coolscan3 backen and Nikon Coolscan IV ED / LS-40 ED?

Hello,
Has anyone tested the coolscan3 backend with the Coolscan VI ED /
LS-40 ED scanner?
I'm getting inconsistent results; I'm using the same arguments to
scanimage, but for most of the images it looks like "--negative=yes"
wasn't specified. Example:

$ scanimage -d coolscan3:usb:libusb:001:008 --format=png
--negative=yes  --frame 2 > f2_1.png
$ scanimage -d coolscan3:usb:libusb:001:008 --format=png
--negative=yes  --frame 3 > f3_1.png
$ scanimage -d coolscan3:usb:libusb:001:008 --format=png
--negative=yes  --frame 4 > f4_1.png
$ scanimage -d coolscan3:usb:libusb:001:008 --format=jpeg
--negative=yes  --frame 1 > f1_1.jpg

of the resulting four images, only one looks ok. I have tested the
scanner with the trial version of VueScan, and it produces consistent
results.

This is using
root@kg-core2:~ # pkg info sane\*
sane-backends-1.4.0_3
on FreeBSD
root@kg-core2:~ # freebsd-version -ku
14.4-RELEASE-p7
14.4-RELEASE-p7
root@kg-core2:~ # uname -a
FreeBSD kg-core2.kg4.no 14.4-RELEASE-p7 FreeBSD 14.4-RELEASE-p7 #0
-dirty: Tue Jun 30 08:53:56 UTC 2026
[email protected]:/usr/obj/usr/src/amd64.amd64/sys/GENERIC
amd64

--
Regards,
Torfinn Ingolfsen