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Thread: Need some suggestions on a webcam

  1. #11
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    It's not my tape--properly, it belongs to JPL and is just one of a batch that I've been doing for them. My current batch includes Apollo, Viking and Pioneer stuff. Mostly Univac 1100-based and a mixture of 7 and 9 track. Some surprises, such as the data from the imaging of Jupiter's moons in 1975-76 using the Arecibo radar observatory.

    Fascinating stuff.

  2. #12
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    I'm not sure what the quality requirements are but I'll throw out another option. How about an older smartphone that you might have in a drawer somewhere, connected to WiFi of course, and have it back up photos to Google photos or local storage or wherever you want, through an app?
    -- Brian

    Working Systems: Apple IIe/II+/Mac+/Mac 512k, Atari 800/520STFM, Commodore 64/Amiga 3000/PET 4032/SX-64, IBM PS/1 2121-B82, Kaypro II, Osborne 1, Tandy 1000 SX, TI-99/4A, TRS-80 Model 4 GA
    Project Systems: Amstrad PCW 8256, Kaypro 2/84 (Bad Chips: 81-194, 81-189).

  3. #13
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    I was going to mention this, because having an FTP server on the phone makes copying the files directly from the PC obvious.

    But I can't see how to get round fumbling with the phone. The battery would need to be constantly charged and the phone screen timeout turned off, and the phone in the camera app. Then you have to use the phone to take the picture (except with some Motorola phones and there might be others, which could be triggered from the computer). This means a very rigid mount for the phone. The only way I've achieved that was by making my own. I even have a copy stand that would be ideal for this.

    But in my experience, something always goes wrong with the phone. If you don't remove or disable Google Play Store and Google Play Services, on any given day it will get an automatic update which will ruin your day. Some phones and camera apps refuse to work if those two apps are removed or disabled. Or the power goes out for just long enough for the battery to drain and then hopefully it will recover, but then you have to start over. Or the wall wart spontaneously quits supplying enough current to keep the battery charged. Or for unknown reasons, the phone reboots itself if you leave it for a couple weeks, and then the SD card gets corrupted or something else quits and you need to do a factory reset. It's an utter nightmare when you need to rely on it.

  4. #14
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    I think I'll just go back to my little Canon and run it from an AC adapter and hook it to USB. I'll still have to push the shutter release, but maybe that will work. Canon is spec'ed at 3.15V, but I think a plain old 3.3V adapter should work just fine--you'll lose 150mv in the cable anyway.

  5. #15
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    I did something similar a long time ago to automate photographing slides; I just used an old Kodak still camera that could be used in USB webcam mode and soldered a couple of wires across the shutter, to be triggered by the computer in sync with the slide projector.

    Looks like you beat me to it. I didn't mind modding my camera, it had been replaced long ago; was/is reversible nevertheless.
    Last edited by MikeS; March 30th, 2019 at 06:14 PM. Reason: Reply to Chuck

  6. #16
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    Quote Originally Posted by KC9UDX View Post
    I was going to mention this, because having an FTP server on the phone makes copying the files directly from the PC obvious.

    But I can't see how to get round fumbling with the phone. The battery would need to be constantly charged and the phone screen timeout turned off, and the phone in the camera app. Then you have to use the phone to take the picture (except with some Motorola phones and there might be others, which could be triggered from the computer). This means a very rigid mount for the phone. The only way I've achieved that was by making my own. I even have a copy stand that would be ideal for this.
    Fair points. I used an old cellphone for my 3d printer and had it run "IP Webcam" app from the play store to turn it into a wireless webcam, but I also had to make a custom mount for it as well. It did on occasion not work so well when it would inevitably crap out and need to be rebooted. I never removed the play store, i'm not sure I would bother to do that myself, but I guess if you want to keep it 'more like standard linux' and just run without ever updating it then that might be an option (or if you were so inclined, use a phone that supported cyanogenmod/lineage) but this is all going too far into the weeds. I did also switch to some crappy webcam i found for the 3d printer hooked up to a raspberry pi i have running for Octoprint anyway for some of those same reliability reasons. That said, I switched to the webcam route because I have timelapse and live stream going on where a webcam is more optimal than photos. If I was doing something similar to chuck, I probably would just make a dock for my phone to sit in and just put it in there and in camera mode whenever i'm doing this kind of work, since my cellphone is actually the best camera i own and all my pictures automatically sync to google photos anyway.

    if you can stand up your props against a wall, something like this would be easy enough for that:

    iphone-bracket-2.jpg
    -- Brian

    Working Systems: Apple IIe/II+/Mac+/Mac 512k, Atari 800/520STFM, Commodore 64/Amiga 3000/PET 4032/SX-64, IBM PS/1 2121-B82, Kaypro II, Osborne 1, Tandy 1000 SX, TI-99/4A, TRS-80 Model 4 GA
    Project Systems: Amstrad PCW 8256, Kaypro 2/84 (Bad Chips: 81-194, 81-189).

  7. #17
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    I built a mount for my phones that matches standard camera mounts. I have a professional copy stand which places the camera horizontally above the target work, to take pictures from above. This is ideal for most work, especially anything that isn't flat.

    I have one of my best phones (actually a phablet) live streaming right now, mostly to make sure it will work two Tuesdays from now when I have to rely on it to do this.



    I'd almost put money on the fact that it won't actually work when I need it. Something major goes wrong with it every month (I only use it once a month, normally).

  8. #18
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    I'd recommend an inexpensive USB webcam. Cheapies are < $5: [http://vi.raptor.ebaydesc.com/ws/eBa...1000000&ver=0].
    If you need the software to control the recording then the mainstream, e.g. Intel or Logitech, cameras are a better choice, at around $20.

    There are a few variables that are important to you: image quality and computer interface. You want to be able to record a picture at your command (manually or under software control) and you want sufficient resolution to be able to make out the labels, ideally with OCR.

    Most digital cameras these days come with USB interfaces and software that allows the computer to trigger, display and store the camera's image. For you that's overkill. A webcam can do the same thing, using the same principles, if it comes with the right driver.

    A 12x12 field of view from 24 inches away is the equivalent "field of view" of about a 50mm lens on a 35mm camera. In other words, a pretty standard focal length, not very wide angle. Webcam lenses tend to be shorter focal lengths because the sensor size is also smaller: It is the ratio of the focal length of the lens to the size of the sensor that determines the field of view, assuming a sufficient circle of coverage**. I'd estimate that the average webcam has a field of view about equal to a 35mm lens on a 35mm camera; slightly wide-angle. Some surveillance cameras are extremely wide-angle but their image quality is poor*; you don't want one of those.

    Resolution is a function of the combination of the lens and the recording medium; usually the recording medium is the limiting factor. Resolution, for lenses, is stated in "lines per inch". 75 lines per inch is about equivalent to a newspaper photo's resolution. 300 lines per inch is equivalent to the old laser printers of decades ago. 1200 lines per inch is "image-setter" territory, again from years ago. Today even a $50 ink-jet can do better than that. But that's only half the equation.

    Your desired area of reproduction is 12 inches across. If your Hi-def sensor has 12 megapixels (and has a 1.5:1 format, as usual) then it has 3000 rows each composed of 4000 pixels. Divide 4000 by 12 and each inch of your field of view is represented by 333.3 pixels. That is plenty for reporoduction at life size and plenty for OCR. If you "blow up" (magnify) the image 2x then there are only 150 pixels per inch. At 4x you are in newspaper or CRT resolution.

    I'm sorry to say that I recently threw out a web cam that would have suited your purposes exactly. But I hope this (lengthy) explanation helps you to find what you are looking for.

    -CH-


    *Feel free to skip this explanation: [Extreme wide-angle lenses are characterized by their relatively short focal lengths and relatively large fields of view. "Relative" here means relative to the norm for the size of the image sensor. It is hard to make a quality lens of this type that achieves evenness of sharpness, even illumination, focuses on a single plane, has low chromatic distortion and draws straight lines (does not feature the "barrel distortion" characteristic of "fish-eye" lenses.) Cheap wide angle lenses may sacrifice one or more of these desirable attributes for the sake of coverage.]

    **Feel free to skip this explanation: [ A 90mm lens is considered a "short telephoto lens" when fitted on a 35mm camera, but is considered an extreme wide-angle lens when fitted on a 4x5 camera, because the size of the coverage circle has to be much larger for the 4x5. The diagonal of a 35mm frame is about 2 inches, so a 90mm lens on that camera has to have a "coverage circle" of at least 2 inches in diameter. The required coverage circle for a 4x5 sheet of film is about 6.5 inches. Obviously the larger coverage circle requires a more complicated lens design. However, both resolve infinity 90mm behind the nodal point of the lens.]
    Last edited by clh333; March 31st, 2019 at 07:19 AM.

  9. #19
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    Back to my original question, what does "High Definition: 12.0M pixels/Dynamic Resolution: 640 x 480" actuall mean when it comes to still photos? Do I get 12 Mp or are the pixels simply duplicated to make it seem as if I have 12 Mp when I'm only getting 300Kp?

  10. #20
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    The two specifications appear to be at odds with one another. Perhaps 640x480 refers to the window in which the image is represented on the PC when using the OEM utility. But I wouldn't assume that: Get an answer from the seller. 640x480 is too small for anything you want to do. 640 / 12 = 53 ppi.

    -CH-

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