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OT using a tv lens on a digital camera

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  • OT using a tv lens on a digital camera

    I coupled one of my tv zoom lenses to a digital camera and that works, but I wanted to see if it would work directly in place of the existing lens. So- needing a hack project for a couple hours, I took apart one of my digital cameras and removed the lens setup. With just the sensor showing, I positioned the zoom lens as close as I could get it to the right distance from the sensor, and it seems to work fine- coloring is changed a little, and the image size is a little larger than the sensor at the focal plane, but that's not a particularly bad thing. I can't line up the lens perfectly because there's a pc board in the way, but otherwise I've found that this lens is entirely workable as a replacement for the built-in optics.

    So- maybe one day a hurting digital camera will come my way, and once again I'll be able to marry up two things that were never meant to go together.

    Just thought I'd mention this, for no particular reason.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  • #2
    Heh. One of my favorite pastimes is messing with optics. You can hang just about any kind of lens on a camera and get a picture. There is one I want to try with the Rebel but haven't gotten around to doing yet. It is (was?) a popular pastime with film enthusiasts but the Rebel should work fine because of the unlimited exposure control. The lens is no lens at all, just a pinhole in the body cap. Pinhole photography is very cool because it has infinite depth of field. If you want to try it give it a shot but the camera will need to have the ability to do exposures in the seconds.

    Have a look here:

    http://www.pinhole.org/
    Free software for calculating bolt circles and similar: Click Here

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    • #3
      Evan,
      I'm not familiar with a Rebel camera that has very long exposure times. Is this a film camera or digital?

      I have a friend that dreams of having VERY long digital exposures for astronomy.
      Thanks,
      Dave

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      • #4
        I modified my Sony DSC-V3 to do infrared photography. The camera has a built in night shot mode but it is effectively disabled in many of the more advanced camera modes. So I popped it apart and found the H-bridge chip that controls the solenoid that moves the hot filter out of the way and installed my own switch.

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        • #5
          Not sure about the rebel, but the rebel xt can go to 30 seconds exposure. That should be plenty long enough for a pinhole aperture in good light. Chances are I'm going to give it a try. For the pinhole I could use a pin- or I might experiment with a spark blast method. All I have to do these days is scuff along the carpet, then discharge myself through a sheet of black paper. The more the charge, the larger the aperture- and the higher I jump

          Speaking of optics- I read recently that a layer of silicon has the ability to act as a reflector when applied to a glass surface. Hmm, isn't glass silicon- this was to be a replacement for aluminizing as I understood it. Kind of sounds too easy- there must be a catch somehow.

          As far as my tv zoom lens, I'm just trying to find the best use for it. Seems a shame to have it here just doing nothing.
          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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          • #6
            The Canon Rebels, all models, have unlimited exposure time in bulb mode. The battery can hold the shutter open for over two hours. It's also one of the unusual things I like about my Nikon 4300. It will do up to a one minute exposure with an automatic dark field noise subtraction after the exposure.

            The Digital Rebel is the premier camera for astrophotography. Canon even makes a model without the internal infrared filter for that purpose.

            It's easy to modify the average web cam for IR photography. On many you just unscrew the lens and pick off the tiny bit of greenish colored glass stuck on the back side of the lens. It makes colors rather pinkinsh in normal light but it increases the low light performance tremendously as long as there is a source of infrared in the scene.

            I have a Sanyo monochrome security camera with a true CCD that has no filtering. It is so sensitive to IR that at dusk people almost start to glow on their own in the image.
            Free software for calculating bolt circles and similar: Click Here

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            • #7
              On the subject of pinhole photography, I just discovered that there is a pinhole photography day- the last sunday in april. There seems to be a following, and there's a pinhole photography exposure calculator wheel on one of the sites.

              Now we need to adapt this to metalworking. Hmm, the subject could be how to bore the pinhole.
              I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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              • #8
                It is possible to get extraordinarily accurate laser drilled pinholes in brass for pinhole photography. I spotted these while researching laser drilling for one of my research projects at work.

                see
                http://www.lenoxlaser.com/pinholepho...ed_lenses.html

                --Cameron

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