The Arri M18 has to be my new favorite daily work horse. The M18 HMI is perfect for those people looking for maximum output off a household power point. Not only because of the impressive output but the ballast size and no need for lenses means faster setup and less trips to the van.
Here is some key points from my testing of the light:
At Full Flood
The M18 is 1/2 stop brighter with more spread than the 2.5.
This I believe is the strongest point of this lamp as we are finding most users of Pars are bouncing or putting thru diffusion. Therefore the M18 makes sense in all those situations.
At Full Spot
The 2.5 Par is almost 2 stops brighter with a spot lens in at full spot.
Of course The Par is a clear winner at full spot.
The head of the M18 weighs 10.5 KG
The head of the 2.5 Par weighs 18.5 Kg
The ballast of the M18 weighs 8kg
The ballast of the 2.5 Par weighs 20kg
Cartage and Components
The packing of the M18 takes up nearly 1/2 the space of the 2.5 Par.
There is no lens case with the M18 therefore less trips to set up one light and less potential for broken glass due to handling and hot lens changes and rain.
The M18 is only 1800w as opposed to 2500w so there is far less chance of blown circuits and overheating of extension leads.