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Scratch testing and sharpness testing


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#1 Michael Collier

Michael Collier
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Posted 26 September 2006 - 04:52 PM

I have a scratch test I need to do for my new short, and since I have never worked with film before, I just thought I should put a quick post to ask for suggestions.

I will proccess at alphacine in seattle (closest lab to me) and found they can do a minimum of 100' So I figure I can do between 50 and 100 feet and just have them charge me for 100 feet. Now I don't want to telecine, or even have them ship the negs back to me (read my other post where I admit I am $500 over budget right now). They said I can call and ask their tech how the neg looks, see if there are any scratches, and I figured that would be a good chance to test its lens sharpness and calibration.

Here are the tests I have planned:

First backfocus the camera to make sure its set properly, and adjust the diopter in the viewfinder for my eyes.

Run 10 feet on something, preferably outside so I can check if there is a scratch. run 10 feet for both mags to see if either has a problem (slating of course to identify mag so lab can inform me which one is scratching, if any)

Run 10 feet on a sharpness chart (SMPTE standard line resolution chart) focused by tape measurement.

run 10 feet on the same chart, but this time with it focused by eye, so I can see if the GG is aligned with the film plane. (presumably both eye and tape focus should be on the same marking, if not there may be a problem)

then I have up to 60feet I can run on various tests. Are there any that would be useful that the lab can report on from the negative, or should I just worry about saving film at that point.

Also what is typical procedure for downloading such a short roll? Should I try and get some plastic cores to put in the film when unloading it, or just leave it rolled without a core in the can? I don't want a scratch to occur during shipping or handling. any procedural tips on that would be helpful, since this is the first time I have dealt with film. each roll will only be 20-40 feet. (also does anyone have any extra cans, or know where I can get some shipped to ak cheap? for 16mm film)
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#2 grantsmith

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Posted 26 September 2006 - 05:10 PM

Hi Michael,

You dont need to send in film for a scratch test. Just use some gash film, check it dosnt have any scratches and run it through the camera. Open the mag, take out the film and examine it for any scratching. The most important side is the emulsion side. Do this for each mag.

There are two important tests to do.

1) Check focus for each lens. Start of close to your chart and gradually move the camera back, filming and slating each focal distance. Use your tape measure for this and the markings on the lens. Mark each slate with the lens you are testing and the type of lens. The tech guy at the lab will tell you if any of the markings are out or if there are any problems at any distance.

2) A steady test. Film a grid of squares. Centre the viewfinder crosshair on an ege of one. Rewind the film in your changing bag (have a search in the assistants forum or read david elkins' camera assistant book as this is a bit tricky) then make a double exposure of the grid, this time with the crosshair in the centre of a square. When this is developed the tech at the lab can tell if there is any unsteadyness in the camera.

You dont need to worry about cores when downloading the mag (there is a very good topic on the assistants forum on this).

Lab shout give you cans and sheets.

Make sure your sheets are spotless, legible and neet as the lab will treat your film like you treat your sheets (so I get told)

Anyway, I'm not an expert on this so hopefully someone else will be able to offer some further advice to you.

Good luck
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Gamma Ray Digital Inc

Media Blackout - Custom Cables and AKS

Aerial Filmworks

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Glidecam

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Visual Products

Ritter Battery

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Tai Audio