Measurements of my three D4's using sapphire crystal glass, ar coated glass and without glass.

Hi guys. My D4, which I carry every day, already has a slightly scratched glass. Recently, I have an FWAA with sapphire glass in my pocket (that is, one that apparently does not scratch) and for now I am satisfied (but I know that the diameter of the head may matter). I decided to order some for my D4 instead of the standard ar coated. I bought them on AE here (non affiliate link). Below are some measurements from my three D4s, no glass, ar glass, and sapphire crystal glass.

flashlight no lens ar lens sapphire lens
1. D4 - 4x 319a 3500k, 10622, 5A 1624 1526 1489
1. D4 - 4x 319a 3500k, 10622, 4/7 321 297 288
2. D4 - 4x xpl hi 5000k, 10623, DD 2836 2660 2552
2. D4 - 4x xpl hi 5000k, 10623, 350mA 112 105 100
3. D4 - sliced lh351d 2x2700k + 2x5000k, 10623, DD 3370 3052 2973
3. D4 - sliced lh351d 2x2700k + 2x5000k, 10623, 350mA 146 130 124

Only the first one has Anduril. 4/7 is the fourth mode in stepped ramp. The other two have D4 UI v2. 350mA is after tightening the battery tail.

Note. Above measurements are illustrative only, they are not intended to show the maximum performance of these flashlights. They all had different batteries, partially discharged. I also don't have professional measuring equipment, I use my own shoebox with ceilingbounce app.

I hope someone will find it useful.

I’ve never personally broke a sapphire lens but I have definitely cracked a few AR coated lenses. Probably worth the tradeoff in output when you consider a lot of AR coated lenses tend to negatively impact the tint. Cool results.

thanks for the data on change in output, from replacing glass with sapphire

your first numbers show only 2.5% loss… totally worth it imo

Today I also noticed that the tint is a bit warmer with the sapphire crystal glass. And of course a little less greenish.

very interesting data, thanks!

7.7% losses for AR coated lens? That’s much more than expected.
I wonder…maybe the bezel seats differently depending on whether the glass is there? Maybe the o-rings have an impact?

3.6% when averaged over all combinations.