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Road ruts with Jobo



 
 
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  #61  
Old January 26th 04, 04:22 PM
Nicholas O. Lindan
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Default Road ruts with Jobo

"Brian Kosoff" wrote

Every photographer I knew in NYC, either bracketed in 1/4 stop
intervals or push/pulled in 1/4 stop intervals ...


We must move in very different circles. Most photographers I know
bracket in 4-stop intervals.

Or is it true that most people can not discern differences smaller
than 1/3 stop?


For normal processing, with normal contrast material, I claim a 1/3 of
a stop won't be noticed. With high contrast material, grade V paper
as an example, a 1/3 stop difference is significant and shadows or
highlights drop in and out - at least I can see a difference; my
neighbor, that's a different story.

We can jaw on this subject till everyone in the group is pushing
up daisies. The only way to find out is to experiment.

Let me explain what I mean by noticing a 1/3 stop difference:

o Day 1: make two prints, one 1/3 stop under or over and one at
'ideal' exposure. Put them away.

o Day 2: At random, look at one print. Don't look at the other.
Look at the print as you would in a gallery, from a civilized
distance.

o Day 3: Look at the other print. Again, never look at both at
the same time.

o Day 4: Can you tell which was which? Do you think anyone else
can. Do you think a gallery viewer would care?

For grins, take your favorite original print by another photographer.
Visit someone who also has a print. Compare the two. When I tried
it there was quite a difference between the two. Even better compare
an original with a duotone reproduction - they are almost different
photographs - yet the viewer, seeing each separately, likes them both.

The eye is very good at detecting local, abrupt, changes in tone -
that's a fundamental principle of vision. If two 18% grey
tones, normal paper, normal processing, but differing by 1/3
of a stop are placed side by side (a test strip made with
no negative makes a good test vehicle) the demarcation between
the two exposures is plainly visible. To an experienced eye
it is even possible to make out the demarcation at 1/10th of a stop.

I don't think small stop differences are noticeable in
most prints, and certainly aren't worth chasing.

As an experiment cut out the two squares from the above test
strip, place one in each room. My result is that an observer
walking between the rooms can't tell the difference.

A 'road rut' of 1/10th of a stop difference is another matter,
though, and I believe an eye looking for the rut will find it.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
  #62  
Old January 26th 04, 05:43 PM
Brian Kosoff
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Default Road ruts with Jobo


Nicholas,

in my conversation with sinar we were discussing LF chromes, please note
the reference to "e-6 processing". For most people I agree that a 1/3 stop
difference in B*W negative will not be noticeable, unless that 1/3 stop is
an uneven area against an even background.



On 1/26/04 10:22 AM, in article
et, "Nicholas O. Lindan"
wrote:

"Brian Kosoff" wrote

Every photographer I knew in NYC, either bracketed in 1/4 stop
intervals or push/pulled in 1/4 stop intervals ...


We must move in very different circles. Most photographers I know
bracket in 4-stop intervals.

Or is it true that most people can not discern differences smaller
than 1/3 stop?


For normal processing, with normal contrast material, I claim a 1/3 of
a stop won't be noticed. With high contrast material, grade V paper
as an example, a 1/3 stop difference is significant and shadows or
highlights drop in and out - at least I can see a difference; my
neighbor, that's a different story.

We can jaw on this subject till everyone in the group is pushing
up daisies. The only way to find out is to experiment.

Let me explain what I mean by noticing a 1/3 stop difference:

o Day 1: make two prints, one 1/3 stop under or over and one at
'ideal' exposure. Put them away.

o Day 2: At random, look at one print. Don't look at the other.
Look at the print as you would in a gallery, from a civilized
distance.

o Day 3: Look at the other print. Again, never look at both at
the same time.

o Day 4: Can you tell which was which? Do you think anyone else
can. Do you think a gallery viewer would care?

For grins, take your favorite original print by another photographer.
Visit someone who also has a print. Compare the two. When I tried
it there was quite a difference between the two. Even better compare
an original with a duotone reproduction - they are almost different
photographs - yet the viewer, seeing each separately, likes them both.

The eye is very good at detecting local, abrupt, changes in tone -
that's a fundamental principle of vision. If two 18% grey
tones, normal paper, normal processing, but differing by 1/3
of a stop are placed side by side (a test strip made with
no negative makes a good test vehicle) the demarcation between
the two exposures is plainly visible. To an experienced eye
it is even possible to make out the demarcation at 1/10th of a stop.

I don't think small stop differences are noticeable in
most prints, and certainly aren't worth chasing.

As an experiment cut out the two squares from the above test
strip, place one in each room. My result is that an observer
walking between the rooms can't tell the difference.

A 'road rut' of 1/10th of a stop difference is another matter,
though, and I believe an eye looking for the rut will find it.


  #63  
Old January 26th 04, 06:41 PM
LABFIX 2
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Default Road ruts with Jobo



Jean-David Beyer wrote;

2500 drums with 2509N reels work fine for me, and give even development.



LABFIX2 wrote;
Good for you!


Jean-David Beyer wrote;
I always use a stop bath. What is the reason for avoiding it?



LABFIX2 wrote;
I have seen it cause a blotchy appearance, mosy evident with high key
backgrounds.

Jean-David Beyer wrote;
That is very unlikely.


Maybe I should have my eyes checked. And the other 4 photographers that saw the
test.

Labfix2 wrote;

The volume listed on the tank only indicates the amount of chemistry needed
to
cover the film. You may need to use more than indicated. (especially with

b&w
diluted developers)


Jean-David Beyer wrote;
I am not convinced of that. I cannot imagine anyone used a developer
until the last few ions are depleted.


whatever...I'm not trying to convince you of anything.
It's been several years since trying to help folks with processing problems on
these newsgroups. Now I remember why I left. My suggestions were for people
having problems. If your processing methods work FOR YOU, don't change them.
Simple enough. I'll check back in a couple years.


  #64  
Old January 26th 04, 08:12 PM
Nicholas O. Lindan
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Posts: n/a
Default Road ruts with Jobo

"Brian Kosoff" wrote

in my conversation with sinar we were discussing LF chromes, please note
the reference to "e-6 processing".


Most of the folks on this thread are talking B&W. Including you, it seems.
Your quoted complaint to Jobo:

I have used d-76 1:1 (1000ml for 4 *120s), Xtol
(straight 1000ml for 4 rolls 120), xtol 1:1 (1000ml for 4 rolls of 120). On
the advice of your tech people I do not use stop bath, but use 4 rinses
prior to a 5 minute fix in kodak rapid fix


So I guess keeping track of what emulsion is being discussed
is a bit confusing.

Are your road ruts with B&W, as indicated above, or e-6, or both?

Additionally, I have been doing much testing with small f-stop
differences in B&W. As the subject is much on my mind right now,
so I am sure I am reading B&W into every post, even if the subject
matter changes in the middle.

Even so. If two Ektachromes are taken 1/3 stop apart can the difference
be spotted if one slide is viewed one day and the other the next -- double
blind conditions, of course.

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

  #65  
Old January 27th 04, 01:08 AM
Michael Scarpitti
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Posts: n/a
Default Road ruts with Jobo

Jean-David Beyer wrote in message ...
Brian Kosoff wrote:
I think the reason why many people here say that they have even
development is that they are either shooting and processing scenes
with uneven, irregular backgrounds which essentially camouflage any
un evenness, or they are not perceptive enough to see a difference.


I am not convinced. It is usually true that if I point a camera
somewhere, that what is photographed is not all that even, and the
unevenness of the subject matter can conceal unevenness of emulsion over
the size of the negative (I have never seen that, and imagine it does
not occur), unevenness of processing, etc. But the opposite is true,
too; some people photograph something like an "even" sky and see a
variation. I notice that the sky, even a clear blue sky, is not all that
even in practice; at least here in New Jersey. What appears even can
vary quite a bit if you actually measure it with a spot meter. It is
pretty obvious on the ground glass, too, if you use something like a
90mm lens on 4x5. So just as unevenness in processing can be obscured by
unevenness in subject matter, so also unnoticed unevenness in subject
matter can mistakenly appear to be the result of uneven processing.

I would never use actual negatives (or transparancies) of real subjects
to evaluate evenness in processing. For measuring uniformity of
processing, you need a means of making uniformly exposed negatives.
While not trivial, anyone who is processing his own films is probably
able to come up with a means of making such negatives.



Precisely. Fogged film is probably ideal.
 




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