3rd Photo: No Lens approx. 6" away from Arduino Mega
4th Photo: Lens attached approx. 3" away from Arduino Mega
I just went through a similar process and thought I'd post some comparison photos for the next person trying to choose a lens. I used the stl that
Georges80 posted on Shapeways (it complained about thin walls, but it printed fine.) I bought both
a 2" and
a 4" from
bingo929. The lens is a bit loose in the holder, so after making my choice, I used Elmer's to glue the lens in place.
The subject for these is a BK 9130 power supply:
You can see a number of warm areas. For the purposes of these comparisons, I'm going to be looking at that bright spot in the upper left, and the regulators in the center. With the macro lenses, I also captured an area with some SMD parts on it, however the parts didn't have much temperature variation, so you'll just have to get an idea what's going on from the pads.
It was really hard for me to pull the trigger without making things blurry on the macro shots, so these samples are often blurrier than the best you can get. In all of the macro pictures, I was able to get some part of the image in decent focus. The point of these samples is to show off the kind of feature size you can make out with the different focal lengths.
Lens | Regulators | Diode | SMD |
default | | | |
4" | | | |
2" | | | |
Sorry I had the camera rotated for the regulators with the default lens. It should be rotated ccw to match the others, but it still easily shows how blurry it is.
The camera wasn't able to resolve the high temperature diode without a lens: not only was it a blurry blob, but it was showing as 33C instead of 50C. The regulators were big enough that they measured as roughly 50C both with and without the lens (although the sample here has the 3 lenses looking at different parts of the regulator, oops.) As I said above, the SMD parts themselves are too uniform a temperature to really make out. You can see some... I think they were 0805 parts that are just barely warm.
I went with the 4". 0603 is still discernable, and the depth of field on the 4" focal length was enough to have the entire TO220 parts basically in focus (where the 2" lens could only focus on the top or the bottom.) There were also areas of the board I couldn't get into focus with the 2" lens because taller parts got in the way.
The holder + lens cost about $25, and makes my $1k camera so much more useful for PCBs!