Newbie here cool site have any insight on this?

[ZERTIS]

Hello all, I am new to this site and would like to throw out a few questions that someone might want to help with?

I purchased two 12 volt Optronics spotlights. I also purchased a 12 volt Blazer brand spotlight which is identical in design, size and lens shape. The two Optronics came with an H3 55 watt lamp which were rated at 500K candlepower. The Blazer came with an H3 35 watt lamp and is rated at 70K candlepower.

I replaced the two H3 55 watt lamps in the Optronics spotlights with H3 100 watt lamps and there was an expected dramatic difference in the brightness. I know that the term candlepower is really a bogus term and more accurate measures of light intensity are lumens and candela. I am still in a fog about the formulas. My questions are;

If I have a 12 volt spotlight with an H3 55 watt lamp that equals 500K CP as per Optronics, do I now have close to 1 million CP with the upgrade to the 100 watt lamp?

I have seen identical spotlights rated at 1 million and even 1.5 million and higher CP. I am just looking for a rough idea on the difference in lamp choices and the intensity or brightness expected with different types, brands and wattage of lamps. Hope someone will take a stab at this for me.

Thank you
Zertis

 

[Patriot]

:welcome:



You're correct in saying that candle power or candela is nearly meaningless to us with regards to being helpful in judging a performance difference between lights. In order to double the cp rating you'd have to double the surface brightness of the filament while it remained the same size. Going to a 100W bulb doesn't accomplish this since all that actually happened is the doubling of the filament length/size, while the surface brightness remains essentially the same. With that said, you have increased the lumen output and because some of that extra output is being focused by the reflector the cp rating does climb some but only by about 25%-50% depending of the filament design. The actual candle power rating of a 100W bulb with a reflector on the Optronics is around 300,000cp give or take 100,000. A 130W halogen bulb in a 9" reflector can produce upwards of 1m cp.

A much better gauge for measuring throw is to state lux with the help of a light meter. One good quick base reference is Vee73's page here:
http://www.kuvaboxi.fi/mediaobjects/orig/pub/2009/07/26/8143010478553041683orig.jpg

As you can see there is a "1 million CP" spot in there rated at 1420 lux, so it's probably safe to say your light is between 1000-3000 lux depending on the reflector size. Typical lux readings would normally be higher but since lux testing is often informal and differs from person to person & test to test. These readings are only helpful on a relativistic but it helps to paint a picture.

Probably the easiest way to determine relative spotlight performance is just to use the figure of bulb lumens. A 55W bulb produces around 900-1200 lumens and a 100W bulb around 1700-2000 lumens. Beyond the lumen rating you can take into consideration the size of the reflector, since the larger it is the better the light will throw, generally speaking. HID bulbs will always throw further than halogen and Short-arc HID will always throw farther than standard long-arc HID.

I hope that helps some.

 

[ZERTIS]

Patriot, Thanks so much for the info. I now understand the concept as you were so kind to explain and it seems that the key is lamp type and surface area of the reflector measured in lux if you just happen to have a light meter hanging around. However, measured in lumens as the examples you provided is a more common way of measurement. I purchased these three spotlights 100% due to the design and now that I have more info I can explore the possibilities of the different lamps you mentioned. Thanks again.
Zertis