[pure-silver] Re: Ralph Lambrecht / EM10 enlarging meter?
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 6 Jan 2005 14:37:38 -0800
----- Original Message -----
From: "Ryuji Suzuki" <rs@xxxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>; <titrisol@xxxxxxxxx>
Sent: Thursday, January 06, 2005 12:37 PM
Subject: [pure-silver] Re: Ralph Lambrecht / EM10 enlarging
meter?
> From: titrisol <titrisol@xxxxxxxxx>
> Subject: [pure-silver] Re: Ralph Lambrecht / EM10
> enlarging meter?
> Date: Thu, 6 Jan 2005 11:56:36 -0800 (PST)
>
>> - Use a grayscale in the negative holder (6x6) then
>> measure the Em10
>> setting for 2 or 3 stops. Then print a test with the
>> Kodak Wedge
>> and determine exposure for zone 1, 5 and 8 After that
>> since I had
>> made a table of +- stops I can determine the times
>> required to
>> generate any gray tone for the paper.
>
> I've tried to calibrate EM-10 but it's not that useful...
>
> EM-10 uses CdS as the photosensor, and this cell is
> sensitive to wide
> range of spectrum including safelight. Unless you put a
> blue-green
> filter on the hole, you'll have to shut the safelight when
> using
> EM-10. But then how are you going to deal with contrast
> filters?
> (Fine, my most precious paper is graded.)
>
> With that limitation in mind, calibration can be easily
> done with an
> ordinary incident light meter. With Sekonic L-408 meter
> set at 100
> speed, 2.5 * 2^EV is pretty close to lux. (Note: different
> light
> meters are calibrated differently. I've compared my meter
> with my
> friend's Minolta meter, but it was significantly
> different. Light
> meters are not designed for this purpose anyway, I'm
> merely suggesting
> they can be used this way if you know the meter's
> calibration.) You
> can set an empty neg carrier and change the aperture
> and/or head
> height to create a range of illuminances at which you make
> a
> calibration table for EM-10. Then fit a suitable curve and
> interpolate.
>
> But when I'm *mass* printing something, I usually fix
> exposure time
> and change aperture to adjust the illuminance. (Don't use
> clicks on
> the lens) If the negative is exposed rather uniformly,
> this generally
> works very well and EM-10 doesn't need to be calibrated.
>
> --
> Ryuji Suzuki
> "Keep a good head and always carry a light camera."
The safelight near my enlarger is connected to the timer
so that is is off when the enlarger is on. I've not had a
problem from this. The EM-10 seems to give the right
exposure for various VC filters, I have not had a problem in
practice with this. It is more sensitive than my Luna-Pro,
certainly much faster in very dim light. One can also
calibrate using a pin hole source and inverse square law.
The pin hole is small enough to act as virtual point source.
By pin hole I mean a small hole but one large enough to let
enough light through. If the minimum distance is a couple of
feet a hole the size made by a paper punch is small enough.
I have simply marked the dial on my EM-10 with a fine point
"Sharpie" marker at one stop intervals. I don't often use
the EM-10 to measure contrast because I have an ancient
densitometer which is adequate for B&W but it is capable of
the measurement. I generally make proofs either at No.2 or
by visual guess and then adjust both contrast and exposure
according to what I see. The EM-10 is very useful for
getting ball-park exposure when changing magnification, and,
with a little experience, when changing papers.
Speaking of old favorite papers, I recently tested some
very old Agfa Brovira. This is probably paper given to me by
a friend who closed his darkroom and must be more than
twenty years old. It seems to print without fog and at
normal speed. I have rather a lot of old graded paper and
will be testing it in the near future. My past experience is
that Agfa paper is very long lived.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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