50w White SON: Philips SDW vs Iwasaki SDX 2

I decided to fire up and compare both a Philips 50w SDW-T and an Iwasaki EYE 50w SDX lamp.
It's interesting to compare these two lamps as they have quite different electrical characteristics and are quite physically different also.
Both lamps give off a lovely warm white colour with excellent colour rendering that is better than a lot of fluorescent!

This image shows the differences in the construction of the arc tubes better and it does show that the Iwasaki lamp appears to have a slightly cooler colour to it but this may be due to the much shorter arc gap and resulting brightness.