I decided to test out some different mediums across the TA Tube sensor to see if they are consistent.
I used my S2+ on medium measuring from 210 to 225 depending on whether I turned it off and back on. So I would leave it on and keep getting reference levels to eliminate any discrepancies.
I tested one layer of the wax tissue paper that I talked about earlier. I measured the lumen drop relative to the reference brightness level. I tested 10 different sections of a single sheet. Here are all 10 results showing the lumen drop in lowest to highest order:
24 24 27 27 27 32 35 35 37 37
Almost a 50% difference. So not very consistent, especially when doing multiple layers.
Next was a Walmart white plastic bag. I just did 4 samples from all over the bag. No printed sections and no folds. Here is the drop in lumens:
37 41 45 50
About a 35% difference. So again, not very consistent. (On average this particular white plastic bag gives me a correction factor of .80)
Lastly I did the same test as above using a Kroger grocery brown plastic bag. Here is the drop in lumens:
72 78 79 82
About a 14% difference. (On average this particular brown plastic bag gives me a correction factor of .65)
I think the trend is that the more light a medium blocks, the more consistent it is.
As I find more materials laying around the house I’ll try and give some accurate samples from it.
I think the bottom line is that when TA announces his official correction factor we will need to find some type of paper, plastic, etc… medium that drops the readings that exact amount and then not mess with it. For example, if different sections of the same plastic bag can vary so much, then we will need to cut out a specific section to use and reuse. Then not get it mixed up with a different bag or different section of bag. See what I mean?
Then we will be back to direct lumen readings right off the meter.
I assume TA is going to figure out something better than paper sheets / plastic bags etc. and send us the part that can then be permanently installed. (or tell us what/where to buy it)
Yes, I plan to figure out a more universal option. I cut out some acrylic discs yesterday that fit into the meter hole. So I can stick some form of diffuser to them to get the readings correct.
Yep, even 1mm will have a noticeable effect. The same goes for the 1st piece of PVC as well, how hard it is pressed in can have a surprisingly noticeable effect on the readings.
Now factor that by the 4 joints in the sphere (which you had to take apart to make any changes and then reassemble to measure and hope you got it together with the same force every time, which you never did) and you start to see the tip of the iceberg these were to calibrate lol.
Missed this before, I have not tried much yet, until I have a more exact correction factor to aim for it is hard to know what will work.
I am thinking some form of DC-Fix type sheet is what I would like to use, unless I happen to find something that works perfectly. I am going to check home depot sometime to see what kind of options they have. Some very light window tint could work but I have a feeling it would drop the readings too much.
I also cut some discs out of the left over/broken diffusing sheets I used in the spheres to see if they happen to drop the readings by the right amount.
So i tested my fenix tk35ue… there is a guy name Kospap who tested the fenix tk35ue and we got similar result… I got 3486 lumen @30 seconds… below is his graph… look like my TA tube is working great with .70 factor.
Yes, the silver paint was an experiment to try to make things simpler but it didn’t work. Too bad, that reflective tape was way way more work then it seems.
I spent last night reading through all the posts - interesting stuff!
Curious, does ambient light impact the measurements at all? In other words, does it matter if the measurements are taken in a dark room vs outside in the sun?
