Re: Microfilm: Positive or Negative? (Helen Aiello) ANN ERCELAWN 31 Mar 1994 19:59 UTC

Date: Thu, 31 Mar 1994 12:22:53 LCL
Subject: RE: Microfilm: Positive or Negative? (Melissa Nasea)

>Our representative said that positive film looks better and he
>suggests that we switch to positive film.
Positive film may "look" (?) better but in fact is harder on your eyes.
The negative polarity film is easier on the eye since the light source is
'darkened' by the negative background allowing light to come through the
letter's only.  The negative format also seems to allow a sharper resolution
to the letters: again making reading easier on the eyes.
Admittedly, for film readers with indirect light sources the concern of the
light causing eyestrain may not be considered an issue.  However, we find
that many of our users prefer to sit at a reader/printer rather than our
'read only' equipment (which have the indirect light source) since the user
wants to be able to have the option to make a photocopy on demand.

>Does anyone have any preferences for positive or negative film?
Wesleyan University Library's microform Center will always try to
purchase the negative format when available.  We have never had a
complaint from a user on the negative format (our complaints are still
that they don't like the microformat-regardless of
film/fiche/positive/negative/16mm/35mmm,etc.!!!).   In addition, with
the newer reader/printer technology that adjusts automatically the
print mode to yield positive prints regardless of source format (we
have a Minolta 605Z - and I know other machines offer this type of
ability) printing in the reverse format is no longer an issue. We do
still have some rather old clinkers that have to be manually adjusted
but use these only as a last resort when we get very busy.

>Which produces better copies for text? for black and white and color
>illustrations or photographs?
We have found that it is not so much the source format (negative or positive)
that yields a better copy for text but the photocopy mechanics.  The newer
generation of reader/printers that use plain paper and toner seem to do a
consistently good job, regardless of the source microformat.
As for photographs: it makes copies. Perhaps the better question is: Have you
ever had a regular photocopier
(run of the mill, workhorse library paper to paper copier) make truly acceptible
copies of illustrations?  Not a good answer, but illustrations are a problem

Helen M. Aiello, Serials/Microforms Librarian
Wesleyan University, Olin Library
Middletown, CT 06457
Bitnet: HAIELLO@Wesleyan.Bitnet
Internet: HAIELLO@Eagle.Wesleyan.EDU
Tel: 203-347-9411 x2372
FAX: 203-344-7969