Epson Expression 800 Reference Manual page 68

The printed image is larger or smaller than the original size.
Problem
You may have adjusted
the image size settings
in your scanner
software.
The colors of the preview for your negative film image look strange.
Problem
The wrong Document
Source setting is
selected in your
EPSON TWAIN Pro
software.
The film guide or slide
transparency guide
affects the exposure
of the scanning area.
The TPU may be
letting in external light.
Troubleshooting
Solution
Change the image size settings in your scanner software to resize the
scanned image. Don't use the size of the image on your monitor to
judge the printed size.
Solution
Make sure TPU for Neg. Film is selected as the Document Source
setting.
The scanner software perceives the dark film guide frame as white,
which alters the exposure of the scanning area and causes the scan to
appear darker. To see the colors that will actually be scanned, select an
area by clicking and dragging the mouse over the preview, then click the
zoom preview button.
Make sure the TPU is closed and that the narrow window near the
hinges is covered.
Page 68