![Image](http://www.astrosurf.com/buil/forum20/_ratio1200_blaze400_blaze500.png)
The 400 nm blaze give 25% more signal at Ca II H&K lines wavelength relative to 500 nm version, and more then 50% near 350 nm.
Of course the 400 nm blaze is not well appropriate for cover visible part.
(measure by comparing laboratory 2900K halogen lamp spectra).
Christian