Light meters and flourescent bulbs

[Rothie]

I have been looking at light meters,and I see that some have switches or buttons for different types of lighting.Is this a necessary feature,or is there a formula to convert readings between sunlight,flourescent,MH,etc?
I'm just looking for a dependable meter at a reasonabl cost.I will be using it mostly for sun and flourescent readings.
Does anyone have a brand and model they are happy with?

[snow]

ross knows a lot about good lightmeters

[Ross]

The light meter I use is Visible Light Meters from $98 I use the 840020 Lux/FC but the plain Lux would be OK. Just divide your reading by 10 to get approx Foot-Candles. In answer to your question, the cheaper meters use a switch for different types of lighting because of magnitude of light. One sensitive enough for florescent lighting will "blow out" in sun. The one I recommend here has a magnitude button as well as buttons for calibration to known amounts of light. I just let mine self-zero with the cap on (cap on=zero light).

[Rothie]

Thanks,Ross.Actually this is a feature on more expensive meters.If you look at the Advanced Light Meter, 840022 at the link you provided,it has this feature.
I think it uses a correction filter due to light color and light frequency.It's hard to find any actual info on the internet.Since I only see feferences to foot candles and lux on the plant boards,I guess there isn't much need for any measurement beyond foot candles.I am really surprised that PAR is not mentioned more often when measuring light for plants.It is the only measurement we use for growing corals.It has to be measured with a quantum meter-I think they start about $350.It's not a meter that a normal hobbiest would purchase.I think Ocellaris linked to one of Sanjay's threads on RC.Sanjay has done extensive studies on MH PAR ratings and is now looking at T5.The general rule of thumb seems to be that the higher the K rating,the less PAR is available.The reef side uses bulbs mostly in the 6500-20,000(very blue)K range.It would be interesting to see if the bulbs used for plants,3000K-5500K,have much higher PAR readings than the reef bulbs.

[Ross]

Originally Posted by Rothie

I think it uses a correction filter due to light color and light frequency.

I can tell you for certainty there is no filter. It is using a "white" dome and calculating LUX and/or Foot-candles based on that. Color temperature is something we aren't all that concerned with in orchids. All we care about is that the "red" end of the spectrum is represented along with the "blue" end. Some have chosen to exclude all other portions and get a garrish purple light. Most of us, though, opt for so-called "full spectrum" bulbs because they come close to providing the color temperature (K) of the sun at noon at the equator. I. personally, have a different agenda. Since I license my photography to hi-end magazines and book publishers, I need a reference color temperature to get the correct colors in the orchid blossoms. I've gone to great expense to assure I can achieve this end result. My light meter is simply an off-shoot of my photography and has helped me immensely when I evaluate light sources. In all this, PAR has not been an issue. If it is for you, then I would suggest discussing with Ocellaris as to best source of such a meter. Hope this helps.

[Rothie]

PAR is what the plant uses to grow.It would have no correlation to photography,or what you see with your eye.