They used 28 observers to subjectively rank image quality,graininess and sharpness. (They were actually studying different films).
Perhaps Alan is right to highlight how perception of an image can be measured using no photographers eyes, which is what eclarke was also hinting at.Ian
I have to say in response to Sandy, that I agree and disagree that testing is difficult. I think it is complex but easy, or difficult but not complex, depending on how the tests are set up. I have the expensive test charts Sandy refers to. They are evaporated metal on glass. The problem I have is making the exposure properly in the darkroom onto film.
PE
Interesting points, but are you referring to the development of regular B&W films? :confused:Many people purport to have new developer formulations. This is GREAT!
However, to pass the test of time, Kodak and others have established a method for determining if a developer is better, the same, or worse than previous developers.
It requires running an experiment in which the new developer is exactly compared to the old developer, say D-76 or the like.
1. Is the contrast the same? If it is not, then the subjective speed may be different.
2. Is the speed the same at the same contrast? If not then you are fooling yourself.
3. Is the grain the same at the same speed and contrast?
4. Is the sharpness the same at the same speed and contrast?
These 4 factors are used to determine if the new developer equals the current reference developer. To be better, the new developer must be better than 2 or 3 of the above.
So, a new developer presented to you as being "better" should have:
1. Reference pictures to an older reference developer.
2. Be better in 2 or 3 of the above characteristics.
If not, then the developer is questionable, and if there is no reference, then the new developer tests are totally meaningless in that you have no comparison to make with the new developer.
PE
nworth put together much better what I was trying to say in my post. In your OP, you were suggesting that a `new` developer should be measured against a standard developer such as D-76. The point I was trying to make was that although D-76 could be used for regular B&W films such as FP4, Tri-X, T-Max etc, it wouldn`t be a good choice for processing a special-purpose film such as Kodak Technical Pan, hence the need for a specially formulated developer. Now do you see what I meant?Nworth;
Very well put. Thank you for your contribution.
You are right, I did limit my criteria but many people helped with excellent suggestions to fill those gaps. I constrained myself to quantifiable items, but the subjective items and other quantifiable aspects are just as important.
PE
I`m not quite sure, but I think that the Agfa and Ansco 17 developers are the same formula. The other formula that Ian mentioned was the Adox Borax M.Q.Dear Ian;
have you posted the formulae for Agfa's Fine Grain MQ and Ansco 17? I'm vaguely familiar with both but have never used either and have not seen their formulae. I believe your point is well taken about developing a standard all can agree on.
Denise Libby
I don't know about everyone else,
but I'm not going to trust 28 strangers to tell me what I thnk is best!
How about Strumpet?
Anyhow, yes, Sandy I understand what you are saying and much of the evaluation of prints is subjective. This is why some prefer Kodak film and some prefer Fuji film when it comes to color, and the problems with the Kodachrome market evaporating has something to do with subjective preference as well.
As I said, when it comes down to the wire, you are going to sell someone on a photo, not the curves of the material used to make that photo. I am merely pointing to some objective factors or tests that help one go in the right direction.
PE
I don't know about everyone else,
but I'm not going to trust 28 strangers to tell me what I thnk is best!
I`m not quite sure, but I think that the Agfa and Ansco 17 developers are the same formula. The other formula that Ian mentioned was the Adox Borax M.Q.
Ron,
I believe you know that I am not against careful testing when such testing can clearly show some of the objective differences between developers. By that I mean such things as film speed, curve type, and average gradient with a certain type of development. I have done this type of comparison testing with all of the Pyrocat variants against D75 1:1 with a wide range of films. And I did the same comparison recently with the one solution Pyrocat-Uno formula that I introduced.
However, grain, sharpness and image quality are factors that have a large subjective component and because of this are inherently more difficult to evaluate. So we inevitably get into an area of subjective opinions. At this point I guess it is pretty much a "buyer beware" issue and some opinions turn out to weigh more than other opinions because of credibility.
Sandy King
I wasn't talking about true scientific research...How else can you determine such subjective things when one's own personal reality is so biased? You can't do a double blind study with just person.
In the paper I mentioned I assume the 28 observers are representative of the public.It is interesting to note they reached the same consensus opinion about perceived quality as might a group of photographers.
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