with every raw shot, canon gives 2 files
.CRW and .THM
what is the .THM file used for? thumbnail? if so, is it for thumbnail when viewed on the cam lcd?
the *.THM file can be viewed using the viewer bundled together with ur cam. other than wat was mentioned, it really has no purpose. IMO, its just taking up precious storage space.
if u like me using the 300D, u can try hacking it so dat u can change the size of the THM file. by default, its medium fine jpg. i hacked it to give me small normal jpg. gives me abt 30-40 shots more on my 1GB CF card.
anothing thing i found is that after deleting the .thm file, ps cs takes longer time to generate thumbnail and preview in the file browser
this makes sense as the thumbnail file is gone
And I recall reading somewhere that upon first entering a raw picture directory, CapturOne uses the THMs to draw quick thumbnails before regenerating from the CRWs.