I'm currently TIGing some thin stainless (0.55mm) sheet and this
requires very low currents.

The problem I'm having is that my auto-helmet only goes down to DIN 9
and it seems way too dark.

I don't really want to go back to a fixed filter (and even if I did,
none of the local welding stores have anything lighter than a DIN 9
anyway) so I've tried using a spotlight to illuminate the work --
which means the auto-helmet simple goes dark anyway (damn!)

Is DIN 7 or DIN 8 an uncommon shade or something?

I tried using a pair of sunglasses but they seem to be only about a 5
(I estimate) and don't shade enough and my oxy goggles seem to filter
out the wrong part of the spectrum because it's still very bright -
but also very green :-)

Any ideas folks -- or do I just hunt down a DIN 7 or 8 from somewhere?

And yes -- it's a pig of a job doing a good fitment for a long butt or
lap weld with metal this thin. I'm using a chill-bar behind the seam
but trying to do a fusion weld on a 2mm lap still causes problems now
and then when the two sheets aren't quite touching.

I also have to do a lot more practice on filling holes (how did they
get there? :-)