Another IR pic.
I just got a Nikon Z6 converted to IR from LifePixel (you can actually buy the converted camera from their site). Both yesterday's and today's pics were taken with it as part of the process of testing out lenses to see how they perform in IR.
I have several bodies converted to IR, the "best" being a Nikon D810. There are 2 major obstacles to shooting IR: focus and lenses.
The IR wavelengths don't focus at the same plane as visible light. So standard AF with an optical viewfinder tends to not work well at all. You really need to use at least Live View. But mirrorless cameras have somewhat overcome that obstacle, since you can focus from the sensor. For my D810-IR I actually moved the switch to block out the OVF altogether and always used LV. Nikon LV AF focus isn't phenomenal in general and it doesn't magically get better with an IR converted camera. You don't have access to all of the AF modes available with the OVF. The D810 has a non-articulating rear LCD which can make it challenging to use in LV whether hand held or on a tripod.
The Z6 overcomes all of the focus issues when shooting IR by having both an EVF and an articulating LCD screen. You can also use all of the AF modes with the camera when shooting IR. This is huge. I honestly can't overstate how much easier it is to get focus in IR with a Z6 compared to a D810.
Lenses are a whole separate issue. Many (most?) lenses are plagued by "hot spots", central areas of lightness and color shift (blue) that are secondary to IR light bouncing around within the lens. More evident with stopping down. Can be a significant challenge if wanting to keep the final pic in color. Converting to B&W can somewhat mitigate this.
One of the potential things I was excited about with the Z6 conversion was the ability to test all of my Leica lenses with IR. Most of them ended up being not that special. The exceptions were the 18mm, 21mm, and 24mm lenses (in each case the ones with maximal aperture of either f/3.4 or f/3.8). All of my other Leica lenses showed hot spots of varying degrees of severity. These 3 lenses did not. However, they did show artifacts related to sensor thickness and ray angle. M lenses are finicky and tend to not perform well on non-Leica bodies (like Sony mirrorless or Nikon mirrorless--though they do better on Nikon than they do on Sony in my experience).
Today's pic was taken with the Leica M 18mm f/3.8 on a Nikon Z6 converted to IR. The color version is a bit wonky because of ray angle issues with the M lens on a non-Leica body (sensor cover glass thickness that distorts the light hitting the sensor in a manner not intended with the lens design).
I might use the Leica M lenses if I didn't have another option. As it turns out, I do. The Nikon 19mm PC-E has a fairly minor hot spot. It also has the ability to tilt and shift, though I haven't tested the performance of tilts/shifts in IR (yet).
A very long-winded post for the POTD thread (and one that might deserve its own thread with examples).
Nikon Z6 converted to IR (720nm) and Leica M 18mm f/3.8. Hand held.
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