What are the scanner that can conveniently scan the image frame-by-frame, (i.e. not as 2 frame in one image).
I've looked at Epson v500 but not sure if it is a good choice or are there better options.
Are you looking for a budget solution?
The V500 or V550 would suit just fine , many film photographers use these scanners to scan their work. They are also relatively very cheap solutions while they still return good quality scans.
Note: these scanners are flatbed scanners adopted for the use of transparencies. Although flatbed scanners work and give decent results, you do lose some quality in comparison to dedicated film scanners such as Plustek OpticFilm scanners.
With most software available, such as that from Epson, you can select/specify the area to be scanned. Thus, half-frame scanning would be feasible without a problem.
I have no experience with dedicated film scanners, but I am sure you should be able to select the scan area with those machines, too.
Another scanning option is to use a (full-frame) DSLR to scan your photos with. This method generally yields scans of higher quality than when using a flatbed scanner. This can be a slower process, and of course it requires a larger initial investment.
The best flatbed scanners have an EFFECTIVE resolution of about 2000 dpi (forget what they state on the box). If you have half frame, you end up with an image that is about 2000x1500 pixels.
That's a 3 Mpx image.
I think you need a better scanner.
Use a dSLR as suggested or some specialised film scanner.