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Scratch test results....


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#1 Stephen Perera

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Posted 17 October 2017 - 10:12 AM

I have dummy film and I practice loading etc and I am wondering what I need to look out for in a proper scratch test when the time comes.....

 

1. Scratches or marks on the emulsion side only? (yellow side)

2. What if there are 'rubbing' marks on the other 'dark' side? or should there be NOTHING on either side?

 

In other words what should I look out for?


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#2 Tyler Purcell

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Posted 17 October 2017 - 01:02 PM

For 16mm I run 50ft or so through the camera. Then take it out and put it on my rewinds. I'm looking for anything noticeable in the emulsion or remjet.

If I don't see anything during the rewind process, I'll re-load the film and do it again. I'll do it 3 times and if there is nothing after 3, then the camera/magazine should be fine. If I get something within those 3 times, then I stop and try to figure out where it came from.

I know this technique is excessive, but I really like to know the weak spots of the camera and usually you won't get anything after one or two run throughs on the same roll.

Honestly, my XTR hasn't scratched shit, ever. I have a s16 dummy roll that I use for scratch tests and it looks brand new after loading it 50 times for training students. Pretty amazing!
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#3 Stephen Perera

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Posted 18 October 2017 - 08:23 AM

thanks as usual Tyler...this is my dummy film...been used countless times.....I'm wondering what this tells me.....I can't see 'scratches' as such.....

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  • 16mm_film_marks.jpg

Edited by Stephen Perera, 18 October 2017 - 08:30 AM.

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#4 Stephen Perera

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Posted 18 October 2017 - 08:31 AM

..and this one....

 

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#5 Dom Jaeger

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Posted 18 October 2017 - 02:41 PM

I really don't think you need to waste 50 ft of film or do it 3 times. If the camera and mag are clean you can run 10 or so feet through, and if there is something that will cause a scratch it should show up. If the camera hasn't scratched after 10 ft why would it start after 50, or 150?

If you keep running the same piece of film through again and again it will start to scuff, but that doesn't mean the camera is scratching. It's more likely due to dust or dirt having contaminated the dummy roll and then getting caught in the gate or pressure plate. For scratch testing you need to use a pristine piece of fresh film.
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#6 Gregg MacPherson

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Posted 18 October 2017 - 02:43 PM


 


Stephen, that film is worn and dirty.  You need some clean,  unused stock for the scratch test.  Old expired film can be fine,  but bear in mind that if the perf pitch has shrunk and or the lubrication is compromised it may sound different,  noisier.

 

EDIT: Dom's post arrived while I wrote...


Edited by Gregg MacPherson, 18 October 2017 - 02:45 PM.

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#7 Tyler Purcell

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Posted 18 October 2017 - 03:24 PM

thanks as usual Tyler...this is my dummy film...been used countless times.....I'm wondering what this tells me.....I can't see 'scratches' as such.....


Yea unused film is important.

Let me say that I teach people how to load pretty much weekly when my cameras leave on rentals. I've run the same few rolls through my camera's dozens of times and none of them have anything like those marks. In fact, I just looked at one last night as I was training someone and rewound it and the emulsion side looked brand new, nothing on it what so ever, even though the remjet had some very light sinch marks on it.

One run of 10 ft doesn't do much in my opinion. If something is wrong, you gotta keep reloading the camera and running it, especially with cameras like the XTR where the loading is done in magazine and you can't see the loops. Every time you re-load it will be slightly different and other issues may pop up that you didn't catch the first time around. With cameras you thread inside the body, it's a lot easier to get it identical every time because you can see the loops. I'm really thinking more of scratches caused by the magazine then anything else at that point.

I also do my testing with super old (10 - 20 years) junk film. So the idea you can't use old (unused/sealed) film is bogus.
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#8 Dom Jaeger

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Posted 18 October 2017 - 04:13 PM

So.. You never get scratches with your flawless XTR, but still feel it necessary to tell others to waste 50 feet and run the film through 3 times because .. Why again? The film runs differently through the mag each time? Hmm. Sounds like a crock to me.

I used to scratch test cameras for a rental house, I used about 10 ft each time, and if nothing showed up the camera went out. Never had an issue.

You can use expired film for scratch tests, but if you wanted to check the noise, shrinkage can make a camera sound louder than fresh film. It's worse with pin registered cameras like SRs.

Stephen's dummy roll is pretty scratched up, but like I said, you can't really make a judgement about the camera because it could be dirt on the film rather than an issue with the camera itself.
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#9 Stephen Perera

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Posted 18 October 2017 - 04:36 PM

Thanks for all the tips as usual and yes fresh film is the answer this roll ihas had its day....
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#10 Tyler Purcell

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Posted 18 October 2017 - 05:24 PM

So.. You never get scratches with your flawless XTR, but still feel it necessary to tell others to waste 50 feet and run the film through 3 times because .. Why again? The film runs differently through the mag each time? Hmm. Sounds like a crock to me.


Well it ain't. I don't send nothin' to nobody without re-loading at least 3 times.

Why? Because the film will never be in the same place when you put the magazine on the back of the camera. The upper or bottom loop, maybe bigger or smaller, even by 1 perf and the camera will work/sound fine, but since YOU CAN'T SEE THE LOOPS then you don't know?

This is why when rental houses send out a magazine with 10 feet of film in it, but every roll the customer shot is scratched, it gets me pissed off. I've heard this happening to friends of mine, through reputable rental houses and it's never going to happen to me. It may sound "excessive" but if you TRULY wanna know if your camera will scratch film... ever, ya can't just run 10 feet through it and say "ok all done".

We don't have the luxury to re-shoot things because the camera wasn't perfect. Again, this goes back to the "check the gate" discussion and why I've NEVER had a hair in a 16mm or 35mm gate in my entire life. Cuz I test the living shit out of the gear I use and I keep it clean. When I'm at Panavision renting a camera, I bring a roll of film with me and run the entire roll through the camera at least 2 times, maybe even more. I'll then go home and rewind it to check for anything and only then is it "approved" for use on any prodution I'm involved with.

Wanna know something else? My stuff comes out perfect every time. It's only been some technical hiccups due to over-sized rolls that have given me some issues this year.
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#11 Dom Jaeger

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Posted 18 October 2017 - 07:31 PM

Well you can check your cameras wearing a clown suit and chanting mantras if you like, it doesn't mean that's what made your footage come out perfect. Nothing you're saying changes the fact that your techniques are not what other more experienced people have been doing for decades. You have no idea what caused the scratching from the "stories" of your friends, or whether it was a rental house mistake. Keeping the camera and mags clean is the best way to prevent scratches, if there was a burr causing "every roll the customer shot" to be scratched it would show up in the first 10 ft. Presumably in this story it wasn't a "shifting loop" mag issue either if it happened on every mag. Much more likely to be a rookie loading error. An experienced operater would notice the build up of film dust if the entire first roll had been scratched and do a quick scratch test before shooting the rest of the rolls.

 

There's nothing wrong with being meticulous, I'm just saying 50ft for a scratch test is a waste of film, with no added benefit. What changes after 10ft have passed through to warrant shooting 5 times as much? Putting a dummy roll through is a good idea to check for any transport or other camera issues, no argument there, but a scratch test should use fresh film that has never been through a camera, to avoid introducing any contaminants that might lead you to think it's the camera that is scratching rather than the dirt that got introduced. In this way, you can have a dummy roll for camera testing/loading practice, and an unused roll that you can use 10 ft at a time to check for scratching.


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