Drawing Beams

[ghunter64]

I am having problems trying to draw beams from Lighting Instruments in Vectorworks 12. I have a vertical truss set as lighting position in the wings on stage right and a Selecon Pacific 23-50 attached to the truss at around 500mm from the floor to be used as sidelight. I have a focus point center stage at 1500mm. When I click the "Draw Beam" property of the instrument I get an error "Incalculable angle.......". I have experimented by moving the lamp around to different positions, basically it works fine when the lamp is placed in a position well about the focus point, or when the focus point is raised, but not when the lamp is on a fairly shallow angle (as it would be with side light).

The main reason I want to do this is to be able to check beam angles from lamps that are placed either as sidelight or from positions very close to the floor. From what I can see when you place a focus point at around 1500mm the "Draw Beam" function only works when the lamp is hung fairly high. Another example of using such a shallow angle might be with footlights positioned downstage, or strip lights positioned on the floor and pointed at a fairly steep angle to light a cyclorama.

Also, when I position any lighting instrument on a lighting position, the instruments don't seem to move with the position (e.g. a 6000mm high truss with 4 instruments on it). Should the instruments "follow" the truss around as it is moved or do I need to set the instrument height independently of the position and group the objects?

Does anyone have any experience with this and am I missing something?

Thanks

[Cris with no H]

As far as I know, instruments are moved independently of the light position they're on; they're not associated as families like instruments and accessories are. The main advantage to even having light position objects is the auto-numbering features.

Spotlight will pop up that incalculable angle error with most shallow angles, unfortunately. But try turning the light on and rendering, you should get a better visual, if not a quick one.

[Jim_Allen]

when I tried seting a Source 4 - 40 at the same height as focus point I get a message that the angle has to be greater than 19 degrees. when i did the same with a S-4 par WFL I got - must be greater than 10 degrees????

Instruments do not attach to a position, and you need to set their Z on the position. If you move you need to select all intruments & the position - if you group you are not going to be able to select individual instruments.