Lens artifacts recorded on IR film

[lonesome_dave]

Seeing the recent discussion of lenses good for IR made me think of some unwanted but amusing lens artifacts I've recorded when using IR film.

Not sure what the proper name for these are but I just call them axial internal lens reflections. When viewing the full frame image a line connecting the artifact and it's probable source is bisected by the exact center of the image.

 

These were all taken by a Yashica Electro-35GS rangefinder camera with its Yashinon 45mm f/1.7 lens.
I can't find any similar artifacts in straight visible spectrum images taken with this camera & lens.

 

First, the forest faeries.

 

The second one has the eerie effect of appearing to illuminate the ground around it. These were taken north of Flagstaff AZ in the 1970s. I didn't notice the apparitions until I got the film back from Kodak weeks later.

 

Finally, the UFOs.

 

This type of image is often cropped and presented as mystery sky objects. Sky buffs will recognize Scorpio rising in the background.

[OlDoinyo]

I have seen these in digital images as well. I guess they could be called a type of flare, but the non-optimization of most AR coatings for IR can make them really spectacular. Some of them undoubtedly describe interesting geometric shapes. They are an example of optical caustics.

[lukaszgryglicki]

A lot of this stuff when using wide lenses in IR on GFX.