On Fri, 26 Oct 2018 05:38:27 -0700 (PDT), TimR
wrote:

On Thursday, October 25, 2018 at 9:50:18 PM UTC-4, Clare Snyder wrote:
I find my "direct replacement" LED tubes significantly brighter than
my Deluxe Warm White 34 watt tubes. Not sure about the old 40 watt
units.

I'm not so sure. I don't have any way to actually measure but I offer the following anecdote.

I replaced two 34 watt T12 fluorescent tubes with two 17 watt LED replacement tubes, direct wired (no ballast.)

To my eyes the replacement LED looked as bright or brighter.

But that location is where I occasionally shoot a video of myself playing an instrument. The LED shines on my front, there is another older fluorescent fixture behind me. In the past video quality was good, but with the new system and everything else in the same place, the video now comes out silhouetted. The light hitting the front is apparently much less than before.


My RCC340 illuminometer shows 970-990 Lux at 2 feet with the LED The
old deluxe warm white tubes were about 740-750. Don't know about the
colour sensitivity, and the human eye responds more to blue than
yellow (blue appears brighter)

Just pulled out the documentation - it is pretty peaky at about 570nm
which is yellow-green - meaning it should be more sensitive to the
warm white tube than the bluer (shorter wavelength) Only 80% as
sensitive at 500nm