How much light do you get using the Ray Flash?
Use of the Ray Flash results in minimal light loss from your flash's standard output, according to photoshooting distance:
-1,5 - 2 Exposure value (EV)
Will the Ray Flash change the color temperature of my flash?
No. The Ray Flash will not change the color temperature of your flash.
Does the zoom setting on the flash affect the light output from the Ray Flash?
No. Changing the zoom setting on your hot shoe flash will not affect the light output from the Ray Flash.
The zoom setting on the flash does change how the light is shaped, and output from the bare flash itself, but because the Ray Flash efficiently absorbs the light energy and redistributes it through a fixed shape, the output remains the same regardless of the flash's own zoom setting.
TTL Functions 1. Can I still use on-camera flash TTL metering with the Ray Flash installed?
Yes. The Ray Flash will not interfere with your camera's TTL metering functions.