T-Max Film and Using Yellow Filters?

[rodeo_joe1]

Maybe, but some things are more fun than others, even if it is just physics.

That reminds me of a lecture on colour photo-chemistry that I attended some time ago. The lecturer was a visiting research photo-chemist from Kodak.

 

After explaining about coupler dyes he threw it open for questions. I asked something along the lines of "Isn't it really lucky that such chemicals exist then?"

 

The lecturer looked puzzled and a bit annoyed, then proceeded to carefully explain that those chemicals weren't just 'lying around' to be discovered, but were painstakingly chemically engineered into existence by people such as himself.

 

That was a lightbulb moment that put an entirely new perspective on colour photography for me.

but it just seems like fooling around to me,

Sometimes just 'fooling around' gets better results than a carefully planned, but mundane, exercise.

[glen_h]

That reminds me of a lecture on colour photo-chemistry that I attended some time ago. The lecturer was a visiting research photo-chemist from Kodak.

 

After explaining about coupler dyes he threw it open for questions. I asked something along the lines of "Isn't it really lucky that such chemicals exist then?"

 

The lecturer looked puzzled and a bit annoyed, then proceeded to carefully explain that those chemicals weren't just 'lying around' to be discovered, but were painstakingly chemically engineered into existence by people such as himself.

 

(snip)

 

And with the technology of the time.

 

Color developing agents have gone from CD-1 up to CD-4, and aren't all that different.

 

In the case of Kodachrome, where each color was separately developed, they might have used a different developing agent, along with a different coupler for each.

But for coupler incorporated films, one developing agent has to be able to make all the color dyes.

 

And even more, the developer and couplers have to be reasonably priced, even in large quantities.

 

At some point we are lucky that carbon allows for such interesting molecules, as life depends on molecules not so different.

[rodeo_joe1]

And with the technology of the time.

Hey, steady on. It wasn't that long ago Glen!;)

 

Somewhere between the steam age and the C21st.:oops:

[glen_h]

Well before electronic computers.

 

I am not so sure how much computing is used in organic chemistry, but if

for nothing else, keeping track of experiments and results.

 

They are only up to CD-4 by now, so after so many years only three improvements

to the color developing agent. Since people do like to cross-process film, it seems that

the different CD agents aren't all that different.

 

As well as I know it, besides needing to react to produce appropriate color dyes,

in films with the couplers included the couplers are in oily drops. The color developing agent

needs to be water soluble to be used as a developer, but then oil soluble to make the dyes.

Some of the changes are related to doing that.

[rodeo_joe1]

Well before electronic computers.

Nope! They were around before I was born. Used to break German codes in WWII. Not to mention Babbage's 'difference engine'. And one of my first jobs involved programming a horrible little automated IC tester that used Octal coding and had 12 bit registers. Uuurgh! Gives me the heeby-jeebies just thinking about it now.

[glen_h]

Kodachrome is 1935, ENIAC is 1946.

 

Electromechanical computers are older, and mechanical but not electrical ones even older than that.

[AlanKlein]

Nope! They were around before I was born. Used to break German codes in WWII. Not to mention Babbage's 'difference engine'. And one of my first jobs involved programming a horrible little automated IC tester that used Octal coding and had 12 bit registers. Uuurgh! Gives me the heeby-jeebies just thinking about it now.

When I worked for Sperry Rand Univac Division in the late 1960's, I installed and service their third generation computer - a Univac 494. (10x3 bits). It was an octal machine with 30 bit registers Discrete components - transistors, resister, etc. No IC. Their next machine an 1108. IBM had their System 360 a four bit byte machine. Univac still had a predecessor at the time that used decimal registers with ten stage electronic bulbs. You could see the counting and bit storage in each of the bulbs that had ten filaments lighting up in sequence. Very pretty to look at. Univac made the Eniac but that was before my time. I'm not that old. :) Well, I was two or three.

[glen_h]

By the way, Unisys, successor to Univac, still sells ones' complement machines, confusing everyone.

 

In any case, Kodachrome is older.

[glen_h]

So, dye-coupler, couplers added during processing, Kodachrome was invented about 1935.

 

I was only recently thinking about how that works, or how it almost doesn't.

 

As usual in reversal films, a first developer develops the exposed halide.

 

Then, in one step, the film is exposed from the back to red light, and then the

now exposed grains are developed while creating cyan dye.

 

Then it is exposed from the front, and the yellow dye image is created.

 

Now (and this is the part that I only recently considered) there are only two sides,

front and back. The green sensitive layer is chemically exposed, and developed

to produce the magenta image. Note that it couldn't be optically exposed, as the

negative (first developer) and two positive silver images are already there.

Those would block any light attempting to expose the green sensitive layer.

(Actually, shade it in a way that would change the result.)

 

Fortunately for us, only three are needed.

 

One result of the last step is that it also develops, and puts magenta dye into,

still undeveloped halide in the other layers. As the process isn't 100% efficient,

there will be some of that, which affects the colors in a certain way, which I

suspect is the "Kodachrome look".

[AlanKlein]

By the way, Unisys, successor to Univac, still sells ones' complement machines, confusing everyone.

 

In any case, Kodachrome is older.

The Univac 494 I worked on could only subtract 1's and 0's, never added bits. When it added, it would subtract then invert the bits. Talk about stupid. Of course, subtracting is harder actually. Today's smart machines apparently can add. That's all they do today. Everyone makes a big deal with AI. How creative can a machine that can only subtract bits be? I think film is smarter. :)

[Vincent Peri]

As an anticlimactic announcement, I'm going to shoot a roll of T-Max 100 using a yellow Nikon Y48 filter tomorrow.

 

Hmm... yellow... that re-

minds me of bananas...

http://bayouline.com/o2.gif

[glen_h]

The Univac 494 I worked on could only subtract 1's and 0's, never added bits. When it added, it would subtract then invert the bits. Talk about stupid. Of course, subtracting is harder actually. Today's smart machines apparently can add. That's all they do today. Everyone makes a big deal with AI. How creative can a machine that can only subtract bits be? I think film is smarter. :)

 

Yes, that is one fix for ones' complement machines. Otherwise it is usual to do subtraction by adding the complement.

 

(A little off topic, but oh well.)

 

The problem with ones' complement machines is that you can have a negative zero.

There are two fixes. One is to put in extra logic so negative and positive zero compare equal.

 

The other is to not generate them.

 

You can build a ones' complement subtractor that doesn't generate negative zero as long as neither

operand is negative zero. You can even build one that won't generate negative zero as long as the

first operand isn't negative zero. You then add by subtracting the complement, with no problems.

 

Otherwise, pretty much everyone else uses two's complement which doesn't have a negative zero.

[rodeo_joe1]

In any case, Kodachrome is older.

I was referring to the date of the lecture I attended Glen.

 

Sometime in the 1980s I believe it was. So colour film dyes were still being researched at that time.

[rodeo_joe1]

Of course, subtracting is harder actually

Not at the logic level. All it needs is an array of NAND gates. Whereas adding requires XOR gates plus AND gates to generate an overflow to the next highest bit.

 

Shall we stop dredging up these memories of 'past lives'?

[AlanKlein]

Yes, that is one fix for ones' complement machines. Otherwise it is usual to do subtraction by adding the complement.

 

(A little off topic, but oh well.)

 

The problem with ones' complement machines is that you can have a negative zero.

There are two fixes. One is to put in extra logic so negative and positive zero compare equal.

 

The other is to not generate them.

 

You can build a ones' complement subtractor that doesn't generate negative zero as long as neither

operand is negative zero. You can even build one that won't generate negative zero as long as the

first operand isn't negative zero. You then add by subtracting the complement, with no problems.

 

Otherwise, pretty much everyone else uses two's complement which doesn't have a negative zero.

It's been 50 years. I do remember something about that and carries. But I forget how the machine handled it.

 

Speaking of bits, I used to be on-site maintenance for Univac at Bache and Co, a big Wall Street brokerage at that time. They had about six million dollars of computers, drums, tape machines, etc on a raised floor. Their programmers worked in Fortran IV. One night their shift supervisor came to me complaining that they were getting wrong computations. When I subtracted what they got from what they expected, it was $4096. Bingo. 2 to the twelve = 4096. Being a discrete component machine built on hundred of circuit cards unlike today's IC computers, you actually had to troubleshoot problems like this. I tracked it down to a transistor that was driving the twelve bit to a memory stack (bistable ferromagnetic cores). It wasn't driving them every once in a while. So I replaced the driver and we were back in business, Today you'd throw out the whole computer like an old toaster and get another one from Dell. Back then, you really learned how a computer work on an instruction level like you were describing to follow it through the machine stepping instruction one step at a time.

 

The point about this is that one bit can so screw up the outcome, like a bad hangover the next morning. So a bit machine - just how smart is it? The idea that it can figure out all the perceptual - conceptual ideas and take over from man, is just nonsense and a great sales pitch from companies selling AI. It all comes down to human ingenuity and how it's programmed by man.

[AlanKlein]

Not at the logic level. All it needs is an array of NAND gates. Whereas adding requires XOR gates plus AND gates to generate an overflow to the next highest bit.

 

Shall we stop dredging up these memories of 'past lives'?

You're right. Subtracting requires less circuitry.

[glen_h]

I was referring to the date of the lecture I attended Glen.

 

Sometime in the 1980s I believe it was. So colour film dyes were still being researched at that time.

 

Oh, OK. I was referring to the idea of dye couplers and oxidized developers combining to form dyes.

The developing agents have changed just a little over time, such that I believe that the older ones will still form dyes with new films.

It seems that cross processing is getting more popular.

 

There have been changes to the couplers that make the dyes more stable, but again fairly small changes.

(But big if it is your film that hasn't faded.)

 

It seems that the idea of film incorporating couplers goes back before Kodachrome,

but they didn't get it working quite as fast.

 

The idea that I was not making so well, is that with computers and computational

chemistry now, one could come up with some newer and fancier process, but they

did it all without electronic (no mechanical computing parts) computers.

[Moving On]

I hate to 'burst your bubble' James, but it isn't magic. Just applied physics and chemistry

Yes but ignorance being bliss, I like the Magic.......