TASMAN 1:8 500 mm Long Focus Lens Information

[Lumina]

Hi,

I've just hooked up some of my grandfather's old 1970's M42 mount manual focus lenses (namely a Zenit Helios 44-2 1:2 58 mm and a TASMAN 1:8 500 mm) to my Canon EOS 600D Digital camera using an adapter and have been stunned at the spectacular results these old lenses can render.

However, I noticed a problem and have done something VERY stupid. On, noticing fair amount of mould on the back elements of the TASMAN unit, I released the back screw mechanism in order to clean them. This would have been fine except on doing so, my final two elements suddenly fell out onto the (thankfully carpeted) floor. Neither element was damaged at all and I can replace them into the lens tube just fine but the trouble is, because they FELL out before I had time to note their orientation, I now have no idea which of the 8 possible combinations to return them to.

I have searched and searched in vane for information on the lens on the internet with the hope that I might find a schematic but I cannot even find out who manufactured it. All I know is that it was bought in Australia in the late 70's and says it is Japanese made.

Both elements seem to be of the type 'positive meniscus' and of approximately the same diametre. One element is thinner than the other and curiously has a diffuse pattern etched onto it's mildly concave side. I am reasonably confident that this is the final element in the group (although not sure) but I still don't know which direction it or the preceding element should face.

If anyone knows a) where I might find information on the construction of this lens, b) how I might determine the orientation of the lens elemets for myself, d) understands lens optics well or c) where I might begin to find someone who can work it out for me, any advice would be GREATLY appreciated. My locals camera stores seem to me far less informed on... well... anything really than they were back in my grandfather's day.