Beam angle vs view angle

[Ed Palma]

Okay, I did a search and found nothing directly related to the topic. Couldn't find anything in wikipedia ...

Anyway, I've decided to make the jump from using an MR11 Halogen bulb to an LED bulb. While looking over the specs of some bulbs, I saw the following:

Beam angle 30 degrees
View angle 15 degrees

What's the difference ?

 

[Ed Palma]

Any light gurus out there?

 

[MikeRD03]

Hi Doc,

I never heard of a viewing angle in terms of a light bulb. The only interesting thing is the beam angle and this is with 30 degree much too large for a diving lamp. Normaly 10 degree is a good start.
If you ask me forget about every multi 5mm LED bulb..

greets,
MikeRD03

 

[Charlie99]

Beam angle is usually defined as twice the angle from the axis to the point at which the illuminance (candlepower) is down to 1/2 of the brightest point in the center spot.

"Field angle" is the same, but from the 10% of peak points.

Just to confuse things even more, although most manufacturers call the beam angle the entire angle of the cone that covers both sides of the dropoff point, some manufacturers use the half-angle --- i.e. the angle from the center axis to the drop off point. While most guys would spec a certain bulb as a 30 degree beam angle, these oddball guys call it a 15 degree bulb -- so you have to be careful to find out what definition that specific supplier is using.

Since that manufacturer says "beam angle 30, view angle 15", it sounds like he is just putting in the half angle number so that it is clear that his 30 degree beam angle is from side to side, rather than from central axis to one side.

 

[Ed Palma]

Thanks!

And... oh no. That means the MR11 bulb I got has a 30 degree angle! meaning another relatively wide beam for a primary!

What measurement is being referred to when looking for cannister lights with a 6 degree angle?

At any rate, 15 or 30 is still kinda wide I guess. Oh well.

 

[Ed Palma]

Hi Doc,

I never heard of a viewing angle in terms of a light bulb. The only interesting thing is the beam angle and this is with 30 degree much too large for a diving lamp. Normaly 10 degree is a good start.
If you ask me forget about every multi 5mm LED bulb..

greets,
MikeRD03

Hi Mike!

I read your recommendation in the other thread about LEDSEE, but decided to go for something closer to home. Anyway here's the bulb I got, along with its data. Well, at any rate, at least it'll increase my burn time

Brightest MR11 12V AC/DC High Power LED White 80 Lumen - (eBay item 220165755381 end time Nov-02-07 22:34:30 PDT)