For PCB inspection there is little doubt that a camera that is capable of manual very close focus is more capable than a fixed focus camera plus auxiliary lens. Both do work however. The fixed focus camera + close-up lens has a very small depth of field and the camera has to be moved back and forth to find correct focus. With a manual close focus lens the user is able to set the focus without moving the camera. Sharper images are also achievable with a manual focus lens as the optical block may be optimised for image focus rather than a compromise fixed focus design.
What do I use ? My 'go-to' thermal camera for quick PCB checks is the E4 (320x240+menus) with a 100mm FL close up lens
It is just so convenient !
I have a 160 x 120 Testo 880 camera that I should use more as it has manual focus BUT, many manual focus thermal cameras will only close focus to 30cm. This is too far from the DUT for me so I would still need a close-up lens ! The Testo has a large diameter lens, so a large diameter 100mm FL close-up lens would be needed. Such are not cheap but I do have a couple
For really high quality images and in depth PCB thermal profiling I would use one of my FLIR PM series or NEC AVIO cameras as they were designed for such detailed work and have greater capabilities for thermal analysis.
Given the choice, I would always buy a camera with manual focus in preference to one with a fixed focus lens block. I have many cameras so can see the difference in imaging performance in practical usage. The trouble is, decent manual focus 'all in one' thermal cameras tens to be the more expensive models in a range. There are manual focus mobile phone add-on thermal cameras now though. Not all are born equal though so care is needed in selecting which to buy.
Finally...... Auto focus.... yes, some thermal cameras have an auto focus capability
My FLIR PM695 has both manual and auto-focus modes
Luxury, pure luxury
Fraser
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