Thinking of making a moon blaster!

[The_Driver]

Any Updates?

 

[Domdom]

Would be good to call BATMAN

 

[thinkFlashlights01]

Better get past the law of not pointing your light up in the sky.:nana:

 

[FRITZHID]

Damn sky Nazis.

 

[scotsguy]

Can you explain something for me as a noob?
You're using a p-vip 120 lamp which i understand is a 120watt lamp, powering it from 3SLAs & an invertor?
Why wouldn't one use a 2000watt lamp powered with 110volts from said invertor? Like this lamp>
http://www.ebay.co.uk/itm/2000-watt...443?pt=LH_DefaultDomain_0&hash=item339bb2a1f3
Am I just confusing the watts/light output values?
By the way, great spec sheet for your lamp here > http://www.ebay.co.uk/itm/SAGEM-HDD-45S-P-VIP-100-120-1-3-E23h-TOP-OSRAM-TV-LAMP-/270647129745

 

[FRITZHID]

I'm not 100% sure why the OP chose that particular bulb but the fact that it's a small point light source (arc lamp) not a large heated coil probably has allot to do with it, as well as runtime, bulb life, cooling, size, etc....

 

[The_Driver]

@scotsguy: answering your question is going to require a lot of explaining. I will try to do some of it.

The short answer: brightness (lumens) of a lightsource (the bulb) is not what causes a light to throw. The luminance of the lightsource (basically the intensity) is what determines throw together with the diameter of the reflector. The Osram P-VIP is a high-pressury mercury short-arc HID (high intensity discharge) bulb (filled with gas) that is way more intense than the 2000W Halogen bulb that you mentioned. Luminance is measured in cd/mm^2 (Candela per square millimeter).
The very best Halogens have a maximum luminance of about 65 cd/mm^2. The 2000W bulb that you mentioned will have a luminance of about 22cd/mm^2. See here for more information regarding the luminance of different light sources (it's in German, so use google translate).
The 120W P-VIP has a luminance of ~1000 cd/mm^2. This means that the P-VIP bulb is around 45-50 times more intense compared to the 2000W halogen. This means 45 to 50 times more throw (cd or lux) with the same reflector compared to the 2000W halogen.

The intensity of the light source only determines how far the brightest spot in the center of the beam will throw. It does not determine how much light is produced by the lightsource or how much comes out of the light. It also does not determine how big the hotspot of the light will be. The size of the hotspot is determined by the size of the light source (the size of the arc in the HID bulb in this case) and the size and shape of the reflector. However, the size of the arc has no effect on the intensity of the hotspot and thus the throw. If have you have two different lightsources with the same luminance, but one is bigger than the other, they will both throw the same distance when paired with identically sized reflectors. The bigger lightsource will just make the hotspot bigger.

It just so happens that short-arc HID bulbs are the ones with a very high luminance. So if you want very extreme throw you will always have a rather small hotspot.

For comparison: with modern LEDs the highest luminance one can achieve is right around 220cd/mm^2 (de-domed Cree XP-G2 S3 on copper PCB @ 5A). That is noticeably better than even the best halogens, but not in any way close what the best short-arc bulbs can do.

 

[FRITZHID]

Yea, what ^^^he^^^ said.

 

[scotsguy]

@scotsguy: answering your question is going to require a lot of explaining. I will try to do some of it.

The short answer: brightness (lumens) of a lightsource (the bulb) is not what causes a light to throw. The luminance of the lightsource (basically the intensity) is what determines throw together with the diameter of the reflector. The Osram P-VIP is a high-pressury mercury short-arc HID (high intensity discharge) bulb (filled with gas) that is way more intense than the 2000W Halogen bulb that you mentioned. Luminance is measured in cd/mm^2 (Candela per square millimeter).
The very best Halogens have a maximum luminance of about 65 cd/mm^2. The 2000W bulb that you mentioned will have a luminance of about 22cd/mm^2. See here for more information regarding the luminance of different light sources (it's in German, so use google translate).
The 120W P-VIP has a luminance of ~1000 cd/mm^2. This means that the P-VIP bulb is around 45-50 times more intense compared to the 2000W halogen. This means 45 to 50 times more throw (cd or lux) with the same reflector compared to the 2000W halogen.

The intensity of the light source only determines how far the brightest spot in the center of the beam will throw. It does not determine how much light is produced by the lightsource or how much comes out of the light. It also does not determine how big the hotspot of the light will be. The size of the hotspot is determined by the size of the light source (the size of the arc in the HID bulb in this case) and the size and shape of the reflector. However, the size of the arc has no effect on the intensity of the hotspot and thus the throw. If have you have two different lightsources wit the same luminance, but one is bigger than the other, they will both throw the same distance when paired with identically sized reflectors. The bigger lightsource will just make the hotspot bigger.

It just so happens that short-arc HID bulbs are the ones with a very high luminance. So if you want very extreme throw you will always have a rather small hotspot.

For comparison: with modern LEDs the highest luminance one can achieve is right around 220cd/mm^2 (de-domed Cree XP-G2 S3 on copper PCB @ 5A). That is noticeably better than even the best halogens, but not in any way close what the best short-arc bulbs can do.

TY for that, the Leuchtdichten/luminances thread was a good read. I was making a noob mistake reading the simple watt value of a lamp as its brightness.
Off to look at high-pressure discharge lamps now.

 

[FRITZHID]

TY for that, the Leuchtdichten/luminances thread was a good read. I was making a noob mistake reading the simple watt value of a lamp as its brightness.
Off to look at high-pressure discharge lamps now.

Lot's of helpful info among the threads & most of us flashaholics are very helpful!