Not a reflected reading. The flat disc takes an incident reading but from a single pointed light source- not the 3D reading of the half sphere. Good for pre-lighting all the hanging lights one by one. On set the quickest thing is to just cup your hand around the half sphere as you point it at the source that you want to meter so as to stop other lights from contaminating the reading…and so know whether to drop in a scrim or spot, etc... The reflected reading was accomplished by sliding the sphere aside.
I believe a spot meter is much more useful and precise in any situation regarding light metering because of the narrow angle of metering. For overall scene metering, a simple reflected meter will do the job. I really can't justify the use of a incident light meter. But I'm no expert, and regarding metering expertise, I believe is worth reading Ansel Adams The Camera and Ansel Adams The Negative books.
Looks pretty similar to a lot of other digital incident / reflected light meters around this price (like Gossen Luna Pro). Does it allow you to set shutter at 1/48th? Some meters jump from 1/30 to 1/60th... I also don't quite understand what that other disc is supposed to do: does it just give you a reflected reading with a narrower intake of light (like a narrow spot meter reading)?
I have the 308S which is almost identical, just looks like the 308DC is more dslr friendly. It's a good and accurate light meter. Best part is the size.
Hmm...It looks very very similar to the 308s.... Are you planning on hacking the firmware? ;)