First contact prints done. Problem with light uniformity.

"Fabio BERETTA" wrote

Height of the bulb within the head... that's probably the mistake!!

Now is there any method to correctly estimate if evenness of the light
has been reached?

The evenness of the contact sheet is a good indication...

Seriously:

o Eyeball it as best you can

o Use a lightmeter with an incident disk attachment or
an enlarging meter and see if reads the same in the corners as the
center. Most light meters are not sufficiently sensitive and
don't have enough resolution, though.

o Check by installing a grade 5 polycontrast filter and making
a neutral (18% - or so) grey exposure with no negative. See
if is even enough to satisfy you. Tear off a corner and place
it in the middle of the print to make the comparison.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.

Thanks.

Nicholas O. Lindan wrote:
"Fabio BERETTA" wrote


Height of the bulb within the head... that's probably the mistake!!

Now is there any method to correctly estimate if evenness of the light
has been reached?


The evenness of the contact sheet is a good indication...

Seriously:

o Eyeball it as best you can

o Use a lightmeter with an incident disk attachment or
an enlarging meter and see if reads the same in the corners as the
center. Most light meters are not sufficiently sensitive and
don't have enough resolution, though.

o Check by installing a grade 5 polycontrast filter and making
a neutral (18% - or so) grey exposure with no negative. See
if is even enough to satisfy you. Tear off a corner and place
it in the middle of the print to make the comparison.

"Dennis O'Connor" wrote in message
...
Sounds to me like he needs to install the correct condensors/mixer for the
lens...
denny

yep... you sound like you've got two Sivocon 80's in it. Are both
condensors identical? I just tried a 50mm lens with the two '80s and
there's definite light fall off. With a Sivocon 50 and one '80 (the 35mm
setup) it looks quite even, which I'd expect since I've never had to edge
burn my prints. FYI, the '50 condensor has a lot more curviture to it than
the '80.

Nige.