doublet achromat lense in my finderscope

[bambuko]

In my infinite wisdom I have taken apart my Altair Astro RACI finderscope and now I do not remember which way is the lense supposed to go in?

Quick search on interweb tells me that there are four types of achromatic doublets, but only one is used in practice and that means that crown (the narrow bit when viewed from the edge) should go to the front? .... or am I talking out of my rear orifice?

 

Help please.

[Peter Drew]

The convex curved lens faces the shy.

[Peter Drew]

Or even the sky!   

[DRT]

Does it look anything like this?

If so, as Peter has said, the Crown faces the shy sky

 

[bambuko]

Thanks Peter!

So for total avoidance of doubt, in the drawing in link it is type A and sky is to the left?

[DRT]

That is correct.

[bambuko]

Thank you guys (must have posted my follow up question as you were typing yours Derek)

All sorted!