Quote:
Originally Posted by Hughesie89
i have heard of a bounce focus
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Hughesie, don't complicate or confuse matters.
"Bench focus" is exactly as Icewolf described: optimizing the fixture's output by aligning the lamp into the focal point of the ellipsoidal
reflector. But let me elaborate just a little. The Center Screw on the 360Q lampcap is a roundhead slotted screw which also has one or two hex nuts on it also. At 120° apart are 3 flathead slotted screws. On older fixtures all 4 screws can become almost welded in place, so it's not a bad idea the day before to apply a tiny amount of penetrating oil or WD-40 on the screw threads. Be sparingly with the oil, it's going to smoke and burn once the lamp comes on. The procedure is 1) loosen the center screw about 1/4". 2) if there is a defined hot spot or dark spot, loosen or tighten the three outer screw until you get it in the middle of the beam. 3) Then loosen or tighten all three screws the same amount to make the field as even (flat) as possible. 4) If the fixture is horizontal, the lamp and socket will want to sag due to gravity, so it helps to hold in the lower screw while making all adjustments. 5) It shouldn't take any more than about five turns either direction on any screw. 6) Once you're satisfied with the results, tighten the center screw, but don't be surprised of something moves out of whack when you tighten the center screw, just correct whichever screw was not in properly and re-tighten the center screw. Then tighten the hex nuts down to prevent the center screw from moving in or out. 7) Theoretically, this process should be redone every time you change the lamp, but that seldom, if ever, happens. Once a year is sufficient in most cases. 8) While the
instrument is in the bench (actually a horizontal pipe about head high is the best) is a great time a)blow the dust off of/out of the fixture using an air compressor, b)to clean the reflector using Windex diluted half with water and a soft, lint-free cloth, and c) likewise the lenses d) best to do the cleaning before the aligning, so you won't have to wait for the fixture to cool down. Also the lamp need not be at 100% during bench focus, if you have a
dimmer available, run it at whatever level allows you to see the beam clearly with the worklights on. If you're in a traditional
proscenium theatre, a good way is to bring the First
Electric in to about 5', and then focus your lights on the
cyc. You can do an assembly line, so one's cooling wile you're working on another. Or if you have help, one cleans while another aligns, and then you switch.
"Bounce Focus" has two meanings:
1) Focusing a fixture from the ground, guessing at the pan, tilt, shutters, sharpness,
etc., then running the electric back to
trim. Make note about what you guessed wrongly, bring the electric back in and redo, repeat until satisfied. Also known as yo-yo focusing.
2) If using a "bounce drop"--a white surface upstage of a translucent drop or
scrim, bounce focus would be lights facing US, even though they're lighting the drop DS of them. Often achieve a more even wash this way.