I had some spare time and the weather was fair so I thought I’d give my big lens a trip into the garden to see if I could finally get some images out of it. If you’ve been following the saga you’ll know I acquired this lens last year but haven’t managed to decent pictures from it yet; a forum member said he was pretty sure a diverging ‘interface’ (my word) lens was required to make it work, and that lens was built into the body of the camera this behemoth was intended for.
The few tries I gave it definitely showed some promise, but no clear and well-focused images resulted. Until now.
I tried all the various lenses I had to hand, to no avail, until I hit upon the combination of my unknown-source 40 or 50mm lens, reversed, placed in front of the Therm-App 13mm f/1 lens. Success! Bad vignette, to be sure, but the images I saw today definitely indicate that, assuming I can get the interfacing right, this is going to be one heck of a lens.
These images variously show the big lens front and back; the thermal view using the regular 13mm germanium lens and a view through the big lens showing the chimney stack from the centre of the previous image. Finally, a diagram of how things were set up. This was all hand-held, so highly unstable, but I did manage to capture an image to prove it works.
It’ll be a while until I can return to playing with this beast. Meanwhile, has anyone got any odd diverging lenses of 1.5” diameter or more that they’d consider lending (or selling) so I can try that approach?
Edit 2 Apr: I've just checked on Google Earth and the chimney is 60m (190ft) from the lens.