Enlarger timer accuracy required for relative paper speed tests

Hi,

I would like to embark upon the relative paper speed test described by
Steve Anchell in _The Variable Contrast Printing Manual_, pp. 45-53.
In this test, you establish a target exposure that is a bit lighter
than middle gray, and then do subsequent expsoures that match the
target exposure with each of the VC filters. You then use the data --
the exposure times reqired to achive the target gray -- to compile an
exposure factor chart, which can then be used to calculate exposure
differences for switching from filter to filter.

Anchell's exposure test examples resolve to increments of exposure
that require an enlarger timer with a resolution of 1/10 second (12,
11.8, 11.6, 11.4, etc.). I have an old-fashioned analog gralab
enlarger timer, the finest resolution of which is 1/2 second (if
that). Do the exposures have be done as finely as Anchell's examples
indicate in order to give useful data?

Thanks.

--Phil

"Phil Glaser" wrote in message
om...
Hi,

I would like to embark upon the relative paper speed test described by
Steve Anchell in _The Variable Contrast Printing Manual_, pp. 45-53.
In this test, you establish a target exposure that is a bit lighter
than middle gray, and then do subsequent expsoures that match the
target exposure with each of the VC filters. You then use the data --
the exposure times reqired to achive the target gray -- to compile an
exposure factor chart, which can then be used to calculate exposure
differences for switching from filter to filter.

Anchell's exposure test examples resolve to increments of exposure
that require an enlarger timer with a resolution of 1/10 second (12,
11.8, 11.6, 11.4, etc.). I have an old-fashioned analog gralab
enlarger timer, the finest resolution of which is 1/2 second (if
that). Do the exposures have be done as finely as Anchell's examples
indicate in order to give useful data?

Thanks.

--Phil

You can actually see a difference of a 1/12th of a stop on hard grades.
So, if your standard exposure is pretty long, a 0.1s precision is not useful
but if you're constantly below 10s. it may be helpful.

When I did similar tests, I've been impressed by the error I got when
exposing the paper twice similarly, that was caused by voltage fluctuations.
That may take you into wrong conclusions ...

I do prefer working with a transparent step wedge (Stouffer, Kodak, ...)
combined with a reflection step wedge (or a reflection densitometer if
you're luvky to have one) for this kind of tests as it gives you the speed
change but also the real contrast of the filter.
This is especially useful for color heads used for B/W Multigrade printing.

Regards,
--
Claudio Bonavolta
http://www.bonavolta.ch

(Phil Glaser) wrote


I would like to embark upon the relative paper speed test...


You would like to? With VC paper have you any choice? and for
each and every paper you choose to use.
I used VC paper in 1958 and again a few years ago. I've gone all
graded. I could'nt get out of my mind the LIGHT darkrooms of years
gone by; graded paper darkrooms.
If you need all that calibration in the dark routine, stick
with VC.
For those not aware, there is a great variety of graded fiber base
and resin coated papers available. Dan

(Phil Glaser) wrote


I would like to embark upon the relative paper speed test...


You would like to? With VC paper have you any choice? and for
each and every paper you choose to use.
I used VC paper in 1958 and again a few years ago. I've gone all
graded. I could'nt get out of my mind the LIGHT darkrooms of years
gone by; graded paper darkrooms.
If you need all that calibration in the dark routine, stick
with VC.
For those not aware, there is a great variety of graded fiber base
and resin coated papers available. Dan

In article ,
(Phil Glaser) wrote:

Hi,

I would like to embark upon the relative paper speed test described by
Steve Anchell in _The Variable Contrast Printing Manual_, pp. 45-53.
In this test, you establish a target exposure that is a bit lighter
than middle gray, and then do subsequent expsoures that match the
target exposure with each of the VC filters. You then use the data --
the exposure times reqired to achive the target gray -- to compile an
exposure factor chart, which can then be used to calculate exposure
differences for switching from filter to filter.

Anchell's exposure test examples resolve to increments of exposure
that require an enlarger timer with a resolution of 1/10 second (12,
11.8, 11.6, 11.4, etc.). I have an old-fashioned analog gralab
enlarger timer, the finest resolution of which is 1/2 second (if
that). Do the exposures have be done as finely as Anchell's examples
indicate in order to give useful data?

Thanks.

--Phil

Yep they do. I can see differences at 3 tenths of a second.
Now whether waht you do requires that fine tuning is your call.
There are so many factors 1/2 second may not be that great a
problem however to calibrate more precise is always better.
--
Duzz that A moose you ?

Phil Glaser wrote:

Hi,

I would like to embark upon the relative paper speed test described by
Steve Anchell in _The Variable Contrast Printing Manual_, pp. 45-53.
In this test, you establish a target exposure that is a bit lighter
than middle gray, and then do subsequent expsoures that match the
target exposure with each of the VC filters. You then use the data --
the exposure times reqired to achive the target gray -- to compile an
exposure factor chart, which can then be used to calculate exposure
differences for switching from filter to filter.

Anchell's exposure test examples resolve to increments of exposure
that require an enlarger timer with a resolution of 1/10 second (12,
11.8, 11.6, 11.4, etc.). I have an old-fashioned analog gralab
enlarger timer, the finest resolution of which is 1/2 second (if
that). Do the exposures have be done as finely as Anchell's examples
indicate in order to give useful data?

Not if you use much longer exposures to begin with, but the utility of
knowing that information is suspect if you can't reliably change your
exposure by 2% or 3% to compensate for a filter change anyway...

--
I may be a scwewy wabbit, but I'm not going to Alcatwaz!
-- E. J. Fudd, 1954

Donald Qualls, aka The Silent Observer
Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm
Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm

Opinions expressed are my own -- take them for what they're worth
and don't expect them to be perfect.

There's an easier way to use VC papers and not have to go through all that
testing. It's called split filter printing, and can be used either with
actual VC filters or with a colorhead (which is what I've got on my
Beseler 45).

First, put a sheet of VC paper in your easel. Set your colorhead at
maximum magenta (or yellow--doesn't matter which one you start with), pick
your optimum f-stop (I usually begin with f11), and then expose in broad
bands across the paper sheet at 3 second intervals, using a card to block
the light except on the band you're exposing. I usually do about five or
six exposures. If you're using filters, use the highest and lowest
contrast filters in your set.

Then do the same with another sheet of paper using full yellow (or
magenta, depending on which you started with) or the equivalent
filters--highest or lowest.

Develop both sheets, and study the exposure bands carefully. In a part of
the print where you know what value you want, choose the exposure for that
color (yellow or magenta) or filtration. E.g. on my setup, perhaps I
discover that at 11X14 enlargement height, I need 9 seconds of full yellow
and 12 seconds of full magenta to give me the desired values in an area of
the print that I know which value I want. Or 9 sec. at 00 filter and 12
sec at #5 filter if you're using filters.

Then do a test exposure of the full negative at those times. Develop and
study. You will probably be very close to what you want. You may decide
you need a little less time at full yellow or a little more time at full
magenta, but you'll be close enough to tweak it. That will become your
standard printing time for that paper at that enlargement.

I find that with Agfa Multicontrast Classic, I usually need (supposing
I've got a good "normal" negative to begin with) equal amounts of yellow
and magenta--same exposure with each. With Ilford Warmtone, I need about
25% more magenta than yellow. If you know you're starting with a somewhat
thin (underexposed) negative, you can judge whether you're going to gave
to tweak your standard times, but you've got a good ballpark to begin with.

I often find that I'm close to a perfect print on the first or second try,
with only minor finishing touches to do.

If you need to give more exposure to one part of the print (but don't want
to alter the relative value/contrast of that part) then give proportional
amounts of burn at each filtration. E.g. I need to burn in the sky to
give it more tone, so if my standard time is 10 sec each Y and M, after
I've exposed the basic time, I may give another 5 sec at full Y and 5 sec
at full M to the sky. Fractions of seconds will not be noticeable to the
eye when using split filter printing. It's rare that I can even tell a
difference with a full second.

Besides the consistency and convenience, another real benefit for me, and
why I originally began printing this way, is that I found that the split
filter method gave me much more enhanced local contrast--- there's a
"snap" and "sparkle" within the tones that wasn't there when I was
laboriously trying to work out an exposure/filtration combination for a
single exposure print.

It may take some practice to get your mind around how to burn and dodge at
first, but once you do, I think you'll be pleased with the ease and
simplicity of this method.

LRK

On 6 Jun 2004 14:49:08 -0700, Dan Quinn wrote:

(Phil Glaser) wrote


I would like to embark upon the relative paper speed test...


You would like to? With VC paper have you any choice? and for
each and every paper you choose to use.
I used VC paper in 1958 and again a few years ago. I've gone all
graded. I could'nt get out of my mind the LIGHT darkrooms of years
gone by; graded paper darkrooms.
If you need all that calibration in the dark routine, stick
with VC.
For those not aware, there is a great variety of graded fiber base
and resin coated papers available. Dan



--
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

You can actually see a difference of a 1/12th of a stop on hard grades.
So, if your standard exposure is pretty long, a 0.1s precision is not useful
but if you're constantly below 10s. it may be helpful.

When I did similar tests, I've been impressed by the error I got when
exposing the paper twice similarly, that was caused by voltage fluctuations.
That may take you into wrong conclusions ...

Based on what you and others are saying, my inclination is to wait
until I have a more accurate enalrger timer for doing this particular
test.

I do prefer working with a transparent step wedge (Stouffer, Kodak, ...)
combined with a reflection step wedge (or a reflection densitometer if
you're luvky to have one) for this kind of tests as it gives you the speed
change but also the real contrast of the filter.
This is especially useful for color heads used for B/W Multigrade printing.

Yes, I read about that in Anchel also and am thinking that this is a
better option for now. It seems like knowing that one filter is n
number of 1/3 stops faster or slower (based on counting the number of
completely dark steps until there's a density change) than another is
about as accurate as I would get with my enlarger timer and about as
useful.

One question about this approach. I'll need to slice up my 21 step
stouffer step wedge into three segments and project that. Since I'm
only set up for 35mm, I would need to make my own cardboard carrier
for this purpose. It will be 1.1 cm wider than the standard 35mm
carrier. I don't know if that means I'll need to adjust the condensor.
If I do adjust the condensor, will it affect the outcome of the test?
I mean, it seems to me that in relative terms, the exposures should
work out correctly. But I'm thinking, perhaps the intensity of the
light, which would be changed by the condensor adjusgement, changes
the callier effect? Is this another variable I need to control?

--Phil

I would like to embark upon the relative paper speed test...

You would like to? With VC paper have you any choice? and for
each and every paper you choose to use.

Heh. Well, no, I'm not looking forward to the testing process, but it
does seem to be necessary.

I used VC paper in 1958 and again a few years ago. I've gone all
graded. I could'nt get out of my mind the LIGHT darkrooms of years
gone by; graded paper darkrooms.
If you need all that calibration in the dark routine, stick
with VC.
For those not aware, there is a great variety of graded fiber base
and resin coated papers available. Dan

As often happens, these discussions take me into uncharted waters. Are
you saying that graded papers have a completely constant speed from
one grade to another, so that, for example, a change from a grade 1 to
a grade 5 made at the same exposure has no effect on highlight
densities? And that all this relative speed testing is _only_
necessary for VC papers? I mean, geeze, that could be worth the cost
of a few extra boxes of paper . . .

--Phil

Phil Glaser wrote:


One question about this approach. I'll need to slice up my 21 step
stouffer step wedge into three segments and project that. Since I'm
only set up for 35mm, I would need to make my own cardboard carrier
for this purpose. It will be 1.1 cm wider than the standard 35mm


Why not contact print it?

Nick