8mm Forum: 9.5 format?

This is topic 9.5 format? in forum 9.5mm Forum at 8mm Forum.

To visit this topic, use this URL:
https://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=9;t=000090

Posted by Brian Collins (Member # 761) on October 01, 2009, 01:51 PM:

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

Posted by Paul Adsett (Member # 25) on 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.

Posted by Dino Everette (Member # 1378) on 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.

Posted by Brian Collins (Member # 761) on 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

Posted by Dino Everette (Member # 1378) on 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]

Posted by Simon Wyss (Member # 1569) on 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.

UBB.classic^TM 6.3.1.2