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I made some researches online to try to understand how the first enlargers worked.
I think that first enelargers started being used in the 1880s, considering kodak produced its first camera in 1888.
What I really want to know is the main idea behind the enlargement process, what instruments played the most important roles (what kind of lens was used), and if the process had any impact on the quality and the sharpness of the image.

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    Haven't you done some basic research? – Zenit Dec 21 '17 at 9:43
  • @Alex.S I did read the article several times, It just doesn't satisfy me, there are plenty of things I did not understand. Such as how it was enlarged, I mean what kind of lens was used, how was discovered it was possible. All things that wikipedia may assume the reader knows or just doesn't care, but that are really important to me. Moreover wikipedia talk about enlargers in general, I'm more interested on the first models to catch the simple idea behin them. – Gabriele Scarlatti Dec 21 '17 at 10:08
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    I am not sure what you are asking exactly. We knew the principles of optics centuries before cameras (and enlargers) were produced. Once we discovered light-sensitive materials, making cameras and enlargers were a trivial engineering problem that applied pre-existing optics knowledge. – Aram Hăvărneanu Dec 21 '17 at 11:35
  • I don't think we can tell you "all the things" that aren't described in the Wikipedia article, and that would certainly make your question too broad, but you might find what you're looking for in other Wikipedia articles. You might start with History of optics. – Caleb Dec 21 '17 at 14:53
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    As I tried to show in my earlier answer, the optics of enlarging are easy. The hard part was chemistry of positive process. Once that was figured out an enlarger was a camera in reverse = by that time a well understood problem. – Jindra Lacko Dec 21 '17 at 14:59
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Why the past tense? B&W enlargers are alive and kicking to this day :)

A couple comments:

  • the idea behind enlargers is Camera Obscura, which has been around since ever, certainly since European Renaissance.

  • similarly lantern slides have been around for longer than photography.

  • special lens for enlarging are yet more recent innovation; in the past your average photographer had just one lens, and used it both to take and enlarge the picture (which is one of the reasons why enlarging lens come in Leica standard 39mm screw)

  • the key reason enlargers started so late in the history of photography was not optics, but chemistry. Positive materials used to be of very low sensitivity, and needed a lot of light to work. In addition they worked the best in UV spectrum, which is blocked by a glass lens.

  • the quality and sharpness of enlarged picture actually decreased when compared to contact copied large format negative. What mattered was the portability of camera and the ease of setting it up - Oscar Barnack created his tiny camera because his poor health did not allow him to carry a clunky 4×5" or larger field camera to the mountain tops he loved.

For the first photographers it was a simple engineering problem: it was easier to enlarge your camera and contact copy from a large negative, than blow up the positive image.

In the quest to make big positives some truly humongous cameras were produced . Only with improvement in positive process in the early decades of the 20th century did enlargers become feasible.

  • Why are you bringing positive materials into the discussion? 'Classical' film photography and enlarging uses only negative materials (both film and paper). Every source I can find says that even if the principle of enlargement was known, the process was mainly limited or made impossible by the lack of a suitable light source. At that time, photographic materials were not sensitive to the longer wavelengths emitted by artificial light sources. – jarnbjo Dec 21 '17 at 16:57
  • By positive process I mean preparing the final prints from negatives. The early techniques such as salt prints or cyanotypes were unsuited for enlarging. By the time enlarging became feasible inertia had set in and the alt-processes gained enormous prestige (think bromoil and platinum - don't they even sound luxurious?). It took a generation change to realise photography should be fast and look to capture a moment of time. This meant small format and thus enlarging. – Jindra Lacko Dec 21 '17 at 17:20
  • Making paper prints from negatives is also a negative process. A positive process is when you make the final print directly in the camera, shoot reversal film or make paper prints from reversal film. Salt prints and cyanotypes are unsuitable for enlarging for the same reason why the at that time 'regular' photo paper was unsuitable for enlarging: Lack of sensitivity and lack of a suitable, artificial light source. – jarnbjo Dec 21 '17 at 18:36
  • I guess we are talking linguistics. By "positive process" I mean a fancy word for printing. It is not the same as negative developing: your exposure times are tens of seconds, not fractions. You do not work in total darkness, and your material is not panchromatic; in fact it is carefully selected to be not sensitive to the color of your safelight. You use different developer for papers and develop to full (you can not overdevelop a paper). It is the same in principle, but different. And by the way you do not need a particularly powerful light source; 75W bulb is enough. – Jindra Lacko Dec 21 '17 at 20:55
  • A good, full spectrum 75W is enough. No such bulbs existed in 1880, or even 1900, though. – Michael C Dec 24 '17 at 23:38
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enter image description here
Check out the Patent of David A Woodard of Baltimore, Maryland Patent US RE 2311E July 10, 1866 and Patent # 16700 February 24, 1857. Solar Camera

An instrument used for throwing the object to be traced, painted, or photographed on a canvas or other suitable material by the transmitted light from the sun.

To enable the photographic artist to print a picture on prepared paper, canvas, or other material of greater or less dimensions than those of the negative ordinarily used for such purpose, whereby he is enabled to use a more perfect negative produced by bringing the entire field of his picture within the focus of his instrument, and afterward throwing it up and printing it by concentrating the rays of light through the negative in the instrument and focusing the object on prepared paper or canvas, instead of printing by superposition in the usual way.

By the way: John Draper had proposed making enlarged copies of daguerreotypes in 1840. Alexander S. Wolcott patented an enlarger camera March 1843. Henry Fox Talbot patented a collotype enlarger making prints from paper negatives. None achieved widespread popularity. With the introduction of collondion negatives in 1850 Achille Quinet introduced the first vertical enlarger/camera. It required super long exposures. David Woodward’s solar enlarger solved this problem. This system used a mirror together with a condenser lens and focused sunlight on photo paper via using a copy camera lens. This device was also sold with a clockwork mount that followed the sun allowing shorter exposures. The Woodward design was modified by Desire Charles Emanuel van Monckhoven in 1864. He mounted a Woodward enlarger to the wall. Installed a more complex lens. and using a mirror to track the sun via a hole in the wall, made 17 ¾ X 23 1/4 inch enlargements. The exposure time was 2 hours.

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The principles of a photographic enlarger have changed very little if at all since their inception. There is a light source, a carrier to hold the negative, a lens, and base board to hold the the paper (or other material coated with photosensitive chemicals). Allen Marcus provided the info for the reflected light source so i will limit my description to those with an electric light source.

The light source is at the top. In the first enlargers this was just a basic incandescent light bulb contained within a housing that allowed the light to be directed down to and through the negative but not out into the room and controlled with a switch. Below that is a platform to hold the negative carrier,(the negative carrier holds the negative) this platform will hold the negative carrier up to the bottom of the housing containing the light source. Below that is platform on which you can mount a lens.

All of this is on a carriage that can be moved up and down in relation to the base board at the bottom. The baseboard is where you put the easel containing the enlarging paper. Moving the carriage up or down will change the distance between the carriage and the baseboard and this will change the size of the image that is projected on the paper (i.e. changing the size of the endearment or the print you are making). There are adjustments on the carriage as well: one to move the lens closer to or further from the negative to allow focusing of the image and one to allow you to move the light source closer to or further from the negative to insure that the entire negative is being illuminated (this is to accommodate negatives of varying sizes). This is still the basic setup for today's enlargers.

Things that have changed are:

  • The ability to use a variety of different light sources such as a fluorescent cold light head or LED's and the ability to filter the light before it passes through the negative to facilitate color printing or change the contrast of B/W prints. Filters can also be placed just under the lens.
  • The ability to control the time of the exposure with timers instead of just a switched-on the light. Modern timers are highly programmable.
  • The ability to use different lenses. The lens for an enlarger is essentially the same principle as camera lenses but optimized for enlargers. (I will let others with more knowledge on optics speak to that.) They have f-stops to control aperture. Focusing is accomplished by moving the lens up and down.
  • Some enlargers will allow you to tilt the carriage up so that you can project the image onto a wall for making enlargements much larger that you could on the base board.

I am sure there are things I am missing but the point is the principles are the same now as they were then.

Just as in camera lenses, enlarger lenses have an optimum aperture/f-stop for sharpness. You should know what that sweet-spot f-stop is for each lens you use and try to use it for best results. A focusing aid or scope is very useful in obtaining sharp focus. It a scope with a mirror. You place it on the base board as the light is projecting the image through the lens. you can then look through the scope and see a magnification of the image and adjust your focus more precisely.

A Beginner's Guide to Enlargers

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