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Darkroom forum. Equipment and printing?


m._hilo

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I can't understand why everything that isn't digital should be called "analog"...

Especially when it isn't. At the grain level there are no shades of grey. Every AgX crystal in the film or paper is either developed to opaque silver, or it's not, and you can't get much more digital than that.

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Especially when it isn't. At the grain level there are no shades of grey. Every AgX crystal in the film or paper is either developed to opaque silver, or it's not, and you can't get much more digital than that.

 

It isn't the grayness, it is the analogness.

 

Density is analogous to light exposure, more or less.

 

Magnetic tape holds a magnetic field that is a not quite linear function of the current in the record head.

The current is, after equalization and such, a close to linear function of the air pressure on the microphone.

 

Note that regarding your digitalness, current is some number of electrons moving through a wire,

and air pressure comes from some number of atoms hitting the microphone diaphram.

 

Take a top and spin it. How many different speeds (angular velocities) can you spin a top?

Angular momentum always comes in integer multiples of hbar/2. That is small enough that you

believe you can spin it at any speed, but no.

 

Light comes into the camera in whole photons.

 

It isn't digital until you convert it to a number, even though it comes in discrete values.

 

In the case of signal processing, such as audio or video signals, there are two things

to consider. One is that the signal can be discrete in time, that is, sampled.

The other is that the sample values can be quantized. There are audio recording

systems that hold samples as voltages on capacitors. Sampled, but not (other than

counting electrons) quantized. A voltage is read out, not a number.

 

Grains come in a lot of different sizes, larger ones more sensitive than small ones.

We look at the density, averaged over some grains, which depends on both the

number and size of the silver grains. If it was only the number, if all were the same

size, then you could count them. But they aren't, and we don't.

-- glen

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The favorite way to expose silver halide paper now is with a scanned laser

(well, three of them) with intensity set by a DAC, from a digital image.

That is, it is done in the dark, other than the lasers, and qualifies as a

digital darkroom. (Well, closer to dark box.)

 

I suppose some people take their computers into their darkroom,

though with the lights on, and edit their digital photographs, but is

that really a digital darkroom?

 

As well as I know, the scanning laser AgX printers are out of the price

range for most home users.

 

I once looked up the data sheet for Fuji Crystal Archive, which gives

reciprocity values in microseconds to minutes. You can use it with either

scanned lasers, or optical enlargers.

-- glen

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I can't understand why everything that isn't digital should be called "analog

Especially when it isn't. At the grain level there are no shades of grey. Every AgX crystal in the film or paper is either developed to opaque silver, or it's not, and you can't get much more digital than that.

Not to mention that digital is analog at the same step in the process that "analog" is digital. Even more confusing, when an analog ("digital") image is converted to digital, it is called "digital"; but when a digital (film) image is output on digital media (photo paper or scanned), it is referred to as "analog."

 

Referring to film as "analog" used to bother me until I realized a basic distinction: Film images can look pretty darned good--superb in the right hands--but "analog" images usually look like crap.

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Referring to film as "analog" used to bother me until I realized a basic distinction: Film images can look pretty darned good--superb in the right hands--but "analog" images usually look like crap.

lol +1

_______________________

 

“For a large class of cases–though not for all–in which we employ the word 'meaning' it can be defined thus: the meaning of a word is its use in the language.”

—Ludwig Wittgenstein

"You talkin' to me?"

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Just thinking aloud... If we have to name "digital darkroom" to the digital image edition, I prefer the term "traditional" darkroom instead of "analog" darkroom... I can't understand why everything that isn't digital should be called "analog"... :D

 

Correct! Traditional Darkroom covers it better.

 

Even implying there's more than that: namely the Digital Darkroom

 

Analog to me sounds non-committal

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It isn't the grayness, it is the analogness.

 

Density is analogous to light exposure, more or less.

 

Magnetic tape holds a magnetic field that is a not quite linear function of the current in the record head.

The current is, after equalization and such, a close to linear function of the air pressure on the microphone.

 

Note that regarding your digitalness, current is some number of electrons moving through a wire,

and air pressure comes from some number of atoms hitting the microphone diaphram.

 

Take a top and spin it. How many different speeds (angular velocities) can you spin a top?

Angular momentum always comes in integer multiples of hbar/2. That is small enough that you

believe you can spin it at any speed, but no.

 

Light comes into the camera in whole photons.

 

It isn't digital until you convert it to a number, even though it comes in discrete values.

 

In the case of signal processing, such as audio or video signals, there are two things

to consider. One is that the signal can be discrete in time, that is, sampled.

The other is that the sample values can be quantized. There are audio recording

systems that hold samples as voltages on capacitors. Sampled, but not (other than

counting electrons) quantized. A voltage is read out, not a number.

 

Grains come in a lot of different sizes, larger ones more sensitive than small ones.

We look at the density, averaged over some grains, which depends on both the

number and size of the silver grains. If it was only the number, if all were the same

size, then you could count them. But they aren't, and we don't.

So you're saying that everything is quantized at some level, but it's only when we count those quanta in binary that they become 'digital'?

Sorry, but I fail to see that fine distinction as relevant.

 

If I have more sand than I can count the grains of, does that make it an homogenous liquid?

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So you're saying that everything is quantized at some level, but it's only when we count those quanta in binary that they become 'digital'?

Sorry, but I fail to see that fine distinction as relevant.

 

If I have more sand than I can count the grains of, does that make it an homogenous liquid?

 

It isn't that it is, or isn't a count, but that you use, or don't use, the count.

 

If you make a copy of a negative, using AgX chemistry, the copy will be different.

The grains will have different sizes and positions. Hopefully, and depending on how

good you are at making the copy, the density will be close, when not looked at too

closely. But the copy is based on optical density, and not grain count. With a fine

grain film, the density might be close, but the grain count very different.

 

Using the sand analogy, you have more than you can count, but you can weigh the sand,

and divide by the average weight of a grain. That will give a good approximation to the

number of grains. Not exact, but sometimes close enough.

 

You could use a bag of sand as a weight standard, for comparing other objects.

That is, using it like. a homogeneous liquid, even though it isn't. Note that the

homogeneous liquid is composed of molecules, which you also can't count.

-- glen

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If I have two bags of pennies, and want to find out which one has more, I could count them.

 

I could also put them on a two-pan balance, and see which one weighs more.

I this case, the weight would be analogous to the number, with some assumption

on the variability of weight of pennies. There are only whole pennies, but the

measurement method doesn't depend on that. The variation in weight should

be small enough, not to affect the accuracy.

 

On the other hand, there is a large variability in grain sizes in most films.

Counting the grains is not an accurate way to determine density.

 

As well as I understand it, when ATMs dispense bills, they count them,

but that isn't quite as accurate as it should be. They can stick together,

especially when new. Measuring the optical density with IR light is

an accurate way to be sure it is right. Analog backup to digital counting.

-- glen

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Glen, I fear we're falling foul of the difference between a popular interpretation of the word "analogue" (or analog) and its truer meaning of "being analogous to". The popular interpretation being more like "continuous and infinitely divisible", which known physics shows is impossible.

 

But even at greater than an atomic or fundamental particle level, it's easily provable that the number of tones represented per unit area (of image) is greater with digital capture than with film. In other words; more similar to the popular (mis)conception of the word "analogue".

Sample crop from T-max 100 film:

T-Max-100_Pentax-SPF.thumb.jpg.4ade67fc1d8290063377ee739ad8e777.jpg

 

Sample crop from old Canon 5D digital camera:

Canon-5D.thumb.jpg.527b478a1935cc924315fa463ae2c73e.jpg

 

I think it can easily be seen that the digital capture has smoother tonal quality - and is therefore closer to being analogous to the direct perception of the human eye.

 

If we examine the cause, it's because even in a crude compressed JPEG, each digital camera pixel area (about 8.5 microns square) can contain 255 levels of tone. Whereas the same area of film quite obviously can't equal that fineness of tone differentiation.

So area for area, the 'digital' image actually looks, and indeed is, more 'analogue'. QED.

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Measuring the optical density with IR light is

an accurate way to be sure it is right. Analog backup to digital counting.

And how is that IR light quantised? By some human eyeballing it and comparing it to a sample chart? Nope, but by an IR sensor's output being digitised and the binary number being compared by computer to some stored threshold value.

Edited by rodeo_joe|1
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Very old group (prior APUG). Very Analog. Very darkroom technical. Very many darkroom & film fora.

 

Photrio.com Photography Forums

 

Yes, their traditional or analog fora are plenty. Lots of knowledge. Folks seem to react mostly when they know more than usual about a subject. In my case that is about Leitz enlargers which I have used since the late seventies and I still do. Let's say you don't find me in threads about Leica cameras. I use Olympus since way back then, but I still find there's not much to say about them. Or perhaps cameras interest me less.

 

I suffer from insomnia and when the newspapers are too depressing the forums are a welcome distraction.

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(snip)

In my case that is about Leitz enlargers which I have used since the late seventies and I still do.

(snip)

 

As well as I know it, the Nikon forum allows posts for any Nikon product.

That would include printing with an enlarger and EL-Nikkor lens.

 

If I make contact prints, I put negative and paper under glass, and expose them

with the enlarger, and EL-Nikkor lens. I don't normally discuss that in the

Nikon forum, though it should be allowed.

 

Discussions of Leitz enlargers might be allowed in the Leica forum, though I

haven't read the actual rules. Normally they would find more answers here.

-- glen

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Discussions of Leitz enlargers might be allowed in the Leica forum, though I

haven't read the actual rules. Normally they would find more answers here.

 

Don't fret. Over on APUG/Photrio, there are many who will set you straight if the content wanders near long-treasured boundaries... :cool:

 "I See Things..."

The FotoFora Community Experience [Link]

A new community for creative photographers.  Come join us!

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