Microdensitometery for understanding Stand Development

[df cardwell]

Tom

Good.

Do you know what the results will look like ?

 

[Tom Hoskinson]

Tom

Good.

Do you know what the results will look like ?

The proposed design will use Edmunds chrome-on-glass Tri-Bar Targets and Stouffer step wedges as test patterns for contact printing onto film.

We will be looking for repeatable and predictable differences in microdensity based on varying agitation, pH, concentration, developer buffering, etc for a film/developer combination.

To design efficient test plans, I have proposed the use of Statistical DOE ( Design of Experiments) methodology.

The original APUG thread asked the question in reference to Pyrocat-HD with stand development versus various agitation schemes and it will be one of the developers considered. Several B&W films will be utilized.

Pat Gainer is currently investigating the properties of an Amidol/Ascorbate/TEA film developer with several films.

 

[df cardwell]

Yes, Tom

I follow that.

I'm not asking about process, or methodolgy.

I'm not asking to predict the outcome.

I'm asking if you can describe what the results will look like.

 

[Tom Hoskinson]

I'm asking if you can describe what the results will look like.

The primary hypothesis is that there is a difference in image microcontrast in negatives stand or semi-stand developed in Pyrocat-HD (or other developers). This hypothesis is based on visual comparisons of negatives developed by the stand or semi-stand method compared with identical negatives developed with conventional agitation.

The results should show that there are (or not) quantifiable differences in image microcontrast related to the agitation methods.

If there are quantifiable differences, then the next questions on the table relate to the reasons for the differences, with the purpose of predicting, controlling and optimizing them.

 

[gainer]

The primary hypothesis is that there is a difference in image microcontrast in negatives stand or semi-stand developed in Pyrocat-HD (or other developers). This hypothesis is based on visual comparisons of negatives developed by the stand or semi-stand method compared with identical negatives developed with conventional agitation.

The results should show that there are (or not) quantifiable differences in image microcontrast related to the agitation methods.

If there are quantifiable differences, then the next questions on the table relate to the reasons for the differences, with the purpose of predicting, controlling and optimizing them.

I'm sure you have or will consider this, but I bring it up anyway. There will no doubt be objective difference in the adjacency and other effects of agitation and developer constitution. There will also be subjective differences among viewers, and certainly a particular objective edge characteristic enlarged from 35 mm will not be either objectively or subjectively the same as a contact print from an 8X10 negative.

I used to design the kind of experimental plan you want to use. I hope I don't ever have to do the grunt work to make this one happen. It will be more like a barrel than a can of worms. It's bad enough when you are dealing with a multivariate linear process. There are times when serendipity is not such a bad thing. What I mean is, I hope you get lucky.

 

[Kirk Keyes]

I'm asking if you can describe what the results will look like.

I'm hoping that something as simple as graphs of the density vs. distance could be produced. By making comparison graphs of two different edges, then maybe some more info could be derived, even something as simple as this development technique has "more" edge effect than another.

Beyond that, I would think that some sort of "index" could be derived to make numerical comparisons. All very clean, heartless, and sterile, I know. But it would be something that could save a lot of time for people interested in these questions.

Kirk

 

[Kirk Keyes]

I can try to duplicate these onto film, but I am not sure that the duplicated quality would be satisfactory using my equipment. Not sure, but if you think so, suggest a film and developer and I'll give it a try.

Ron, what about using litho film, or perhaps some Tech Pan with high contrast developer?

I was looking at the Edmunds site, and they have the USAF 1951 chrome on glass for around $120. I'm temped to get one, but that's a bit of cash... If you could make me a contact of your target, that would be coool.

 

[Kirk Keyes]

Yes, chromium on glass and somewhere I have some dupes we made on Tech Pan and developed in D-19 that are pretty good. BTW, I have a lot of 70mm perf'd Tech Pan in the freezer - don't know how good it is anymore...

Tom - is it possible you could send me one?

I bet the Tech Pan would last a long time in a freezer.

 

[Kirk Keyes]

However, what we use (to process SEM, TEM and Xray and optical microscopy images) is a site licensed MediaCybernetics product called Image Pro Plus. This software is currently only available for IBM PC type hardware.

There is considerable "sticker shock" associated with Image Pro. The "light" version costs just under $1000.00. However, many Universities and Companies have bought site licenses.

My microscopy buddy uses this program. I've played with it some and it is very nice and would be perfect for a project like this. But it is definitely out of the price range I was hoping that this project could be brought in for...

 

[Kirk Keyes]

Silicon phototransistors are obtainable with very small apertures and very high sensitivity and linearity. High quality silicon diodes have an exponential voltage-current transfer which, in the feedback loop of a high quality operational amplifier with the phototransistor connected as a current source to the inverting input of the op amp, provide an output that is accurately the logarithm of the input times a constant.

Pat, could you (or someone else as well would be fine) sketch out a circuit that could do this? I'm not really skilled in circuit design... but I could build something if I had a schematic to work from. I've even got some 20 year old LM 741s laying around, I think.

Something that could use a cheap op amp, had a zero adjust, a gain fine adjust, and hopefully had a 10 stop linear range would be nice. And prehaps specs for the phototransistor.

 

[Kirk Keyes]

I fear there is a great danger that, said and done, the Test will simply Test the Testers rather than the intended process.

It's very well possible that it will come out like this. It may be that this kind of measurement is beyond the skill level of the casual amateur photo technician. Let alone the construction of a device to make the measurements.

But it would be neat to try and do it...

 

[Photo Engineer]

Ron, what about using litho film, or perhaps some Tech Pan with high contrast developer?

I was looking at the Edmunds site, and they have the USAF 1951 chrome on glass for around $120. I'm temped to get one, but that's a bit of cash... If you could make me a contact of your target, that would be coool.

Kirk, I'll look into what I can do. I have no Tech Pan, and have not used Lith for years. No real problem, but the chrome chart looks interesting.

PE

 

[df cardwell]

....There will no doubt be objective difference in the adjacency and other effects of agitation and developer constitution. There will also be subjective differences among viewers...

I'm hoping that something as simple as graphs of the density vs. distance could be produced. By making comparison graphs of two different edges, then maybe some more info could be derived, even something as simple as this development technique has "more" edge effect than another.

Beyond that, I would think that some sort of "index" could be derived to make numerical comparisons...

This is a bit of what I was wondering about. One of ny hobby horses, looking back over how photography was done prior to WW2 and how it is now, has to do with the various ways we've described Film Speed and contrast. Over time, we've gained precision and repeatabilty in the laboratory, yet picking on the concept of CI for a moment, we've lost a great deal in how photographers think of the negative in practise. The CI approach has made many things possible, but here is an ideal case where the Laboratory has perhaps had too much influence in the actual picture making process. By limiting our Vocabulary, we shape our way of thinking. And our thinking determines, too often, uniformity in expression.

I would hope that we establish a descriptive process that allows the photographer to determine the value of a particular film and developer system.

With this in mind, I wonder just how deeply we need to dig in order to be able to make informed expressive choices, and support them by sound, but not, necessarily Research Facility, technique.

 

[Jon King]

Pat, could you (or someone else as well would be fine) sketch out a circuit that could do this? I'm not really skilled in circuit design... but I could build something if I had a schematic to work from. I've even got some 20 year old LM 741s laying around, I think.

Something that could use a cheap op amp, had a zero adjust, a gain fine adjust, and hopefully had a 10 stop linear range would be nice. And prehaps specs for the phototransistor.

Something to look at could be light-frequency or light-voltage converters. TAOS www.taosinc.com is one company that has integrated this function. One advantage of the light to frequency converter is that the you can use the processor to measure frequency and do your calibration in the software. If you set your 0.0 density point high enough, I don't think you have to worry about a zero adjust, and you'd have a single point calibration to perform.

 

[Tom Hoskinson]

There are times when serendipity is not such a bad thing. What I mean is, I hope you get lucky.

Thanks Pat, but I will try to design an efficient Statistical DOE (like a modified Taguchi,etc.) rather than try to get lucky. Of course, getting lucky wouldn't hurt.

 

[Tom Hoskinson]

Tom - is it possible you could send me one?

I bet the Tech Pan would last a long time in a freezer.

Kirk,
I'll see if I can remember where I put the Tri-bar dupes. If I can't find them, I'll make you a fresh contact on Tech Pan (then we'll see if it's still good).

PM me your address.

 

[Kirk Keyes]

Something to look at could be light-frequency or light-voltage converters. TAOS www.taosinc.com is one company that has integrated this function.

The TSL250R from Taos looks good, or perhaps the TSLG257. But I could not find someone that sells there to regular people, i.e. orders less than several thousand parts. Do you have an recommendations for sources?

 

[gainer]

Thanks Pat, but I will try to design an efficient Statistical DOE (like a modified Taguchi,etc.) rather than try to get lucky. Of course, getting lucky wouldn't hurt.

You have to be prepared to find that the real answer is outside the range of the experiments. That means you have to know how to tell if you have what you're looking for. That's not always easy when you're looking for a maximum or minimum in a system that may have several inflection points. You know all this. I'm just sympathizing. Cheers.

 

[df cardwell]

Good luck guys: this looks cool.

 

[Jon King]

The TSL250R from Taos looks good, or perhaps the TSLG257. But I could not find someone that sells there to regular people, i.e. orders less than several thousand parts. Do you have an recommendations for sources?

Future Electronics www.futureelectronics.com has both parts, qty 1. for less than 3.50. Their web site can be frustrating, but I've ordered small quantities from them before. I'll pm you with more info.

 

[Kirk Keyes]

Future Electronics www.futureelectronics.com has both parts, qty 1. for less than 3.50. Their web site can be frustrating, but I've ordered small quantities from them before. I'll pm you with more info.

I see what you mean about there site. I'll get something from there.
Kirk

 

[Kirk Keyes]

So here's some more thoughts to bounce off you all -

I would prefer light to volts, and not light to freq, as I think it will just make things simpler to measure, i.e. it's more direct to the tools I have - volt meter and A to D (sound) card.

Right now, I'm thinking of using an old view camera to make a lens stage to hold a telescope eyepiece up to the film. The nice thing about using a view camera stage is that it moves in x,y, and z axes. So I can focus, as well as move the film back and forth and up and down to better align the area of interest with the sensor.

With a bright halogen lamp (from my Beseler 67 dichro maybe) behind the film ,the image will then be projected onto whatever detector I end up using. By focussing a 12.4 mm eyepiece focused on the film, at a distance of 633 mm from the detector, that gives me 50X magnification. (I also have a 9.7 mm eyepiece and at 980 mm that will give a magnification of 100X if needed.)

I can then move the sensor at 1 mm or less increments between readings. By using a stepper motor I have from an old astronomy Barn Door I build to take star photos with, I can automate the movement of the sensor. Hooking the sound card up will give me a 0-1 V signal aquisition.

The output of the Taos chips can be more than 1V depending on how bright things get, so some attenuation may be needed, depending on the range of illumination needed.

Well, that's my thoughts for now. Any comments?

 

[Tom Hoskinson]

Go for it! Let us know how it goes as you get into it.

 

[gainer]

Kirk,
I'm not ignoring your request for a circuit. I have had viral encephalitis and computer crrashes since I built my device, and I'm trying to reconstruct the plans. Actuall, the PC board layout has more on it than you need, and stuff I'm not even using. Give me a few days.

 

[Kirk Keyes]

Kirk,
I'm not ignoring your request for a circuit. I have had viral encephalitis and computer crrashes since I built my device, and I'm trying to reconstruct the plans. Actuall, the PC board layout has more on it than you need, and stuff I'm not even using. Give me a few days.

No hurry, Patrick. I understand the computer crash bit myself. Sorry to hear about the viral encepalitis - I crushed a few of the disks in my neck last month that put my arm into a bunch of pain for some time. Thing's are getting much better but I'm not moving as fast as I would like either...