Re: filmscanners: cleaning neg's, sharpening

["Ezio" <ezio@iname.com>]

OK, I am scared  ... I am going to use compressed air and soft material only
.

Sincerely.

Ezio

www.lucenti.com  e-photography site


----- Original Message -----
From: "Mark Thomas" <markthom@camtech.net.au>
To: <filmscanners@halftone.co.uk>
Sent: Monday, March 19, 2001 2:33 AM
Subject: Re: filmscanners: cleaning neg's, sharpening


> Just a couple of quick comments..
>
> 1. Cleaning neg's with water
> Bear in mind that if you use anything but 'unexposed' distilled water as a
> cleaning agent, you are in fact using carbonic acid..!
> I used to work in a oceanographic lab, and while checking the pH levels of
> a distilled water producer, I was surprised to discover how acidic the
> 'pure' water was.  The resident chemist gently explained that H20, when
> exposed to air, absorbs CO2 and degrades quite quickly to a carbonic acid
> solution, of about pH 5.0-5.5 I think. (I'm flying by memory here - any
> chemists on the list feel free to correct..)
>
> Keep that in mind if considering water for cleaning fragile items!!
>
> 2. Sharpening
> >Sharpening should be done before retouching the image, because sharpening
> >causes many details to show up which have to be retouched.
>
> I guess we are all different, but at the low levels of sharpening I use,
> I've not encountered sharpening effects that needed retouching.  I would
> have thought that other types of re-touching, eg cloning/rubber-stamping
> areas, is more likely to produce 'edges' that sharpening  may pick up and
> worsen.  So I *always* sharpen last, if at all.
>