I am not growing with any of these bulbs, or am even intended to do so. I design and sell LED grow light panels/lamps and grow a lot with those, but this thread is not about them :). I've just seen many growers use household bulbs but without having any data of how much they are putting out and what distance they should be used at to achieve a certain intensity.How much are you guys spending setting up these lights? Just seems like it may be close to what it would cost to build a cob light, which is more efficient and puts out less heat.
These tests mainly started out with the idea that I am not fond of the CFL-technology (e26/27), partly because it is inefficient (in lm/w), spreads the light inefficiently (PPFD/w), but also because they contain mercury.
I am just trying to help growers solve intensity-problems. For example, many have a single small succulent plant or other ornamental that needs artificial light to survive during the winter. Obviously, there is no need for a huge grow light panel that chews away at 150 watts with only blue and red diodes, creating a completely purple living room. Instead, a 5-14w bulb could be the perfect match for a small single plant, hung at 3-10", depending on the intensity needed.
Same goes for starting cannabis seeds. The intensity required early on can easily be covered with a 14w bulb, or even 9w (not to mention a 2,2w bulb that I am about to test). When a lot of power is needed to cover a big area, I would instead recommend a proper grow light since they are made for the purpose and oftentimes are a lot more efficient at 150+ lm/w, than regular LED household bulbs performing at 85-110 lm/w. Why hang a huge grow lamp very high above a couple of small plants when the job could be done with one or a few small household bulbs a lot closer to canopy. Even more practical and logical for a plant with a 24/0 photoperiod.
Everyone should use the technology they are most comfortable in using. I am only creating maps and information for the average Joe to easier see and choose the proper lighting for his/her situation and needs.
DIY'ing a real grow light is obviously great and gives a very good lamp. I am with you on that one. Although it's not for everyone.
When I did the 17-measurement 2x2' grid, I noticed it usually wasn't uniform. The north side might have stronger readings than the south. (Maybe the socket wasn't hanging perfectly straight. I should slip an iron pipe over the cord, let it rest on the top of the socket housing. Maybe it would plumb itself better.).
I like where this discussion headed, light and measuring is very interesting.
To be able to closely compare bulbs in a good way, I agree with you on your theory and thinking. Although if you are being this exact in your measuring, you might want to consider mounting your lamp to something, instead of having it hanging with and added weight on it.
This is just a pair of barbeque sticks and a pretty bad example, but you get my point.
It also needs to be very carefully centered over your map or it could give uneven values, I guess. Especially important if you are going to measure at certain spots in every test.
As you can see on my maps, I did not manage to centre the bulb perfectly, or they were uneven/leaning slightly.
I choose 6" height as I tried to find a good seedling-intensity at around 100-175 PPFD, with a good bulb (9w for $1,5), as I think that's what these bulbs are suited best for.
If the intended use of your achieved measurements will be situations that require more than seedling-PPFD, such as growing a whole CB plant, it may be more useful to measure the bulbs at a greater distance as this could potentially make it easier to calculate overlapping intensities and give a better whole picture (depending on the wattage).
If your intended use of measuring is just to compare bulbs, for the sake of comparing bulbs, I guess there are a lot of ways to do so.
I would love to get an update when you get your tools. Even though we seem to be on slightly different missions, It has been very interesting to share thoughts :).