Difference between revisions of "User:Dustin McAmera"

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* Search the wiki for any existing page referring to the origins of automatic exposure. There are already [[aperture priority]], [[shutter priority]] and [[exposure]]; of these, only apoerture priority comes close to what I'm thinking of. Useful links include [http://worldwide.espacenet.com/publicationDetails/originalDocument?CC=GB&NR=190305608A&KC=A&FT=D&ND=3&date=19040204&DB=worldwide.espacenet.com&locale=en_EP British Patent 5608] of 1903 which describes an invention by a Max J Richter (not Max A Richter of Ernemann). It comprises a mechanical shutter, with electrical timing (the mechanical system is restrained by an electromagnet) and depending on the variable resistance of a selenium crystal to affect the time of exposure. Need to do a bit more searching to see if this patent was ever exploited, and look for other early designs. The first commercial one I know of is by [[Durst]] and fairly soon after by [[Agfa]], using Durst's mechanism.
 
* Search the wiki for any existing page referring to the origins of automatic exposure. There are already [[aperture priority]], [[shutter priority]] and [[exposure]]; of these, only apoerture priority comes close to what I'm thinking of. Useful links include [http://worldwide.espacenet.com/publicationDetails/originalDocument?CC=GB&NR=190305608A&KC=A&FT=D&ND=3&date=19040204&DB=worldwide.espacenet.com&locale=en_EP British Patent 5608] of 1903 which describes an invention by a Max J Richter (not Max A Richter of Ernemann). It comprises a mechanical shutter, with electrical timing (the mechanical system is restrained by an electromagnet) and depending on the variable resistance of a selenium crystal to affect the time of exposure. Need to do a bit more searching to see if this patent was ever exploited, and look for other early designs. The first commercial one I know of is by [[Durst]] and fairly soon after by [[Agfa]], using Durst's mechanism.
 +
Another relevant patent: [http://worldwide.espacenet.com/publicationDetails/originalDocument?CC=GB&NR=190504020A&KC=A&FT=D&ND=3&date=19051214&DB=worldwide.espacenet.com&locale=en_EP British Pat 4020] of 1905 describes a selenium-resistance circuit as part of a photometer (they don't mention photography as an application). Here, they note that the resistance of the selenium upon a change from dark to light starts fairly linear, then flattens out. They base the reading on the short-term change in resistance, to avoid the complication of a non-linear relationship, so they use the reaction of the selenium to operate a blind shading the cell after a short exposure. It's not much like Richter's design, but shows that more than one set of people thought the selenium cell was a workable idea at about this time. Search for selenium next.

Revision as of 20:08, 7 January 2013

Hello!

My real name is Pete; on here and on Flickr I'm Dustin McAmera. I live in Leeds, in England.

I was promoted to be one of the admins here. If you're here in search of an admin, to ask something about CW, or complain about something, feel free to do that (best to do it next door on my Talk page).

I have more cameras than I can do justice to as a user (a few dozen), but I resist the idea that I'm a collector. That said, the pleasure of using the cameras is sometimes just as important to me as the photographs. My oldest cameras are from the 1920s, but I like to try to write about earlier stuff, just because it's under-represented here.

My own cameras include several that I feel guilty for owning, because I use them so little: in particular my Century Graphic, my Mamiya 645 Pro and my Ensign Reflex. I notice that since I started editing on here, that problem is worse.

Quite a few of my cameras are for 127 film, and I usually do something for 127 Day in July and January. 2012 was the centenary year of Kodak's introduction of the 127 film size, and I think I did quite a good effort for the summer day. I didn't do so well on a special extra 127 Day (7 December), but I shall give year-101 a run for its money.

I usually observe Take Your Box Camera to Work Day in February and Worldwide Pinhole Photography Day in April, too. Taking my box camera to work may not be possible this year - I changed my job to one which doesn't really tolerate such eccentricity.

Cameras I've been using quite a bit recently: a Zenit 3 and a Solinette II, both lucky internet buys, and my father's Pentax P30n.


www.flickr.com


Vague to-do list

Thse are things I hope to do some work on soon-ish. Feel free to comment on these, especially if you think any of them is a really bad idea. (This isn't an invitation for anyone to insert jobs for me to do: I hate that! .. If you know enough to write one of these ideas up before I get to it, go ahead, of course.)

  • Write the Century Graphic its own page (perhaps the Crown should also be separated from the Speed too: a focal plane shutter is quite a big deal, and the lens usage of the two is different too). The CG isn't a small Speed, it's more like a small Crown; and what the hell is a flexible wire viewfinder? (Ross: if you want to do this, go ahead. I know you have one of these too! :) )
  • Check all members of Category:4x5 and its subcats: 4x5 is for 4x5 centimeter format (perhaps stupidly, since inch cameras are surely much more common); correct the cat to 4x5in where required.
  • While we're doing format categories, look up some of the stereo cameras; there are already cats for 6x13 and 47x105 I think. Check, and see if there should also be 9x18
  • Look at the Canon A-series SLRs: the AE1 page needs rewriting, and the AE1 Prog page actually says very little about the camera.
  • I have added links to related patents to some articles, especially ones on early and innnovative cameras. Patents may be available as PDF at Google Patents or Espacenet. Here's stuff to do: find out how we stand on using the diagrams from Patents. Some of these would be excellent illustrations.
  • Search the wiki for any existing page referring to the origins of automatic exposure. There are already aperture priority, shutter priority and exposure; of these, only apoerture priority comes close to what I'm thinking of. Useful links include British Patent 5608 of 1903 which describes an invention by a Max J Richter (not Max A Richter of Ernemann). It comprises a mechanical shutter, with electrical timing (the mechanical system is restrained by an electromagnet) and depending on the variable resistance of a selenium crystal to affect the time of exposure. Need to do a bit more searching to see if this patent was ever exploited, and look for other early designs. The first commercial one I know of is by Durst and fairly soon after by Agfa, using Durst's mechanism.

Another relevant patent: British Pat 4020 of 1905 describes a selenium-resistance circuit as part of a photometer (they don't mention photography as an application). Here, they note that the resistance of the selenium upon a change from dark to light starts fairly linear, then flattens out. They base the reading on the short-term change in resistance, to avoid the complication of a non-linear relationship, so they use the reaction of the selenium to operate a blind shading the cell after a short exposure. It's not much like Richter's design, but shows that more than one set of people thought the selenium cell was a workable idea at about this time. Search for selenium next.