Jump to content

Dom Jaeger

Basic Member
  • Content Count

    1987
  • Joined

  • Last visited

  • Days Won

    60

Dom Jaeger last won the day on March 13

Dom Jaeger had the most liked content!

Community Reputation

273 Excellent

About Dom Jaeger

  • Rank

Profile Information

  • Occupation
    Other
  • Location
    Melbourne, Australia
  • Specialties
    Cinema camera and lens technician

Contact Methods

  • Website URL
    http://cinetinker.blogspot.com.au

Recent Profile Visitors

39974 profile views
  1. I haven't worked on Cartoni heads, but in other heads play like that is often due to wear which requires replacement parts. Given that these heads are long discontinued, a repairer may find it hard to source parts. You could try asking somewhere like Visual Products, but I suspect it might be easier to just invest in another head. I don't think these are very expensive heads are they? I don't know if a newer Cartoni head will fit to the same tripod, or if you need to replace the whole thing. It's worth checking that the play isn't simply a loose fitting somewhere, such as where the head mounts to the tripod. Sometimes a loose rosette where the pan handle attaches can feel like play in the head itself.
  2. Shooting 2x anamorphic for a 16:9 aspect ratio means you will be cropping down to 8:9, or about 0.9:1. Even if the lenses cover the full height of the sensor, you would need to crop the full 6K frame of 1.5:1 (3:2) down to 0.9:1 which is a significant loss, a 3/5 reduction in width. 3/5 of 6K is 3.6K. It’s possible you may have to crop in even more if the lenses don’t fully cover.
  3. Have you followed all the set up procedures as detailed in the manual? Things like focus and iris settings? Is it like this: http://movie-mobile.com.preview8.logate.co.il/userfiles/downloads7_15_file_url.PDF Diagnosing this sort of vague issue is virtually impossible.. is the monitor compatible, are the settings correct, cables ok, tap set up correct, do you have a split prism diverting some light from the viewfinder etc? If it’s an electrical fault with the tap itself you’re probably better off sourcing another one.
  4. Panavision have modified some of their probe and periscope lenses to work with large format using the SP70 mount. I recall reading that there were Imax periscopes made for Dunkirk, not sure where they are now. Arri must have options for the Alexa 65 or LF? I’m sure other manufacturers will step up in time if there’s a demand, but it’s still a small market.
  5. It's actually physics, not theory or witchcraft! A filter placed behind a lens will offset the back-focus by about a third of the filter thickness. In the case of wratten filters, which are usually 0.1mm, that's about 0.03mm difference. I usually collimate lenses to within 0.01mm, and the shorter the focal length the more critical back-focus becomes. So for a 6-66 zoom, an error of 0.03mm will definitely throw the wide end out when filming at maximum aperture. You may focus sharply at 66mm, but as you zoom out, the image will get softer. Now whether you notice this depends on what stop you shoot at, and whether you're shaking the camera about, as Andries mentions. It's also possible that a lens is not perfectly collimated, or that the ground glass depth of the camera isn't exactly set to match the film plane, so even with the internal filter left in place there could be small errors. And of course Super 8 through a wide lens will have a lot of depth of field and natural softness, so gauging whether it's a bit softer than it should be can be tricky. The benefit of removing a crusty old filter probably does more good than the back-focus error introduced does bad. But if you want images as consistently sharp as the format and lens can produce at all f stops, it's best to have the whole shebang checked and adjusted as necessary. As an additional piece of evidence, your honour, to convince Andries that this is not just witchcraft, Bolex mentions in their manuals that placing a filter in the behind-the-lens filter slot will slightly alter the lens focussing. However on a Bolex the filter is in front of the reflex prism, so the alteration to focus happens to both film and viewfinder images. In other words (and as the manual goes on to say), using the reflex viewfinder will adjust the focus automatically. (They were also assuming the use of prime lenses on a turret Bolex, rather than a zoom lens.) By contrast, the reflex mirror on a Beaulieu 4008 is in front of the filter, so removing the filter affects the film plane but not the viewfinder image. So in this case the reflex viewfinder will now be out compared to the film.
  6. It's curious that Hitchcock often mentioned 50mm as having a "natural" perspective that "gives you what your eye sees", but he shot on various formats including silent aperture, Academy and VistaVision, where a 50mm would give different angles of view. It's possible he felt that looking through a viewfinder the magnification of a 50mm seemed to match what his other eye saw, but of course that depends on the magnification of the viewfinder optics too. Most likely I think he was talking about the distortion or sense of depth, as in how a long lens can flatten perspective while a wide angle lens stretches things out and makes spaces seem larger than they are. But again whether a lens is deemed long or wide is a function of the format size, and the distance then determines the perspective. The question of what focal length/format combination (or field of view) mimics human vision is a tricky business. Peripheral vision extends out to about 140 degrees, which you can test by holding your arms out to the sides and while wiggling your fingers bringing your arms slowly forward until you notice the wiggling movement. But our area of sharp focus is only about 10 degrees or less. So where between those extremes do you choose an angle that seems "natural"?
  7. It’s all V mount here in Oz except for when US crews come over and demand all the cameras get swapped over to Gold mount. Luckily our lenses are already marked in feet and we speak passable English so it’s only the road rules where they have to drive on the left side of the road and comply with km/hr speed limits that still confuses them.. 😉
  8. As I mentioned earlier, the N35 1.78 Arri ground glass works on 3 or 4 perf cameras, as detailed in the relevant page of the format guide I linked to. You don't need to mark a custom one up if you can source a N35 1.78 ground glass for the camera. If you can't source one, using a N35 1.85 ground glass is much more sensible than trying to mark 1.78 yourself. It's very hard to get it exactly right, and your margin of error is probably not going to be much better than 1.85 anyway. However, I would again suggest that shooting S35 is a much more reasonable approach for an inexperienced filmmaker attempting 35mm for the first time. That is what most modern cameras will be set up for and S35 1.78 ground glasses will be far more common. The difference in equivalent focal lengths from N35 to S35 is about 1.2 x so a 21mm will be similar in view to Kubrick's 18mm for example. But slavishly copying Kubrick's focal lengths on N35 will not make your film look like Kubrick's films. There is also the fact that older lenses breathed a lot, so for example an 18mm lens changed considerably in field of view from close focus to infinity, and the numbers written on lenses can often be approximations of focal lengths anyway. Each set-up was a unique arrangement of set dimensions, and distances to subjects. Don't get caught up in such technical imaginings when you have yet to shoot a foot of film. The first thing to do is work out what budget you have, and what is possible. Where are you going to source a camera and lenses? You may not have a vast choice in terms of focal lengths and formats, so go with what you can afford and concentrate on the actual film - script, locations, actors etc, rather than technical details that really don't matter so much at this stage. My two cents, feel free to disregard!
  9. Bolex sells them new, but even $600 on ebay is too much. They used to sell for much less but the mirrorless stills crowd discovered C mounts a few years back and prices went through the roof. Wait for an auction where you can buy them for more reasonable prices. Often a complete camera with 3 lenses is the most affordable option, but greedy sellers usually seperate kits and sell the lenses seperately. The earlier non-Macro Switars are almost as good and cheaper.
  10. You won't find an "academy gate" for a 535 or any Arri camera since the 90s. Modern Arris use gate masks on a full aperture gate. You can see them pictured in the format guide I linked to earlier. You re-centre the lens mount very easily on modern Arris by turning the mount 180 degrees. Centring prevents zooms from tracking off to the side, and distortion being more visible on one side than the other, as well as preventing possible vignetting from lenses with a small image circle. Of course Arricams can shoot academy - scope ground glasses only came in N35 so for anamorphic you need to switch to N35. But as mentioned the gate is rarely masked, so shooting academy is basically just recentring the lens and baseplate.
  11. The straight 1.78 ground glass is what you want, the other one has added aspect ratio marks which were useful when people were framing with several display formats in mind (ie 16:9 HD TVs and also older 4:3 screen TVs). As David mentioned, you don't really need to mask the gate, but that is the correct mask if you really want to. You can shoot 1.78 in 3 perf N35, as described in the 3 perf column of the N35 TV 1.78 trans ground glass page. There is a small extended viewing area outside the 1.78 frameline, which is useful to see if a boom or something is about to enter the frame, the grey area is masked. I don't know if Arri still sells all these obscure variations of ground glass, you may need to just use what the camera comes with or what you can find. Shooting N35 to exactly match the view of Kubrick's focal lengths, but then also wanting to frame for the modern 16:9 aspect ratio seems like a futile exercise to me - you're creating hurdles for no real reason. If you have no experience with 35mm, make your first efforts as hassle-free as possible I reckon. S35 1.78 ground glasses will be much easier to find.
  12. Do other Bayonet mount lenses fit OK? Try and check that the lens is not hitting any internal baffles or other things inside the camera mount. The camera doesn't look like it has the old auto-aperture mechanism, but check there is nothing like that preventing the lens from being fitted. (See old manuals like this: http://www.duallcamera.com/Arri 16SR.pdf where they describe fitting steel Bayonet lenses.) As Jean-Louis mentioned, check for any signs of impact or deformation. The lens should clear the mirror, but check that when it is pushed in as far as it will go you can still inch the camera (turning the mirror) without any resistance. If nothing helps you may need to send it to a technician for a proper inspection.
  13. In theory, yes, if you can find a ground glass for the camera. But you will lose a bit of area. Look at Arri's ground glass catalogue and compare N35 1.78 to S35 1.78: http://www.arrirental.com/pdf/format_guide.pdf
  14. Moviecam SL is rated at 25dB, similar to an Arricam LT, and quieter than an Aaton 35III. I wouldn't consider that MOS at all. From an old list of camera weights I have, an SL with 400 ft mag in steadi mode is only about 4 lbs more than the Aaton.
  15. What modern cameras are Academy only? Super 35 was the defacto standard since the 90s, so unless you're talking the 35BL range and older (and many 35BL4s were Super 35 compatible), in my experience most 4 perf cameras are full aperture with an offset PL mount that rotates between Super and Standard. You could put masks in the gate to reduce the aperture, but many people didn't bother and just left the camera exposing the full aperture, since it could be matted later. Switching to Standard was really only done for anamorphic shoots to centre the lens to the Academy frame, but again the gate was often left full aperture. If in doubt, check that the camera has a PL mount with 1 and 2 engraved in the top right and bottom left corners, to indicate Super/Standard positions.
×
×
  • Create New...