I have a question that I actually may know the answer too,
but not 100 percent sure. From my understanding there is a focus point in a
lighting instrument. This focus point is inside of the instrument. I wonder is
there another one outside of the instrument and is this the reason why when
light shoots through the grind in the XMPL the reflection of the grid is not
displayed on the floor? Also how does
this work when it comes to LED?
All lights have a Focal Point 1 and 2.
ReplyDelete#1 is where the lamp sits (in the middle of the reflector)
#2 is where all beams converge. This, in a Leko, is at the gate (where the shutters are) which is why we can get a crisp shadow of shutters, gobos, etc.
#2 exists on Fresnels, PAR's and all other lights that have a reflector but it is out in front of the light so it is not usable to us. F2 of a fresnel is about 8' in front of the light. Theoretically if you hung a Fresnel or a PAR about 8' above the grid in xMPL you would see a crisp shadow of the grid - because there is not a light with F2 around 2' in front of the light, we can use a tension grid.
To be honest I am not sure how to figure this out on an LED, as F2 is determined by the shape of the reflectors (Leko Ellipsoidal Reflector bends the beams of light so they converge inside the light) and the Fresnel and PAR with the Spherical (Fresnel) and Parabolic (PAR) reflectors, they do not bend the light as much so they come together much further outside of the light.
If this does not make sense, ask me about it tomorrow.