Re: my first photo

> > I placed a #0 filter behind my camera and took photos. They're still
> > drying, but looks like they are really much better with tonality than
> > without the filter. Filter kit I have is Ilford Multigrade. The tests I
> > made showed that in a clear sunshine without filter 30 sec. was enough
> > but using filter 2 mins. had to be exposed. Any reason for this long
> > exposure? The guide in the filter box says that when enlargening using
> > #0 filter has no effect in exposure time.
>
> 2 reasons:
>
> -Those filters are made to filter tungsten light and you are using them to
> filter daylight. That may account for the increased time.
> -Since the use of the filter increases the uncorrected exposure time,
> reciprocity corrections become a bit drastic and increases the reciprocity
> corrected time even more.

Hi Matti,

There may be another reason for your long exposure with # 0 filter.
Reading again your procedure, it seems that you compare a no-filter time with a # 0 time
exposure; what Ilford says in their guide is that there is no correction factor to apply
when using # 0 to # 3.1/2 filters and a factor when using # 4 to # 5. That makes the
"Normal # 2" filter time identical (in theory!) to the # 0.

But there is an important difference when you have NO filter at all with the filtered
paper. No filter is a little less contrasty than # 2 filter but it needs a far shorter
time when you print. This is due to the transmission of light being seriously slowed down
by the physical presence of any filter. It's why the effective "speed" of paper is
diminished when you interfere a filter !
Let's go pinholing now
Jean
***********************
Jean Daubas, auteur-photographe
16 rue de Bourg-sec
25440 LIESLE France
03 81 57 50 13 ou 06 81 53 12 89
j.daubas.photo@free.fr
Received on Mon Apr 15 10:08:03 2002