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Those "rounded" holes nevertheless have sharp corners, in contrast to those "straight" holes.
Last edited by AgX; 02-20-2013 at 10:12 AM. Click to view previous post history.
Reason: wording: corners instead of edges
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As AgX indicates, the "rounded" (B&H) holes have two flat sides which join abruptly, with no radius. The KS (Kodak Standard) has 4 radiused corners which should be better with respect to stress raisers. In practical terms, though, I think either style works pretty well.
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I have shot hundreds of feet of cine film in various cameras and never had a problem with either registration or film transport.
A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.
~Antoine de Saint-Exupery
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 Originally Posted by grobbit
Those Orwo films at 90USD for 400ft are a great deal, just wish there was a UK distributor,
Did you check the filmotec.de web site? http://www.filmotec.de/?page_id=353&lang=en looks like their is a sales contact in the UK. They may want to direct ship from germany, but that is not as big a deal as it used to be within Europe as I understand. perhaps one of the other eurpean delers could ship to you.
Charles MacDonald
aa508@ncf.ca
I still live just beyond the fringe in Stittsville
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 Originally Posted by polyglot
Sharp internal corners are where stresses get focused and tears begin. Rounded sprocket holes spread the load more uniformly and reduce the probability of tearing, especially at higher frame rates.
Yes, it is a long history and as one person said a lot of standrds conferences.
Edison used round perfs, but they caused problems making prints particularly when the (Nitrate) film shurnk. Bell and Howell made a perf with rounded ends and stright sides, (now called BH perf or N (Negative) perf, but the sharp transitions would sometimes crack at high speeds. Kodak made the perfs still photographers are familar with to avoid this wih all sides stright and rounded corners. The "height" of the hole is a bit higher however. These are called KS (Kodak Standrd) or P (positive).
Just to allow for the fact that more modern films shrink less than the nitrate ones did, it was found useful to space the Negative perfs a bit (4 ten thousands) closer than the positive perfs to avoid slippage in the printer. so you generaly find Movie negative with a "BH-1866" perf while positive print film is supplied as KS-1870, as is most film inteded for still camera use. I have never heard of a still camera that is bothered by the difference, and since still cameras one use the perfs once, the risk of the BH perf causing a rip is rather remote. A movie camera would become very noisy if trying to use the wrong perf pitch.
there have been other specs, the Duvray-Howell DH (like a Kodak but with a bell and howell hight, CS (cinemascope- AKA Fox Holes) with smaller perfs to allow room for magnetic soundtracks.
As for why the 100 ft rolls are not standrd items any more, remeber that 35mm Movie film runs at 90 feet a minute, so a 100 ft load is really only useful for some special applications like a "crash Camera" that is mounted in harms way. They used to rig up eyemo cameras which take a 100 ft spool for car crashes and the like. If you order a lot of film Kodak will "finish to order" a lot of stocks but the price and Minimum order is a lot higher then for warehouse items.
If you can find some friends that want to split a roll, some of the local movie labs will re-spool film to smaller rolls for a few bucks a roll. if you can't supply empty cans they will probaly want a couple more bucks for a can/bag/core combination. They are most likly to use a 2 inch core. If you say that you are not using the editing numbers they don't have to rewind the rolls to put them "start end out" so that might save them a few minutes.
Charles MacDonald
aa508@ncf.ca
I still live just beyond the fringe in Stittsville
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I should metion that if you were to want to do a lot of switching sizes on film, a set of "rewinds" and a 35mm "split reel" would be useful. The split reel as the name implies comes apart with the two flanges attched to a center which will accept a 2 or 3 inch core. You can then wind the film off in the dark onto another roll using a set of rewinds. For my puroposes I generaly just use a spool on the other side, as it is hard to justify the cost of two split reels. I saved several 35mm spools from the Legacy Pro Bulk Film. (they spools are somecalled "daylight spools" or "Eyemo" spools if you are searching online to find them. You need rewinds that have a long enough spindle to accept 35mm rolls, some only are long enough for 16mm.
Charles MacDonald
aa508@ncf.ca
I still live just beyond the fringe in Stittsville
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Double-X 100' rolls Special Order??
See all this talk and now I want to shoot on double x just to see what it's like. But I don't do bulk loading lol. And mostly shoot 120 (some 35mm though)So what's a boy to do...? Lol
~Stone
Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk
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 Originally Posted by cmacd123
Just to allow for the fact that more modern films shrink less than the nitrate ones did, it was found useful to space the Negative perfs a bit (4 ten thousands) closer than the positive perfs to avoid slippage in the printer. so you generaly find Movie negative with a "BH-1866" perf while positive print film is supplied as KS-1870, as is most film inteded for still camera use.
Any change in degree of shrinkage affects both, the negative and the print film. The idea of using a larger hole distance on print film is due to films whilst copying running over a drum as sandwhich with the print film being the outer one.
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 Originally Posted by AgX
Any change in degree of shrinkage affects both, the negative and the print film. The idea of using a larger hole distance on print film is due to films whilst copying running over a drum as sandwhich with the print film being the outer one.
exactly, in the Nitrate days the shrinkage of the negative created the difference "automagicaly" - once they switched to low shrink stocks they had to "Build it in"
Charles MacDonald
aa508@ncf.ca
I still live just beyond the fringe in Stittsville
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