Canon FS4000US scanner - film grain or noise?

Archived from groups: alt.comp.periphs.scanner (More info?)

Scanning slides or negatives at 4000 dpi on this scanner - as I zoom in I
lose detail in multi colour speckly effect. How can I tell if this is film
grain or noise/problems with the scanner? Its supposed to be a very good
scanner

Archived from groups: alt.comp.periphs.scanner (More info?)

It is unclear what you are describing.
If you are selectively scanning a small area of film at high dpi you will
scan any grain in the film with exquisite detail.
Also there is a difference between what you see when you blow up the scanned
image on your monitor and what is relevant to normal viewing and printing.
If this is not taken into account no digital camera today can make a usable
image at greater than ISO 200 equivalent.
You also do not say if you are making adjustments to the image with scanning
software prior to the scan: this really involves selective amplification of
portions of the electronic signal and will increase apparent noise.
Dust? Dirt? Scratches on the film?