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Making smaller pictures
I know nothing about darkroom equipment. I am interested in reducing
picture sizes. Specifically I make my own circuit boards, but I am wanting switch over to photographic methods to be able work at smaller sizes. The plan it to print an image to a transparency and then produce a smaller image. It looks like I would use a photographic enlarger, but I can not find any information about how that would be used for image reduction. Can someone point me in the right direction as far as literature or equipment. |
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#3
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On Fri, 21 Jan 2005 02:24:10 GMT, PGG
wrote: Of course I've _never_ used it before as why would I ever want to make a reduction of a 4x5 negative?? You wanted a wallet-sized photo ? Regards, John S. Douglas, Photographer - http://www.puresilver.org Please remove the "_" when replying via email |
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I already use the toner transfer technique and have gotten great
results from it. Down .4mm pin spacings, even though that one was a challenge. However I am looking to achieve better quality and also be able to get down to smaller scales. |
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wrote
I know nothing about darkroom equipment. I am interested in reducing picture sizes. Specifically I make my own circuit boards It looks like I would use a photographic enlarger, No. You need a reducer! Er, camera. but I can not find any information about how that would be used for image reduction. Natch. Can someone point me in the right direction as far as literature or equipment. What you are looking for is a 'process camera'. These are available on ebay and from local printing shops for not very much money, a few hundred dollars max. Some print shops will give one to you for free if you will haul it away, but some cameras are 12 feet long and weight is measured in tons: so look out!. A small 14x18" camera capable of 3x reduction is what to look for. nuArc VV1418's are quite common and very easy to use: two people, or one with a hand cart, can move it. With a bit of disassembly it will fit into a small station wagon, they are about 4.5 feet tall. Agfa Repromasters are usually 20x24" and take up a bit more room, but are also common. A process camera can make copies of both reflective artwork (IJ/LJ printer) and transmissive artwork (remember paper-crepe tape on mylar? - they can make a copy of a piece of film is the useful feature). A problem with photographic methods is that most do-it-yourself PC boards have 'positive resist': as for exposing with printer-output artwork. With a camera you will get a negative film that you will have to contact print to another film to get a positive film. If you are patient, and the material is _very_ sensitive, you can expose the PCB directly in a process camera if the a/w is illuminated with quartz-halogen lamps. This is a _lot_ less work for 1-of boards. A process camera has a vacuum back and will just suck the PCB board to the platen for exposing. All that said... If your board size is less than 4x5" then an enlarger can be used as a copy camera: you put the film where the negative should go, the artwork where the paper should go and illuminate the artwork for 10-15 seconds with some bright lights. The lith film and developer are easily available, and the film is not red sensitive so you can see what you are doing with at bright red safelight. _Do not_ try to use an ordinary camera for PCB work (unless you are OK with really sloppy dimensions). Camera lenses have too much distortion. Getting the camera _exactly parallel_ to the artwork is a PITA, though it can be done with the ole' two mirror trick. Enlargers and process cameras are made (or should be made) for precise alignment. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
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Thanks for the execellent explanation and information. I did see a
nuArc on ebay for $50 starting bid. Too bad it is in Massachusetts and weighs 300lbs. However, the boards I make at most get to 4x5 so the photographic enlarger would should work for a start. For the photographic enlarger, do you think an lcd display could be used in place of a copy of the image. Not sure if a backlit display would be bright enough, but maybe an older reflective display. I suppose contrast could be a problem as well. I do not think that the issue of positive and negative would be a problem. I could just print the image out opposite to the correct display. I also ordered a few books on darkroom techniques. Hopefully that will increase my understanding of what all will be required to attempt this. Nicholas O. Lindan wrote: wrote I know nothing about darkroom equipment. I am interested in reducing picture sizes. Specifically I make my own circuit boards It looks like I would use a photographic enlarger, No. You need a reducer! Er, camera. but I can not find any information about how that would be used for image reduction. Natch. Can someone point me in the right direction as far as literature or equipment. What you are looking for is a 'process camera'. These are available on ebay and from local printing shops for not very much money, a few hundred dollars max. Some print shops will give one to you for free if you will haul it away, but some cameras are 12 feet long and weight is measured in tons: so look out!. A small 14x18" camera capable of 3x reduction is what to look for. nuArc VV1418's are quite common and very easy to use: two people, or one with a hand cart, can move it. With a bit of disassembly it will fit into a small station wagon, they are about 4.5 feet tall. Agfa Repromasters are usually 20x24" and take up a bit more room, but are also common. A process camera can make copies of both reflective artwork (IJ/LJ printer) and transmissive artwork (remember paper-crepe tape on mylar? - they can make a copy of a piece of film is the useful feature). A problem with photographic methods is that most do-it-yourself PC boards have 'positive resist': as for exposing with printer-output artwork. With a camera you will get a negative film that you will have to contact print to another film to get a positive film. If you are patient, and the material is _very_ sensitive, you can expose the PCB directly in a process camera if the a/w is illuminated with quartz-halogen lamps. This is a _lot_ less work for 1-of boards. A process camera has a vacuum back and will just suck the PCB board to the platen for exposing. All that said... If your board size is less than 4x5" then an enlarger can be used as a copy camera: you put the film where the negative should go, the artwork where the paper should go and illuminate the artwork for 10-15 seconds with some bright lights. The lith film and developer are easily available, and the film is not red sensitive so you can see what you are doing with at bright red safelight. _Do not_ try to use an ordinary camera for PCB work (unless you are OK with really sloppy dimensions). Camera lenses have too much distortion. Getting the camera _exactly parallel_ to the artwork is a PITA, though it can be done with the ole' two mirror trick. Enlargers and process cameras are made (or should be made) for precise alignment. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
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wrote
For the photographic enlarger, do you think an lcd display could be used in place of a copy of the image. That's getting pretty low-rez, isn't it? Not sure if a backlit display would be bright enough but maybe an older reflective display. I suppose contrast could be a problem as well. I would not bother. And lith film is slower than treacle. I do not think that the issue of positive and negative would be a problem. I could just print the image out opposite to the correct display. I tried that. I failed. I use a LaserJet for output and the printer just doesn't like make a uniform black over large areas. My Calcomp 1043 would just grind forever and run out of ink. And my software won't work properly with the ink-jet I have. I also ordered a few books on darkroom techniques. Hopefully that will increase my understanding of what all will be required to attempt this. It should. You may want to check your library for books on 'Pre-Press Graphic Arts' and 'Lithography'. I am sure Usenet/WWW has a group or two on home-brew PC boards where you may get more (and better) advice. It doesn't cost that much to have a service buruae take your Gerber files and mail you back the films the next day. Probably less than setting up a darkroom and enlarger or process camera. But it just wouldn't be as much fun. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
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Nicholas O. Lindan wrote:
javaguy11111 I am sure Usenet/WWW has a group or two on home-brew PC boards where you may get more (and better) advice. My question started out in the homebrew pcb group at http://groups.yahoo.com/group/Homebrew_PCBs/ No one really had much information about the technique. A lot of people have done printing to transparency and exposing, but no reduction techniques. Homebrew_PCBs is a very active and informative list. I am sure many people in that group would be interested in hearing you describe the technique in more detail. Pictures are good too. I did find out there is a local art museum that offeres classes in darkroom techniques. So I will sign up for that class when it is offered in a few months. That should give me the best opportunity to find out if this method is the way I really want to go. It doesn't cost that much to have a service buruae take your Gerber files and mail you back the films the next day. Probably less than setting up a darkroom and enlarger or process camera. But it just wouldn't be as much fun. Agreed -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
#10
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Two things, you need more extension between lens and carrier than you can
usually get on an Omega D-2 or D-3, Omega made extension bellows for both units (Auxiliary Focus Units or some such name, I have one for each system) to get more distance between lens and film plane (sort of like macro photography). With enough extension you can use shorter focal length lenses that will not normal "cover" a given negative size and that will yield even more reduction. With a D-5 or Besseler MC-series there is "extra" bellows length and auxiliary attachments are not normally need. For other enlargers you can usually rig something to get the extra extension (I used the lid to a spray paint can as a spacer between lensboard and lensmount on a D-2 one time and attached the two boards with 2" long screws). The second issue is focus. It is much easier to rack the lens out to the approximate reduction needed and then focus by moving the enlarger up and down the column than to try to focus using the bellows. Trust me, it doesn't work since your reduction ration changes with changes in lens to film plane distance. If you can't bring the enlarger head down far enough to achieve focus raise the easel with paper boxes or books. -- darkroommike ---------- wrote in message oups.com... I know nothing about darkroom equipment. I am interested in reducing picture sizes. Specifically I make my own circuit boards, but I am wanting switch over to photographic methods to be able work at smaller sizes. The plan it to print an image to a transparency and then produce a smaller image. It looks like I would use a photographic enlarger, but I can not find any information about how that would be used for image reduction. Can someone point me in the right direction as far as literature or equipment. |
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