Altman 360Q

[lighttechie5948]

What's the formula for 360Qs, again? In a 6x9, what does the 6 stand for and what does the 9 stand for?

Just need a reminder!

Thanks!!

 

[Les]

The 6 is the lens diameter, and the number following that (9) is the focal length. All measurements are in inches.

 

[RonHebbard]

What's the formula for 360Qs, again? In a 6x9, what does the 6 stand for and what does the 9 stand for?

Just need a reminder!

Thanks!!

Following up on what Les posted:
4 1/2 x 6 1/2 is approximately 50 Degrees
6 x 9 - 36 Degrees
6 x 12 - 26 Degrees
6 x 16 - 19 Degrees
6 x 22 - Sorry, I'm forgetting but very close to Strand's 2112, not their 2212 but their 2112.

Toodleoo!
Ron Hebbard

 

[derekleffew]

...
6 x 22 - Sorry, I'm forgetting but very close to Strand's 2112, not their 2212 but their 2112.

~11°.

Note also that all luminaires listed above (except the 360Q-6x22 and Strand/Century 2112) have TWO plano convex lenses, installed belly to belly. Thus to determine the effective focal length (EFL) of the lens train, one must apply Gullstrand's Equation.

More maths in the Collaborative Article: Mathematical Formulas for Lighting Designers.

 

[sk8rsdad]

While not strictly correct, a rule of thumb for the 6 x __ nomenclature is to treat the first number as the diameter of the field and the second number as the distance from the fixture. So a 6 x 16 produces a 6' circle at 16' from the fixture.

 

[hobbsies]

While not strictly correct, a rule of thumb for the 6 x __ nomenclature is to treat the first number as the diameter of the field and the second number as the distance from the fixture. So a 6 x 16 produces a 6' circle at 16' from the fixture.

Woah, interesting!

 

[derekleffew]

While not strictly correct, a rule of thumb for the 6 x __ nomenclature is to treat the first number as the diameter of the field and the second number as the distance from the fixture. So a 6 x 16 produces a 6' circle at 16' from the fixture.

Never heard this before, so... let's test it.

According to Michael Zinman's Pocket LD for iPhone/Pod:
360Q-4.5 x 6.5 at 6.5' throw: Beam Dia 2'-7", Field Dia 6'-5"
360Q-6 x 9 at 9' throw: Beam Dia 2'-7", Field Dia 5'-12" (!?)
360Q-6 x 12 at 12' throw: Beam Dia 2'-5", Field Dia 5'-7"
360Q-6 x 16 at 16' throw: Beam Dia 2'-4", Field Dia 5'-6"
360Q-6 x 22 at 22' throw: Beam Dia 3'-2", Field Dia 4'-4".

Works pretty good for 6x9, 6x12, 6x16. Not so much for the 4.5x6.5 and 6x22. Still, myth proven.