I agree. I'm a scientist looking for new and better ways of doing things -- not the typical grower. I also want to grow my green in the greenest way. Believe it or not, this research we are all doing on LED grow lights may lead, in the future, to more efficient ways to raise food and allow all food to be grown locally. Imagine your basement grow room which grows all you veggies too!
As for starting small an posting results -- that's a great idea. My latest thought on experimental design is to grow with hydroponics with baskets that can be removed AND WEIGHED. Weigh each plant each day or week and compare mass accumulation rates! Time series photography would also be great because seeing is believing to many people. With time lapse you could keep the plants in place, but every day switch the type of light between HD and LED. With the same wattage, you might literally be able to "see" the difference grow rates!
Both of your ideas are fantastic. I think the second one (for me, at least) is quite feasible. Since I'm now sourcing separate grow cabinets to allow comparison growing (also the reason I'm buying two 300W LED grow lights instead of one 600W), I would think it would be pretty easy to set up a webcam to take a picture every 15 minutes or so. That should provide a very smooth transition through the images. 24 frames a second, with 96 frames per day, comes to 4 seconds. Every 15 days is a minute of footage, which makes every month two minutes of footage. This comes to around a 7 minute film from veg to flower to harvest. If I had the money, I would buy two more setups, so I could do your first idea at the same time. I will try to come up with a way to do both without disturbing the plant.
Now, as far as the comparison goes, I'm deciding exactly which type to get, but I'm going to buy two 150W MH bulbs and ballasts (for veg), and two 150W HPS bulbs and ballasts (for flower). This will give me 300W (same as the LED fixture) of HID lighting, thus providing an even comparison, watt for watt. If you want to get really technical, the wattage of the LED fixture is actually 288W, so the HID would be
slightly more powerful. No matter, it'll be all the better if the LEDs perform better than the HIDs. Since I'll have them in separate enclosures, no light from the LED cabinet will leak into the HID cabinet, and vice versa.
Since I'm not planning on using the HID lights for anything but comparisons, I don't want to spend a great deal of money on them, or their respective ballasts. I'm thinking about getting two of each of these:
http://www.expresslightbulbs.com/high-pressure-sodium-hps-ballast-p-3.html
and
http://www.expresslightbulbs.com/metal-halide-ballast-p-4.html
and then their corresponding bulbs and sockets.
Any thoughts? I'm no electrician, but I know my way around a soldering iron pretty well. I'll be observing, measuring, and documenting everything involved in the grow. The only thing is, I'm concerned that if I do multiple plants from seeds, even feminized, the genetics may differ enough from one seed to the next. This would, obviously, skew my results from one grow to the other, something that would essentially waste any time and effort spent trying to control all aspects of the grow.
EDIT: Another aspect of the grow that I just thought of would involve checking the nutrient/water solution daily to see the concentration in PPM, to see if the type of light affects the nutritional requirements. And as far as the webcam thing goes, since green light doesn't affect plant growth, I'm going to illuminate the plants at night in their enclosures with green LEDs. This will allow the night-time growth to be observed and recorded, while leaving the plants unaffected.
