Light meter

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gumball

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Is there a tool that we can use to show customers how much light is getting through their yellowed headlights-then their reconditioned HLs?If so, where?
 
Finemess thanks for your help. Ifound what I needed at symtech.AG should carry this product.:dblthumb2:
 
I'm sure if you took before and after readings with a light meter used for photography you would see a difference.
 
But wouldnt the lighting conditions outside etc.. all come into factor when trying to measure the light output from the headlights on a before and after scenario? it would have to be the exact surrounding lighting same lights on in the shop with doors closed etc.. to be extremely accurate
 
JC PAINT WORKZ said:
But wouldnt the lighting conditions outside etc.. all come into factor when trying to measure the light output from the headlights on a before and after scenario? it would have to be the exact surrounding lighting same lights on in the shop with doors closed etc.. to be extremely accurate
Click to expand...

You would obviously do this at night in an enclosed space (like a garage or shop) or in an area with no ambient light. Or, you could take a reading of the ambient light, then subtract it from the reading you get with the headlights on.
 
Gary Sword said:
I'm sure if you took before and after readings with a light meter used for photography you would see a difference.
Click to expand...

If you use a photo meter, it will give you results in "camera settings" to get a well-lit shot. It won't give you a reading in the amount of illumination or "lux". Trust me, I already posed the same question to a photo shop.
 
You can use a TRUE photo light meter. That said, you'd want to do it in the shop/garage and NOT in the direct sunlight.

In the 'photo world' a gray scale is used for to gauge the REFLECTED light. So, if you have a light meter (have NO idea of the cost nowadays), you'd shine the headlight on the gray paper before correction and again AFTER correction. There should be a notable difference to show the customer.

Does that make sense?

Bill
 
g35_coupe said:
If you use a photo meter, it will give you results in "camera settings" to get a well-lit shot. It won't give you a reading in the amount of illumination or "lux". Trust me, I already posed the same question to a photo shop.
Click to expand...
Should have asked professionals. Not schmucks at a photo shop. They are generally enthusiasts and claim to know more then they actually do.

BillE said:
You can use a TRUE photo light meter. That said, you'd want to do it in the shop/garage and NOT in the direct sunlight.

In the 'photo world' a gray scale is used for to gauge the REFLECTED light. So, if you have a light meter (have NO idea of the cost nowadays), you'd shine the headlight on the gray paper before correction and again AFTER correction. There should be a notable difference to show the customer.

Does that make sense?

Bill
Click to expand...

Incorrect. Gray cards are use for incamera metering. Cameras see the world in 18% gray. So do give it the most precise meter reading possible you need to show it an 18% gray space for it to meter off of. This also helps cameras with white balance as well. Useful for preparing to take pictures of your detailing job :xyxthumbs:

What you guys need is a hand held light meter. I prefer sekonic and the methods im about to describe work flawlessly on these units. there are cheaper units available even used sekonic's As long as they take an incident reading (they all do) and can give you an output reading in EV (exposure value) then you can follow these instructions. I have done this exact conversion before, just not for headlights of cars. I had to measure my lights power at a distance to apply for a permit for a photo shoot. Anyway. I use a Sekonic L-358 Flashmaster meter.

This method will give you a EV reading on a light meter which is then converted to either Lux or Foot-Candle. Lumens and Foot-Candle are basically the same. Lux = FC x 10.76, same with Lumens

All you need to do is set the light meter to EV mode, and set the ISO to 100

here is an Online chart on how to convert your EV reading to Lux or Foot-candle. Sekonic

Here is a more in-depth guide on how to do this as well.
http://www.blankmediagroup.com/Pictures/Andrew/detail/MeasuringLux.pdf

The instructions are important if you do not follow them it will not work properly.

Remember you will not be able to do this outside, you will need a garage, with the lights off, no windows preferably. You may be able to get an reading at night as well. Basically you need the headlights to be more powerful then the ambient light.
 
Forum would not let me have this in my initial post. so i had to split them up. Weird i know.

Alternative Method
if you understand photography (might be difficult to explain to clients) is to simply measure the light output in stops. Set your meter to Shutter Priority. The ISO does not matter so long as it does not change and that its at a level that the meter can output a real exposure. If its to high or too low you will get a E.o or E.u for Exposure Over and Exposure Under. If i were doing it i would set my meter to 60 for shutter speed (1/60th of a second) and then all you do is get a reading from the headlight that is not corrected and write it down. then from the same distance get a reading of the corrected headlight. i suggest about 8-10 feet away from the head light. The difference in f-stop's will be your difference in light transmission through the headlight lens.

All of that said. you might not notice too much of a difference except in extreme cases. Also to better see your results you may want to be like 12-20 feet away. as the light fall off from a bad lens is going to be most noticeable there. but make sure you are still in the head light beam. remember, Left and Right headlights are aimed differently. so just make sure.
 
AndrewBall said:
Forum would not let me have this in my initial post. so i had to split them up. Weird i know.

Alternative Method
if you understand photography (might be difficult to explain to clients) is to simply measure the light output in stops. Set your meter to Shutter Priority. The ISO does not matter so long as it does not change and that its at a level that the meter can output a real exposure. If its to high or too low you will get a E.o or E.u for Exposure Over and Exposure Under. If i were doing it i would set my meter to 60 for shutter speed (1/60th of a second) and then all you do is get a reading from the headlight that is not corrected and write it down. then from the same distance get a reading of the corrected headlight. i suggest about 8-10 feet away from the head light. The difference in f-stop's will be your difference in light transmission through the headlight lens.

All of that said. you might not notice too much of a difference except in extreme cases. Also to better see your results you may want to be like 12-20 feet away. as the light fall off from a bad lens is going to be most noticeable there. but make sure you are still in the head light beam. remember, Left and Right headlights are aimed differently. so just make sure.
Click to expand...

Tthank you so much for clearing that up. I guess the guys at the photo shop only had half of their information.
 
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