5 ms·

I have lots of pictures from about the same epoch (probably from some great-great-great-grandparents or something like that), also on glass, with a similar name

I have lots of pictures from about the same epoch (probably from some great-great-great-grandparents or something like that), also on glass, with a similar name (I'm on vacation atm so I don't have them handy): maybe not "Photocrom" but something not unlike that. And I've seen people "developing" them using another method: I'm not sure if they're the same thing or not. I clearly remember reading a blog where the person did built a little wooden box, padded the inside of the box with aluminum foil, then put a DSLR camera on a tripod. He'd then place one of these "glass" photo on the box, take a picture with the DSLR, then move on to the next "glass" photo. And then do some processing in whatever software (and the result was great). If I recall correctly I read that these old glass photos now after 100+ years begin to fade and those that aren't developed are soon going to be lost.

actionfromafar 3y ago
By developing is generally meant the chemical process of converting the invisible image created by photons changing the electron state of silvery stuff on the plate or film, into a fixed, visible image. What you describe is the process of inverting a negative image into a positive. (Black to white and vice versa.) Also very important because as you say, the images can fade over time.
sys32768 3y ago
I scanned a couple dozen of them from the 1910s on an Epson Perfection V600 flatbed scanner. Incredible detail on the resulting scans, so the original camera must have had quite a lens, not to mention a good photographer.
- jacquesm 3y ago
  Old lenses were either pinholes or very large because the emulsions were so slow they needed a lot of light to gain exposure. My dad collected old cameras, the pinhole ones would work but were a complete pain for anything that wasn't a still-life, for a Daguerreotype you had to sit still for a very long time but it did work if you were patient enough. The lens based cameras did a better job, and also could make Daguerreotypes in a much shorter time. Making these is not without danger: you sensitize the copper silver coated plate (which you apply using silver nitrate) with iodine and you develop it using - no kidding - mercury vapors. I wonder if the very large bottle of Mercury that he had is still sitting in the basement there. I also remember playing with the iodine crystals that had migrated through the double walls of glass that they were supposedly contained in...
  - actionfromafar 3y ago
    The lenses were large, but the film (or plate) was proportionally even larger.
    - jacquesm 3y ago
      Yes, but that is because the film was the picture. You don't put a 35 mm slide on your mantelpiece.
      - actionfromafar 3y ago
        I was mostly thinking about how much light goes through the lens. These old lenses are often f8 or f5.6 while a modern prime is easily f1.4
        jacquesm 3y ago
        Sure, the glass has gotten much better. But so did the recording material, in fact that's where the real revolution happened and even though superficially there isn't much difference between the earliest light sensitive emulsions and what was used with modern film until not that long ago (and still by some people). There was something called the Schneier (sp?, that guy is everywhere :)) film speed rating, but I no longer have access to any of that stuff (the whole family archive got destroyed :( ), it makes for interesting reading. It was possible to have short exposures but they'd be severely underexposed unless you brought your magnesium flash with you! I've sat for hours for pictures in low light.
  - foldr 3y ago
    As the sibling comments says, if the the lenses were large that was because they had to project a large image circle, not because they gathered more light (per unit area) than modern lenses. Modern lenses generally have wider maximum apertures than lenses from ~100 years ago. Also, because the maximum f-number was generally around f4-f8 for lenses from that period, it's not really true that these lenses were much bigger than modern 'full frame' lenses. There are plenty of old lenses that have a diameter of just a few centimeters. Here is an example: https://www.etsy.com/uk/listing/1256001801/vintage-19th-century-beck-symmetrical-f8 https://www.etsy.com/uk/listing/1256001801/vintage-19th-cent...
- qingcharles 3y ago
  This. If you find glass slides, just throw them on a flatbed and it will almost always focus on them perfectly and you can pull some great detail out of them. The next step which will get you 95% of the way to a great print is to go into Photoshop or similar and do a negative on the image, then, and this is the key, set the black point and white point. Somewhere in your app should be a tool where you can pick the darkest and brightest parts of the scan and it will re-set the levels and the photo will look immaculate. [You can do this on any faded photo, B+W or color] Add a little sharpening and Bob's your uncle.
TedDoesntTalk 3y ago
> probably from some great-great-great-grandparents How did these come to be in your hands, and are you interested in the lives of you great-granparents^3 or does it not matter?

actionfromafar 3y ago

By developing is generally meant the chemical process of converting the invisible image created by photons changing the electron state of silvery stuff on the plate or film, into a fixed, visible image. What you describe is the process of inverting a negative image into a positive. (Black to white and vice versa.) Also very important because as you say, the images can fade over time.

sys32768 3y ago

I scanned a couple dozen of them from the 1910s on an Epson Perfection V600 flatbed scanner. Incredible detail on the resulting scans, so the original camera must have had quite a lens, not to mention a good photographer.

jacquesm 3y ago
Old lenses were either pinholes or very large because the emulsions were so slow they needed a lot of light to gain exposure. My dad collected old cameras, the pinhole ones would work but were a complete pain for anything that wasn't a still-life, for a Daguerreotype you had to sit still for a very long time but it did work if you were patient enough. The lens based cameras did a better job, and also could make Daguerreotypes in a much shorter time. Making these is not without danger: you sensitize the copper silver coated plate (which you apply using silver nitrate) with iodine and you develop it using - no kidding - mercury vapors. I wonder if the very large bottle of Mercury that he had is still sitting in the basement there. I also remember playing with the iodine crystals that had migrated through the double walls of glass that they were supposedly contained in...
- actionfromafar 3y ago
  The lenses were large, but the film (or plate) was proportionally even larger.
  - jacquesm 3y ago
    Yes, but that is because the film was the picture. You don't put a 35 mm slide on your mantelpiece.
    - actionfromafar 3y ago
      I was mostly thinking about how much light goes through the lens. These old lenses are often f8 or f5.6 while a modern prime is easily f1.4
      - jacquesm 3y ago
        Sure, the glass has gotten much better. But so did the recording material, in fact that's where the real revolution happened and even though superficially there isn't much difference between the earliest light sensitive emulsions and what was used with modern film until not that long ago (and still by some people). There was something called the Schneier (sp?, that guy is everywhere :)) film speed rating, but I no longer have access to any of that stuff (the whole family archive got destroyed :( ), it makes for interesting reading. It was possible to have short exposures but they'd be severely underexposed unless you brought your magnesium flash with you! I've sat for hours for pictures in low light.
- foldr 3y ago
  As the sibling comments says, if the the lenses were large that was because they had to project a large image circle, not because they gathered more light (per unit area) than modern lenses. Modern lenses generally have wider maximum apertures than lenses from ~100 years ago. Also, because the maximum f-number was generally around f4-f8 for lenses from that period, it's not really true that these lenses were much bigger than modern 'full frame' lenses. There are plenty of old lenses that have a diameter of just a few centimeters. Here is an example: https://www.etsy.com/uk/listing/1256001801/vintage-19th-century-beck-symmetrical-f8 https://www.etsy.com/uk/listing/1256001801/vintage-19th-cent...
qingcharles 3y ago
This. If you find glass slides, just throw them on a flatbed and it will almost always focus on them perfectly and you can pull some great detail out of them. The next step which will get you 95% of the way to a great print is to go into Photoshop or similar and do a negative on the image, then, and this is the key, set the black point and white point. Somewhere in your app should be a tool where you can pick the darkest and brightest parts of the scan and it will re-set the levels and the photo will look immaculate. [You can do this on any faded photo, B+W or color] Add a little sharpening and Bob's your uncle.

TedDoesntTalk 3y ago

> probably from some great-great-great-grandparents How did these come to be in your hands, and are you interested in the lives of you great-granparents^3 or does it not matter?