Help ! - computing a Balmer line

I've posted a simple OG spectrum of Comet Machholz and Algol at

http://home.freeuk.com/m.gavin/digsky.htm

where the star records on the Canon CMOS sensor to the Balmer line
H-lambda [line 11 where H-alpha = line 1 at 656.3nm] in near UV.

Can someone compute the wavelength of H-lambda please?
I've got the formula but don't think H-alpha = 1 and in any case my
calculator's dead!