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  #41  
Old 10th September 2014, 09:22 PM
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Originally Posted by Miha View Post
Not really. Too low for Multigrade 'grade 2' which it isn't.
Try to think as if contrast filtration doesn't exist and you may get my point.
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  #42  
Old 10th September 2014, 10:11 PM
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I think the point is that it is a combination of BOTH negative contrast and filtration which results in overall print contrast.

That means you can use a soft neg with hard filtration OR hard neg with soft filtration and the result can be the same overall contrast.
And this is totally irrespective of which type of enlarger you are using.
However, whilst the overall contrast can be the same there is a difference and that is the shape of the curve, particularly at the toe and shoulder and generally it is desirable (IMO) to keep the toe and shoulder as short as possible because that provides better separation in the shadows and the highlights. And that is usually obtained by a negative with a short toe and as hard a paper grade as you can get away with. And the negative overall contrast needs to fit the paper exactly.

So there is an argument for using grade 3 as standard but it certainly isn't one that I adhere to although I often end up at grade 3 having started at 2.
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  #43  
Old 11th September 2014, 07:30 AM
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Originally Posted by dsallen View Post
Sorry, a silly omission on my part.

The general rule of thumb has always been that

a) when you are using a light source that has either has condensers or a point light source, you should do your tests with a #2 filter.

b) when you are using a diffuser light source (either a colour head, or an enlarger with a diffuser in the light path or a multigrade head) you should do your tests with a #3 filter.

The reason for this is that films are developed for less time (lower contrast) for a condenser/point light source because these light sources are inherently more contrasty. Films intended for diffuse/colour/mulltigrade light sources are developed for longer (higher contrast) because these light sources are inherently less contrasty.

Although this has been the accepted norm for a very long time, many printers that I know use a #3 filter for their tests irrespective of the type of light source as they feel that testing and standardising at #3 is more flexible as this is the mid-point in the range of grades generally available (i.e #1 - #5).

As you are using below the lens filters, I presume that you may have either a standard condenser light source, a diffused condenser light source or a diffuser light source. So based on the accepted norm, you will need to choose the appropriate filter for your light source.

However, I personally would choose to use the #3 filter for all of your tests as you will have the widest possible range of options of interpreting your negatives as you move forward.

Let us know how you get on.

Bests,

David.
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Originally Posted by cliveh View Post
I would respectfully disagree with this and suggest that if using a condenser or diffuser enlarger you print initially with no filtration. In this way it will help you develop your exposure and negative development technique to require no filtration for the given enlarger of your choice.
Clive,

Your response is to a follow-up post that I made in response to questions from the OP relating to my earlier post outlining a testing procedure for roll film users.

Sure you can calibrate your negatives to Multigrade paper with no filters (or to fixed grade papers for that matter) BUT this is only practical when you:
  • Use sheet film so that each negative can be processed individually to match the subject brightness of the scene and how you wish to interpret it (i.e. Full Zone System methodology).
  • You only photograph scenes with very similar brightness ranges across the whole roll of film.
  • You work with a camera with 5 interchangeable backs so that you can tailor processing to N-2, N-1, N, N+1, N+2.
In practice for many people - especially roll film (135, 120, 220, etc) users - this is not practical and so other methodologies need to be employed.
By using the tests that I outlined, you fix your Exposure Index (or put another way the ISO rating for the film when using your equipment, your way of metering, your developer of choice and your chosen printing time), placement of dark shadows in which you wish to retain detail, placement of highlights in which you wish to retain detail and the minimum exposure for the print to ensure a full black in the print. This fixes a great number of variables and ensures that you have consistent negatives.

The reason for suggesting these tests be done at #3 are:
  • By processing to match #3 you can give slightly less development which (given the intrinsic characteristics of the film and developer used) will produce lower grain in the final print.
  • Having fixed your negatives to give consistent results at #3, you can then use the full spectrum of contrast grades from #0 (or #00 in some cases) to #5 to fine tune the contrast of the final print to either the subject brightness range or how you wish to creatively interpret the scene to match how you pre-visualised it. Using this approach is a practical replacement for Zone System N-2, N-1, N, N+1, N+2 development techniques not easily available to roll film users.
Ultimately, as I mentioned in my original post, one’s approach to technique should be to remove as many variables as possible and strive for consistently printable results. However, whether this represents the scene how YOU want it to look / how you visualised it as a finished print is quite another question. For example, all of my negatives produce a good tonal range on #3. In practice, I often print at #4 - 4.5 with localised dodging and burning (often at a lower grade) to achieve the interpretation of the scene that matches how I visualised it at the time of exposing the film. Put simply, I am not at all interested in creating a ’straight’ rendition of the world as it is but how I want it to look in my photographs.

Bests,

David.
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  #44  
Old 11th September 2014, 07:31 AM
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BTW, is there a standard for grades?
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  #45  
Old 11th September 2014, 11:37 AM
JOReynolds JOReynolds is offline
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Hi Miha
I researched this last year and found that ISO 6846:1992 is the only current standard referring to paper contrast. It does not mention the contrast grades 00...5 that we are familiar with.

The Standard text states: "Each manufacturer has established a unique system for grading of papers and designations which makes it extremely difficult for users to identify products which are comparable for printing characteristics. The ISO range number is introduced to reduce this source of confusion." It defines paper contrast as ISO Range in the form, for example, "ISO R140".

I found the following table of range/grade equivalents for Multigrade IV RC paper and Multigrade filters on the Ilford/Harman website:
http://www.ilfordphoto.com/Webfiles/...1231142522.pdf page 2

Filter 00 R180; 0 R160;1 R130; 2 110; 3 R90; 4 R60; 5 R40
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  #46  
Old 11th September 2014, 12:11 PM
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Quote:
Originally Posted by JOReynolds View Post
Hi Miha
I researched this last year and found that ISO 6846:1992 is the only current standard referring to paper contrast. It does not mention the contrast grades 00...5 that we are familiar with.

The Standard text states: "Each manufacturer has established a unique system for grading of papers and designations which makes it extremely difficult for users to identify products which are comparable for printing characteristics. The ISO range number is introduced to reduce this source of confusion." It defines paper contrast as ISO Range in the form, for example, "ISO R140".

I found the following table of range/grade equivalents for Multigrade IV RC paper and Multigrade filters on the Ilford/Harman website:
http://www.ilfordphoto.com/Webfiles/...1231142522.pdf page 2

Filter 00 R180; 0 R160;1 R130; 2 110; 3 R90; 4 R60; 5 R40
Thank you. It's easy to see from the attached pdf how soft the Multigrade inherent contrast is compared to other makes. A negative that fits unfiltered Multigrade paper must have quite a high contrast.
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  #47  
Old 11th September 2014, 12:44 PM
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Originally Posted by Miha View Post
BTW, is there a standard for grades?
Joe is correct but to expand on this see attached chart.

This is made by printing a transmission step wedge onto paper and then measuring reflection densities of the paper for each step of the transmission wedge (0.1 LogD transmission steps in my case).

The standard for ISO(R) states that the paper density is measured from between 0.04 LogD and 90% of max logD for this test and paper. The two horizontal red lines are those two containing limits.
So the ISO(R) is calculated only on the data between those upper and lower limits.
The ISO(R) is the transmission range (the R in ISO(R)) between those two limits as read off the bottom axis in logD and multiplied by 100 (just to provide an integer value instead of demical places values)

So taking grade 2 filter, the red curve, the lower point where it crossses red line reads off 0.63 and the upper point it crosses red line reads off 1.72. The range difference between two points on bottom axis is therefore 1.09 and that multiplied 100 is 109 so the ISO(R) I got for my test is 109.

So when you see the little chart that Joe pointed you to saying that grade 2 is ISO(R) 110 it means that the negative density range required to produce G2 with G2 filter is 1.1 LogD

Remember of course that you will need a bit more density range to hit pure white and pure black in the print. And from my tests I have determined that the optimum density range target of any negative is 1.3LogD or thereabouts which will result in very easily printable negative on G2 (or no filtration) on MGIV paper.

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  #48  
Old 11th September 2014, 12:53 PM
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Thanks. But for a negative with an effective density range of 1,32 log a grade 1 is needed, says Ilford. Go figure. I have the reference negative made by Ilford (FP4 in ID11), it should print nicely on unfiltered MGIV. I'll make a test during the weekend.
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  #49  
Old 11th September 2014, 01:05 PM
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Quote:
Originally Posted by Miha View Post
Thanks. But for a negative with an effective density range of 1,32 log a grade 1 is needed, says Ilford. Go figure. I have the reference negative made by Ilford (FP4 in ID11), it should print nicely on unfiltered MGIV. I'll make a test during the weekend.
If you read it carefully what Ilford actually says is:

Quote:
As an example, for a negative with an effective density range of 1.32 log exposure units
EFFECTIVE means between the upper and lower limits (0.04 to 90%) and NOT the whole negative density range.

If you look at my chart the range between upper and lower for G1 is on or about 130.

Last edited by Argentum; 11th September 2014 at 01:33 PM.
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  #50  
Old 11th September 2014, 01:59 PM
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As a bit of a generalisation you can add 20 (0.2 LogD) to the ISO(R) value of any grade to find what your overall negative density range should be for any specific grade. So for a grade 1 then you get 150 which is 1.50 LogD.

All these numbers are pretty useless in real world photography from day to day. However, if you do own a densitometer and have been through the learning curve it makes testing a new film developer combination a breeze. You know what the target is and can see from a single test how close you are to it. So much so that at most you can nail it with two tests or be close enough with a single test to be able to make intuitive adjustment and go straight into using new film dev combination with a high degree of confidence that you will get it spot on first time out.
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