Altman 360q beam/field angle


Active Member
So, I was trying to explain to someone about different altman fixtures and their beam/field angles. I knew what the relative degrees of each 6x were (6x9=35° etc or whatever it is, not the point) but I was wondering what the numbers 6x9,4.5,12,22 etc actually refer to. Any ideas?


Senior Team Emeritus
Premium Member
Ooooo...good question.

I know the answer...but lets see what some folks can come up with. Think about it--All lights now are measured by degree. But the old 360Q's were measured for reference differently at the time...

I'll give you the first number--the 6 has to do with the lense size, in this case being a 6" plano-convex lense...the second number is... :)

Lets see some thoughts from members...

360q uses a lens chain composed of two Plano-convex lenses arranged in a belly-to-belly configuration. Lenses are specified by their diameter and focal length. A 6x9 lens is 6 inches in diameter and has a 9 inch focal length and this is measured from the aperture plate to the end of the lens. The average length of the aperture plate to the back the light is about 7.75in. So if you were to measure the total length of the instrument you would find that a 6x9 would be about 16.75 inches long.

Here are the degrees
1- 50ø (4.5x6.5)
2- 40ø (6x9))
3- 30ø (6x12)
4- 20ø (6x16)
5- 15ø (6x22)


Well-Known Member

The Altman website has this stuff:

Field / Beam

4.5 55/22
6x9 37/16
6x12 26/11
6x16 19/8.5
6x22 11/8


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