Get some food this will be a long read - hopefully informative though
In the EU incandescents have been phased out and will be banned, once the stocks have sold there will be no more, in favour for LEDs. You'll still be able to get certain incandescents for specialist applications so reptile basking bulbs, generally just makes it a little more expensive.
Lighting in captivity is at best poor - there is no bulb on the market that can emulate the sun. We can use a mixture of bulbs to try though. Chameleons see differently to us, lightbulbs are designed with us in mind so help us see better, by using a mixture of bulbs we can cover a wider spectrum which arguably is more natural.
As you can see the spectrum goes from UV-B, UV-A, Visible light and Infrared. UV-C is dangerous, some cheap UV bulbs can produce this so always choose brands with good reputations, that send tubes to independently tested and don't try to save money by using cheap UV tubes without spectral information.
UV-B and UV-A - we add those by using a UV tube, I'm sure we are all aware of the benefits there.
Choose good brands and I'd always recommend investing an a solarmeter 6.5 so you can measure the UV-B the tube is producing yourself - they are an investment but can save you money in the long term since you only replace the UV tubes when it is actually needed and you ensure your Chameleons are being exposed to a safe amount.
Next we have visible light - this one is more tricky since light bulbs are designed for our photoreceptors. Chameleons actually have more, they see more than we do which is why using multiple bulbs to cover most of the solar spectrum is IMO beneficial.
https://www.ncbi.nlm.nih.gov/pubmed/16025336
For this I use two LED bulbs, I use a 4000K and a 6500K - combining two spectrum to cover more of the visible spectrum available for my Chameleons - the plants also thrive. LEDs are ideal for this because they're low wattage, don't produce much heat, cheap to run and you can get lots of lumens.
Next up we have infrared - this is basking. I love Halogens but any standard incandescent can work (don't use red or blue ones - just the standard household types) .
Incandescents are amazing because they produce near infrared, infrared a (IR-A) and infrared b (IR-B), which is what the sun produces to give us that warm tingly sensation because near infrared penetrates into the skin to warm more effectively and naturally. Far infrared, infrared c (IR-C) is produced when heat is reflected back, think warm roads, sand, rocks in the evening after a warm day and it's naturally produced by incandescents similar to the sun.
Ceramics also produce IR-C, ceramics also dry the air and aren't very good basking bulbs for any reptile IMO. They can be ok for raising ambient temps but I'd never use a ceramic for a Chameleon.
You can see how incandescents more closely emulate the sun's infrared wavelengths in blue. The irradiance isn't drawn to scale.
https://c1.staticflickr.com/1/906/26905860087_d72438d8d9_b.jpg
When choosing incandescents make sure you check the beam angle - avoid spot lights unless used at a great distance from the animal.
Wide or flood beams 30-50° are best - they diffused the heat over a wider area and reduce the risk of hot spots, which can increase the risk of burns. We want a large enough basking area to cover the whole Chameleon - it's fine to use two lower wattage bulbs side by side to create a larger basking area - commonly seen with Monitor lizards.
A good check to see if your basking light is producing hot spots is to place a white A4 piece of paper at basking height - the light should be evenly diffused over the paper, no intense spot in the middle.
Don't take basking temp readings at branch level, Chameleons are taller so you risk casque or back burns.
My lights are setup on timers
Sunrise/Sunset - 2700k Halogen 38° (beam angle)
Early Morning/Late evening - 2700k Halogen and 4000k 13W Philips LED
Day - 2700k Halogen, 4000k 13W Philips LED, 6500k 13W Philips LED and Arcadia 24W 12% UV-B.
* My basking lights come on and off throughout the day, ideal for my species to give them a chance to bask, typically early morning and afternoon. However how long you use basking lights depends on your species.
In my enclosures the combination of UV tube, two LED bulbs and basking light produce around 4,000 lumens - sounds a lot but the sun is much more intense. The larger spectrum available and the more lumens produced is ideal for their eye sight and stimulating their parietal eye which in turn helps thermoregulation, hormone regulation and circadian rhythm. It's also why it's important for complete darkness at night. My enclosures are heavily planted - my Chameleons can escape the light easily to seek shade but during the day they rarely do.
Humidity
I hand mist (empty the contents of a 1L hand sprayer) one hour before lights on and an hour after lights off - takes around 5-6 minutes. Drippers are used during the day - just in case but I've never seen them used.
Then I have an ultrasonic fogger running throughout the night to keep humidity high (very important).
Very rarely mist during the day - when I do, all lights go off 30 minutes before I mist and my Chameleons go hide, only coming out when the lights are back on after the spraying has finished. Which is natural behaviour - observed in wild chameleons.
In the wild it doesn't rain every single day, never mind every hour - in fact it doesn't rain for months for some species, when it does rain - people observing these animals in the field see Chameleons run for cover... they are well hydrated from breathing in the cool moist air and fog during the night - they don't enjoy getting wet.
When it rains in the wild Chameleons typically have warnings - ones we can easily replicate are, it goes duller and temps typically drop because of cloud cover but in captivity we tend to blast them with water, without warning. That's why on the very rare occasion I mist during the day - I'll turn lights off 30 minutes before and only turn them back on when I've stopped misting.
In captivity we have it backwards - often having high humidity during the day and low humidity at night... which isn't what Chameleons would get in the wild. Therefore they often have to compensate throughout the day by drinking.
Ambient temperature and relative humidity are linked - those cooler night time temperatures help keep humidity higher for longer. Warm temperatures mean relative humidity drops.
I never see any of my Chameleons actually drink - apart from when they first arrived with me. My Chameleons are healthy, show no signs of dehydration, their urates and faeces are perfect. Something to look into for you
I know it's a long post but I think we should always be striving to replicate the best of the wild and improve our captive husbandry.
