my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Strong Millenium heat shield/shutter contact (Page 1)

This topic comprises 3 pages: 1  2  3

Author Topic: Strong Millenium heat shield/shutter contact Bryan M. Montgomery Film Handler Posts: 47 From: Chillicothe, Ohio Registered: Jul 2007 posted 10-23-2007 12:49 AM                        Some of you have probably experienced the ticking, and then the eventual grinding of the heatshield as it contacts the shutter inside the cramped shutter box of the millenium projectors. I've tried many things, including taking bolt cutters last Thurs. to the heat shield to prevent this. Does anyone have any tips or ideas I havent tried?  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 10-23-2007 03:58 AM                     Take out that front "heat shield" (actually, it's called a light baffle) and your noise will go away and your light will be brighter... They're all gone out of my Mils and PR-1050's -Monte  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 10-23-2007 06:53 AM                     Would that be safe on the film with the larger lamps?  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 10-23-2007 01:29 PM                     Hi Ken - I did it at a Drive-In on a PR-1014 with a CFS console behind it having a 4500w bulb inside .. and it did brighten up the imagery some. And the film temperature coming out of the gate (water cooled) was the same. The heat comes from from the entire beam, but your main light source from the mirror is actually from the outer edges of the mirror. Thus, the baffles actually cut down some of that edge reflected light causing less light to enter the aperture. What those two baffles "supposed" to do is to keep the light from "crawling" around the edge of the shutter blades and causing excess flicker, since the blades are so close to the aperture and you don't have the large shutter blade wings like with the older projectors and the Centurys (this is where the early Christie 35 kinda goofed up with that little 'bowtie' shutter blade) that can effectively cut the light, but even then, you still get a little bit of edge "light crawl" with the Centurys. thx-Monte  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 10-23-2007 06:23 PM                        Stupid question: why does the size of the shutter matter? The Century shutter is physically larger than the PR-1014 shutter, but I can't tell the difference in image quality on screen (assuming similiar lenses, etc.). Am I missing something?  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 10-23-2007 06:43 PM                       FWIW, the diameter of the shutter has to be large enough to cover the aperture entirely. There were some Century shutters out there in the early 80s that weren't quite large enough around, so the light leaked around the edge of the blade. This manifested itself as a travel ghost that couldn't be eliminated. Generally speaking, the closer the shutter is to the aperture, the quicker it can blank the light, and the narrower the blades can conceivably be made (not necessarily the diameter, though) - resulting in higher light transmission  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 10-23-2007 08:14 PM                     Scott, Shutter diameter translates into shutter velocity (linear) which translates into potential brightness improvements and reduced perceived flicker. While the angular velocity of a smaller shutter will be the same, the linear velocity is a function of the angular velocity multiplied by the radius of the shutter. A Christie bow-tie shutter is annoying to watch...very flickery as the shutter is almost always closing or opening the light path. With a single wing shutter, the angular velocity is doubled, which is effectively like doubling the radius of a double wing shutter. I forget if the christie blade is 4 or 5 inches in diameter...as such its single wing version performs a little worse than Century's shutter which is nearly 12 inches in diamter (11" and change). Simplex's conical shutter cuts the aperture more evenly than the Century or Christie style. As such, the Simplex has a better chance at a more uniform image illumination. Steve  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 10-23-2007 08:39 PM                        Tim and Steve--thanks! So, the "ideal" machine would have the shutter with the highest linear velocity (all other things being equal)? Where do double-shutter machines fit into this? (Is there such a thing as a double-shutter Simplex, not counting the front-shutter Super and E7 variants?) Related question: what is it about Kinoton projectors that makes the image look so great? Is it just a steadier movement, or is there some other magic in the shutter design or elsewhere? Unlike Simplex vs. Century, I can definitely tell the difference on screen between Kinoton and everything else...not sure why. I have never dealt with Christie projectors and can't comment on their image quality. From what I can tell, this is probably a good thing.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 10-23-2007 09:03 PM                     quote: Steve Guttag Simplex's conical shutter cuts the aperture more evenly than the Century or Christie style. As such, the Simplex has a better chance at a more uniform image illumination. I don't quite agree with that line. In fact it has do to with both shutter velocity and working distance from the film plane. In the Simplex the shutter is about 1.5" from the film plane... cutting off a bit larger diameter cone of light but the large diameter shutter gives a decent velocity within the aperature opening itself. In the Christie the shutter is about .7" back from the film plane... you could amputate your finger! So being closer the Christie is cutting a smaller cone of light but with a smaller diameter shutter it doesn't have the velocity of the Simplex... thats the main reason Christie stepped it up to double speed with a single blade. With the Christie shutter closer to the film plane than the Simplex and running at double speed it translates to roughly the same velocity as the larger diameter Simplex blade and as a result the Christie has more or less the exact same light efficiency as the Simplex. Scott, Christies can put out great images. You have the same basic star and cam that is in the X-L combined with a long curved gate with upper AND lower lateral guide rollers. Regarding Monte's removal of the inner light shield... The shutter blade is going to be sinking ALOT more heat and the outer shutter bearing isn't going to like that over the long haul! Mark  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 10-23-2007 11:48 PM                     Thus, going back to the original question of the light baffle running into the back of the shutter blade - and if one doesn't want to do this mod - is to loosen the shutter blade and to see if it can be pushed back a bit, or loosen up the light baffle bracket screws to see if the baffle can be moved back a bit. If you got a bouncy shutter blade, then it could be a bearing problem that needs replacing ..  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 10-24-2007 09:29 AM                     Monte, What I do sometimes is to mount that baffle on the back side of the L bracket that it normally mounts to the front of. This affords alot more clearance between it and the shutter blade. If it gets warpped its also a very inexpensive part to replace... less than 20 dollars. I always kep them in the light path!! Mark  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 10-24-2007 02:12 PM                     Thx Mark. Yea, found that out the hard way when th two baffle mounting screws came loose and the baffle leaned forward into the shutter and froze the projector up. Busted up the shutter, and had to replace two vertical shaft gears let alone rebuild the shutter drive assembly...  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 10-24-2007 05:23 PM                     The shutter distance to the aperture has its ups and downs...while it is cutting a smaller cone of light, it is closer to the focal plane which makes the transition more visble...it make the Christie bow tie shutter all that much more annoying (it really is a horrible thing to sit through, in my opinion). Mark not agreeing with the method of cutting the aperature aside...it is a fact none the less. The Simplex (conical) shutter will cut the aperture square, or more square, than either Century or Christie's bow-tie. Turn the machines over by hand and look right down the lens receiver at the aperture and see how the various shutters block and unblock the aperture...some do it better than others. As to Kinoton...their mechanical machines have long since used a single wing largish conicalish shutter (we not so conical but angled...the AA2 shutter has a slight conicalness to it). As such, it is spinning at twice the angular velocity of a standard shutter but due to its larger radius, its linear velocity is also great there. This velocity means for a faster opening/closing off of the light as well as their ability to use a greater than 50% shutter without ghosting. Their "E" projectors use a bow-tie shutter, angled (except for the FP75) and its velocity varies based on film speed. As such, they don't tend to look identical between a mechanical and a "E" projector. But then again, the "E" projector is notably steadier too so you are going to get a different look there. Note, the steadiness of the projector does not affect the flicker or brightness, but it does improve image resolution as you eye will see more detail rather than using persistance of vision to morph an unsteady image into a soft appearing one. Double shutters are another means to increase blade velocity. By adding the second shutter (counter-rotating) you double the linear velocity of the blade. This is most often used to increase light output. By making each blade smaller (less blade, but same radius), you effectively increase the "open" time so that the average light level is increased. The disadvantage to this method is that the center of the image is the last to close and first to open...as such, it will induce a hot-spot. I find they also tend to have a bit of a pulsating light to them as well. Steve  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 10-24-2007 06:56 PM                     Steve, The bow tie was obsolete well over 10 years ago on the P35GP machine and I don't know of a single one still being used although I do have a box full of them. is I will grant you that the conical is much faster cutoff than the bow tie... but lets compare apples and apples and not mislead everyone here. Compare the now ages old and still current single blade Christie shutter and the Simplex conical shutter and you'll find the cutoff angles almost identical as well as the light efficiency of each. Also the diameter of the cone of light you are cutting off has as much to do with efficiency as does the distance from the film plane. You can cut a smaller cone of light much faster and be able to use a smaller cutoff blade and so on and so forth... Sorry, I can't get around the laws of physics but if you can please enlightn us on how you do it. Thanks, Mark  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 10-24-2007 07:45 PM                       If anyone were to read this post a few years down the road we will all look mighty silly arguing about this while D-Cinema takes over. The main advantage of the Simplex is the closeness of the shutter to the film plane. This makes for a more precise light cutoff (I.E. the shadow of the blade is in focus with the film plane) vs. Century and way less chance for stray light to get around the shutter. This is similar in effect to projectors with apertures close to the film plane vs. those further back. The aperture shadow is much fuzzier or the transition from black to white take s more room on a Century vs. an XL? I doubt even the double speed shutter Christie is as efficient as the XL or the DP70, but as long as we are playing this how many angels can dance of the head of a pin sort of discussion, someone who knows how should do the theoretical and practical efficiency tests.  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 3 pages: 1  2  3

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.