LensBaby UV Test

[alanb]

LensBaby makes special effects lenses, intended for soft-focus portraits and such. This particular lens is the double-glass optic (more or less equivalent to what they now sell as the Sweet 50): Essentially it's a doublet with chromatic aberration corrected, but spherical aberration intentionally uncorrected off axis. The spherical aberration causes the center of the frame to be fairly sharp, with sharpness rapidly declining toward the edges. The effect can be controlled with the aperture. It's very strong at f/2, somewhat controlled f/5.6, and continues getting weaker the more you stop down. However the edges are not sharp at any aperture. The optics are mounted such that the lens can be tilted. Tilting the lens has the effect of moving the center-of-lens-axis sweet spot around the frame, so it can be put off-center.

 

Since it's just 2 elements in 1 group, I wondered if it was suitable for UV. I had an original LensBaby 2.0, but that one has a flexible tube, which is impossible to hold steady for longer exposures. I hunted down a used Composer Pro, which can be locked in place and holds its position. The Composer Pro optics take 37mm filters, but it turns out they retract into the Composer Pro tube, so it isn't possible to use step-up rings. Instead I glued a 62-67mm step-up ring onto the outer rim of the Composer Pro body. I then mounted a 67-to-52mm step-down to use my 52mm LaLaU UV filter.

 

Here's the flowers in visible light. ISO 100, f/5.6, 1/640 s. Camera is a full spectrum Canon EOS M3.

 

 

And UV. ISO 3200, f/5.6, 0.2 s: A loss of 12 stops of light.

 

 

I'm no botanist, but it looks like the flower is some variety of lantana. These are quite small flowers. I had 26mm of extension tube in the mix to get so close.

 

I found it interesting that the yellow and pink blossoms are pretty much the same color in UV. Also the tiny (disease?) spots, barely visible in the visible light photo, are bright white spots in UV.