TK75 2015 output comparison (early production vs. latest production)

Since we own(ed) three TK75 2015 lights (two from the most recent production run and one early production run), we thought it would be fun to do a side-by-side comparison.

On Saturday night eight of us got together and sat around the campfire and played with lights. It didn't take long for all of us to notice that the two latest production TK75 2015's were a little brighter and threw a little further than the early production one.

Just to be sure we weren't seeing what we wanted to see or to rule out the batteries/carrier, we did a little test.

We taped over the serial numbers, mixed them up, and in small writing numbered each light 1-2-3. This time we placed a white USPSA full silhouette target at 400 yards at the base of a small hill. Each of us then proceeded to test all three lights using the same batteries/carrier between all three. After a few minutes we wrote down the number of our top two and put that piece of paper in our pocket.

After we were all done we compared numbers and took off the tape.

7 of us unanimously picked the early production light as the loser. My buddies dad had the early production light as his middle pick.

That was fun. We then headed inside for a little more.

My buddy is a wedding/portrait photographer and has a Lux Meter app on his iPhone 6 plus that he swears by. We installed fresh batteries into our test carrier, and did some ceiling bounce tests.

The Low/Medium/High readings were nearly identical in each of the five runs for each of the three lights.

Low = 42
Medium = 605
High = 1452

The Turbo results are where it got interesting.

Light #1 read:
4250...4220...4220...4205...4205
Average = 4,220

Light #2 read:
4865...4855...4820...4815...4805
Average = 4,832

Light #3 read:
4885...4840...4825...4825...4820
Average = 4,839

The numbers show the two newest production run lights to be ~15% brighter than the early production run light.

Absolutely nothing scientific about our testing, but at least the numbers matched what we all saw with our eyes.

Sold my buddies dad the early run light for a great price. We all had a great time and he left grinning like a kid on Christmas!

A few questions.

What app was he using? Lux Meter by chance?

Distance from light to ceiling? Height of ceiling? Color of ceiling paint? What camera on the iPhone was he using, front or rear? Distance from the phone to ceiling.

I know, I'm full of questions, but I'd like to be able to replicate what you've done with the three TK75 lights I have. One 2600 lumen, one 2900 lumen and one Vinh KT light.

I've got the iPhone 6S covered, plus a Gossen Ultra Pro and a Minolta Flashmeter IV to compare to.

Ceiling height: 94-3/4"
Flashlight lens to ceiling: 38-1/2"
Phone screen to ceiling: 39"
Distance between bezel and phone = 2-1/2"
Flat white ceiling with flat hand troweled texture.
Front (screen side) camera.
Will have to ask which app.

Thank you.

The front screen camera on the iPhone is a lower resolution unit than the rear mounted unit. In my case, the 6S rear camera is 12 mp verses I believe 8 mp for the iPhone 6. I'll see if the sensors make a difference.