LUX Meter

[Malloot 0]

Buying a new Lux meter;

I'm in the market for a new Lux meter. Does anyone have a suggestion.

 

Also I saw once a lux meter where you could put a CCTV lens on and then read the lux rating. Does anyone know where I can buy those?

[tomcctv 190]

Buying a new Lux meter;

I'm in the market for a new Lux meter. Does anyone have a suggestion.

 

Also I saw once a lux meter where you could put a CCTV lens on and then read the lux rating. Does anyone know where I can buy those?

 

 

putting a lens on to a lux meter and then putting it back onto a camera i just dont see the point ......... its the camera that does the lux.

 

using a lux meter is for light at that time (it can change with in 10 mins) are you looking for this to do cctv ???

[Malloot 0]

Buying a new Lux meter;

I'm in the market for a new Lux meter. Does anyone have a suggestion.

 

Also I saw once a lux meter where you could put a CCTV lens on and then read the lux rating. Does anyone know where I can buy those?

 

 

putting a lens on to a lux meter and then putting it back onto a camera i just dont see the point ......... its the camera that does the lux.

 

using a lux meter is for light at that time (it can change with in 10 mins) are you looking for this to do cctv ???

 

It's the camera that does the lux and the lens decreases the light before it falls on to the chip.

So you need to know how many light you loose when you use a vari-focal zoomed in to select the right camera for a specific situation.

 

You don't use a LUX meter for een average situation, experiance should suffice, but for some specific situations a LUX meter is essential.

[cglaeser 0]

for some specific situations a LUX meter is essential.

 

You may already own a lux meter. All you need is a digicam capable of taking long exposures and a basic understanding of light. Take a picture, determine the exposure (combination of ISO, F stop, and shutter speed) and convert to lux.

 

Best,

Christopher

[Malloot 0]

for some specific situations a LUX meter is essential.

 

You may already own a lux meter. All you need is a digicam capable of taking long exposures and a basic understanding of light. Take a picture, determine the exposure (combination of ISO, F stop, and shutter speed) and convert to lux.

 

Best,

Christopher

 

Can you tell me the formula to calculate the LUX value?

[cglaeser 0]

Can you tell me the formula to calculate the LUX value?

 

Exposure Value (EV) is more common in photography, so first calculate the EV, then convert to Lux. Use the table here http://en.wikipedia.org/wiki/Exposure_value to calculate the EV. Note that Table 1 assumes ISO 100.

 

Once you have calculated the EV, then convert to Lux. Here is one table here http://www.ndavidking.com/Tech%20Articles/EV%20to%20Lux%20conversion%20tables.pdf. Unfortunately, the table does not include low lux values, but it's easy to compute them. To extend the table to include lower values, subtract 1 from EV and divide Lux by 2. So, adding another row, EV -2 is Lux 0.75, for example.

 

Hope that helps.

 

Best,

Christopher

[Malloot 0]

Can you tell me the formula to calculate the LUX value?

 

Exposure Value (EV) is more common in photography, so first calculate the EV, then convert to Lux. Use the table here http://en.wikipedia.org/wiki/Exposure_value to calculate the EV. Note that Table 1 assumes ISO 100.

 

Once you have calculated the EV, then convert to Lux. Here is one table here http://www.ndavidking.com/Tech%20Articles/EV%20to%20Lux%20conversion%20tables.pdf. Unfortunately, the table does not include low lux values, but it's easy to compute them. To extend the table to include lower values, subtract 1 from EV and divide Lux by 2. So, adding another row, EV -2 is Lux 0.75, for example.

 

Hope that helps.

 

Best,

Christopher

 

It helps, but using a LUX meter suits me more then doing the math for several camera positions.

[cglaeser 0]

It helps, but using a LUX meter suits me more then doing the math for several camera positions.

 

Yeah, at first glace, the *math* looks scary, but it's really just a table look-up, which can be done in a couple seconds. Also, just be aware there are lux meters and there a lux meters. Post a link to the meter you intend to purchase and we may be able to offer additional comments.

 

Best,

Christopher

[Malloot 0]

I was thinking about this one:

 

http://www1.conrad.nl/scripts/wgate/zcop_nl3/~flNlc3Npb249UDkwX05MX0IyQzpDX0FHQVRFMDQ6MDAwMS4wMDg2LmQ2NDBiMmMxJn5odHRwX2NvbnRlbnRfY2hhcnNldD1pc28tODg1OS0xJn5TdGF0ZT04ODYxMDY0Nzg=?~template=PCAT_AREA_S_BROWSE&mfhelp=&p_selected_area=%24ROOT&p_selected_area_fh=&perform_special_action=&glb_user_js=Y&shop=NL2&vgl_artikel_in_index=&product_show_id=&p_page_to_display=DirektSearch&~cookies=1&zhmmh_lfo=&zhmmh_area_kz=&s_haupt_kategorie=&p_searchstring=luxmeter&p_searchstring_artnr=&p_searchstring_manufac_artnr=&p_search_category=alle&fh_directcall=&r3_matn=&insert_kz=&gvlon=&area_s_url=&brand=&amount=&new_item_quantity=&area_url=&direkt_aufriss_area=&p_countdown=&p_80=&p_80_category=&p_80_article=&p_next_template_after_login=&mindestbestellwert=&login=&password=&bpemail=&bpid=&url=&show_wk=&use_search=3&p_back_template=&template=&kat_save=&updatestr=&vgl_artikel_in_vgl=&titel=&darsteller=&regisseur=&anbieter=&genre=&fsk=&jahr=&jahr2=&dvd_error=X&dvd_empty_error=X&dvd_year_error=&call_dvd=&kna_news=&p_status_scenario=&documentselector=&aktiv=&gewinnspiel=&p_load_area=$ROOT&p_artikelbilder_mode=&p_sortopt=&page=&p_catalog_max_results=20

[cglaeser 0]

I was thinking about this one:

 

http://www1.conrad.nl/scripts/wgate/zcop_nl3/~flNlc3Npb249UDkwX05MX0IyQzpDX0FHQVRFMDQ6MDAwMS4wMDg2LmQ2NDBiMmMxJn5odHRwX2NvbnRlbnRfY2hhcnNldD1pc28tODg1OS0xJn5TdGF0ZT04ODYxMDY0Nzg=?~template=PCAT_AREA_S_BROWSE&mfhelp=&p_selected_area=%24ROOT&p_selected_area_fh=&perform_special_action=&glb_user_js=Y&shop=NL2&vgl_artikel_in_index=&product_show_id=&p_page_to_display=DirektSearch&~cookies=1&zhmmh_lfo=&zhmmh_area_kz=&s_haupt_kategorie=&p_searchstring=luxmeter&p_searchstring_artnr=&p_searchstring_manufac_artnr=&p_search_category=alle&fh_directcall=&r3_matn=&insert_kz=&gvlon=&area_s_url=&brand=&amount=&new_item_quantity=&area_url=&direkt_aufriss_area=&p_countdown=&p_80=&p_80_category=&p_80_article=&p_next_template_after_login=&mindestbestellwert=&login=&password=&bpemail=&bpid=&url=&show_wk=&use_search=3&p_back_template=&template=&kat_save=&updatestr=&vgl_artikel_in_vgl=&titel=&darsteller=&regisseur=&anbieter=&genre=&fsk=&jahr=&jahr2=&dvd_error=X&dvd_empty_error=X&dvd_year_error=&call_dvd=&kna_news=&p_status_scenario=&documentselector=&aktiv=&gewinnspiel=&p_load_area=$ROOT&p_artikelbilder_mode=&p_sortopt=&page=&p_catalog_max_results=20

 

That appears to be a session link.

 

Best,

Christopher

[ak357 0]

Buying a new Lux meter;

I'm in the market for a new Lux meter. Does anyone have a suggestion.

 

Also I saw once a lux meter where you could put a CCTV lens on and then read the lux rating. Does anyone know where I can buy those?

 

That what I use

http://www.extech.com/instruments/product.asp?catid=10&prodid=55

[Soundy 1]

It helps, but using a LUX meter suits me more then doing the math for several camera positions.

 

Yeah, at first glace, the *math* looks scary, but it's really just a table look-up, which can be done in a couple seconds.

Great on the bench... not so handy in the field, unless you pack a smartphone or want to carry a printed copy of the table.

 

Far more convenient to just carry a light meter and read the dial...

[cglaeser 0]

Far more convenient to just carry a light meter and read the dial...

 

Agreed. An installer should have a meter in their kit. A DIY can save money using a camera.

 

Best,

Christopher

[Sawbones 0]

Mobotix cameras can give you a lux reading, IIRC.

[Stanislav 0]

Lux meter with possibility of connecting lens would be an useful device. But it must have feature to enter lens F-number and scene reflection factor. In addition, to get correct lux, its sensor must have CIE spectral response curve like an human eye.

On the other hand in CCTV spectral response curve like silicon sensor is more preferable, but it will be no lux meter. It would necessary to take into account difference in spectral response between clear silicon sensor, sensor with color filters, IR filter, ExView sensor....

It is much easier to take a real camera which is planned to use and get real pictures

 

But how to get expected image having known illuminance in lux and camera sensitivity? How to include F number, shutter speed, AGC, sensor spectral response, light source spectrum and scene reflection ? VideoCAD offers real tools for this http://cctvcad.com/Files/the_principles_of_cctv_design_in_videocad_part4.pdf

 

Lux meter is necessary for independent measuring camera sensitivity. It is very good practice to know real camera capabilities. Here is a technique http://www.cctvcad.com/videocad_help/prim10_.htm

[survtech 0]

Buying a new Lux meter;

I'm in the market for a new Lux meter. Does anyone have a suggestion.

 

Also I saw once a lux meter where you could put a CCTV lens on and then read the lux rating. Does anyone know where I can buy those?

 

That what I use

http://www.extech.com/instruments/product.asp?catid=10&prodid=55

Ditto. Great meter!

[Malloot 0]

Thanks all for your thoughts.

 

I will order a Extech meter. Probably the HD-400.