Unable to set CanoScan 8400F for color slides. The protective sheet has been removed from the document cover, and the slide film guide installed. Photo Studio Acquire panel Source selection has only "Platen." Even though I have done this many times before, now I cannot find the "negative film color" setting. I re-installed the software, but no success.

'Tain't necessary. And not getting the part can be an improvement.
I cut out a cardboard template that allows me to scan 10 slides rather than the 4 of Canon's official slide adapter.

All the Canon part does is position them precisely so cropping and rotation are automatic. With Photoshop skills (File ' Automate), you can do the same yourself for whatever size. I ended up doing Brownie, 35, and 126 (gasp!) also.

For extra credit, make your adapter(s) out of genuine plastic rather than whatever cereal box you have lying around.

You have to remove the white protective sheet from the the lid. Once you remove it you will be able to scan film. Also make sure the lock button is not in the lock position.

Open the Canoscan Toolbox.
Click the Save option.
Put a check in the box that states "Display the Scanner Driver".
Click Scan.
Click the Advanced Mode tab.
Make sure Select Source is set to "Platen".
Click the Preview button at the top left

Another thing is this can be caused by a faulty FAU cable. One or more of the eight wires within this cable has fractured

lost film guids for canoscan 9900f. looking for 35mm strips and slides 120 and 4"x5" format film holders in the accessory kit for canoscan 9900f

Please see my other postings (wireguy) regarding this same problem. It's caused by a faulty FAU cable.

Check the cable that connects to the cover at the hinge end. If this is loose, the scanner will not allow you to scan film or slides.

You should be able to download the manual.

http://consumer.usa.canon.com/ir/controller?act=DownloadDetailAct&fcategoryid=351&modelid=10242

To scan film, you'll need to first remove the white cover on the underside of the scanner lid. That is where the backlight is. Also, you must be using the ScanGear driver and NOT the WIA driver. The WIA driver does not support film scanning. Locate your film guides. These are the templates that will hold the film and are placed on the scanner glass to be scanned. Lastly, there should be a Select Source option in the scanner driver that allows you to select Film as the source.

Hope this helps.

Keep the protective cover on except when scanning slides or film.

Check the cable that connects to the lid of the scanner. If it is disconnected, you won't get the Film options.

Scanner sensor is defective,,,you need a new scanner.

Turn off the thumbnails view and you can manually set the cropping box.