Photographer's lightbox for indoor pH color comparison


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

That would work...

I just hold a piece of white paper, or paper plate, up behind the comparator and it works for me...

I also find that using a larger comparator works 100% better for my old eyes..


Jim R.


TFP Expert
Platinum Supporter
May 23, 2015
Tucson, AZ
Hey, guys, thanks for the info. I ended up getting Verilux HappyLight Liberty Personal from Amazon for $29.95.

Try comparing a CYA test with it. Wait for a really clear and bright day and do the CYA test at high sun with your back to the sun and the tube at waist/belly height. Then take the comoarator indoors with the very same test solution and hold the comparator up to the light box so light is directed at the tube. See if the results are different.