Originally Posted By: tgrudzin
"...Get it out in the sunlight with a camcorder so it can shoot at 1/1000 sec for "freeze frame". Paint a mark on the crank pulley, start it up, hold it at "1800 RPM".
The camcorder will film at 30 frames/sec, or 1800 frames/ min, and the paint mark will appear still if your tach really is 1800 RPM. It'll do the same thing at 900 and 3600 RPM, though the 900 would be "every other frame" yet should still hold still, just flicker.."
Your not doing this with an ordinary camcorder. Your camera would have to have the ability to manually set shutter speed and ISO rating. Otherwise the automatic ND filter is kicking in. And don't forget frames per second. The video camera I work with allows 1/1000 shutter speed, only at 24 and 60 FPS, not 30. Since this type of camera is running around $+4k, it's not in everyone's neighborhood. And you still need the mark to show on the camera side, don't you. Otherwise it could always be on the far side of the pulley when the photograph happens?
The playback would then be frame by frame or what? Cool idea, though.
Nah, what you're looking for is the "wagon wheel effect" where the spokes of a wagon wheel appear to be holding still or moving backwards slightly when shot on film, because in each frame the spoke has moved forward almost exactly one spoke's worth and another similar looking one replaces it in the same spot in frame.
OP can't hold 1800 RPM exactly with his foot but he can get it close. If he can get it close, then honk the horn to signify he thinks he's there, he can watch the video to see if the mark stabilizes. Or he can set up a closed circuit TV with the monitor by the driver's window.
And one doesn't have to pick the shutter speed; an auto shutter in adequate bright light should do the trick. What is important is that most of the time the shutter remains closed, otherwise the mark would be a blur.
Another way to handle it would be to run a timing gun in pitch black with a CMOS camera. Aim the gun at a white wall. CMOS's scan "here and there" and you'd get a cool pattern at multiples of its scan rate.
"...Get it out in the sunlight with a camcorder so it can shoot at 1/1000 sec for "freeze frame". Paint a mark on the crank pulley, start it up, hold it at "1800 RPM".
The camcorder will film at 30 frames/sec, or 1800 frames/ min, and the paint mark will appear still if your tach really is 1800 RPM. It'll do the same thing at 900 and 3600 RPM, though the 900 would be "every other frame" yet should still hold still, just flicker.."
Your not doing this with an ordinary camcorder. Your camera would have to have the ability to manually set shutter speed and ISO rating. Otherwise the automatic ND filter is kicking in. And don't forget frames per second. The video camera I work with allows 1/1000 shutter speed, only at 24 and 60 FPS, not 30. Since this type of camera is running around $+4k, it's not in everyone's neighborhood. And you still need the mark to show on the camera side, don't you. Otherwise it could always be on the far side of the pulley when the photograph happens?
The playback would then be frame by frame or what? Cool idea, though.
Nah, what you're looking for is the "wagon wheel effect" where the spokes of a wagon wheel appear to be holding still or moving backwards slightly when shot on film, because in each frame the spoke has moved forward almost exactly one spoke's worth and another similar looking one replaces it in the same spot in frame.
OP can't hold 1800 RPM exactly with his foot but he can get it close. If he can get it close, then honk the horn to signify he thinks he's there, he can watch the video to see if the mark stabilizes. Or he can set up a closed circuit TV with the monitor by the driver's window.
And one doesn't have to pick the shutter speed; an auto shutter in adequate bright light should do the trick. What is important is that most of the time the shutter remains closed, otherwise the mark would be a blur.
Another way to handle it would be to run a timing gun in pitch black with a CMOS camera. Aim the gun at a white wall. CMOS's scan "here and there" and you'd get a cool pattern at multiples of its scan rate.
