V700 and Vuescan - can't scan full area of glass

I'm trying out Vuescan (8.4.48) with my Epson V700 to scan some fairly
large format negatives.

It seems to me that Vuescan isn't scanning the whole area of the glass
in preview mode. If I place a negative at the edge of the scan area
(with the "film area guide" in place) it only shows me about half of
the negative. Negatives placed in teh same place get fully scanned
using the Epson software.

Have I done something wrong or is this just a limitation/quirk of
Vuescan?


Vuescan does appear better in other ways though:-

There's a Linux version, much more convenient for me.

The results look decidedly sharper to me.

--
Chris Green