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I obtained a Century C with two aperture plates. One measures 0.825 x 0.598, so I know that it is for Academy 1.375:1. But the other measures about 0.734 x 0.710. It has the same optical center as the Academy plate. What format could this have been for? I could file out the width to make it an anamorphic 2.39 plate, which I need, but I'm curious what it was used for. I found it being used in another Century C. And if I do file it wider, how would I file that much off and keep the edges straight? Thanks.
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FilmTech has plates if you prefer not to file those mystery ones. At that size I would guess a version of scope 2.35 or scope 2.0 was the intent?
Remember plates/lenses/screens are generally a set after filing. So I would assume those "found" ones are not perfect for you anyway, if you can turn it into a useful one due to it being smaller than needed, go for it.
I recently did some plates starting from blanks, I found wider files, perhaps angled until they match the width of the opening, useful for removing bulk material while trying to maintain the line.
But the general rule is just to go real slow removing a tiny bit at a time, have your masking preset on screen to your target opening, ideally using the film but a good SMPTE 35PA reference image can also work to set your masking. Then just file up to your masking with no film in the gate. If your masking is movable you can blow it out after and check how straight your lines ended up, but at that point it is often too late to do much touch up without putting more image on the masking.
Once you are into the precision range, a diamond nail file works pretty well too if you don't have one of the more intentional plate files.Last edited by Ryan Gallagher; 11-23-2024, 08:53 AM. -
Also if you haven't encountered a list yet, here are the plate openings from the OEM century JJ manual. Note I'm not sure if the plates themselves were equivalent to those in Century-C units.
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Thanks Ryan for the explanation and suggestions! This will be for a home cinema with an 8 to 10 foot wide image, so I don't anticipate needing to file or being able to find exact size lenses. I will contact Film-Tech also about the plates -- didn't know that they sold them. Thanks!Comment
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Cheers. For home use I would think standard flat and scope and/or plates filed to the relevant SMPTE 35PA reference lines would suffice as a starting point. 1.33 and 1.66 are nice to have eventually. Undersized prints (which are pretty common) will just expose matte lines, but works fine for home use. If you don't have a ton of keystone or a weird size screen/lens combo... not much call to start from severely undersized plates and file custom ones.Comment
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And a word of caution. Apologies if you are aware. When testing without film in the gate, don't leave the lamp house dowser open for longer than a minute or so, to protect the lens elements from the extra heat, Same principal as when tuning the lamp xyz alignment and field.Comment
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I'm not sure what I will use as a lamp house. I do have access to obtaining an Orcon 1 kW self-contained xenon lamp house, but I'm concerned that it will be too bright for the screen size (although I was thinking that I could stop down the lens or insert a fixed aperture disc and get great corner sharpness). I was aware of the issue with running light through the lens with no film, but is that still an issue using a 1 kW or smaller lamp?
And then I'd need more space, and a heavy iron pedestal to support it. I was thinking of possibly designing an LED lamp house, or finding a 550 W xenon (I have a 500 W slide projector, but not sure how I would adapt that safely). I could also do incandescent, but then the color temperature would be wrong.Comment
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I'm wondering if somehow, that old aperture plate that Adam has might have been made for some compromised version of the old format known a "Superscope". That process was brought out around 1954 to be a low-budget competitor to CinemaScope. To keep it "legal", they had to somewhat differentiate the process from the specifications of CinemaScope, so they devised a projection aperture that was defined as 0.715 x 0.715" and, using a 2X squeeze factor, the result would be a 2:1 aspect ratio on screen. (There were also some bulky Superscope projector attachment anamorphic lenses that had a variable squeeze factor, accomplished using a crank handle on the top.)
Your mystery plate is oddly close (but no cigar.) The original Superscope hasn't been used as an originating format since about 1960, so this is really just speculation on my part, but the similarity in dimensions caught my eye. Never heard of Superscope (not to be confused with "Super 35")? Take a look here: https://www.widescreenmuseum.com/widescreen/wingss1.htm . Another one is here: https://www.widescreenmuseum.com/wid...pespecs.htm
One other comment: If you do file out that plate to bring it to some currently-used projection ratio, you'll save yourself some headaches if you obtain a so-called "safe edge" file to do the filing. These files only have cutting edges on the wider (or "flat") side of the file. The edges are not a cutting surface, so you won't discover yourself accidentally filing in 2 dimensions at once ...Comment
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Definitely agree. That is one thing those nail files have going for them too, if you don’t have anything better handy.Originally posted by Paul H. Rayton View Post
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Thanks all for all the input! The only thing close appears to be Superscope. I found a comprehensive list of film formats on Wikipedia: https://en.wikipedia.org/wiki/List_o...e_film_formats
Ryan or others, do you have any comments on the questions in my previous post in this thread (I know they are a little off-topic)?:
1) Would an Orcon 1 kW self-contained xenon lamp house be way too bright for a home theatre with max 10' wide image?
2) Is running a projector with the dowser open and no film in the gate a problem for the lens, even with a 1 kW or smaller lamp?Comment
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Chances are that you'll never see a movie in that format, whatever it actually is. You've got aperture plates for all the formats you plan to use. Right? That aperture plate is extra. Why not keep it around, just in case. If you ever need another aperture, you might be able to recut it... maybe...
As to shining bright light through a lens, that all depends. Newer lenses that don't use cement between the elements can withstand more heat that cemented ones. If you are using newer lenses, you'll have less to worry about. (Not nothing but LESS.)
I never worked on projectors, leaving an open gate for more than a minute or two, closing the manual dowser for another minute before continuing. Yes, if you overheat a lens, modern or the old, cemented type, you WILL destroy it! You can melt the cement or plastic components inside the lens. You can crack or deform lens elements. You could burn away the anti-reflection coating on the surface of the glass. If you REALLY screw up, you might even damage the projector, itself.
Luckily, taking reasonable precaution, I have never seen a lens actually get damaged by leaving the dowser open with the lamp on. I have even seen a couple of times when, somehow, the projector was left running with the dowser open for fifteen, twenty minutes or more. It usually happens when somebody starts the projector manually, without automation, then forgets to come back before the film runs out.
Just be mindful and use common sense and, with modern, un-cemented lenses, I don't think you'll have a problem.
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The only other plate that I currently have is for Academy 1.375:1. I'm still looking for plates for wide (1.85:1) and scope (2.39:1) (for Century C). Thanks!Comment
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Randy answered your lens protection question I believe. Unfortunately I only have experience with Strong lamphouses, someone else with more experience in the low wattage houses will have to chime in relevant to home cinema use. I'm sure there is some formula to ballpark your needed wattage relative to the throw and screen size (and gain values) to give you some tuning headroom relative to the 16fl +/- 2 foot lamberts in the corners standard.Originally posted by Adam Liberman View PostComment
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