the arrangement can be as simple as fixing it inside the existing anti-reflection cone with custom washer-shaped pieces and some tacks of adhesive or remaking the cone as a complete barrel to support the optical cell, with internal thread for very fine focal adjustments. A PL-Mount version looks like it may be doable but the lens choice will be limited to the Zeiss CP2 and possibly the Rokinon Xeen range. These are already available in EF-Mount and F-Mount versions which makes the PL version somewhat pointless except for more robust construction and solid fixture which really matters when using wireless follow-focus.

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.

I have sent you a message here regarding a possible alternative product your shop might be able to make. Cheers.

Purely for curiosity and theoretical interest. - The first 4K Blackmagic Cinema Camera, although it is smaller in the optical throat than the "big" URSA, nevertheless has enough real-estate within to accommodate the focal reducer 0.71 optical cell from an "Ultra" series Metabones Speedbooster. There are caveats. The only lens system which may be possible to use may be the Nikon F-Mount AI/AIS family of manual lenses. The original Canon EF-Mount lenses which have a flange to focal plane distance of 44mm, cannot be moved the few millimetres rearwards, without destructive surgery to the BM4K front body. The Nikon lenses with their 46.5mm flange to focal plane distance may be in with a chance with a very thin custom mount made to replace the Canon EF-Mount, which on the BM4K is 5mm thick, front to rear. PL-Mount lenses have a very deep rear shoulder and many have rear elements which penetrate in the camera throat deeper than stills lenses designed for mirrored SLR cameras. Many will come up against the optical cell. The Cooke Speed Panchro Series II lenses are definitely not contenders for use with a Speedbooster. The Nikon lenses likely will require trimming of some of the rearward protrusions inside the mount ring to enable them to be set back without catching on the internal fitments within the BM4K body. This of course will spoil the lenses as genuine Nikons. In manually offering up Nikon lenses to a jigged up arrangement, it was not possible to move the lens rearwards enough for inifinity focus but it was within a whisker of being there. Sharp focus upon an object two feet distant from the focal plane occurs when the witness mark on the lens barrel reads ten feet. There you go. - Some useless information for you.

There is likely a special vice to depress the concealed latches to start the separation of the two halves of the case. There are visible four small rectangles top and bottom in one half of the case. These are actually extensions from the opposite case half, They depress to release but it is a little harder than that. The ends have latch ridges which have to be forced as well. In absence of the proper tool, each latch can be forced by inserting the tip of a 1/8th" broad bladed jeweller's screwdriver into the tight join between the two case halves at a latch point, wedging it in towards the latch raising the opposing case edge over the latch, jamming it in as far as you can then levering up so the latch is depressed. You will need to have another jeweller's screwdriver to shove in to keep the latch depressed whilst you then use a third jeweller's screw driver to wedge the two halves of the case apart at that point. The plastic is tough but chances are you will crack it. You will most definitely injury the finish. Chances are you will at least once put the jeweller's screwdriver fair through the web between fingers one and two if you are not careful and it slips. Take care with those screwdriver ends. You will likely injure the circuit board immediately below or puncture a lithium cell in which case you are in for a big surprise. As holding wedges, once you have an edge raised, it is safer to use wooden satay skewers. There should be findable at this website, an image which shows a Dionic in bits. The site counsels quite strongly against amateur recelling of Lithium Ion batteries. Compared to playing with Ni-MH cells, Lithiums are a high science fraught with danger. http://www.rathboneenergy.com/batteries/broadcast/anton_bauer_rebuilding/dionic_90/dionic90_rebuilding.htm

If you are going to tamper with lithium cells, it may be best not to. If you must, then do it outside, not inside your house. Wear fire resistant personal protection. Chances are, the electronics inside of the AB battery may not work after they have been disturbed or somehow will not play nice with the new cells.

A sticky mechanical governor hunting for speed on an old clockwork Bolex H16 which needs maintenance may shake almost un-noticeably with a long lens. I only ever saw it once when I was using a ridiculously long lens and there were shiny rail lines in the shot. Even then I could not really make up my mind if it was not instead a localised mirage over the rails except I could also hear the camera gears loading and unloading. An Aaton would have to awfully sick to vibrate in the manner you describe.

Like enemies, they may well be keeping parts of their registered designs even closer. By trial and error, I may be able to arrive at the correct thread pitch with the lathe gears but it is really fine and likely beyond my meagre engineering abilities. It is an internal cut and my machine does not turn true off the main bed which is what is used when cutting threads. There's a guy down the hill from here who is a German-trained wizard at this stuff but prefers to CAD everything these days which means big money relatively speaking for a one-off job.

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. Navigating to someone who can actually help, assuming the company would want to, is proving an enigma.

The subject of fitting a focal reducer optic to the 4K URSA has surfaced fro time to time. Recently on reduser, there was a post regarding fitting a focal reducer optic within the throat of the DSMC2 style of camera. The results were encouraging. So prompted and having recently had a big URSA PL turret partially apart in order to design and fit a custom Nikon F-Mount, I also examined the possibility of fitment of the Metabones "Ultra" 0.71 optical cell within the throat of the big URSA camera. It seems that it is a workable possibility. The flange face of a particular mount is set back about 4.2mm when this optical cell is in the image path. It is unlikely that PL-Mount cinema lenses can be accommodated. The deep shoulder of the lens mount takes up space. Many of the lenses have rear elements protruding significantly rearwards, which means that many will clash with the front element of the "Ultra" optical cell. My tests thus far attempting to offer up Cooke Speed Panchros, a Kinoptik Tegea 9.8mm and a Cine Xenon 28mm to the Speedbooster arrangement demonstrates that their rear structures are too far rearwards and clash with the front element of the Ultra optical cell. The Rokinon Zeen and Zeiss CP2 series of lenses seem likely to work so long as their rear barrel structure is no wider than the opening in the front of the URSA camera body with the intermediate adaptor removed. Comparitive image pairs with and without the speedbooster element in place can be seen here. The Speedbooster optical cell and 20mm f1.8 Sigma-for-Nikon lens were placed with a primitive jig arrangement for the rough test. http://www.bmcuser.com/showthread.php?20423-UM-PRO-Speedbooster-INTEREST-GROUP/page5

Thank you for your replies. All seems too be good regarding the iris.