Can you tell me how to do a differntial image using Windows 10 and with the what free software?
Aaarrgh. I posted my reply to the wrong message. Serves me right for doing this at 6:00 am.
OK. I recommend using the free version of Macrium Reflect. In order to do a differential image you must first do a full image otherwise you won't have an image to compare for differences. To take a full image you select the "disk image" tab in the left pane. Then select omly the partition you want to image in the right pane. Then (there is a drop-down menu at the far left (it says "Actions...") where you can select "image this partition only". Specify a folder to store the image and, optionally, a more descriptive file name. Click on "Next". On the next screen you can select "Full" or "Differential". Incremental is only available in the paid version. Select "Full" the first time then click "Next". On the next screen you can deselect "Save backup..." to not create a batch file and click OK to just run the job once.
To create a differential, use the same folder abd select "Differential". It will create a much smaller image that will contain only the differences since the full image was taken.
I've been using Macrium Reflect for a few years to take automatic daily images and never had a problem.
I should point out that when I installed Windows 10 I relocated all my user folders to D: so that restoring an image of C: would not result in loss of data.