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Robert Hart

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Everything posted by Robert Hart

  1. Another spin on the subject of dioptres. Feel free to shoot this messenger, metaphorically of course. There are dioptres and dioptres. The bad ones are a simple single element in a ring which screws into the camera lens filter thread. They sometimes were referred to as "close-up" lenses or "filters". The better ones are known as achromatic dioptres. They have several elements in them. The simple ones do crude cruel things like pinpoints stretched radially/colour separation closer to the edges of the image. The achromatic dioptre images are clean. You might achieve a cool effect with a single element dioptre or maybe even an achromatic dioptre if you mounted it off-axis so that one portion of the image is more out-of-focus and artifacted. I once mounted a fisheye lens off-axis so that the lower portion of the image looked more "normal". You might also degrade its performance by mounting it too far ahead of the camera lens with spacers but not so far ahead as to vignette the image. With a single element dioptre, the colour rendition in the soft area would be rather muddy.
  2. Roberto. Very valid. I had forgotten to mention that. In a documentary shot in the Pibara region of Western Australia, landscape aerials had to be shot from a Robinson R22 helicopter with a Bolex H16 film camera at its highest frame rate to minimise the shake. It worked very well.
  3. Cover the lens glass first with thick wad of tissue or cloth to insulate it. Try some canned air directed onto the lens ring with the little plastic straw with the can turned upside-down so that liquid gas comes out onto the lens ring. This may contract (shink) the metal enough to thermally shock the seized thread loose. Try removing the chilled lens ring before it can warm up again. On another forum it was suggested that a piece of automotive inner tube or other thin sheet rubber on a flat surface may find enough grip on a stuck lens ring to shift it if it is pressed firmly whilst being turned. Be extra careful not to get any liquid gas onto the glass because it WILL shatter from thermal shock.
  4. I assume by now you may have made your attempt. I have only just read the post. The available workspace within the Piper aircraft will be very confined especially with a 35mm camera. Shooting through the window transparencies may be chancy if the surfaces are deteriorated by polished-out scratches. Of the small four-seat light aircraft, the most user-friendly is the Maule. A Piper Cherokee Six which has been converted for skydivers may be workable. The Maule aircraft is certified for rear door-off operation which removes the scratched window problem. Your camera needs to be tethered for safety and you would need to be restrained by the existing belts or better, a harness. In the Maule or the Cherokee Six, your direction of view will be slightly rearwards. The Maule has a high wing with two lift struts each side that you have to dodge. An 18mm wide angle lens may pick up parts of the aircraft like wingtips or struts. In this example, I was shooting with a 50mm-500mm zoom lens on a Super16mm SI2K digital cinema camera with a singe Kenyon KS8 gyro. The objects in the image area a cargo rope rigged on the door to stop me from falling out although I was also harnessed and the camera on a lanyard.
  5. The colour slashes could be the result of copying from an original distribution which was subjected to an old copyright protection tech which was I think called "Copyguard". I understand there were two processes One diminished the vertical stability to the bare minimum which would apparently defeat some older VHS players when paying legit distribution copies. The other was some sort of trickery applied to the colour information.
  6. That problem may be related to a small memory battery leaking onto the motor control circuit board. It ruins the circuits which control motor speed and the park function which then fails to stop the motor even of both run switches are "off". You could enquire with Visual Products and Whitehouse Audiovisual if they have the means to repair. It is sadly the way most CP16Rs die.
  7. Variable area tracks look like an audio waveform in a digital edit timeline. Variable density tracks are a constant width with what looks like very fine bars across the full width of the track. Before magnetic audio recording media came along, there were optical audio recorders. Some like Auricon were integrated into the camera itself. Others were separate boxes which rolled film and recorded an optical soundtrack and was used just liike a tape recorder. The optical track was later mated to the final film negative to strike release prints. Synchronisation was achieved by using AC motors in cameras and audio recorders driven by a common source. My understanding was that variable density recording was by using a galvanometer which rocked a mirror instead of a display needle on a gauge, disturbing the direction of a beam of light. There may have been a fine slot aperture and the mirror and light beam may have been larger than the film track itself and scaled to the area of the track using a lens. My understanding of variable area recording is that there was a light emitting device which was similar to the very old visual recording level green displays on old tape recorders. It was some kind of discharge tube. The length of the band of light varied with audio level. Such a display may have been scaled to film track width via lenses and maybe narrowed by a transverse slot aperture to improve higher audio frequency response. Calibrating and setting levels must have been a nightmare but there may have been a live-viewing method for calibrating. Some of the old tech was large and brutally heavy. If anyone has more definite information and can correct my comments, please do so.
  8. 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.
  9. 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
  10. 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.
  11. 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.
  12. 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.
  13. 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.
  14. 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.
  15. 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.
  16. 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.
  17. 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.
  18. 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.
  19. 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.
  20. A good outcome then. I hope I did not send you off on dead-ends with the first few responses.
  21. 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.
  22. 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.
  23. I just got locked out again. further to the above. Before you go messing with the clutch tension, check those little felt pads to see if they have become shiny with contamination. If they have, you will feel them squeal under your fingers as you attempt to spin the white nylon wheel. Be very careful not to bed or pull on that yoke or you will ruin it. It will probably ne sufficient to clean them by wetting a piece of paper with isopropyl alcohol and easing the paper back and forth between the pad and the wheel in the same and reverse direction of the rotation. Don't try any adjustments until that alcohol has had a chance to dry off. If the felt has become polished and squealy, then the texture of the paper may roughen it up sufficiently. Do not try roughening the white wheel. You'll only bugger it up for good. Do not use any sort of abrasive to soften the felt. It will remain in the felt and ruin the polished surface of the white wheel. Be careful dressing the felt. It may pull off from the yoke if you apply pressure to the yoke. Just let it do its thing from the clutch tension pushing it not by adding pressure. It is does come off, you will find that toluene-based contact adhesive will re-attach it successfully. Just use a little smear on the felt and the metal tab and don't let it soak or press into the felt. Again, wait for better brains than mine to contribute, preferably from the ARRI service manual.
  24. Furthur to the above, I had a look at your video and I think I understand the clutch system. It is similar to that of old tape reel-to-reel tape recorders, old analogue and early pre-servo drive digital video cameras. The amount of pressure upon those little felt brake pads which push against the nylon wheels appears to be determined by a common clutch on the rocking yoke. There appears to be a diaphragm spring with spokes at the pivot point of that rocking yoke. It is too hard for me to see in your video on my computer but my bet is on there being an adjustment screw in the centre of that rocking yoke's spoked diaphragm spring. Clever ARRI because it is a system which historically has been very reliable. That diaphragm spring likely has a friction disk beneath it. Now this is where it will get tricky. ARRI servicemen probably used a tension gauge to measure the resistance of that clutch. If you go taking it all apart without counting rotations of an adjustment screw or whatever, you could be on a ride to the hell of frustration.There may be a very narrow margin between too loose and too tight. If you can, get somebody to video your adjustment efforts so you can return to go. The clutch may be gummy and incapable of adjustment to a consistent tension. If you are lucky, then backing off the tension in quarter turn increments may get you what you want.
  25. Something went pearshaped when editing the previous response so here is another try. The ARRI is very likely different however in loading your magazines, it is possible for the film to pass on the wrong side of an outfeeding roller. This can happen with a CP16 magazine's light trap roller. The CP16 camera will tolerate it but also may scratch the film. I observed that you were dragging on the film to action the camera motion. You will damage the film as the gearing becomes an increase drive. It is a reduction drive when powered by the camera motor. If the film is walking off the side of a sprocket then what may be happening is the sprocket itself bending off-axis due to an overload. The bend may not be in the sprocket shaft or its bearings although if they are worn, then this is possible. there may be flexing of the magazine's structure under an overload state which forces the sprocket shaft off-axis. If that is happening, what then is causing that overload state? Is the film passing on the wrong side of a roller of sprocket? Is the film loop within the camera too short and pulling up tight on the infeed or outfeed sprockets, imposijng an overload, bending the sprocket/shaft/magazine case off axis and walking off? Are the clutches on the magazine spool axles adjusted too tight or have become contaminated with oil and become grabby? - I am assuming that the ARRI magazines use a clutch on the take-up spool axle or underneath a driven gear. There may also be a clutch on the in-feed spool axle it the driven gear if the camera is capable of reveerse operation. While the rotational speed of the transport sprockets remains constant with the camera speed, the take-up spool must rotate at varying speed to compensate for the roll of film becoming wider and by necessity must turn increasingly slower. In the CP16, the magazine is driven by two belts, one an elastic belt which can slip before film is broken and another cogbelt. In the event of a lockup, the worst that can happen is to wipe the little teeth off the cogbelt. The ARRI has a gear system which will not so easily forgive an overtight or jammed clutch. It will bog and eventually ruin the electric motor. The narrow magazine gears may warp and skip teeth which will ruin them soon enough. I have no idea how the film tension is adjusted with the clutches on the ARRI. As I mentioned above, they may be on the magazine's spool axles or may be inside or behind the driven gears. If they are on the axles like the CP16, then the adjustment will be a threaded nut or wheel on the axle shaft, which pulls a flat disk down onto a short coiled spring which pushes against a clutch plate. The clutch plate may be free-sliding on the shaft with a key or spline to rotate it or a diaphragm spring which does the same job s the coil spring and plate. It will look like a really skinny wide washer and may have holes or spokes in it. In both systems, the threaded wheel or nut will be secured by a small grub screw which binds it to the axle shaft and hold the adjustment until wear makes another adjustment necessary. The friction material ay be a thin phenolic disk or felt. If contaminated by oil wicking out from the shaft bearing, the phenolic disk will simply slip easier and lose tension. The felt disk may become skippy, alternately slipping then gripping hard. This will affect the speed stability and in extreme conditions may cause varying exposure of the film as the transport stutters. Depending upon the direction of rotation and thread being either clockwise or anticlockwise, if that grub screw loosens, the clutch adjustment may self-tighten or self-loosen. If the clutch self-loosens, the take-up spool will stop winding the film which will gather up inside the camera and jam. If it self-tightens, then the tension on the film will increase and loading on the geardriven sprocket will increase and cause the issues you are having. If the clutch tension is to strong, then the film will wind on very tight and may cinch the emulsion causing short vertical scratches. If the wind is too loose, then it will fall apart like a roll of toilet paper off the plastic core when you try to extract the roll and send you insane trying to wind it back on. Knowing just how particular ARRI was with precison engineering and how well thought out the film drive itself is, there may be user-adjustable knobs on the centres of the take-up and infeed centres on the outside of the magazine to fine tune the clutch adjustments. However I am really only guessing here. Wait for better brains than mine to contribute advice based on the actual service manual for the camera.
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