Clay Paky Alpha Spot HPE 1200 Manuel d'utilisateur télécharger pdf (Page 2)

www.lightingandsoundamerica.com • January 2006

seen in a discharge spot unit—very clean and smooth, with no “jaggies,” or artifacts,

even at the lowest levels. Unfortunately, this excellent optical system is somewhat let

down by a very poor choice of dimming curve (Figure 4: Dimmer curve), where

everything useful happens in the top 20% of the dimmer. The unit is down to under

10% output when the control channel is still at 60% and is essentially out when the

control channel is at 40%. This is a real waste of resolution and means that the Alpha

Scan will dim differently from everything else in the rig, unless the user creates a

custom dimmer curve on the control desk. This is something Clay Paky could improve

on very easily with a software revision to really show off and capitalize on this excellent

dimmer.

As mentioned above, the fixture reduces the lamp power to 600W when the unit is

dimmed or blacked out through the strobe flags for more than three seconds, reverting

to the full 1,200W as the strobe flags open or the dimmer channel returns to 100%.

The lamp recovered very quickly and no color shift was apparent.

Color-mixing

Next in line is the color-mixing system. The Alpha Spot uses a linear “pair-of-curtains”

system with etched dichroic blades in each of four colors—cyan, magenta, yellow, and

CTO. Each color uses two blades, which move into the beam from opposite sides.

The resultant color-mixing is acceptably smooth, with little visible aberration in the

beam. You can see some color-fringing on the sides of the beam when focused on a

gobo and mixing pastel colors (Figure 5: Color fringing) but nothing worse than

competitive units. This is one area where Clay Paky has inevitably had to compromise

slightly from the almost perfect flat mixing of its units with condenser optics.

The transmission data above shows that Clay Paky has chosen fairly saturated

colors for its mixing colors with 4-6% transmission when mixed to the full primaries.

The variable CTO system performs well and can be used as a color modifier with the

color-mix system, if desired, to help make some pastel colors.

Unusually, the Alpha Spot has a second hot mirror, mounted immediately after the

color-mix assembly—I’m sure this is to keep the gobo system as cool as possible.

There is a lot of hardware mounted in a very small space, and cooling these systems

must have been difficult (Figure 6: Fixture optics). It certainly works well and the

downstream optics are kept very cool.

Strobe

Next in the optical train are the strobe flags, it is getting unusual to find strobes

separate from the dimmer these days, but it does make sense. The needs of both are

different—the dimmer needs to be as far out of the focal plane as possible and,

preferably, somewhere where the beam is large, to give you smooth dimming. The

strobe system, on the other hand, can be positioned where the beam is much smaller,

allowing for short flag movement and, thus, high speeds. The Alpha strobe system was

excellent—using two opposing flags for maximum speed, it was solid and smooth with

a measured range of 1-12Hz.

Color wheel

Completing the Alpha Spot’s color system is a fixed color wheel (six colors + white).

The manual talks about these being removable; however, in the test unit provided, the

colors were glued in (Figure 7: Color wheel) and would be difficult to change. (Note:

Clay Paky tells me that this has been changed in current production units and the

colors are now fitted without glue and are fully replaceable.) The system allows half

Color change speed – end to end 0.6 sec

Color mixing

Color Cyan Magenta Yellow Red Green Blue

Transmission 36% 15% 50% 6% 4% 6%

Fig. 4: Dimmer curve

Fig. 5: Color fringing

Fig. 6: Fixture optics

Fig. 7: Color wheel

1 2 3 4 5 6

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Clay Paky Alpha Spot HPE 1200 Manuel d'utilisateur Page 2

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