Yes, scanning the negatives is much better, providing they are in good condition. Otherwise, scanning the picture will provide fairly good results up to about 2x enlargement (i.e. 4x6 > 8x12).
I have a Canon 9000F, which I believe is the model you are talking about. It does a good job of scanning negatives using the bundled Canon MP Navigator EX software, and requires minimal color correction. I recommend selecting 'Use The Scanner Driver' mode,' which will allow you to optimize your scan settings. There doesn't seem to be much advantage to scan higher than 4800dpi, but make sure you have 'Enable 48/16 bit Output' and 'Enable Large Image Scans' under Preferences> Scan checked. I also suggest setting 'ProPhoto RGB' profile under Preferences> Color Settings and check Target 'Monitor.' When saving the scans use TIFF mode. You will need to apply fairly aggresive sharpening (~1.2 Radius, Amount 100) in LR, which is typical for this type of dual-purpose scanner. But overall it produces very good scan output.
The one anomaly I have noticed is that the saved TIFF files do not have the ProPhoto RGB profile assigned to them, so you have to do that manually using Photoshop or other editing application, or LR will assume the files are sRGB profile.
Here's what Canon Tech Support told me:
Dear TR Shaner:
Thank you for writing to us. Unfortunately assigning the color profile in Photoshop would be the only workaround for this. I apologize for the inconvenience.
Please let us know if we can be of any further assistance with your 9000F.
Thank you for choosing Canon.
Sincerely,
Karl
Technical Support Representative
