photography notes

Ultraviolet Zoom Lens, Part 3: Test Images

Test images from custom fused-silica lens
by T.J. Nelson

Test Images

This page shows a number of test images made with the custom fused-silica zoom lens. All the images here were taken with a fully-modified Nikon D90 in Raw 12-bit/channel mode. They have been re-sized and down-converted to 24 bits per pixel but not otherwise modified unless stated otherwise. All in-camera sharpening was turned off. The exposure mode and focusing were set to Manual. For the visible-light photos with the Nikkor, autofocus was used.


Fig. 1 Visible light image of purple flowers

UV photo of purple flowers taken with a fused silica lens
Fig. 1. Visible light image of purple Astilbe flowers photographed with custom fused silica lens

Even though the fused-silica lens was designed for UV, it was also good for visible wavelengths. Compare this photo with Fig. 2 below, which was taken with a Nikkor 80-200 zoom lens. Both photos appear equally sharp, but of course I'm cheating a little here: you would probably not notice spherical aberration in a scene like this unless it was quite pronounced. Not much chromatic aberration or fall-off are visible, either.

All the photos on this page taken with the custom lens have a bright area near the center. This is due to the fact that I used uncoated lens elements. That is turning out to be a mistake.
Camera Settings – Fig. 1
Lens Fused silica custom Focus mode Man­ual
Date 06/30/­2013 Time 10:57 am
Aper­ture Shutter speed 1/200
Focal length 100 mm ISO 200
Filter UV/IR block Dis­tance 2 me­ters

If viewing on a cell phone, drag table left or right to scroll.


Fig. 2 The same scene photographed with a Nikkor 80-200 2.8D zoom lens.

Visible photo of purple flowers taken with Nikkor 80-200 2.8D
Fig. 2. Visible light photo of purple flowers photographed with a Nikkor 80-200 2.8D.
The brighter colors in this image compared to Fig. 1 are caused by the slightly different exposures, and are not due to differences in the lenses.
Camera Settings – Fig. 2
Lens left Fused silica custom Focus mode Man­ual
Lens Nikkor 80-200 f/2.8D Focus mode Auto
Date 06/30/­2013 Time 11:07 am
Aper­ture f/2.8 Shut­ter speed 1/4000
Focal length 80 mm ISO 200
Filter None Dis­tance 2 me­ters

If viewing on a cell phone, drag table left or right to scroll.


Fig. 3 Full-size crops (1.56% total area) from the centers of the above images.

Full-size crops from custom fused-silica lens and Nikkor 80-200 2.8D
Fig. 3. In the center, both lenses are reasonably sharp, although it's not easy to tell because of the narrow depth of field. The fused silica lens (left) appears a little less contrasty. Part of this may be due to the constantly shifting lighting conditions.


Fig. 4 Full-size crops from the corners.

Full-size crops from custom fused-silica lens and Nikkor 80-200 2.8D
Fig. 4. In the corners, the fused silica lens (top) was slightly sharper, which made the spider web strands easier to see, but it also showed a trace of chromatic aberration which was not present in the Nikkor. Unlike with a simple quartz lens, which had bad chromatic aberration, the CA was not easy to see unless the image is shown full-size.


Fig. 5 The same purple flowers photographed using an ultraviolet filter.

UV photo of purple flowers taken with fused silica lens
Fig. 5. UV photo of purple flowers - Fused silica lens
These purple flowers appear uniformly dark in ultraviolet light, looking more like tobacco plants than flowers. Even so, there are always bees around these flowers. This photo challenges the myth that bees require a “target” pattern in ultraviolet light in order to find the flower.

This image also shows a particularly bad example of an internal reflection in the lens. This is caused by my use of uncoated lens elements, which is turning out to have been a mistake. The reflections were eliminated when I added an iris diaphragm.
Camera Settings – Fig. 5
Lens Fused silica custom Focus mode Man­ual
Date 06/30/­2013 Time 11:00 am
Shut­ter speed 2 sec Aper­ture
ISO 200 Focal length
Dis­tance 2 me­ters Filter Baader U filter

If viewing on a cell phone, drag table left or right to scroll.


Fig. 6 The same scene photographed with a Nikkor 80-200 f/2.8D zoom lens set to the same focal length.

UV photo of purple flowers taken with Nikkor 80-200 2.8D
Fig. 6. UV photo of purple flowers – Nikkor 80-200 f/2.8D lens
This photo appears bluer than the previous image because less of the shorter UV wavelengths are getting through the glass Nikkor lens. Because of peculiarities of the red and blue pigments on the camera's sensor, the shortest UV wavelengths appear red and the longest infrared wavelengths appear blue—the opposite of what you would expect.
Camera Settings – Fig. 6
Lens Nikkor 80-200 f/2.8D Focus mode Man­ual
Date 06/30/­2013 Time 11:09 am
Shut­ter speed 4 sec Aper­ture f/4
ISO 200 Focal length 80 mm
Dis­tance 2 me­ters Filter Baader U filter

If viewing on a cell phone, drag table left or right to scroll.


Fig. 7 Infrared, visible, and UV photo of white lilies taken with the custom silica lens.

Infrared, visible, and UV photo of white lilies
Fig. 7. Infrared, visible, and UV photo of white lilies photographed with a custom fused silica lens (cropped and resized)
This is another example of how not all flowers have a dark center in the ultraviolet. In fact, the entire flower is dark, yet bees have no problem finding them. Neither do deer.
Camera Settings – Fig. 7
Lens Fused silica custom Focus mode Man­ual
Date 07/06/­2013 Time 12:17 pm
Shut­ter speed (left) 1/200 sec Shut­ter speed (cen­ter) 1/200 sec
Shut­ter speed (right) 1/2 sec Aper­ture
ISO 200 Focal length 80 mm
Dis­tance 1.5 me­ters Filter (left) X-Nite BPG
Filter (cen­ter) UV/IR block Filter (right) Baad­er U

If viewing on a cell phone, drag table left or right to scroll.


Fig. 8 Larger version.

White lilies
Fig. 8. Larger version of the visible photo of white lilies taken with the custom silica lens (cropped and resized).
A closer view shows that the image is quite contrasty, with no detectable halo, which indicates that spherical aberration is under control. This lens also seems to have a pretty nice bokeh, probably due to the fact that there is no iris diaphragm.
Camera Settings – Fig. 8
Lens Fused silica custom Focus mode Man­ual
Date 07/06/­2013 Time 12:07 pm
Shut­ter speed 1/200 sec Aper­ture
ISO 200 Focal length 80 mm
Dis­tance 1.5 me­ters Filter UV/IR block

If viewing on a cell phone, drag table left or right to scroll.


Fig. 9 UV photo of ivy leaves.

UV photo of ivy leaves
Fig. 9. UV photo of ivy leaves (identified by an alert reader as Virginia creeper) photographed with a custom fused silica lens. Many plant leaves that appear shiny in the visible appear almost metallic in ultraviolet light. I am still hoping to find some poison ivy, which has particularly shiny leaves. We had lots of it back east. If weather permits, I'll go back and grab a bunch. (Photo converted to grayscale, cropped, and resized).
Camera Settings – Fig. 9
Lens Fused silica custom Focus mode Man­ual
Date 07/06/­2013 Time 12:17 pm
Shut­ter speed 1/2 sec Aper­ture
ISO 200 Focal length
Dis­tance 1 meter Filter Baader U filter

If viewing on a cell phone, drag table left or right to scroll.


Fig. 10 UV photo of some weeds.

UV photo of weeds
Fig. 10. UV photo of weeds that I forgot to trim, showing metallic appearance in the ultraviolet.
Camera Settings – Fig. 10
Lens Nikkor 80-200 f/2.8D Focus mode Man­ual
Date 07/06/­2013 Time 11:47 am
Shut­ter speed 1/5 sec Aper­ture
ISO 200 Focal length 100 mm
Dis­tance 1 meter Filter Baader U filter

If viewing on a cell phone, drag table left or right to scroll.


Fig. 11 Tiger lilies in visible and ultraviolet.

UV photo of tiger lily using fused silica lens
Fig. 11. UV photo of tiger lilies photographed with a custom fused silica lens in visible light (top) and ultraviolet light (bottom). Tiger lily flowers close up at night (a phenomenon known as nyctinasty) and re-open in the daytime. In ultraviolet light, the center part of the Tiger Lily is darker than the edges—the opposite of how it appears in visible light. Some other flowers, such as dandelions, also show this effect. But many flowers are uniformly dark when photographed in ultraviolet light, which casts doubt on the popular myth that the dark center is a visual cue for bees.
Camera Settings – Fig. 11
Lens Fused silica custom Focus mode Man­ual
Date 07/06/­2013 Time 11:40 am
Shut­ter speed (top) 1/400 sec Shut­ter speed (bot­tom) 1/20 sec
Aper­ture ISO 200
Focal length 80 mm Dis­tance 1 meter
Filter (top) UV/IR block Filter (bot­tom) Baader U filter

If viewing on a cell phone, drag table left or right to scroll.

UV photo of tiger lily using fused silica lens
Another photo of tiger lily in visible light


Fig. 12 Daisies in visible and ultraviolet.

UV photo of daisies using fused silica lens
Fig. 12. If any flower would have a center that is dark in the UV, you would think it would be a daisy, with its yellow center and white petals. But daisies are uniformly dark in ultraviolet light.
Camera Settings – Fig. 12
Lens Fused silica custom Focus mode Man­ual
Date 07/13/­2013 Time 09:35 am
Shut­ter speed (top) 1/100 sec Shut­ter speed (bot­tom) 2 sec
Aper­ture ISO 200
Focal length 80 mm Dis­tance 0.5 me­ters
Filter (top) UV/IR block Filter (bot­tom) Baader U filter

If viewing on a cell phone, drag table left or right to scroll.


Fig. 13 Infrared photo of trees using XNite BPR infrared filter.

Infrared photo of trees
Fig. 13. The lens also worked in the infrared, as shown by this image of oak tree leaves. The BPR filter only transmits light between 889 and 977 nm (10%T cutoff), which is close to the long wavelength limit of the silicon sensor. This image was not color-swapped. It appears blue because at these wavelengths, the blue pigment on the sensor actually transmits as much light as the red pigment. The mostly clear sky appears dark blue through the leaves.

This image also shows a certain amount of misfocus in the corners, caused by field curvature. Stopping down the lens reduced it somewhat. The field curvature was greater for subjects that were far away. According to Smith [1], field curvature is strongly influenced by the position of the aperture stop. So something will have to be adjusted on the zoom mechanism.
Camera Settings – Fig. 13
Lens Fused silica custom Focus mode Man­ual
Date 07/13/­2013 Time 8:43 am
Shut­ter speed 1/10 sec Aper­ture
ISO 200 Focal length 80 mm
Dis­tance 30 me­ters Filter XNite BPR

If viewing on a cell phone, drag table left or right to scroll.

Fig. 14 Rhododendron

Infrared, visible, and UV photo of flowering rhododendron bush
Fig. 14. Infrared, visible, and UV photo of flowering rhododendron bush. All flowers and leaves, regardless of color, are white in infrared. But despite the pink or violet color, rhododendron flowers are so dark in the ultraviolet they are almost invisible. Even so, they are always surrounded by bees, casting further doubt on the bees-attracted-to-UV theory.
Camera Settings – Fig. 14
Lens Fused silica custom Focus mode Man­ual
Date 05/17/­2014 Time 10:27 am
Shut­ter speed (top) 1/320 sec Filter (top) R72
Shut­ter speed (center) 1/125 sec Filter (center) UV/IR block
Shut­ter speed (bot­tom) 1 sec Filter (bot­tom) Baader U
Aper­ture ISO 200
Focal length 80 mm Dis­tance 2 me­ters

If viewing on a cell phone, drag table left or right to scroll.

Fig. 15 Goldenrod

Visible and UV photo of goldenrod
Fig. 15. You might expect a goldenrod, with its bright yellow color, to be dark in the UV, and you would be right. Goldenrod are highly camouflaged in the ultraviolet. They are so dark in the UV that I had to clamp this specimen in a vise in my ... er ... studio, shine a UV light on it, and take a time exposure before it would show up in the photo. Even then, I had to brighten the image by raising the gamma so the flower would be visible against the black background.

Goldenrod is sometimes mistakenly believed to cause hay fever, but this is a myth.

I should mention that the goldenrod did not seem to like being clamped in a vise and blasted with ultraviolet radiation. It turned brown a couple of hours after this picture was taken.
Camera Settings – Fig. 15
Lens Fused silica custom Focus mode Man­ual
Date 07/20/­2013 Time 08:29 am
Shut­ter speed (top) 1/20 sec Shut­ter speed (bot­tom) 10 sec
Aper­ture ISO 200
Focal length 80 mm Dis­tance 1.5 me­ters
Filter (top) UV/IR block Filter (bot­tom) Baader U filter

If viewing on a cell phone, drag table left or right to scroll.

Fig. 16 Wild carrot flower

Visible and UV photo of white flower
Fig. 16. Most flowers that have small petals are dark in the ultraviolet. This is a common white flower, known as Daucus carota (wild carrot or Queen Anne's Lace), which grows wild by the side of the road. Its appearance is very similar to poison hemlock. This particular specimen had several thyreocorids on it, which I removed before taking the picture.
Camera Settings – Fig. 16
Lens Fused silica custom Focus mode Man­ual
Date 07/20/­2013 Time 10:02 am
Shut­ter speed (top) 1/200 sec Shut­ter speed (bot­tom) 2 sec
Aper­ture ISO 200
Focal length 80 mm Dis­tance 1.5 me­ters
Filter (top) UV/IR block Filter (bot­tom) Baader U filter

If viewing on a cell phone, drag table left or right to scroll.

Fig. 17 Chickory flower

Visible photos of Chickory
Fig. 17. This image was an experiment to help figure out why the edges of some of the images appeared slightly out of focus. These are crops of images of a blue Chickory flower I found growing by the road near the end of my driveway. The top image was made with the lens containing a CaF2 triplet. The bottom image was from an earlier lens made from 2 inch diameter 200 mm fused silica meniscus and a 1-inch 150 mm meniscus. In the lower panel, the flower and stem are much less sharp, and the bright areas have a blue halo due to optical aberrations. Even so, the lower image was equally sharp (or equally blurry) from edge to edge. The lower image is also brighter because of the bigger lens diameter. These photos proved that the problem with the top lens was not spherical aberration, but field curvature. It seems that it may be possible to reduce field curvature by making the front elements bigger than the rear elements.
Camera Settings – Fig. 17
Lens (top) Fused silica custom Lens (bot­tom) Fused silica custom, 2 inch, no triplet
Date 07/20/­2013 Time 7:05 am
Shut­ter speed (top) 1/20 sec Shut­ter speed (bot­tom) 1/100 sec
Aper­ture (top) Aper­ture (bot­tom) f/7.16
ISO 200 Dis­tance 1.5 me­ters
Filter (top) UV/IR block Filter (bot­tom) UV/IR block

If viewing on a cell phone, drag table left or right to scroll.

Fig. 18 Chickory flower in UV

UV photo of blue Chickory flower
Fig. 18. In the UV, this blue Chickory flower was very dark in the center. (cropped)
Camera Settings – Fig. 18
Lens Fused silica custom Focus mode Man­ual
Date 07/20/­2013 Time 7:23 am
Shut­ter speed 6 sec Aper­ture
ISO 200 Focal length 80 mm
Dis­tance 1.5 me­ters Filter Baader U

If viewing on a cell phone, drag table left or right to scroll.

Fig. 19 Black-eyed Susan

Visible and UV photo of black-eyed susan
Fig. 19. Since daisies appear black in ultraviolet, there's no point in looking at a black-eyed susan, right? Wrong. The petals of a black-eyed susan (Rudbeckia hirta) are actually ligher than those of a daisy in the UV, and are two-toned: the 1959 Ford Galaxie of flowers.
Camera Settings – Fig. 19
Lens Fused silica custom Focus mode Man­ual
Date 07/20/­2013 Time 5:25 pm
Shut­ter speed (top) 1/200 sec Shut­ter speed (bot­tom) 2 sec
Aper­ture ISO 200
Focal length 80 mm Dis­tance 0.7 meter
Filter (top) UV/IR block Filter (bot­tom) Baader U filter

If viewing on a cell phone, drag table left or right to scroll.

Fig. 20 Black-eyed susan in shortwave UV

UV photo of Black-eyed susan
Fig. 20. At shorter wavelengths, the two-toned pattern is even more pronounced. (cropped and converted to grayscale)
Camera Settings – Fig. 20
Lens Fused silica custom Focus mode Man­ual
Date 07/24/­2013 Time 5:18 pm
Shut­ter speed 0.5 sec Aper­ture
ISO 200 Focal length 80 mm
Dis­tance 1.0 me­ters Filter Baader U

If viewing on a cell phone, drag table left or right to scroll.

Fig. 21 Leaf trichomes

UV photo of leaves
Fig. 21. UV enhances details like the hairy trichomes of certain leaves, which are barely visible in a regular camera.
Camera Settings – Fig. 21
Lens Fused silica custom Focus mode Man­ual
Date 07/20/­2013 Time 5:29 pm
Shut­ter speed 2 sec Aper­ture
ISO 200 Focal length 80 mm
Dis­tance 0.5 meter Filter Baader U filter

If viewing on a cell phone, drag table left or right to scroll.

Fig. 22 Weeds

UV photo of clover
Fig. 22. Another UV photo of some more weeds in my back yard, showing metallic and non-metallic appearance of different species.
Camera Settings – Fig. 22
Lens Fused silica custom Focus mode Man­ual
Date 07/20/­2013 Time 5:57 pm
Shut­ter speed 2 sec Aper­ture
ISO 200 Focal length 80 mm
Dis­tance 0.5 me­ters Filter Baader U

If viewing on a cell phone, drag table left or right to scroll.

Fig. 23 Dogwood Tree Flowers

Infrared, visible, and UV photo of dogwood tree flowers
Fig. 23. This composite photo (top = infrared, middle = visible, bottom = ultraviolet) once again shows that flowers and leaves always appear white in infrared. Unexpectedly, however, even though the dogwood tree flowers appear pure white to the eye, they absorb ultraviolet light strongly, and appear velvety black in UV.
Camera Settings – Fig. 23
Lens Fused silica custom Focus mode Man­ual
Date 04/27/­2014 Time 6:30 am
Infra­red speed 1/40 sec ISO 200
Visible speed 1/40 sec Dis­tance 0.5 me­ters
UV speed 3 sec IR Filter R72
Visi­ble filter UV/IR block UV Filter Baader U

If viewing on a cell phone, drag table left or right to scroll.

Fig. 24 Plum Tree Flowers

IR, Visible, and UV photo of plum tree flowers
Fig. 24. Plum tree leaves appear deep red to the eye, but appear white in infrared and black in ultraviolet. Plum tree flowers also absorb ultraviolet light strongly, and appear black in UV, but not as dark as dogwood tree flowers.
Camera Settings – Fig. 24
Lens Fused silica custom Focus mode Man­ual
Date 04/27/­2014 Time 6:48 am
Infra­red speed 1/50 sec ISO 200
Visi­ble speed 1/50 sec Dis­tance 0.5 me­ters
UV speed 3 sec IR Filter R72
Visi­ble filter UV/IR block UV Filter Baader U

If viewing on a cell phone, drag table left or right to scroll.


Fig. 25 Dandelions in visible and ultraviolet.

UV photo of dandelions using fused silica lens
Fig. 25. Dandelions have a dark center in the ultraviolet.
Camera Settings – Fig. 25
Lens Fused silica custom Focus mode Man­ual
Date 05/03/­2014 Time 01:10 pm
Shut­ter speed (top) 1/1000 sec Shut­ter speed (bot­tom) 1/4 sec
Aper­ture ISO 200
Focal length 80 mm Dis­tance 0.5 me­ters
Filter (top) UV/IR block Filter (bot­tom) Baader U filter

If viewing on a cell phone, drag table left or right to scroll.

Fig. 26 Dogwood flower in the UV

UV photo of dogwood flower
Fig. 26. Another UV photo of a flowering dogwood tree. In the visible, the center part is green and the petals are pure white. In the ultraviolet, the center part is white and the petals are black. The leaves also appear almost metallic. (Cropped)
Camera Settings – Fig. 26
Lens Fused silica custom Focus mode Man­ual
Date 05/02/­2014 Time 6:05 pm
Shut­ter speed 3 sec Aper­ture
ISO 1600 Focal length 80 mm
Dis­tance 1.0 me­ters Filter Baader U

If viewing on a cell phone, drag table left or right to scroll.


Fig. 27 Pink wild flower in visible and ultraviolet.

UV photo of wild flower using fused silica lens
Fig. 27. Visible and UV photo of an unidentified pink wildflower. The flower appears black in ultraviolet, and the veining of the leaves is more clearly visible.
Camera Settings – Fig. 27
Lens Fused silica custom Focus mode Man­ual
Date 05/09/­2014 Time 05:54 pm
Shut­ter speed (left) 1/125 sec Shut­ter speed (right) 1.3 sec
Aper­ture ISO 200
Focal length 80 mm Dis­tance 0.5 me­ters
Filter (left) UV/IR block Filter (right) Baader U filter

If viewing on a cell phone, drag table left or right to scroll.


Fig. 28 Ultraviolet photo of a buttercup.

UV photo of buttercup using fused silica lens
Fig. 28. Visible and UV photo of a buttercup. Buttercups are two-toned, like black-eyed susans, and have a dark center in ultraviolet light. The outer part of the petals is highly reflective in UV, and the faint green veins are more clearly visible. If you hold a buttercup next to the chin, a yellow reflection indicates that you, like the buttercup itself, are highly reflective to ultraviolet radiation.
Camera Settings – Fig. 28
Lens Fused silica custom Focus mode Man­ual
Date 05/11/­2014 Time 12:57 pm
Shut­ter speed (left) 1/400 sec Shut­ter speed (right) 1/4 sec
Aper­ture ISO 200
Focal length 80 mm Dis­tance 0.3 me­ters
Filter (left) UV/IR block Filter (right) Baader U filter

If viewing on a cell phone, drag table left or right to scroll.


Fig. 29 Ultraviolet photo of henbit.

UV photo of henbit flower
Fig. 29. Visible and UV photo of henbit flowers. Henbits are very small (7 mm diameter), purple flowers that grow like weeds. Their petals have distinctive spotted pattern. You might think that, because it's violet, this pattern would be even more prominent in the UV, but in fact it's not visible at all. The flower is pitch black in ultraviolet light. It's so dark that I had to illuminate it with a 365 nm flashlight in this photo before any details could be seen.
Camera Settings – Fig. 29
Lens Fused silica custom Focus mode Man­ual
Date 05/11/­2014 Time 07:07 pm
Shut­ter speed (top) 1/100 sec Shut­ter speed (bot­tom) 2 sec (il­lumi­nated)
Aper­ture ISO 200
Focal length 80 mm Dis­tance 0.12 me­ters
Filter (top) UV/IR block Filter (bot­tom) Baader U filter

If viewing on a cell phone, drag table left or right to scroll.


Fig. 30 Ultraviolet photo of clover flower.

UV photo of clover flower
Fig. 30. Another surprising one is the common white clover flower, which reflects visible light but strongly absorbs UV, appearing pitch black in ultraviolet. Clover is also known as trefoil, named for the characteristic three leaves.
Camera Settings – Fig. 30
Lens Fused silica custom Focus mode Man­ual
Date 06/22/­2014 Time 07:44 pm
Shut­ter speed (top) 1/20 sec Shut­ter speed (bot­tom) 20 sec
Aper­ture f/7 ISO 200
Focal length 80 mm Dis­tance 0.2 me­ters
Filter (top) UV/IR block Filter (bot­tom) Baader U filter

If viewing on a cell phone, drag table left or right to scroll.


Fig. 31 Ultraviolet photo of diet orange soda.

UV photo of diet orange soda
Fig. 31. Diet orange soda looks cloudy in the ultraviolet.
Camera Settings – Fig. 31
Lens Fused silica custom Focus mode Man­ual
Date 07/29/­2014 Time 07:28 am
Shut­ter speed (left) 2 sec Shut­ter speed (right) 1/100 sec
Aper­ture f/7 ISO 200
Focal length 80 mm Dis­tance 1 meter
Filter (left) Baader U filter Filter (right) UV/IR block

If viewing on a cell phone, drag table left or right to scroll.


Fig. 32 Croissants.

UV photo of croissants
Fig. 32. UV photo of croissants from the grocery store. All baked goods, typically light brown, appear black in the ultraviolet.
Camera Settings – Fig. 32
Lens Fused silica custom Focus mode Man­ual
Date 07/29/­2014 Time 07:30 am
Shut­ter speed 2 sec Aper­ture f/7
ISO 200 Focal length 80 mm
Dis­tance 1 meter Filter Baader U filter

If viewing on a cell phone, drag table left or right to scroll.


Fig. 33 Grapefruit.

UV photo of grapefruit
Fig. 33. UV photo of grapefruit and celery. Grapefruit appear black in UV, as do green tomatoes, but celery doesn't.
Camera Settings – Fig. 33
Lens Fused silica custom Focus mode Man­ual
Date 07/29/­2014 Time 07:17 am
Shut­ter speed 1 sec Aper­ture f/7
ISO 200 Focal length 80 mm
Dis­tance 1 meter Filter Baader U filter

If viewing on a cell phone, drag table left or right to scroll.


Fig. 34 Blue Iris.

UV photo of blue iris
Fig. 34. This blue Siberian iris is not black in UV, but the white lines are no longer visible.
Camera Settings – Fig. 34
Lens Fused silica custom Focus mode Man­ual
Date 05/28/­2015 Time 18:47
Shut­ter speed (left) 1/100 sec Shut­ter speed (right) 1.6 sec
Aper­ture f/7 ISO 200
Focal length 80 mm Dis­tance 1.5 me­ters
Filter (left) UV/IR Block Filter (right) Baader U filter

If viewing on a cell phone, drag table left or right to scroll.


Fig. 35 White Caterpillar (Halysidota tessellaris).

UV photo of white caterpillar
Fig. 35. This white caterpillar (banded tussock moth, Halysidota tessellaris) with black spikes and shiny black head looked exactly the same in ultraviolet, visible, and infrared (UV shown). The body is black and there are yellow spots on the head. The hairs act like whiskers. When the hairs contact a leaf, the caterpillar tries to climb up on it. But when it detects carbon dioxide, it curls up into a defensive ball, hides its head, and freezes. That doesn't prevent the camera from stealing its soul ... such as it is ....
Camera Settings – Fig. 35
Lens Fused silica custom Focus mode Man­ual
Date 09/07/­2015 Aper­ture f/7
Shut­ter speed (top) 1/10 sec Shut­ter speed (bot­tom) 2.0 sec
Time (top) 13:12 Time (bot­tom) 09:07
Focal length 80 mm Dis­tance 0.5 me­ters
Filter Baad­er U Filter ISO Top:­800, Bot­tom:­400

If viewing on a cell phone, drag table left or right to scroll.

UV photo of white caterpillar
Visible light photo of a different specimen of Halysidota tessellaris larva showing the yellow spots on the front of the head. This one is smaller than the one above and has a brown tint on its hairs. (Fused silica lens, 1/13 sec, D7000, ISO 200, 09/07/2015 18:04)

References
[1]. Smith, WJ, Modern Optical Engineering, 4th ed., p.87.


Click here for more UV images.

See also:

Parts 1 and 2

Photography notes
http://randombio.com/uvlens.html
Ultraviolet Zoom lens, Part 1:
Design

Photography notes
http://randombio.com/uvlens2.html
Ultraviolet Zoom lens, Part 2:
Construction

Other articles

Photography notes
http://randombio.com/uv.html
Ultraviolet photography with a modified D90 DSLR

Photography notes
http://randombio.com/d90infrared.html
Modifying a Nikon D90 DSLR for Infrared Photography and Astro­photography

Photography notes
http://randombio.com/webcam.html
Photo­graphing Radio­activity With a Webcam

Amateur Astronomy Notes
Astro­photography Without a Telescope

Images
http://randombio.com/stars.html
Astro­photographs taken with the modified D90

Images
http://randombio.com/infrared.html
Infrared photographs.

Book Review
http://randombio.com/reviews/optics.html
Optical Engineering Books
Name and address
jul 07, 2013; updated sep 07, 2015

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