Off the hacking topic - for those interested in auxilliary lenses
My Inframetrics 3X telephoto germanium lens arrived today. It took a bit longer to get to the UK than expectd, but was worth the wait.
The lens was designed to sit in front of the Inframetrics 525 thermal camera internal lens so is perfectly suited to duties as an auxilliary lens for my FLIR PM series cameras and maybe even the E4 !
The lens does have a fault in that the focus ring was stuck. In order to free it I had to dismantle the lens, which gave me the opportunity to see what lives inside the barrel. It was very simple to disassemble the two barrel sections. One barrel moves inside the other for focus adjustment. I found that one of three small spring loaded plugers had sheared off and jammed the focus ring. The plungers engage in the focus ring and apply equal outward pressure to ensue a nice smooth action. It will make more sense when I post the pictures.
Once the lens barrels were separated I could see the lens configuration. It has at least four complex lens elements and it is most definitely not a lens that you can reproduce using simple 'off the shelf' singlet lenses. I am not able to dismantle the lens groups further as they are solidly fixed in place to protect them and to prevent them working loose whilst in use. A set of four lenses looks likely anyway.
Sorry to those who had hoped that a half decent X2 or X3 lens could be made with two simple ZnSe singlet lenses (that was my hope too).
I bought my lens 'as seen' for $150, which is a bargain for such a high quality unit. These cost several thousand Dollars to buy new and even today you need a second Mortgage to buy a modern version.
The X3 lens has a transmission figure of better than 80% and the lenses are of a decent size. The lens looks to have been very well cared for in its working life, but I suspect the lens case was dropped and the impact, combined with the weight of the heavy outer barrel, sheared off the sprung loaded plunger, jamming the focus. An expensive drop ! Their loss was my gain.
I will make a new plunger assembly on my other new 'toy', a 7x12 mini lathe. I knew it would come in handly soon !
Pictures to follow.Pictures attached
Aurora
Update,
Now I have the lens in a state where I can focus it, I attached it in front of my E4 for a quick check. Hmmm a small issue has arisen.... the lens produces an inverted image ! I shall have to check out the lenses backfocus distance and, if needed, add one of my Plano Concave ZnSe lenses to sort things out. At least I have the quality optics that are hard to source. All good fun
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