Dark Rings.... (Explain please)

After 5 month of usage of PX712A… i have some strange “dark ring`s” on writed disks… what is it?

And i have another new drive Plextor PX 716A… (i buy it 23.01.05) this drive write disk (i try 4x and 8x speeds) with same strange rings… but rings not dark…

I check my old disks writed on PX712A after 1 week of usage… and surface of this disk`s is prefectly no any rings!

p.s. sorry my english

p.s.2. i use only TY disks to writing data

Have you tried scanning these discs? Dark rings are not always a problem and the result of the physical characteristics of the disc and the write speed. Higher write speed means a higher laser intensity which can result in different colours on the write surface of the disc. This doesn’t have to be a problem but I’ve also seen reports of dark rings as a result of a bad drive. These dark rings could not be read at all by the drive indicating a problem. If your discs can be read just fine and the PI/PO scan looks normal then I wouldn’t worry about it too much.

i try test disks
but i not understand why my old disks writed on 712 looking normally w/o any rings