Filter grades

Hi,

Given the exposure times of a two-filter approach to printing, is there
a way to derive the theoretical effective grade without doing print
matching using all the available grades ?

For example, for a given print on VC paper with condenser/tungsten
projection, I need
12 seconds on grade 0
4 seconds on grade 5

If I was to replace that by a single filter grade, what would it be ?

ps: I use Ilford multigrade filters and Ilford recoomends one extra stop
of exposure for grades above 3 1/2

thanks in advance,
waiming

In article ,
Wai-Ming Ho wrote:

Hi,

Given the exposure times of a two-filter approach to printing, is there
a way to derive the theoretical effective grade without doing print
matching using all the available grades ?

For example, for a given print on VC paper with condenser/tungsten
projection, I need
12 seconds on grade 0
4 seconds on grade 5

If I was to replace that by a single filter grade, what would it be ?

ps: I use Ilford multigrade filters and Ilford recoomends one extra stop
of exposure for grades above 3 1/2

thanks in advance,
waiming

Yes you can use a step wedge and measure the density of each wedge
then you can calculate the grade the enlarger gave you at that height
and at that filtration and development time and temp.
--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

Gregory Blank wrote:

In article ,
Wai-Ming Ho wrote:


Hi,

Given the exposure times of a two-filter approach to printing, is there
a way to derive the theoretical effective grade without doing print
matching using all the available grades ?

For example, for a given print on VC paper with condenser/tungsten
projection, I need
12 seconds on grade 0
4 seconds on grade 5

If I was to replace that by a single filter grade, what would it be ?

ps: I use Ilford multigrade filters and Ilford recoomends one extra stop
of exposure for grades above 3 1/2

thanks in advance,
waiming


Yes you can use a step wedge and measure the density of each wedge
then you can calculate the grade the enlarger gave you at that height
and at that filtration and development time and temp.

Before running out to order the step wedge, I like to know what is used
to measure the wedge density. In case it needs a densitometer that I
don't have.

I have never used a step wedge but I guess that some wedges will "fuse"
as one varies the contrast to either the low or high end. Doesn't the
wedge give an indication by noting how many of them has been "fused" due
to grade filtering ? Or perhaps I need to have a reference wedge output
for each filter grade at the specified enlarger height, dev time and temp.

I was thinking of spreading the "wear" of my filters instead of just
using the 0 and 5. If the cost of the wedge outweighs changing a whole
filter pack just for a new set of 0 and 5, I would stay with split
filtering...

In article ,
Wai-Ming Ho wrote:

Before running out to order the step wedge, I like to know what is used
to measure the wedge density. In case it needs a densitometer that I
don't have.

Initially you need to have a wedge that either comes
with established densities (pre-read by the manufacturer)-calibrated
Or you can get a local lab perhaps to read an uncalibrated one
for you.

Then once you know where the step value you wish to print for falls on
the wedge you can print for that value and observe where other values
fall thereby gaining the ability to determine relative contrast.

I have never used a step wedge but I guess that some wedges will "fuse"
as one varies the contrast to either the low or high end. Doesn't the
wedge give an indication by noting how many of them has been "fused" due
to grade filtering ? Or perhaps I need to have a reference wedge output
for each filter grade at the specified enlarger height, dev time and temp.

A typical example some wedges come in increments of 1/2 stop and have 21
increments total, 21 steps are probably the most commonly used.

I was thinking of spreading the "wear" of my filters instead of just
using the 0 and 5. If the cost of the wedge outweighs changing a whole
filter pack just for a new set of 0 and 5, I would stay with split
filtering...

Well, to me the most important consideration is wether you can get
the contrast you desire, realizing that contrast adjustment is separate
from exposure. If you had a Dichroic or adjustable "stepless"filter lamp
house you could adjust the contrast anywhere you desire.

The only way you can completely do that with a Condenser
head is by using a base filtration and then adding yellow or magenta
filters as needed. It sounds like you would need to buy strickly yellow
or magenta filters -not the standard.
--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

"Wai-Ming Ho" wrote

Before running out to order the step wedge, I like to know what is used
to measure the wedge density. In case it needs a densitometer that I
don't have.

The wedge is made in even density increments. The most common are
0.3 or 0.5 od. If you want to be really picky for extra $$ you
can buy a wedge with a calibration slip and you can find that the
1.0od wedge is really 1.045 od - for photography this is overkill.

I have never used a step wedge ...

Assumptions are dangerous then.

but I guess that some wedges will "fuse"
as one varies the contrast to either the low or high end.

No.

Doesn't the
wedge give an indication by noting how many of them has been "fused" due
to grade filtering ?

They don't fuse. Each density patch on the 'wedge' is numbered.

Or perhaps I need to have a reference wedge output
for each filter grade at the specified enlarger height, dev time and temp.

Yes. A series of 12 exposures will do it. I do four 4x5" exposures
on an 8x10 sheet, shift the sheet between exposures. Process all three
8x10 sheets together.

You may want to find someone to measure the test print densities.
It can be quite a revelation: the 'curves' aren't as shown in the
books: lumps and bumps; and many filters make no difference from the
filter next to them [2 1/2 == 2 is common].

I was thinking of spreading the "wear" of my filters instead of just
using the 0 and 5. If the cost of the wedge outweighs changing a whole
filter pack just for a new set of 0 and 5, I would stay with split
filtering...

If conserving money is the object photography is not the answer.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
To reply, remove spaces: n o lindan at ix . netcom . com
Fstop timer - http://www.nolindan.com/da/fstop/index.htm

You first need to use some graded paper to find out what your VC grades
actually are. The filter numbers are often quite different from the
'real' grades.


Wai-Ming Ho wrote:
Hi,

Given the exposure times of a two-filter approach to printing, is there
a way to derive the theoretical effective grade without doing print
matching using all the available grades ?

For example, for a given print on VC paper with condenser/tungsten
projection, I need
12 seconds on grade 0
4 seconds on grade 5

If I was to replace that by a single filter grade, what would it be ?

ps: I use Ilford multigrade filters and Ilford recoomends one extra stop
of exposure for grades above 3 1/2

thanks in advance,
waiming

In article . net,
"Nicholas O. Lindan" wrote:

If conserving money is the object photography is not the answer.

That's for sure.
--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

Wai-Ming Ho wrote:

Before running out to order the step wedge, I like to know what is used
to measure the wedge density. In case it needs a densitometer that I
don't have.

You might want to run out and get Anchell's book "The Variable Contrast
Printing Manual". He has a chapter on calibrating grades. Basically stick
the wedge in the enlarger. Make a print. Count the number of steps that are
neither pure paper white or pure black. Compare that number to the chart and
you get a grade. It's a bit more complicated then that but not much more.



I was thinking of spreading the "wear" of my filters instead of just
using the 0 and 5. If the cost of the wedge outweighs changing a whole
filter pack just for a new set of 0 and 5, I would stay with split
filtering...

Just get a couple of sheets of lighting gels made by Rosco. 20"x24" they
cost about $6 each and will work fine for spilt filtering. Need a green and
a blue. Or put the money towards a colour head.

Nick

--
---------------------------------------
"Digital the new ice fishing"
---------------------------------------

It's nice to be able to compare to a graded paper, so that you can
match the contrast as closely as possible toa graded paper. After all,
graded papers are better.


Nick Zentena wrote:
Wai-Ming Ho wrote:

Before running out to order the step wedge, I like to know what is used
to measure the wedge density. In case it needs a densitometer that I
don't have.

You might want to run out and get Anchell's book "The Variable Contrast
Printing Manual". He has a chapter on calibrating grades. Basically stick
the wedge in the enlarger. Make a print. Count the number of steps that are
neither pure paper white or pure black. Compare that number to the chart and
you get a grade. It's a bit more complicated then that but not much more.



I was thinking of spreading the "wear" of my filters instead of just
using the 0 and 5. If the cost of the wedge outweighs changing a whole
filter pack just for a new set of 0 and 5, I would stay with split
filtering...

Just get a couple of sheets of lighting gels made by Rosco. 20"x24" they
cost about $6 each and will work fine for spilt filtering. Need a green and
a blue. Or put the money towards a colour head.

Nick

--
---------------------------------------
"Digital the new ice fishing"
---------------------------------------

It's nice to be able to compare to a graded paper, so that you can
match the contrast as closely as possible to a graded paper. After all,
graded papers are better.


Nick Zentena wrote:
Wai-Ming Ho wrote:

Before running out to order the step wedge, I like to know what is used
to measure the wedge density. In case it needs a densitometer that I
don't have.

You might want to run out and get Anchell's book "The Variable Contrast
Printing Manual". He has a chapter on calibrating grades. Basically stick
the wedge in the enlarger. Make a print. Count the number of steps that are
neither pure paper white or pure black. Compare that number to the chart and
you get a grade. It's a bit more complicated then that but not much more.



I was thinking of spreading the "wear" of my filters instead of just
using the 0 and 5. If the cost of the wedge outweighs changing a whole
filter pack just for a new set of 0 and 5, I would stay with split
filtering...

Just get a couple of sheets of lighting gels made by Rosco. 20"x24" they
cost about $6 each and will work fine for spilt filtering. Need a green and
a blue. Or put the money towards a colour head.

Nick

--
---------------------------------------
"Digital the new ice fishing"
---------------------------------------