Bazz wrote:Why I always see some lens distortion in all these transfer images? Is it a constant using this machine?
Love to know more about that and how to correct it.....
Please tell me about the lens distortion! What do I look out for?
Hi, Barry!
The thing to remember about your WorkPrinter is that the lens of the projector, the condenser lens as well as the camera lens all work together to form one gigantic lens that provides a microscopic view of the surface of the film. As in any complicated lens, the various elements will move about in tandem to keep the image crisp. The same holds true here. One can not focus the camera and then assume that it will not have to be touched again during set up. Like wise, the projector can adjust the focus of the image as well. In fact, the adjusting the focus lever will manipulate the focus as well as the size and shape of the image.
Therefore, here is the best procedure for setting up the focus on the WorkPrinter:
This is based on the assumption that you camera has the required 12x or better optical zoom. A 10x zoom may cause problems with cropping and final alignment.
With no film in the projector, close the gate and turn on the lamp. Place the focuse lever of the projector in the vertical position to start. Put the camera on a column head tripod (to allow incremental vertical movement). Start with the camera on wide angle and place it ridiculously close to the condenser lens, like about one foot. The out put of the camera MUST be feeding into a full size monitor. Trying to use the built in LCD monitor is a waste of time. In the center of the monitor, one will see a white circle of light. Start physically moving the camera away from the condenser lens very slowly and observe the monitor. The round white dot of light will grow until the gate is visible within. As soon as you feel the circle has reached the edges of the condenser lens, stop and mark the floor with some tape where the center of the tripod is. Now continue moving the camera away from the condenser lens until the circle of light begins to close up again. Stop there and mark that spot on the floor.
You now have a "range" of where the camera can be and still see the entire gate. Place the camera in the middle of this range, which may be an entire foot for some cameras and as little as a few inches for other cameras.
Zoom the camera up to the gate but stop just short of zooming in at this point. You may notice some chromatic aberrations on the edges. Slight re-alignment of the camera up and down as well as side to side will negate these blue or amber aberrations. Moving the camera back a small amount may ALSO be necessary even IF it takes you outside the "range" that you previously marked on the floor. The reason is that zoom lenses will rearrange the elements in the lens when you zoom in, changing the dynamics of the relationship between film plane and CCD. Also, single chip cameras are much easier to align than 3 chip cameras due to the lack of prism in single CCD units.
Load some film in the projector that has a good, crisp image corner to corner. Something bright with good contrast is best. An old black and white cartoon works wonderfully! Adjust the framer knob so that the image is in the middle of the gate. At this point, attempt the initial focus with the CAMERA and NOT the projector. After focusing, note the frame lines of the film. They should be straight across with no bowing or bending (pin cushion and barrel distortion).
Now, this is the most important part: If they are not straight, then adjust the PROJECTOR focus lever (not the camera!) until the lines are straight across, EVEN IF THE IMAGE GOES OUT OF FOCUS. Remember, as noted before, the projector focus lever not only changes the focus, it can change the shape of the image. Also, remember that the camera lens is part of the equation as well. Therefore, if the image goes out of focus as a result of straightening the frame lines, focus can be easily recovered by adjusting the camera focus.
The biggest mistake most people make is adjusting the focus of projector only, when the focus can be manipulated by both the camera and projector. Once the frame lines are straighten and the camera focus is reattenuated, the image should be sharp corner to corner with no soft spots and no chromatic aberrations. If it seems close but not quite correct, move the camera back a bit. The further away (to a point) the better the image will be as longer lenses have a natural flat field characteristic that helps straighten things out.
Try this method of setting up your unit and I think you'll have better results. As I offer to all my clients wherever they are in the world, I am happy to call you and talk you through the set up one step at a time.
Roger
