chuck colburn

Good morning James, I used the Richter collimator for over thirty years of cine lens and camera repair and manufacturing. It and the Zeiss units are to be found in every rental and manufactures facility. What it does is provide a image of a 1951 airforce resoultion reticle focused at infinity. You can check the accuracy of the collimator by unscrewing the eyepiece and mounting it where the light source would generaly be attached and looking at an object at a distances equalling infinity. We use to use the moon when it was about half full as the terminator provided a sharp image of infinity focus. Then if the reticle and the lunar image were in focus at the same time you knew the collimator was in proper adjustment. Chuck Colburn

Hello Satsuki, The only screw on an Arri S camera that controls how loose or tight the turret is to the camera body is the one in the middle of the turret. This one requires an adjustable pin spanner, or the Arri factory tool to loosen or tighten it. There are very thin shim washers under this screw to adjust for the end play in this assembly. That is to say without the proper shims the turret is either going to be too loose or too tight. Any zoom or other heavy lens (telephotos) requires a lens support if used on a standard Arri (non S/B) type turret mount as the only thing on those type camera mounts holding the lens in are two little spring loaded ears at the back of the turret hole. These were fine when the the camera was first disigned as there were no zoom lenses back then. But even back then a lens support was needed for longer focal length lenses. Heres to a happy new year to all, Chuck Colburn

An the same to you and yours Hal, Your target link is actually what the original siemens star target looked like. I just called the one I found that because I couldn't remember, and probally still can't, how to spell sinusodial. The one advantaged to the one I put up is since the divisions are finer they showup astigmatism and certain other video artifacts easier. But for just focus checks your link would be easier to work with. Plus I like the four little targets around the star. A grouping of these on a board would be good for showing curveture of field also. Here is the link to where I found the target. They have many types for quantifying different aspects of video imaging. http://www.sinepatterns.com/i_Stdrds.htm Chuck Colburn

Merry Christmas Herbert, If you don't already have a test target and you have a printer with your computer print one or more of these, (five is good, one for each corner and one in the center) and mount them on a piece of poster board and side light it from both sides at a 45 degree angle (like on a copy stand). These are called siemens stars and work well with video or cine lenses as it is easy to see the image snap in and out focus. Glossy paper seems to work better but is not mandantory. http://www.sinepatterns.com/images/Sector%20Star.gif Chuck

Hi Bob, A zoom lens inhertently has only three positions in it's focal length range where it can be in absolute proper focus at the film plane. This is it's longest and shortest zoom positions and a position somewhere between these two. This is due to the fact that all zooms suffer from what's called the "S" curve, that is as you zoom from the longest to the shortest focal length the focus moves away from optimum focus one way from the film plane untill you reach that position where it begins to move out of focus to the towards the opppisite side of the film plane. By not starting at the longest focal length you are not going to be able to set up optimum back focus be it either with a moveable back focus adjustment like on some video lenses or by shimming the lens mount in or out as on cine lens or a video lens which does not have a back focus adjustment incorperated in the lens. If there is a problem with the movement of the internal moving groups of optics ( the variator and the compensator ) then no matter what you do to set up back focus ( shimming or setting the back focus adjuster you are not going to have a very functional lens. These types of adjustments need to be done in an optical repair shop that has an optical collimator and/or a thru the lens projector. Anywhow heres to happy holidays and peace, love and understanding for the new year. Chuck Colburn

Hello Herbert, With zooms, set the lens on the LONGEST focal length and focus on your test target (if you have one) or use the front page of a news paper, zoom to the shortest focal length. If the image is soft then adjust the back focus setting if your video lens has one or have your cine lens collimated to the proper flange focal depth. Anyhow repeat the process again to see if you need to readjust the back focus slightly. All things being equal the lens should now hold focus (as good as the particular lens will allow) thru the zoom range. Merry Xmas. Chuck Colburn

I'm sure you don't mean nail polish but nail polish remover which is basicaly acetone with oils in it. A bad thing even if it was reagent grade acetone it will streak up a storm. As the other posts said use a proper lens cleaning fluid on a lens tissue working your way from the center of the lens in a circular motion towards the edge. But first make sure there are no chunks of anything not even dust on the lens by blowing it off first. Use an ear syringe or an inert canned air and a lens brush to remove any foregin substances from the lens surface. Also be carefull of particles that can be lodged in the threaded portion of the front lens cell as they can be wiped onto the lens surface during the cleaning process possibly resulting in scratches. An most important no using your shirt tail for lens cleaning. Chuck

Hello Brian, No your not missing anything, it's just a way to do it by yourself. Besides if you got two people one can just throw the breaker and the other can see when the circut goes dead and yell or communicate with a walkie talkie that "Thats the one". But if your working with an unpowerd circut you need something to feed a signal down the line one way or the other. And then there is the, one licensed electrican $75.00 per hour two electrians..... Anyhow have a very merry Xmas and remeber, no kissing the black wire under the misoltoe. Chuck

Brian here's a site that might help. http://www.contractor-books.com/Circuit_Tracers.htm

You don't need two people. The device is called a Fox and Hound. The Fox sends a signal down the line and the Hound sniffs it out.

Hello Yaron, Depth of field is a function of focal length, f-stop and chosen circle of confusion diameter. Moving the lens away from the film plane only results in an out of focus image. Chuck Colburn

Hi Stephen, No holes should be found. If I remember right the Cooke zooms have a base ring made of steel that a knurled or sloted ring screwed on to. This ring mounted a tube that the various lens mounts ( pl etc. ) attached to. As I said I wanted to leave the basic lens in stock form to allow for different uses. Even then in the late eightes and early nineties these lenses were awfully expensive 20k plus as I recall. I'm glad your happy with the glass and remember to keep the lens cap on when not shooting and no cleaning the front element with your shirt tail. Chuck

Hello Stephen. Sounds like it might be one of the Cookes that I modified for the CP-65 (Showscan) cameras. Was the extender unit attached (screwed onto) to the universal mount threads on the back of the lens? I designed it that way to allow removal of the unit so it could be returned to stock configuration and used on 35mm cameras by attaching the appropiate mount for whatever camera one intended to use it on. The extender unit was used to enlarge the circle of coverage for standard 65mm five perf format. Anyhow the Showscan format, 65mm five perf shot at a standard rate of 60 f.p.s. did not survie for very long so I'm sure you got a lens with few hours of use under it's belt. We hand picked these zooms for this use to get the best quality to start with before adding on the extenders. Chuck Colburn

Good afternoon Lance, Perhaps I spoke too soon. I reread your post and now see that you wish to purchase lenses and related equipment. Since we only made one set of lenses for each of the Showscan cameras I don't think Max at paradisefx would want to sell them off. But who knows I could be mistaken. Anyhow Max might be able to steer you toward some other source. As I said coming from a camera/optical tech. background he knows of which he speaks. Here's their web link if you haven't already looked it up. http://www.paradisefx.com/ Good luck on your project, it sounds like the next best thing to film....lol Seriously I would love to see some footage or at least a frame capture here in this forum. I'm also sure that I'm not alone in that. Chuck Colburn

The Showscan 65mm lenses are rebarrled medium format lenses ranging in focal lengths from 28 to 600mm and two Cooke zooms with 2x extenders behind them making them (if I remember right) 40-120mm and 50 to 500mm. They all rotate in the proper direction on both the focus and iris rings. These lenses and any misc. support items I think are still availble from Paradisefx.com Max Penner can answer any and all questions regarding large format equipment.

If you move the camera flange forward 1mm ( .03937" ) you can kiss reaching infinity focus goodby on any properally collimated lens. An if your using the footage scales on the lenses to follow focus you are going to blow your splits, especially with faster stops. Chuck http://www.cinematography.com/forum2004/st...icons/icon9.gif

I've heard gaffers and carpenters refer to a stinger as a short electrict cord that is one male plug splitting into 3 or 4 or however many female outlets. chuck

Good morning Nathan, That's very clever, probally more accurret than the old way we use to check shutter timing by looking thru the lens port and drawing an x from corner to corner on an exposed frame of film and rocking the shutter back and forth and looking for any film movement before the shutter (mirror) completly covered the apereture. An olden days camera tech, Chuck

What are the lenses?

William. I take it from your reply that it is a straight 10x12 Ang. zoom lens and not one with and intergal finder as part of the lens. Not sure what you mean by a metal piece running from the bottom of the lens. Do you mean the threaded part that screws into the camera body? If you can see threads on the lens mount showing perhaps the lens was cross threaded when last mounted and is now stuck and won't turn either way. If you could post a photo or two myself or one of the other techs on this site might be able to offer some suggestions for removal of the lens. Whatever you do don't get to heavy handed trying to break it lose as the lens mount plates on the R16's are rather thin and you would not want to tweak it. Chuck

Hello William, Since you say it's a R16 then it's a self reflexed camera therefor all you do is unscrew the lens in a counter clockwise direction (when viewed from the front of the camera) and the lens should dismount in about three full turns. If the lens has it's own reflex viewing eyepiece it's mounted to a seperate piece called a "C" cup and the lens is removed by turning the large ring just in front of the silver colored piece atached to the camera in a counter clockwise manner. To remove a "C" cup requires a special wrench refered to as a "T" wrench. Chuck

Hello Nick, So far as being radioactive I don't know about that. Their main use was on a large format roll film camera that was hand held in flying aircraft. As I said you can use most any large still camera format lens for this purpose. There are lots of three to nine hundred mm process type lenses that were used for photo repro work for sale on ebay at cheap prices. These lenses were designed for relatively close working ratios ( 1.1 2.1 3.1 etc. ) and are corrected for flat field and chromatic abberations making them very good for this application. Look under Zeiss, Gorez, Rodenstock etc. Another trick was to mount a sandard focal length lens backwards on a set of bellows. Since you will be working in the video domain you won't even have to calculate expouser times for the bellow extension as you can judge it on the monitor. Chuck

And not just light leaks. If your zoom or any wide angle lenses have been collimated with a gel in place and you shoot with out one your back focus will be off appx. one third the thickness of the gel ( around .0015" ). This is enough of an error to blow a split or an infinity shot with wide angle lenses. Chuck

Hey Tim! Being a camera tech I thought you might like this site. http://www.molyduval.org/ Chuck

Hey Tim, Absolutly use the Arri lubes since you have access to them. Way back when, the only lube one could get from Arri was a little squeeze tube of grease meant for lubing the pull down claw on the 2C cameras. As for Mr. Broda, I have only the highest respect for Axle and for anyone else who was factory trained at any manufactures plant. Regards, Chuck