p.1 #1 · Z24-120 lens - HotSpot when shooting InfraRed?
Looking at updating to a Z7 or Z7II in the near future. Body would be converted to 720nm Infrared.
Anyone know if the Z24-120 zoom gives Hot Spots when shooting IR?
Have the same focal length on the D810 IR conversion & it works fine without hot spots .Nice option for general carry around body. When I go to a Z body would rather get the Z lens - supposed to be sharper/cleaner than the older one - so it matches up without adapters.
p.1 #2 · Z24-120 lens - HotSpot when shooting InfraRed?
The Z24-120 does have hot spots, especially at the wide end unfortunately. Very obvious at 24mm, still quite bad at 35mm, broader but still there at 50mm, not great but diffuse enough to perhaps work around at 120mm. I never use it for IR as I consider it not worth the effort. The above all at F/11.
Naturally you can open up the aperture which tends to diffuse the hot spot into a general loss of contrast that might be easier to deal with in post, but again I just use a different lens.
The 24-70/4S is quite a bit better, but not necessarily perfect. You end up with a mild diffuse spot at the center of the image but usually it can be tamed with a radial adjustment layer. That's the lens I pair with the Tamron 75-300 which is excellent for IR when I'm shooting my IR body.
The 14-30/4S acts a lot like the 24-70/4S - not perfect by any means but a mild diffuse hot spot that can usually be dealt with in post.
The 40/2 is inexpensive and excellent for IR. I usually make sure I have that with me when I've got my IR body along.
Again, everything above at F/11. I always test hot spots at F/11 to make them a bit easier to see. Opening the aperture makes them more diffuse, but again general loss of contrast ensues at that point. I usually shoot IR landscapes at F/8.
Regarding that specific lens:
1. the first website says "Significant hotspot at focal lengths less than 50mm, good performance at the longer focal lengths."
2. the second website rates the lens as a poor performer in IR
3. the third website does not yet rate this lens.
I have a Nikon Z7 converted to infrared (590nm by LifePixel). For that camera, I use the Nikon 24mm f/1.8 S lens, the Nikon 50mm f/1.8 S lens, and very occasionally the Nikon 100-400mm S lens. I have yet to notice any IR hot spots on any of those lenses.
p.1 #4 · Z24-120 lens - HotSpot when shooting InfraRed?
FWIW, based on various readings (e.g., Rob Shea's e-book on IR photography), my understanding is that diffraction sets in more quickly in the IR spectrum. For the camera and lenses that I use (see my post above), I rarely stop down more than f/5.6 while shooting infrared. Perhaps f/8 would be fine on a camera with less resolution that the Z7 (e.g., the Z6). I think Rob Shea has some charts on this topic.
p.1 #5 · Z24-120 lens - HotSpot when shooting InfraRed?
kwilliam8 wrote:
FWIW, based on various readings (e.g., Rob Shea's e-book on IR photography), my understanding is that diffraction sets in more quickly in the IR spectrum. For the camera and lenses that I use (see my post above), I rarely stop down more than f/5.6 while shooting infrared. Perhaps f/8 would be fine on a camera with less resolution that the Z7 (e.g., the Z6). I think Rob Shea has some charts on this topic.
Yep. The competing issue is that most lenses are less well corrected in the IR, so you have to stop down the lenses more to get optimal edge/corner performance.
If you care about the central region only then you will typically want to stop down less as you say (especially on a 45MP imager). If you care about the edges and corners, as is typical in landscape shots, you need to test and evaluate each lens to decide what trade off between corner/edge performance and central diffraction works best for you.
