I have an old Sony Cyber-shot DSC-S650. I plan to take a large number (200 - 300) of images of printed text. I can either use artificial light or use the flash. Flash would be much easier (using rechargeable batteries, of course) , but I wonder whether this sort of heavy use will burn out the flash unit. As far as I can tell, replacement flash units are not sold. Is the flash expected to last forever?