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sixleggedinsect
Jun 22, 2009, 6:12 AM
Post #127 of 130
(1704 views)
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Registered: Apr 14, 2004
Posts: 385
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bill413 wrote: Question for everybody photographing the cams - are you trying to hand hold? To set up individually for each cam? Or are you using some sort of jig to ensure reproducibility?
i was hand-holding, but my plumb-line, backdrop camera trace, etc etc setup got me very very reproducible results. i would guess that i was no more than +/- 2 (ish) mm from perfect when taking photos about four inches away from teh cam, and i was hoping this was as good as was needed. four or five photos yielded the same results (hand-selecting points because the light was low, the predicted axle centers were all in the same quadrant and wtihin a mm or so of each other) and i felt that at least i was precise, if not accurate.
i recall that this was mentioned before, but since we're on teh subject ill throw it back out there-
i woudl have thought that the best way to get good results was to get the camera far away from the axle, and optically zoomed in. then just crop the photo before putting it into the cam fitter.
if you are a cm off center from ten feet away, this is a tiny fraction of a degree off compared to 2mm off from four inches away.
to get things centered up from that far away would be very tricky once, but then wiht a little masking tape it could be repeated again and again with no exciting/time consuming setup.
edit: possible 'jig' setup:
snap a chalk line on the floor. put a piece of white paper against the wall with a black line on it riding up off the floor at a perpendicular. tape it there, and put a third-hand soldering/etc arm next to it. the cam should be placed upside down, resting on the floor, with the axle carefully inline with the chalk (or masking tape and sharpie) on the floor. the third-hand arm (or hwatever) holds the stem up and in place. non-offset cams should self-level the axle with respect to the floor, which is probably level enough for these purposes.
then step back to the end of the chalk. mark the distance. sit the camera on shims until the center of the lense is the height of the center of the axle, and take a photo with the optical zoom all the way up and the image centered on the axle (most cameras have a center reticle depending on their focus mode).
lots and lots of light on the cam, from many directions, will make your life easier. i think this woudl be pretty quick to setup, and you could come back to it later and do more.
jsut a thought.
(This post was edited by sixleggedinsect on Jun 22, 2009, 6:26 AM)
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bill413
Jun 22, 2009, 11:29 AM
Post #128 of 130
(1682 views)
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Registered: Oct 19, 2004
Posts: 5674
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sixleggedinsect wrote: bill413 wrote: Question for everybody photographing the cams - are you trying to hand hold? To set up individually for each cam? Or are you using some sort of jig to ensure reproducibility? i was hand-holding, but my plumb-line, backdrop camera trace, etc etc setup got me very very reproducible results. i would guess that i was no more than +/- 2 (ish) mm from perfect when taking photos about four inches away from teh cam, and i was hoping this was as good as was needed. four or five photos yielded the same results (hand-selecting points because the light was low, the predicted axle centers were all in the same quadrant and wtihin a mm or so of each other) and i felt that at least i was precise, if not accurate.
As far as your marking & setup idea, I think of a tripod for the camera instead of shims, but what you're saying should be equivalent.
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sixleggedinsect
Jun 22, 2009, 11:36 AM
Post #129 of 130
(1675 views)
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Registered: Apr 14, 2004
Posts: 385
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bill413 wrote: As far as your marking & setup idea, I think of a tripod for the camera instead of shims, but what you're saying should be equivalent.
tripod + water level = look good doing it.
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