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Robert Hart

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    1st Assistant Camera
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    Perth Australia

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  1. A groundglass viewfinder screen and a fibre-optic viewfinder screen although serving the same purpose are different in their construction. As I comprehend things, the fibre-optic screen may be a coherent glassfibre bundle, a bonded piece sliced thin and dressed smooth as a projection screen like the groundglass. It may be a longer run of fibres arranged to maintain an erect image whichever way a viewfinder eyepiece is oriented. The bundle may be stablised at each end by a transparent adhesive. A similar arrangement is used in tube-based night vision to invert an image instead of a system of lenses. Hit a fibre-optic slice with a high pressure air jet and fibres may disbond causing a blemish in the viewed image. Heed the advice of better qualified people than I.
  2. Aapo. Regarding a lens for a video split, if your C-Mount camera has a 2/3" sensor, you might be able to use Fujian C-Mount lenses with CS to C-Mount adaptor rings to macrofocus the lenses. The rings are 5mm thick from memory. The Fujian lenses are available as 25mm, 35mm and 50mm focal lengths. I was examining this at one time. My notion was to cut an approxiately 5mm thick piece of aluminium in the shape of the little hatch which closed the hole for the video split, mount it in a 4 jaw chuck on a lathe then machine the thickness down to leave a hollow shoulder to cut a thread onto for the filter thread of the lens as a means to mount it then use the lens to support the camera. https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=fujian+C-mount+lens&_sacat=0&LH_TitleDesc=0&_odkw=Fujian+50mm+c-Mount+lens&_osacat=0
  3. Aapo. How difficult would it be to design a simple single-speed crystal-controller for the CP16R with the shutter park function. Multiple speeds are nice but maybe not necessary. Offspeed work is easily done on a Bolex. High speed shooting for slow motion is more conveniently doable with digital cinema and at less media storage cost than 16mm film.
  4. If a slug of liquid gas comes out because of shaking the can from habit or turning it upside-down which you should not, shock-cooling of any optical glass the gas hits may crack it.
  5. Appo Lettinen. How is it progressing? Will your final CP16R system be contained within the camera body. I think I saw a post somewhere that suggested you were thinking about a box outside of the camera. A tidier solution might be to take out pre-amp and amplifier board out of the Crystasound amplifier attached on the right of the RA models and put the extra electronics in there.
  6. Ken Hale of Whitehouse Audiovisual remounted in stainless steel, the Angenieux 10-150mm zoom. I have one. With some examples of the lenses, there may be difficulty with interference to the aperture control ring. I bought the PL-Mount from Ken and fitted it myself in Australia. I would not recommend this route unless you have some serious fine mechanical skills for you will ruin something otherwise.
  7. I can't speak for the Vinten 20 but I have had a roam around inside a Vinten 22. The Vintens have some tricky ways of coming apart. Pulling one apart is not for the fainthearted. You are dealing with some fine precision in some parts. The counterbalance spring mechanism can also be damaged if dismantled incorrectly. The friction material is also proprietary and expensive. So far as I know, if you can obtain it at all, it will be in bulk amounts far more than you would need. The fixed "labyrinths" ( my translation is non-adjustable friction modules ) establish an initial level of friction. They are apparently filled by a vacuum process on models since the SDs. There are extremely fine clearances in the labyrinths and parts are matched in the factory to achieve this. I understand that they are not serviceable but replaced as an assembly. I have taken one labyrinth apart and found that material had squeezed out. There had been a metal-to-metal contact between two aluminium surfaces. They had galled raised patches which snagged lightly as they passed in the tilt motion. People tend to misunderstand what Vintens do differently to other products. They mismanage Vintens and overtighten the friction adjustments as tilt and pan locks instead of using the tilt and pan lock levers. This eventually ruins the adjustable friction. If friction material has become entirely extruded, the catching you describe may be a metal to metal grab happening in an adjustable friction module. These consist of a machined aluminium face and a polished stainless steel face with the friction material in between. The draw motion is mechanically limited. Frustrated users who expect the adjustable friction to increase to lockup, overtighten the adjustment knobs which reach limit stops. The next step is they reset the limit of the knobs to achieve more tightness and eventually break linkages or strip draw threads. If the snatching you experience if happening in the tilt motion, you might be able to correct it by backing off the adjustable friction, storing the head in a warm place on its side with the tilt controls lowest for a few days, then exercising the full tilt motion with the adjustable friction backed off in the hope of distributing friction material evenly across the surfaces. If you are getting snatches with the pan friction you ight be able to restore it by storing the head camera-side down in a warm place with the friction adjustment backed off and exercising as for the tilt motion after a few days. The pan friction adjustment if overtightened will break out a small machining in a bellcrank which holds a hinge pin on the end of a draw rod. Once that breaks, the draw rod will come out some way with the knob and that part of the head will have become ruined.
  8. Some otherwise identical lenses of which some are parfocal and some are not may depend on whether they were coillimated for a camera which shot striped film, the stripes being magnetic tracks. There were two tracks, one being the sound recording media and the other a narrow strip called the "balance track" which ensured the film rested flat in the gate. These tracks set the film emulsion very slightly rearwards. Bare film used in a camera with a lens or camera mount collimated for striped film may rest very slightly forward of the image plane of the lens. The image plane of a lens collimated for a striped film may in a digital cam rest sllghtly rearwards of the sensor plane. Whilst you can focus must fine with a live view digital camera screen, the zoom movement may no longer be parfocal if this condition exists. Thinner shims may be needed between the mount tail of the lens and the lens body. Shimming and collimating lenses and camera mounts to a common standard is a dark art best left to the skilled artisans who do it for a living.
  9. Further to above. On viewing the youtube clip, it does seem to be a wavy tape issue as the artifact and the blue dropout are cyclic at about the same rate as the take-up spool rotation partially through a tape roll. Some VHS rental tapes were straight after being put through the slitter but shape memory made the tapes wavy after a few plays. Rolling the tape through the camera at playback speed with the cassette door facing upwards will wind the tape accurately as best as can be achieved. Thermal cycles may help stabilise the shape long enough for a better playback.
  10. There may have been a climatic reason for the random faulty recordings if the tapes were rested partially wound in the camera and stretched slightly in the heat of a car's cabin. With the old reel-to-reel Sony EIAJ half-inch tapes, there was an issue where they would deteriorate, bind to the drum and leave a coffeestain deposit over the transport, clogging the heads. When that happened the friction and the power of the capstan and roller would cause the tape to be stretched and it would no longer play back cleanly. As a desperation measure you could manually ease the tension bar when you could see a tracking error developing as the tape began to bog. The transport of the reel-to-reel machines was exposed which made this hack possible. With cassette systems it is fully concealed and not an option. I made a home-made tape washer which cleaned the gum off the tapes but by then the stretches had occurred on the tapes and the stretched areas were permanently out of pitch. When you have recovered all your archive with redundant spare copies and there remains no risk of loss, you could try rewiinding the troubles tapes, then playing them through at normal speed to the very end but do not rewind them. Rest the camera on its side with the tape door upwards when you play the tapes through. This will ensure the that wind of the tapes onto the take-up spool is mechanically accurate. Why?? Fast rewinding tends to be less mechanically accurate. Remove the tape cassette. Place it in a freezer bag with a dried dessicant sachet. Thermally cycle the cassette several times by placing the bag in the freezer overnight, then bringing it into a warm environment for 24 hours. After about two week's worth of this process, hopefully the shape of the tape may have stabilised closer to what it was when first used out of the box. If the recording was onto a re-used tape, then all bets will be off but it may be worth trying anyway.
  11. The second of a two-disk DVD set of "Master and Commander" has a generous and comprehensive set of presentations. The single-disk DVD issued has the topic titles in the disk extras menu but nothing happens if you select any of them. Somebody got it a bit wrong. You need to have the second disk of the two-disk set.
  12. I got locked out again when adding to the response above. Here it is repeated. A good outcome then. I hope I did not send you off on dead-ends with the first few responses. On feeding the film-end through the magazine sprockets when loading in a darkroom or blackbag, with the CP16 mags, I find it helpful to make a single-fold arrowhead about 30mm or 1.5" long instead of cutting an arrowhead on the film. The fold holds the end rigid so the film does not curl under and click into the space on the wrong side of the sprocket. That may not be ideal for the ARRI magazine if the film actually wraps around the sprocket inside of a pair of idler rollers. If that is the design, then my folded arrowhead may cause the film to feed badly every time. Another way to be sure is to cut a short leader, feed that through and check it is right, then in the darkroom or blackbag, tape the free end of the raw film to the free end of the leader and draw it through. Use masking tape or the little strip of tape which came with the film roll. If using a new piece of tape, cut it narrow so the sprocket holes are not covered up.
  13. A good outcome then. I hope I did not send you off on dead-ends with the first few responses.
  14. After managing to get the video larger on the screen and stopping the playback, it looks like that the clutch tension in the centred of the yoke is non-adjustable and there may be adjustment knobs in the centres of the white wheels themselves. The little felt pads on the yoke ends may be light brakes to stop rolls from unwinding or flywheeling the motion when the drive is not going to them. If there are not adjustment knobs then they may be fasteners and adjustment of tension may be by spacers or shims under springs like on tape recorders. It is too hard to know what the system is although if I had it in my paws I would work it out easily. That's it from me. Time to go to roost as it is very late.
  15. Once you have adjusted the clutch tension, get hold of a full roll of junk film, load it and run it through to make sure it takes-up firmly all the way to the end but not too tight. You may have to mess around a few times to get it right and it may fall out of adjustment after a few rolls but after re-adjustment should be more stable thererafter. Good luck with it. The ARRI pin-registered transport is as good as it gets. Don't scrimp on getting the cam actuators and little helical gear serviced. If cameras sleep for six months, the lube goes off and needs cleaning then replacing.
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