8mm Forum: 9.5 format?

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Topic: 9.5 format?

Brian Collins
Film Handler

Posts: 96
From: Christchurch UK
Registered: Jan 2007

posted October 01, 2009 01:51 PM

What is the difference between a reversal film and a copy from negative film, can anyone explain please?

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Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003

posted October 01, 2009 02:01 PM

Reversal film is a camera film which is processed directly into a positive image - there is no negative generated at all in the process- what you get back is the actual roll of film that was used in the camera. Unlike say 35mm camera film, where you get negatives back with your positive prints. And professional 35mm motion picture film is processed as a negative then printed to another roll for the positive image.

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Dino Everette
Phenomenal Film Handler

Posts: 1535
From: Long Beach, CA USA
Registered: Dec 2008

posted October 02, 2009 02:27 AM

Might also be helpful to note that depending on the project the terms would imply different results in the way of image. If dealing with 9.5 amateur movies anything that was labeled as "printed from negative" would probably be much older, since after the introduction of reversal film ( for most small formats) fewer people shot negative due to the cost savings found with reversal.....That being said the fact that reversal film is both the originally shot footage and the projection print unfortunately it is all there is..If it is beat up, there is nothing to fall back on to make a new print from, which is why commercially available films would rarely be on reversal.

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Brian Collins
Film Handler

Posts: 96
From: Christchurch UK
Registered: Jan 2007

posted October 02, 2009 04:03 AM

Thank you gents, very interesting, they gave 2 different ways of threading on my Ditmar Duo 9.5 depending on the type of film, much clearer now. Thanks

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Dino Everette
Phenomenal Film Handler

Posts: 1535
From: Long Beach, CA USA
Registered: Dec 2008

posted October 03, 2009 01:46 AM

OH haha, that's much easier, basically then it is only because of the image orientation - one is emulsion up and the other is emulsion down..... [Big Grin]

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Simon Wyss
Film Handler

Posts: 78
From: Äsch, Switzerland
Registered: Apr 2009

posted July 28, 2010 12:56 PM

Sorry for interfering but there is a fully developed negative image on the film in the first place. As second step of the true reversal process the negative image is bleached, i. e. made soluble by an oxidizing compound. Step three is the dissolution of the negative out of the film before a thorough exposure to uniform light.

You understand that all silver salt which did not take part in the formation of the negative image is now totally exposed and can be developed to black. The remainder of the original photographic layer becomes a positive image, fixed, washed, and dried. A true reversal film actually contains two different emulsions well mixed: a rather high speed panchromatically sensitized one together with a low speed non-sensitized one. The low-speed salt will be underexposed in the camera by the factor ten or so.

Besides there are the untrue reversal stocks that need a positive film treatment only. They are commonly of low speed such as ISO 4 and mostly orthochromatic. On the other hand these films have ultra-high resolving power (up to 1000 lines per millimeter). Kodak 2468 with polyester base is one of them, it is used as a duplicating film.

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