The Backstory....
I wanted a wide angle supplementary lens for my Exx series camera but they cost a small fortune from FLIR. Such lenses are not that common on eBay so when they do appear, they sell for decent money. I was considering using an adapter to mount my PM series 0.45x supplementary lens on the Exx lens mount but have yet to progress with that project.
The purchase....
A few days ago I came across an interesting FLIR wide angle lens on eBay. It is an unusual shape so I immediately recognised it as the 90 Degree FOV lens I had seen in accessory catalogues. It is quite large and unusual in shape for good reason. The lens provides a wide field of view and can focus down to 40mm. It is useable for normal target imaging at close quarters, distance work and IR viewport use to image the interior of electrical cabinets.
The lens specification is as follows:
Pt No. T197306 : 4mm F1.3 90 Degree FOV supplementary lens with viewport capability down to 0.5" and near focus capability of 40mm. Distortion is 5% (Eeeek!)
The lens is also listed as Pt No. T197411 (FLIR often use different part numbers for the same item over the life of the product)
https://www.infraredcamerawarehouse.com/content/FLIR%20Datasheets/FLIR%20Lens%20%2890d%204mm%29%20%28T197411%29.pdfCompatibility......
The lens is intended for use with the A /SC3xx / Bxxx and Txxx cameras. The mounting bayonet is the same as on the Exx series cameras but that camera is not listed for use with this lens. The lens is fitted with electronic ID contacts.
As a supplimentary lens I cannot see why this lens would not work with the Exx series. The dimensions and bayonet mount certainly appear compatible. There is the matter of the ID contacts etc though. According to FLIR, a camera using this lens as an accessory, rather than originally supplied with the camera, requires that the camera be calibrated to use it. This is not uncommon to achieve greatest accuracy. I suspect that the Exx series simpler 'lens selection via menu' does not meet the needs of FLIR to calibrate the camera for use with the 4mm lens. There is a custom lens transmission setting however. That is what I will use and I have the required Black Body thermal references to check the lens characteristics.
Conclusion......
I have purchased an unusual FLIR wide angle lens that will hopefully mate with the Exx series camera OK and provide an excellent field of view for large targets or close up work on PCB's. Barrel distortion is likely but in my use, acceptable. This lens will also work with my other thermal camera if a mounting adapter is used. This is the joy of supplemental lenses rather than interchangeable bespoke camera lens blocks.
Was it a good buy ? ........
Well that depends upon your viewpoint and needs. This lens costs around $3000 from FLIR and I bought it for 10% of that. For a new condition thermal imaging lens from FLIR that is a pretty good deal. Still not exactly a cheap lens though ! The question of high lens costs has been raised on this forum previously. Sadly these are specialist products that use expensive diamond turned (rather than moulded) Germanium lens elements of high quality. For many of us that makes them unaffordable new. I have had some excellent supplemental lens buys on eBay, but they are relatively rare as cameras are often sold with their supplemental lens as a kit. I once purchased a complete PM695 kit just to obtain the supplemental lens that came with it ! The price was right
If this lens does not meet my needs, it is easily resold so the risks are relatively low for me. Spending over $300 on a lens did require some thought though.
Once the lens arrives I will provide some images taken with it to illustrate its wide field of view and likely Barrel distortion that occurs in such a wide angle lens. It is the equivalent of a 18mm lens on a 35mm Film SLR.
Fraser
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