LED-How to tell the real ligthing output of led lights?How to compare lighting power?

haring

I am looking at several led light options. Obviously, one of the considerations is how much light the led panel emits.
Some companies list their products specifying out put via "lux"
http://www.adorama.com/fpvl500c.html
Others list Watt, W.
http://ikancorp.com/productdetail.php?id=998
Others use lumens...

My questions: How to measure/compare the lighting output of led lights? Is there a way to convert these numbers? All I want to know how much light these lights output so I can compare them.

mercphoto

Watts are meaningless for this purpose. That measures electrical power consumption, that's it. Its very useful to know, as it dictates battery life, or how big an A/C circuit you need, expected heat generation, etc. But tells you nothing about how efficiently the lighting devices turns electricity into photons.

In terms of light power output its all about lumens.

ziggy53

Ideally I would want to know both lumens and lux because one lux is equal to one lumen per square metre. Then you also need to know the lux at a couple of distances from the source in order to ascertain light spread.

In other words, if all the manufacturer is giving you is either lumens or lux, and if they don't define how they arrive at those figures, that is certainly not enough information to compare between manufacturers nor is it sufficient information about how the light will work at specific distances from the source. If all they give you is watt usage, steer clear because they are telling you nothing about light output at all (as Bill already said.)

Find comparative reviews for more information and definitely purchase from a supplier with ample return privileges so that you can test suitability in your application.

I still cannot recommend LED lights for color accuracy, especially skin tone color accuracy, reds in general and many times specific blues as well. Make sure that you view a sample image of a photographic color chart lit by the particular light prior to purchase if color accuracy is important to your application.

Sam

I just looked at Einstein, and Profoto, nether one had lumen or lux specs.

All they had was watt seconds, temp, flash duration.

These are both good quality reliable manufacturers?? Just saying....................

Sam

dbd

Sam wrote: »

I just looked at Einstein, and Profoto, nether one had lumen or lux specs.

All they had was watt seconds, temp, flash duration.

These are both good quality reliable manufacturers?? Just saying....................

Sam

Paul C Buff Inc gives a table of 10' and 5' required F stop and the guide number (all at 100 ISO) at a wide range of power levels after you select the light modifier for it's products at http://www.paulcbuff.com/output.php.

Profoto provides the required F stop at 2 M at 100 ISO for a selection of light modifiers at a specified power level (Ws) in the technical data section of the product data sheets.

Just saying...???

Dale B. Dalrymple

ziggy53

dbd wrote: »

Paul C Buff Inc gives a table of 10' and 5' required F stop and the guide number (all at 100 ISO) at a wide range of power levels after you select the light modifier for it's products at http://www.paulcbuff.com/output.php.

Profoto provides the required F stop at 2 M at 100 ISO for a selection of light modifiers at a specified power level (Ws) in the technical data section of the product data sheets.

Just saying...???

Dale B. Dalrymple

Yes, these are the types of data important to a true photographer.