Lux Meters?

[bpzle 0]

Do many of you installers use lux meters? I was thinking it could come in handy for selecting cameras/ lenses...

I was thinking of picking one up. Found a cheap one on Amazon for $35.

[zmxtech 0]

sure do, some of us know what where doing !

[thewireguys 3]

I have a Extech EasyView 31 and it works very well. It has a .01 sensitivity and was under $150.

 

I would spend the money and get a good one.

[survtech 0]

We use the Extech LT300 Light Meter. It is reasonably priced and pretty accurate. Here are the specs:

 

* Wide range to 20,000Fc or Lux with high resolution to 0.01 Fc/Lux

* Relative mode indicates change in light levels, peak mode captures highest reading

* Remote light sensore on 12" (305mm) coiled cable - expandable to 24"

* Utilizes precision photo diode and color correction filter

* Large LCD display with analog bargraph

* Backlight for readings in low light levels

* Complete with 9V battery, light sensor with protective cover, protective holster, and pouch case

[thewireguys 3]

We use the Extech LT300 Light Meter. It is reasonably priced and pretty accurate. Here are the specs:

 

* Wide range to 20,000Fc or Lux with high resolution to 0.01 Fc/Lux

* Relative mode indicates change in light levels, peak mode captures highest reading

* Remote light sensore on 12" (305mm) coiled cable - expandable to 24"

* Utilizes precision photo diode and color correction filter

* Large LCD display with analog bargraph

* Backlight for readings in low light levels

* Complete with 9V battery, light sensor with protective cover, protective holster, and pouch case

 

That was the one that I wanted but they where out of stock

[bpzle 0]

We use the Extech LT300 Light Meter. It is reasonably priced and pretty accurate. Here are the specs:

 

* Wide range to 20,000Fc or Lux with high resolution to 0.01 Fc/Lux

* Relative mode indicates change in light levels, peak mode captures highest reading

* Remote light sensore on 12" (305mm) coiled cable - expandable to 24"

* Utilizes precision photo diode and color correction filter

* Large LCD display with analog bargraph

* Backlight for readings in low light levels

* Complete with 9V battery, light sensor with protective cover, protective holster, and pouch case

 

That was the one that I wanted but they where out of stock

I'll buy urs so u can buy the one u want

[Soundy 1]

sure do, some of us know what where doing !

 

Even if we can't spell "we're"??

[scorpion 0]

Owch! I herd that "slap" eko off my walls at home!

 

That was the one that I wanted but they we're out of stock

 

I wanted but they we are out of stock

[survtech 0]

The funny thing is, we've used ours more to show Architects and Construction Supervisors how to properly light an area than for our own information. We did gather a sampling of light levels for areas that were properly lit and areas that were not.

 

After many years doing this, I can usually tell by eye if an area is properly lit. Since our camera locations for many scenarios are pretty much set in stone, we often just install the camera that typically has worked in the past for a particular application, then get any lighting issues fixed after-the-fact. Of course, that would not be an option for many of you.

 

And no, it's not for sale due to low usage!

[zmxtech 0]

wear....

[oldtimer 0]

We use them all the time. We visit the proposed site during the night hours and put the readings in a proposal. Chances are the other guys will not do this. It shows you are a pro. It usually closes the deal.

[3RDIGLBL 0]

We use them all the time. We visit the proposed site during the night hours and put the readings in a proposal. Chances are the other guys will not do this. It shows you are a pro. It usually closes the deal.

 

Until the prospective customer takes your hard earned lux reading and goes back to the competition and grants them the job because they are cheaper after they selected new cameras based on the proper lux measurements.

 

Sometimes these details really screw you up. Sure it's shows professionalism but I'll usually voice details and not put it in writing where it can be used against me in a head to head battle with a competitor. Been burned one too many times. If they ask I'll be clear and honest about my equipment selections.

 

But maybe that's just me.

[cglaeser 0]

What is the lowest reliable lux measurement any of these meters can measure?

 

I have a Minolta IV that I've had for twenty years. I think it can measure -1 EV at ISO 100, which is 1.25 lux.

 

Best,

Christopher

[ak357 0]

What is the lowest reliable lux measurement any of these meters can measure?

 

I have a Minolta IV that I've had for twenty years. I think it can measure -1 EV at ISO 100, which is 1.25 lux.

 

Best,

Christopher

 

For example

Extech Instruments LT300

40.00, 400.0, 4000, 40.00k, 200.0kLux

 

Wide range to 20,000 Foot-Candles

or Lux with high resolution to 0.01 Fc/Lux

Edited January 8, 2010 by Guest

[cglaeser 0]

For example

Extech Instruments LT300

40.00, 400.0, 4000, 40.00k, 200.0kLux

 

Wide range to 20,000 Foot-Candles

or Lux with high resolution to 0.01 Fc/Lux

 

I saw that, but does it really measure to four significant digits? Specifically, can it really measure down to 0.01 lux?

 

Best,

Christopher

[thewireguys 3]

For example

Extech Instruments LT300

40.00, 400.0, 4000, 40.00k, 200.0kLux

 

Wide range to 20,000 Foot-Candles

or Lux with high resolution to 0.01 Fc/Lux

 

I saw that, but does it really measure to four significant digits? Specifically, can it really measure down to 0.01 lux?

 

Best,

Christopher

 

I have no way of proving it but mine reads down to .01 lux.

[cglaeser 0]

I have no way of proving it but mine reads down to .01 lux.

 

Thanks!

 

Best,

Christopher

[ak357 0]

I have no way of proving it but mine reads down to .01 lux.

 

Thanks!

 

Best,

Christopher

 

Yep down to 0.01 Lux

[cglaeser 0]

Yep down to 0.01 Lux

 

A quarter moon on a clear night is 0.01 lux, so it should be relatively easy to test the meter. Here are some other values from wiki.

 

0.0001 lux - overcast starlight

0.002 lux - moonless clear sky starlight

0.01 lux - quarter moon on clear night

0.27 lux - full moon on clear night

1.0 lux - full moon overhead at tropical latitues

 

Best,

Christopher

[cglaeser 0]

Here's the confusing thing about the Extech meters. The LT300, for example, has four digits of precision and plus/minus 5% error. So, if the range is 40 lux, the error margin is plus or minus 2 lux. Suppose the reading is 38.12 lux. What does 38.12 lux plus or minus 2 lux mean? Isn't that really just somewhere in the range of 36 to 40 lux?

 

Best,

Christopher

[ak357 0]

Here's the confusing thing about the Extech meters. The LT300, for example, has four digits of precision and plus/minus 5% error. So, if the range is 40 lux, the error margin is plus or minus 2 lux. Suppose the reading is 38.12 lux. What does 38.12 lux plus or minus 2 lux mean? Isn't that really just somewhere in the range of 36 to 40 lux?

 

Best,

Christopher

 

u have a point but

1 Lux at 5% error is between .95 and 1.05 right ?

do u think we care

just get unit and start to play

its not bad

and educational

[cglaeser 0]

u have a point but

1 Lux at 5% error is ~ is between .95 and 1.05 right ?

do u think we care

 

It was thirty years ago, but I still remember the first question I missed in college. It was a Chemistry 101 exam. Here's the question.

 

- A bottle and a cork cost $1.05. The bottle costs $1.00 more than the cork. What is the cost of the cork?

 

Regarding the LT300, I don't know the details of the UI, but perhaps it was easier to add two junk digits than it was to add more ranges.

 

just get unit and start to play

its not bad

and educational

 

Speaking of educational, tonight I used my $4,500 light meter to take some low lux readings. It is a Canon Mark II, a dual use device that can also be used as a camera. Using ISO 3200 at f/2.8 it took 4 seconds to properly expose the area. That should be equivalent to EV -4. Using the equation lux = 2.5 * 2 ** EV, assuming I don't make any errors, we get 0.2 lux. Plus or minus.

 

Best,

Christopher

[survtech 0]

- A bottle and a cork cost $1.05. The bottle costs $1.00 more than the cork. What is the cost of the cork?

 

Best,

Christopher

2.5¢

[ak357 0]

u have a point but

1 Lux at 5% error is ~ is between .95 and 1.05 right ?

do u think we care

 

It was thirty years ago, but I still remember the first question I missed in college. It was a Chemistry 101 exam. Here's the question.

 

- A bottle and a cork cost $1.05. The bottle costs $1.00 more than the cork. What is the cost of the cork?

 

1.025 and 0.025 2.5 cents

 

i new this joke also 30 years back as $11 total

 

Regarding the LT300, I don't know the details of the UI, but perhaps it was easier to add two junk digits than it was to add more ranges.

 

just get unit and start to play

its not bad

and educational

 

Speaking of educational, tonight I used my $4,500 light meter to take some low lux readings. It is a Canon Mark II, a dual use device that can also be used as a camera. Using ISO 3200 at f/2.8 it took 4 seconds to properly expose the area. That should be equivalent to EV -4. Using the equation lux = 2.5 * 2 ** EV, assuming I don't make any errors, we get 0.2 lux. Plus or minus.

 

Best,

Christopher

 

and speaking about jokes

have u ever seen this one

2x2=5

or

1=2

can be easily proven

[cglaeser 0]

- A bottle and a cork cost $1.05. The bottle costs $1.00 more than the cork. What is the cost of the cork?

 

1.025 and 0.025 2.5 cents

 

That was my answer too, but that's wrong.

 

When I learned the correct answer, I thought to myself, you've got to be kidding me, but later realized it was an extremely important lesson, and I never made that mistake again on any of my college exams.

 

My wife is a personal trainer at a sports club, and the staff use a skin caliper to measure body fat. They take measurements at various locations, enter the numbers into their calculator using a formula, and then declare, you have 17.73% body fat. Wrong answer!

 

Best,

Christopher