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Best settings for laser scanning?
  • kghkgh

    Hi. After reading days in the forum and now being more confused than before I decided to ask all you guys for your opinion. I have a special task for which i need the best possible (re)solution: laser scanning with a line laser.

    The images I take look something like the attached one (just a sample). An recording session is 1-5 minutes and I don't need high FPS.

    I Have a GH-2 with a 64GB SanDisk ExtremePro SDXC Card. To get the best 3D resolution afterwards I need the highest resolution with the best quality i can achieve. The best would of course be to take normal pictures but I don't want to ruin the mechanical shutter.

    Now I have no idea if i should use AVCHD od MJPEG. Overall AVCHD is more efficient but MJPEG has more hacking capabilities (fps and resolution).

    I thought of using MJPEG with ~3k and ~5FPS but dunnow which settings i should take exactly.

    What do you guys think?

    Thanks in advance & bests Konrad

    line.jpg
    400 x 313 - 5K
  • 14 Replies sorted by
  • Vitaliy_KiselevVitaliy_Kiselev

    @kgh

    Best is to use camera that has option to use electronic shutter, ala G5 or GH3.

  • balazerbalazer

    The GH2 in SH burst mode uses the electronic shutter and produces 4 MP stills. If you use an intervalometer that activates the shutter button with short presses, the camera will record just one image per interval.

  • kghkgh

    Thank you both so far! Beautiful tip with the electric shutter.

    I tried it but have another problem now. I noticed that every time i take a picture in SH burst mode the camera lens aperture is set to the given f-stop and then back to the smallest f-stop. This resulting in another mechanical degeneration and more important slower picture intervals (when using a small f-stop it's much faster than with f22) :(.

    I didn't used an intervalometer for this test yet but I assume it will be the same behavier with one cause it will only simulate trigger pushes?!

    Of course I could use the smallest f-stop to overcome this but then I have way too much dof for my purposes.

    I also experimented with the aperture preview mode which closes down the aperture beforehand but when i then push the trigger it's going back to the smallest f-stop (even in manual focus mode) and then closes the aperture for the picture and going back :(.

    Is there any way to prevent this or going arround this? Has this behavier changed with the G5 / GH3 ? Also pressing the button continuously doesn't take pictures infinitly - just the internal ram is filled and then written to the sd card but the camera stops taking pictures when the ram is full (and doesn't going on when ram is available again...)

  • Vitaliy_KiselevVitaliy_Kiselev

    This resulting in another mechanical degeneration and more important slower picture intervals (when using a small f-stop it's much faster than with f22) :(.

    And this is easy, get cheap manual prime.

  • kghkgh

    does manual prime means manual aperature? thanks

  • Vitaliy_KiselevVitaliy_Kiselev

    @kgh

    Yes, of course. This is the goal of getting it for you.

  • windsurfwindsurf

    @kgh If you have manual old lenses you could buy an adaptor and use these lenses. With my GH3 i set "Shoot without lens" to OK. Then i set the aperture i'd like to my old manual Zuiko Lens, and i set the GH3 for example in "M" mode. So i choose the time in the GH3 body, the aperture in the Lens, according to have a correct exposure. In this way i think you could solve the lag time problem of the aperture iris time. ws.

  • Vitaliy_KiselevVitaliy_Kiselev

    Other approach is to close aperture in preview mode and try to pull battery, and after this close lens contacts with some sticky paper (so it'll be like manual lens).

  • kghkgh

    Perfect.

    I will try the "hack" idea from Vitaly so I can use the lens i have at the moment. If this doesn't work for any reason I will get one with manual aperture and do it like windsurf suggested.

    Thanks so much guys. I will report back next days.

  • kghkgh

    Hi. I tried it and it works! I close the aperature in preview mode then unmount the lens (with the camera still powered on) then I cover the pins as Vitaliy suggested, turn the camera on can shoot very fast in SH Burst mode and with no mechanical parts moving.

    Thanks guys!

  • Vitaliy_KiselevVitaliy_Kiselev

    Perfect, just remember to show us results :-)

  • kghkgh

    Hehe which results you wanna see? The setup? The laser scanning process? The taken pictures (just a dark image with a laser line)? The pinmod? The resulting 3D Geometry? :)

  • Vitaliy_KiselevVitaliy_Kiselev

    @kgh

    Personally I want to see all of the above. :-)

  • kghkgh

    Then you will get it all (about next week everything should be ready).

    But currently I'm thinking about switching to a G5 as you can use the electric shutter with full res and you can do longer exposure times.

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