Calibrating color heads for B&W printing.

Recent Classifieds

Forum statistics

Threads
179,580
Messages
2,472,785
Members
94,843
Latest member
ocieb
Recent bookmarks
0

Eric_Fr

Member
Joined
Apr 27, 2004
Messages
5
Location
France
Hello,

I'm new to your forum; I just discover it few weeks ago and find it very
interesting for a newbie in Darkroom process.

I have seen in a previous topic "Determining contrast grade in the Darkroom" that some people consider that the exposure time stay the same as you change contrast grade. I'm surprise by this affirmation and I would like
to know if some of you have realize a calibration of their system like
define by Paul Butzi in is web site.

http://www.butzi.net/articles/vcce.htm

Excuse me for my poor english.

Best regards,

Eric.
 

clogz

Subscriber
Joined
Dec 28, 2002
Messages
2,381
Location
Rotterdam, T
Shooter
Multi Format
Hello Eric,
Welcome to APUG
Butzi's method is very precise. If you are a newbie to darkroom work it may be better to use dual filtration (Y+M). The exposure time you find with a test strip remains the same for grades 1-3 VC paper.Grades 4 and 5 need double length of exposure.
Hope this helps
Hans
 

Ole

Moderator
Moderator
Joined
Sep 9, 2002
Messages
9,250
Location
Bergen, Norway
Shooter
Large Format
Poor English is not a problem on this site, Eric!

I adjust the illumination to give the same exposure at all grades: My Opemus 6 colour head has four filters: C, M, Y, and N. The N is a neutral filter giving two stops fine-tunability.

It just so happens (intentionally?) that my EM10 exposure meter will give the lightest near-white a reading of 85 on all grades of Ilford MG IV RC at 10 seconds exposure. So I twiddle the "N" until the EM-10 shows 85 for the densest part of the negative that I want almost, but not quite, white.'

The meter setting at the thinnest part of the negative (my shadows) determines the grade needed to fit everything onto the paper without burning/dodging. I have a diagram made up that I consult.

So I start without filter, adjust "N" and aperture to give 85 in highlights. Then I measure shadow, determine wanted grade, set "Y" or "M", then change aperture and "N" until highlights are 85 again. Expose 10 seconds, develop and fix.

Then I'll probably decide that the contrast is too flat, change the settings again, and start burnig and dodging. But I stick to that 10 seconds base exposure.
 

Thilo Schmid

Member
Joined
Sep 10, 2002
Messages
352
Location
France
Shooter
Multi Format
Eric,
welcome to APUG.

It is sometimes useful to know some "basics" in order to understand why certain things are the way they are.

VC-Paper is built of two emulsion layers with different spectral sensitivity and different gamma (grade). As long as you stay with grades 1-3, both layers are exposed in a way that the overall speed stays the same. At grades 00/0 and grades 4/5, basically only one layer, with each about half the speed, is exposed.
 
Photrio.com contains affiliate links to products. We may receive a commission for purchases made through these links.
To read our full affiliate disclosure statement please click Here.

PHOTRIO PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Ilford ADOX Freestyle Photographic Stearman Press Weldon Color Lab
Top Bottom