Author Topic: How to deal with an IR hotspot: 28-45 mm f/4.5 Zoom-Nikkor  (Read 749 times)

Bjørn Rørslett

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[ Posted 30 May 2011 - 09:38 Edited and reposted by agreement ]

Some lenses, in particular zoom designs, can have the most annoying hot spots when the lens is pressed into IR service. Worst of all are lenses that show the issue intermittently. You never really can trust the darned thing.

OK, so you're in the middle of nowhere, and all of a sudden those pestering spots start to appear in your shots. I was in exactly that situation a few days ago with the venerable 28-45/4.5 Zoom-Nikkor on my IR-modified D200. In fact, the objective of the trip was amongst a raft of other tasks, to validate the usefulness of that lens for shooting in IR. I had just recently CPU-modified it and thus it had become eligible for in-depth testing. My validated IR lenses get a red square sticker on them to inform me that I can safely use them in IR. If there is the occasional issue, the sticker still is red but now cut to a triangle. If the hot spot or other IR-related issues are persistent it'll of course get no sticker (at least, not the "IR red" one, but it still can receive a "Visible green" or "UV blue" sticker).

I duly noted the 28-45 could at most get a "red triangle", but after having put that comment into my data files, I wondered what escape routes remained if this was the only available lens and I was intent on doing IR no matter what. Here are two examples I came up with. Nothing very advanced, just a spur-of-the-moment response. A refreshing challenge for yourself.

Portal to another world




UV/IR logo (I actually found this company logo on a wall nearby and - of course - couldn't resist shooting it ... The hot spot area enhanced the logo in a natural fashion)