But there is no 'original density' as I'm talking about exposing film to
light - there is only one density involved - that of the developed film.
If you don't have a densitometer how do you know what is .15, .3, .45 etc.
Of course it isn't critical to have exact densities, but it would be nice
to know that your 10 step range was roughly the same as other peoples'.
Either you need a densitometer, or you can actually do it accurately
enough for alt-photo purposes by visual comparison with an existing step
wedge. A card with two holes - one for a step on the wedge and one for the
film you are comparing to it - on a light box is all you need.
>
> >> Its actually easier to do a test strip or strips at various times,
> develop, measure the densities, draw a curve of density v time and
> read off the times you need for the 0.15 steps under the same
> conditions. >>
>
> Yes, and I have made many of my own step wedge this way. But if anyone
> is
> trying to do it this way, you must make sure that your processing
> (temperature, agitation, etc.) is fairly repeatible. I use automatic
> processor
> (Jobo).
>
>
> Dave
Absolutely agreed on this. Choosing a film/dev combination that gives a
reasonably long dev time (perhaps 10-15 mins) at room temperature helps. I
use a Jobo on almost all of my film too and tend to forget that others
aren't so lucky!
Peter Marshall
On Fixing Shadows and elsewhere:
http://www.people.virginia.edu/~ds8s
Family Pictures, German Indications, London demonstrations &
The Buildings of London etc: http://www.spelthorne.ac.uk/pm/