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Thread: How to align camera and flat object ?

  1. #1
    Founder QT Luong's Avatar
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    How to align camera and flat object ?

    For the purposes of lens testing, I need to photograph a flat target so that the film plane and the target are strictly parallel. I have found that for critical MTF measurements, even small deviations affect the results.

    So far, what I am thinking of doing is materializing the normal (line perpendicular) from the center of the target with two Ts, and then attach a laser pointer to one of them. Then I will know that if the laser beam strikes the lens in the center and I point the camera in such a way that the center of the target is in the center of the image, the two planes will be exactly aligned.

    I am aware that there are specialized tools such as the zig-align, but I'd prefer not too spend too much money on that project. One should not assume ground-glass focussing and movements, since I might use the procedures with a variety of cameras. Any other suggestions ?

  2. #2
    Whatever David A. Goldfarb's Avatar
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    How to align camera and flat object ?

    Not as precise as a laser alignment tool, but another option is to use a level for shots on a copy stand and a compass for tests with the target on a wall. I use a Suunto Tandem clinometer-compass in this way sometimes.

  3. #3

    How to align camera and flat object ?

    There's the old-fashion cheap way...

    Take a mirror, mark the center with a 1/4" dot of tape, and place the mirror on the center of your target (coplanar). Set the camera to neutral, stop down a bit, and focus alternating on the reflection of the camera lens in the mirror and the dot, adjusting the camera position to line the dot up with the center of the reflected image of the lens.

  4. #4

    How to align camera and flat object ?

    A simple mirror about 2X3", like the one women carry in their purse will work if it is placed at the center of your target subject and secured with some Scotch Magic Tape. Then set up your camera where you can see your own reflection in the mirror, with front and rear standards at normal. At that point you will be within one or two degrees of arc of being parallel. Sometimes taping a tiny light on your camera or lens will help see when your exact reflection hits the center of your GG. When you see the bright light in your ground glass, from the light shining forward from your lens, you will know you are in business.

    Another trick I use is to use a laser parallel alignment tool for enlargers. Tape this to the center of your subject target and then use your camera and GG to find the center of the laser beam.

    Works like a champ....both tricks.

    Best of luck..

  5. #5

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    How to align camera and flat object ?

    You already make great pictures. Quit wasting your time testing lenses -- it is the first step down from photographer to camerajunkie.
    Wilhelm (Sarasota)

  6. #6

    How to align camera and flat object ?

    To make your laser T-square is not going to be that easy. I'm guessing that you are thinking about rotating it while lasing a far off wall to calibrate it to square. How are you going to attach and adjust the laser pointer so that your measurement is precise? You'll need some time and tools to make this T-square laser jig. And your flats that touch the target may rock unless everything is super flat.

    It seems to me that a three legged laser pointer jig would be easier to make. Find a piece of sheet metal, cut it into an equilateral triangle and bend the three corners down to make legs. Don't make a little sissy tool. Go big! 18 -24 inches on a side and bend down about 6 inches for the legs. Fix the laser pointer in center position in this three legged jig. Get it pretty straight and lock it in place. Putty epoxy might be good for this. If your laser has a threaded housing you could nut it to the sheemetal in a hole drilled in the center. Just make sure its secure.

    To calibrate, keep rotating that three legged jig on a flat surface and adjust the leg length by filing or grinding the legs until you acheive plane by watching the circle the laser draws on the far wall as you rotate. A laser that shoots out both ends 180 degrees opposed would be nice for centering while calibrating and later in use.

    Got a machine shop handy? Make a plate with a hole for your laser and three drilled and tapped holes for threaded legs and you have -- an adjustable three legged jig. Imagine a 3/4 inch aluminum plate about 12" in diameter with nice engine turning on both sides. Knurled bronzed lock nuts and knobs on the legs. Oh yeah - cut some lightening holes in a nice pattern like a bicycle chain ring. Engrave your name on it in a nice script.

    A pinhole cap for your lens is the next thing to make. Screw it on and line up the dot of light in the center of the screen without looking directly into the laser. Probably fairly easy on a view camera and damned tough on a DSLR.
    Or, place a mirror over the lens and line up the reflection with the laser at the target.

    Give up and order a Zig Align.
    ; >)

  7. #7

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    How to align camera and flat object ?

    The tool specifically created to do this kind of work is the animation stand, they can get very involved in complexity and price, although I believe you can track down one of the simpler models, you probably want an older style animation style stand, used.

    Google 'oxberry animation stand' which will give you an idea of what they look like, they were designed for 'old style animation'.
    Jonathan Brewer

    www.imageandartifact.bz

  8. #8

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    How to align camera and flat object ?

    Actually I mis-spoke, more to the point, the animation stand was specifically created to keep things in register and the film plane paralell to whatever you're shooting from image to image, which is why it was the 'bread and butter' tool for the old style 'full' animation technique.
    Jonathan Brewer

    www.imageandartifact.bz

  9. #9

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    How to align camera and flat object ?

    OMT....................they are also excellent for photographing flat art.
    Jonathan Brewer

    www.imageandartifact.bz

  10. #10

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    How to align camera and flat object ?

    Speaking of full animation, if this is before your time, get the Max Fleisher 'Superman' classics from the 1930's, Art deco and high energy fun.
    Jonathan Brewer

    www.imageandartifact.bz

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