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This can be found in New Scientist 9 October 2021 page 20 Quote "Female red postman butterflies (Heliconius erato) see an extra colour in the ultraviolet spectrum that even the males of their species cannot" (Journal of Experimental Biology, doi.org/gx2p ) .... The females correctly chose the UV colour associated with the honey reward under every testing condition, even if the other UV light was 15 times brighter.

Wilhelmson, U. 2021. Verbascum speciosum Schrad. (Scrophulariaceae). Hungarian Mullein. Flowers photographed in visible, ultraviolet light and a combination of both. https://www.ultravio...garian-mullein/ Verbascum speciosum Schrad. NO: Praktkongslys SE: Praktkungsljus DK: Kandelaber-Kongelys DE: Pracht-Königskerze EN: Hungarian Mullein References: https://www.luontopo...t/showy-mullein http://alienplantsbe...ascum-speciosum https://commons.wiki...ascum_speciosum Comment: A plant native to eastern Europe and western Asia, Verbascum speciosum is known in many other regions as an introduced species and roadside weed. It is a biennial herb forming a rosette of large leaves and an erect stem well exceeding one meter in maximum height. The leaves are 30 to 40 centimeters long and have smooth edges and pointed tips. The plant blooms in a large panicle with many branches lined with flowers. Each flower has a corolla measuring 2 to 3 centimeters wide with five yellow petals. There are five stamens coated in long white hairs at the center. The fruit is a capsule up to 7 millimeters in length containing many seeds. The Hungarian Mullein is the most common Mullein species in Sweden with branched inflorescence. It is characterized by the fact that all stamens are symmetrically attached and that the two lower stamens also have hair on the stamens. Source: http://linnaeus.nrm....ba/verbspe.html Plants collected and photographed in the southern parts of Malmö, Sweden, October 2019, just before the first night frost destroyed the last flowers. All the pictures below show flowers from the same individual. Flower at the collection site: Images below by the same camera and light source: Camera: Canon EOS 60D, EL-Nikkor 80mm f/5.6 old metal type-lens Light source: two UV-converted Godox AD200 flashes with uncoated Quartz tubes Front of the flower, overviews Visible light Filter: Schott BG38, 2mm BUG3-stack image Filter: Schott S8612, 2mm + Schott BG3, 2mm BUG5-stack image Filter: Schott S8612, 2mm + Schott UG5, 1.5mm Ultraviolet Image Filter: Schott S8612, 2mm + Schott UG1, 1mm Front, close-up BUG3-stack image, Filter: Schott S8612, 2mm + Schott BG3, 2mm BUG5-stack image Filter: Schott S8612, 2mm + Schott UG3, 1.5mm Ultraviolet Image Filter: Schott S8612, 2mm + Schott UG1, 1mm Rear of the flower BUG3-stack image Filter: Schott S8612, 2mm + Schott BG3, 2mm BUG5-stack image Filter: Schott S8612, 2mm + Schott UG3, 1.5mm Ultraviolet Image Filter: Schott S8612, 2mm + Schott UG1, 1mm [Published 3 July 2021].

After dabbling mainly with my b/w converted camera, I finally worked up the motivation to go out and do some proper colour-UV photos I've searched around a bit, and since nobody knows how bees actually do perceive the EM-spectrum, I've decided to stick to the accepted nomenclature, and to call these photos bee-vision. First, the basics: Camera: Canon EOS 6D, full-spectrum conversion (almost all taken between ISO 100 and 200), WB set to flash (5400 K, I believe) Lens: Nikon EL-Nikkor 80mm, f/5.6 (mostly af f/8), handheld Light: Overcast day, so used a Yongnuo YN-24 EX-TTL macro-flash, where I've replaced the cover with a plastic from a CD-box. Filter: ZWB3 + S8612 (This makes me appreciate by b/w-camera even more, because with a lot of concentration it's possible with this filter-combination to look through the viewfinder and find focus, at the end of the session I only needed 2-3 tries per flower; whereas with teh b/w there is just the S8612 required which makes focussing and composition much easier) Post: WB set arbitrarily to some values where I liked the result (not the same for all photos). Cropping, of course, and a bit of correction to highs and lows, that's about it. Then, the usual admissions: I did try to identify the plants from the plates which are stuck into the ground, but chances are that I got some of them wrong. The VIS-shots werer taken with my mobile phone, and not always from the exact same angle. [Edit]Thanks to Birna for the help. 2 out of 10, that's a new low, even for me [/Edit] 1. Primula Althaea officinalis, Eibisch: 2. Anemone blanda Aster dumosus "Kassel", Kissenaster: 3. Helleborus argutifolius, Korsische Schneerose (reminds me of Audrey II from https://www.imdb.com/title/tt0091419/ ): 4. Pulsatilla halleri slavica, Küchenschelle: 5. Anemone ranunculoides Saxifraga umbrosa, Prozellanblümchen: 6. Ranunculaceae Silene uniflora, ssp.glareosa; 7. Ranunculus ficaria Unknown: 8. Corydalis Unknown: 9. Euphorbia Unknown: 10. Primula Unknown:

With the increase of more sensitive sensors, the question of taking photos of living insects has slowly wormed its way into my mind, and triggered by Stefano's thread (https://www.ultravioletphotography.com/content/index.php/topic/4435-some-bees-on-dandelions/ ), I'd like to ask the question of how to take UV-photos of bungs, flies, bees, etc., and not hurt them. This, of course, under the assumption of using some sort of light source in addition to the sun. In my case, I'm thinking of the Yongnuo YN560-III flashgun with the protective cover removed, turning it into a full-spectrum light-source. I don't know exactly how full its spectrum is, but there's plenty of UV in it. In order to keep ISO not too high, I had to usually use it at half-power or higher when taking photos of plants. I remember reading about this in an older topic somewhere here (can't find it now), with the suggestion of using flash once on an insect ought to be ok. On other sites I've read that using a flash directly on the eyes of a butterfly might easily blind it (that was about VIS-flash, but full spectrum will be even worse, I guess). I wouldn't want to blind an insect just to get a photo of it. So, how are the other members here handling this? Is there some reliable data of how much light (in candela or any other unit) is acceptable?

A new TV programmed aired last night in the UK: Life in Colour, narrated by David Attenborough. (BBC). I think they mentioned it might be available on Netflix for US and other viewers. It showed several examples of UVR in flowers, fish (underwater) and others. They said they had developed a new camera giving "previously unseen images". The set up looked like two cameras at 90 degrees to each other, with a semi silvered mirror between them so they could switch from visible to UV easily. They only showed UVR, not multispectral images showing "insect vision". Very interesting though if you can catch it. There is another episode next week including insect mimicry which should be very interesting!

Hi there! I am Shamali from India. I am a botanist and just entering the field of UV photography. I aim to work on UV reflectance of flowers. I use a Sony a6000 camera. But I think will have to get a conversion done for UV photography. Your guidance would help in understanding the basics. Thanks..

Greetings from Mount Vernon, Washington, USA! I am grateful to have been introduced and accepted into your community! I am interested in all things light and its use in application. My education is BSEET/ABET from DeVry Institute of Technology, Phoenix 1999. I have eighteen years of engineering and technician experience in the following industries: Industrial Nd:YAG lamp and diode pumped laser markers from 3-100 W at IR/Green wavelengths of 1064nm and 532nm (rofin) Semiconductor stepper & scanner photolithography at UV/DUV wavelengths of 365nm, 248nm, 193nm, and 157nm (ASML USA/Veldhoven at Motorola, TSMC, Texas Instruments, Micron, and IBM) Aerospace metrology laser and radar trackers (Janicki Industries) Commercial HVACR R&D full life cycle product development testing for manufacturing (Legend Brands/Dri-Eaz Products) I look forward to working with you to progress the art and science of Ultraviolet Photography! Create a Great Day! Aaron

Hello everyone, They sell off the shelf ROVs that I would like to put my UV camera inside. Any suggestions how to fabricate a dome like this one that will pass UV light? The dome is about 9 inches in diameter. P.S. I have access to an industrial vacuform machine and a laser cutter.

Hello All I am excited to join this group and explore the world of UV photography. My interest are in "insect vision" or simulated insect vision. I work in the flower industry and am starting a little side project to learn more about the unseen variation in our crops. Other than being a nerd, I have no experience in UV photography and am planning on using this as a learning platform and hopefully in the near future share some images.

I just heard a radio interview of Adrian Horridge which you can download or listen to: https://www.abc.net.au/radionational/programs/scienceshow/new-ideas-on-how-bees-see/11878004 Dave

Hello everyone My name is Michelle, was born in Taiwan and immigrated to Texas many years ago. I am a Pentaxian, member of Texas Native plant society and amateur naturalist. I love hiking with my dog. I have a converted Pentax k-01 (full spectrum), Pentax K1ii and a few IR filters from Kolari vision. Pentax k1ii + Jaxman UV flashlight for UVIVF, Pentax k-01 for IR photography. Nice to meet you!

Visible (sunshine, Resolve 60mm quartz lens, S8612 1.75mm + DB850 filter, Sony A7S camera, F16 ISO200 1/60") UV-A (sunshine, Resolve 60mm quartz lens, 330WB80 filter, Sony A7S camera, F16 ISO3200 2") UV video of tiny insects or arachnids coming out of center of flower when UV light is shined on it. They would not come out for visible light. Click through to make it big to see them better. They are very very tiny. https://youtube.com/52LwcRVlzF8 Visible (halogen, Resolve 60mm quartz lens, S8612 1.75mm + DB850 filter, Sony A7S camera, F8 ISO80 0.4") UVIVF (Convoy S2+ torch, Resolve 60mm quartz lens, S8612 1.75mm + DB850 filter, Sony A7S camera, F8 ISO1600 15") SWIR (halogen, Wollensak 25mm lens, Thorlabs 1500nm LP filter, Triwave camera, and god only knows how to quantify the exposure for this.) This is a pano. In situ photo for ID help.

Our friend Adrian Horridge has just published a new book which makes "interesting" reading. The discovery of a visual system https://www.cabi.org/bookshop/book/9781789240894 Dave

Hello, I am not a photographer but I am very interested in understanding what honey bees see. I have access to three feral colonies of bees living wild in in East Sussex, UK. If anyone wants to investigate bee vision let me know. I am particularly interested in what bees see as they approach the entrance to their hives.

Hi All, I am a fungal ecologist in Sweden and have recently been analysing the colour variation in some of the fungi fruit bodies. This got me to wondering about UV reflectance in fungi and whether it would be worth following up as an avenue of research. For instance, do fungi which we think are likely dispersed by insects, but are quite inconspicuous in colour/smell have some sort of UV pattern that insects can see (similar to some flowers)? I know from other photos on this forum that fungi do light up quite spectacularly with UVIVF photography, but I am interested in just the UV reflectance for the purposes of my research. Before I either spend my own money or get research funds to buy the equipment to measure properly though, it would be fantastic if I could get some idea of whether there is likely to be any sort of UV reflectance from fungi. This is especially the case if I am going to make the argument to get research funds to buy equipment. So I was wondering if anyone here might have some UV reflectance photos of fungi that I could just have a look at? I wouldn't need to use these for research itself, just to give me an idea of what is possible. Thanks, Sam

This is not an article, rather it is a list of references, notes and charts which were made as I read about Bee Vision. Kindly note that my bee vision color charts are pure hogwash! They were fun to attempt, but do not represent authentic bee vision. Horridge is the Man, for sure !!!!! Adrian Horridge: Biological sciences, australian national University, canberra, acT, australia correspondence: adrian horridge 76 Mueller street, Yarralumla, acT 2600, australia Email horridge@netspeed.com.au Adrian Horridge What Does the Honeybee See? And How Do We Know? https://press.anu.ed...-how-do-we-know Superb!! May be downloaded free. http://adrian-horrid...rs%20on%20bees/ Horridge: How bees distinguish colors Abstract: Behind each facet of the compound eye, bees have photoreceptors for ultraviolet, green, and blue wavelengths that are excited by sunlight reflected from the surrounding panorama. In experiments that excluded ultraviolet, bees learned to distinguish between black, gray, white, and various colors. To distinguish two targets of differing color, bees detected, learned, and later recognized the strongest preferred inputs, irrespective of which target displayed them. First preference was the position and measure of blue reflected from white or colored areas. They also learned the positions and a measure of the green receptor modulation at vertical edges that displayed the strongest green contrast. Modulation is the receptor response to contrast and was summed over the length of a contrasting vertical edge. This also gave them a measure of angular width between outer vertical edges. Third preference was position and a measure of blue modulation. When they returned for more reward, bees recognized the familiar coincidence of these inputs at that place. They cared nothing for colors, layout of patterns, or direction of contrast, even at black/white edges. The mechanism is a new kind of color vision in which a large-field tonic blue input must coincide in time with small-field phasic modulations caused by scanning vertical edges displaying green or blue contrast. This is the kind of system to expect in medium-lowly vision, as found in insects; the next steps are fresh looks at old observations and quantitative models. Anti-intuitive-bee-vision.pdf Encycloped2015.pdf How bees distinguish black from white.pdf How bees distinguish colors.pdf How bees distinguish green-and-blue-mod.pdf How bees distinguish mirror images.pdf How bees use green-and-blue-modulation.pdf LostQueensAmerBee J.pdf Parallel inputs in bee vision of colour.pdf Tihany2015.pdf colorvisionAusBeeJ.pdf green-and-blue-mod_082515.pdf Lars Chittka Home Page http://www.sbcs.qmul...arschittka.html Chittka Publications http://chittkalab.sb....ac.uk/Pub.html Bee Sensory and Behavioural Ecology Lab Chittka Lab http://chittkalab.sbcs.qmul.ac.uk/ Floral Reflectance Database http://www.reflectance.co.uk/ Chittka, L., Shmida, A., Troje, N., & Menzel, R. (1994) Ultraviolet as a component of flower reflections, and the colour perception of Hymenoptera. Vision Research, 34, 1489-1508. Notes: Bee perceptual colour space is trichromatic with peaks of UV @ 345nm, blue @440nm, green @535nm. Bee colours are: UV, UV-blue, blue, blue-green, green, UV-green. Bees have two opponent channels. Bees see foliage as uncoloured. Bees do not discriminate brightness, i.e., they don't see black & white. 1063 petals from 573 flower species were studied. 68% of the flowers were UV-absorbing. There are no cyan flowers or UV-reflective black flowers. Green flowers are very rare (i.e., red-absorbtion is very rare in flowers). Most blue flowers have a red component. Orange or brown flowers were not included in the study. ******************************* From other papers (listed here: http://www.ultraviol...tanical-papers/), we have that: The longwave bee receptor peaks around 540nm but has an extended tail which tapers out at about 650nm. Bees can discriminate between green, yellow, orange and red reflecting objects regardless of an object's UV reflectivity. Some cues used for this are motion parallax and pattern and shape. Leaves moderately reflect green but also some UV and some blue. Leaves appear achromatic to the bee. In other words, bee colour models should include broadband spectral reflections of objects and not just monochromatic models. ******************************* In the Bee Colour charts below the flower colours and the mappings to the bee colours are taken from the above referenced paper - except for orange flowers which I added. Basic flower colours in the paper are blue, purple/violet, magenta/pink, white, cream, yellow and red. Orange, brown and green flowers are not considered. I note that Chittka uses a colour hexagon of dark magenta, blue and green to represent a bee colour space. Also note that the UV reflectivity in these charts is "all or nothing". This does not model reality well because we quite certainly have some flowers which are somewhere in between, neither UV-dark or UV-bright. I have not added green foliage to these charts. Cream coloured flowers, mentioned in the paper, are an unsaturated yellow. Bees do not discriminate brightness, but I have used 75% grey for the achromatic case. The bee vision colours produced by stimulation of their G and/or B receptors only (no UV stimulation) are easy to model with our human green, cyan and blue colours. For a flower coloured pure red having no UV reflection and thus no stimulation to any bee receptors, I've assigned a light grey colour. I suppose in a sense this flower colour (+R-G-B-UV) is a "bee-black" (-G-B-UV). But if bees have no brightness discrimination, then grey makes more sense in a model. Note, however, (and mentioned somewhere in one of the papers) that there prolly are not any "pure red" flowers in nature. Most all flowers we consider "red" also reflect some blue. It is when a flower colour reflects UV that we run into problems because we must assign some colour to the bee-colour "UV". As with red, there are prolly no "pure bee-UV coloured" flowers in nature, but we must include this in a model anyway. CHART 1: DID NOT WORK OUT For the first chart the bee UV-reflective colours are modeled with a 120º spread of colours from purple to orange (longwave to shortwavew). This mimics the 120º spread between blue & green for the bee UV-absorbing colours in such a way that UV-reflective and UV-absorbing colours do not overlap in any way. In this chart the bee-colour B+UV, or bee-blue, is assigned purple (128,0,255), the bee-colour G+UV, or bee-green, is assigned cerise (255,0,128) and the bee-colour UV, or bee-UV is assigned orange (255,128,0). Why do I not like this chart? Because for "bee white" - when all 3 bee receptors are stimulated equally - we wind up with a magenta representation. That is so very counter-intuitive. CHART 2: NO, DON'T LIKE THIS ONE EITHER For the second chart I decided to emulate "bee-white" with white which makes a little more sense to me. This permits yellow (255,255,0) to be assigned for UV-reflective yellow flowers, orange (255,128,0) to UV-reflective orange flowers and red to UV-reflective red flowers. Again we have the problem of using a model containing a colour which bees cannot see, but as a model it holds together better that the preceding chart, imho. At a glance any UV floral photograph coloured with this model would show which parts are UV reflective if you see colours having some amount of red in them. CHART 3: MAYBE A BIT BETTER? This chart is a result of my thinking that UV-reflective flower colours should be modeled with very light colours. I simply lightened the preceding UV-reflective bee colours to make this chart. The snag here is that if bees do not discriminate brightness, then light/dark colours in a model are not quite right. Oh well, a model is simply a model and not the real thing. ************* RED FLOWERS 23. Chittka, L. & Waser, N.M. (1997). Why red flowers are not invisible for bees. Israel Journal of Plant Sciences, 45: 169-183 http://chittkalab.sb...r_J_Pla_Sci.PDF Boundary between orange & red between 593nm and 625nm with a mean of 611nm. So red starts beyond 611nm. Bee visible spectrum reaches up to red at about 650nm, but bees discriminate single wavelengths only in the range from near UV 350nm to green 550nm. So when adjusted for equal brightness (Abney's law), monochromatic lights from green to red are indistinguishable for bees. Most flowers have simple broadband reflectance functions. Reflectance curves of many flowers are essentially step functions. (41% in experiment.) Red flowers of 3 types: UV peak, blue peak, red peak. reflectance peak below 400nm in the UV: bee sees bee-UV. Papaver rhoeas. substantial reflectance in blue: bee sees bee-blue. Dianthus carthusianorum. low reflectance over 300-600nm range & reflectance everything above 600nm. Ipomopsis aggregata. bee sees ? UV absorbing red flowers: Sarcotheca celebica, Mimulus cardinalis, Zinnia elegans, Salvia splendens(bumblebee), Lobelia cardinalis(bumblebee&solitaryBee), Nonea pulla. Also beetle pollinated Anemona coronaria, Ranunculus asiaticus, Tulipa agensis. There are several other examples of bee-visited red flowers whose UV reflectance still needs to be examined. Carpenter bees (xylocopa californica) rob the tubular "hummingbird" flowers of chuparosa, Justicia californica in warm deserts of the USA and honeybees secondarily use the resulting holes to obtain nectar. (N. Waser, unpublished). The same species of carpenter bee robs (but also pollinates) the red tubular flowers of ocotillo, Fouquieria splendens and these flowers also attract other solitary bees and honeybees along with many other insects and hummingbirds (Waser 1979). Red flowers visited by bees: Pedicularis densiflora, Penstemon centranthifolius, Corydalis cava, Peraxilla colensoi. Red flowers tend to be rare in areas that lack pollinating birds including central Europe. ******************* CONICAL CELLS & SPARKLE Glover, B.J. & Martin C. (1998) Heredity 80, 778-784 They argue that conical cell sparkling sheen bedazzles and attracts bees and perform an experiment about this. But(??) Dafni, Lehrer & Kevan Biol.Rev. 72, 239-282 say that angular resolution of a bee's eye is far too coarse for it to see sparkle. But bees easily learn to distinguish petals of different textures with their antennae or feet. Menzel, R. in Neurobiology of Comparative Cognition, 1990. BEES COLOUR PERCEPTION IS PLASTIC Reser, Witharanage, Rosa & Dyer (2012) Honeybees (Apis mellifera) Learn Color Discriminations via Differential Conditioning Independent of Long Wavelength (Green) Photoreceptor Modulation LINK BEE VISION: Each facet "sees" differently Wakakuwa, Kurasawa, Giurfa & Arikawa (2005) Spectral heterogeneity of honeybee ommatidia LINK INTERPRETING UV "COLORS" Kevan, Peter G. (1979) Vegetation and Floral Colors Revealed by Ultraviolet Light: Interpretational Difficulties for Functional Significance. Am. Journal of Botany. 66(6): 749-751

In the end of May last summer I found some Pasque flowers, still in bloom. Here in southern Sweden they are blooming quite early and I wasn't I wasn't sure I'd find any. The Swedish name of this flower is Backsippa, Here it is a rather rare, protected plant. My filter collection at the time was rather small, resulting in only four different image versions. I tried and failed using a PTFE-target for white balance. The target in the images was overexposed. White balance to taste, by clicking around in the images until a reasonable balance was found. All images reduced to 22% from the original raw-files. The big images has a lot more details. Camera: Canon EOS 60D, ISO100 . Lens: EL-NIKKOR 1:3.5 80mm Nippon Kogaku Japan, the first version of the old metal-type lens. VIS. Filter: S8612, 2mm. Exposure: 1/50s, f1/22: UV + B. Filter: S8612, 2mm + BG3, 2mm. Exposure: 0.4s, f1/22: UV + BG. Filter: S8612 + UG5, 1.5mm. Exposure: 0.8s, f1/22: UV. Filter: Baader U. Exposure: 4s, f1/22: In the second image the golden hues at twi the petals at the bottom is not due to saturation. The raw files was not saturated in any channel. Could it be conical cells? I have no idea what such cells are. Please explain. I want to learn.

I have recently been given a selection of mounted tropical butterflies (around 50 years old) and photographing them in visible and UV. Some interesting results, though not sure how scientifically useful they are. Just like flowers, UV of course is only a third or even a quarter of what the butterfly sees, so I am now working on some multispectral versions, though matching filters to the spectral response is proving tricky! Has anyone here done this? Some butterflies, such as longwings and swallowtails can see quite far into the red end of the spectrum. Interesting that the bright "flash" that we see on some wings disappears in a couple of the species. All images: Nikon D300 full spectrum conversion, with El Nikkor 80mm lens, and Baader U filter. Two "full spectrum" Metz 45 CL1 flashes, "white balanced" in Photo Ninja. !/160th @f/8, 400 ISO. Battus belus. Panacea prola, underside Papilio aeneas

Davies, A. (2017) Additional Example of Iris pseudacorus L. (Iridaceae) Yellow Iris. Plant photographed in visible light, ultraviolet and "bee vision". http://www.ultravioletphotography.com/content/index.php/topic/2251-iris-pseudacorus-yellow-iris-additional-example/ Location: Ashtead, Surrey, UK Synonyms: Comment: Iris pseudacorus is a flower of wetlands and pond edges found in spring through to early summer. Rørslett (2013) first showed Iris pseudacorus in ultraviolet(2). Reference: 1. Wikipedia (15 May 2017) Iris pseudacorus. Wikimedia Foundation, San Francisco, CA. https://en.wikipedia...ris_pseudacorus 2. Rørslett, B. 2013. Iris pseudacorus L. (Iridaceae). Yellow Iris. Flowers photographed in visible and ultraviolet light. http://www.ultraviol...us-yellow-iris/ Technical Details: Nikon D300S full spectrum conversion. 105mm El Nikkor lens. UV image: Baader U filter; "Bee vision" Schott UG5 and S8612 filter stack. Lighting: 2 x Metz 45 CL4 flashes "full spectrum" modification. Colour balanced in Photo Ninja using home made grey PTFE target. [Editor 22 May 2017: Added required page link. Added required reference to first I. pseudacorus on UVP. Added required scientific name to title.]

In the UK one of the earliest and prettiest wildflowers is the Primrose (Primula vulgaris). It is found in two forms - pin eyed (long style) and thrum eyed (short style) to enable cross pollination by insects. I wondered if the two forms might have a different UV signature? The answer appears to be no! They look identical in a UV reflected image. Full spectrum converted Nikon D300S, 80mm El Nikkor with Baader U filter.

I have been photographing Marsh Marigolds (Caltha palustris) in UV reflected recently (centre) , and tried an entirely backlit version (right) . An interesting result! Full spectrum converted Nikon D300S, El Nikkor 80mm, Baader U filter. Two "full spectrum converted" Metz 45 CL5 flash guns. 1/160th @ f/8

Here's an interesting review, together with good references which gives some idea of where the frontiers of insect vision lie at the moment: More than colour attraction: behavioural functions of flower patterns http://www.sciencedirect.com/science/article/pii/S2214574515001364 It looks like a good journal to keep an eye on Dave

EDIT 24 Jan 2017: I have added further explanations. Introduction This flower color template attempts to illustrate the reflected color appearance of a flower as seen by humans, a UV-pass camera, a bee having trichromatic UV/B/G vision and a chicken having tetrachromatic UV/B/G/R vision. I made this template to illustrate a point elsewhere. But I think it might be useful to give it its own thread so that others could use the idea to work out what a particular subject might look like if viewed by an animal with vision differing from the human RGB. Warning: This attempt at illustrating insect or animal vision is very much oversimplified. I cannot emphasize that enough! The physiology and neurology and behavioral characteristics of bee vision or chicken vision is so very complex that we have no real way to show what the creatures see. We can only model small parts of it and then stand back and admire its magnificence. Notation: R = red G = green B = blue UV = ultraviolet IR = infrared Reference Chittka, L., Shmida, A., Troje, N., & Menzel, R. (1994) Ultraviolet as a component of flower reflections, and the colour perception of Hymenoptera. Vision Research, 34, 1489-1508. Color Reflectance & Absorbance Notation In the preceding paper the authors use the following notation indicate the absorbance or reflectance of a particular color X by a subject. +X = colour X is all or mostly reflected -X = colour X is all or mostly absorbed +x = colour X is partially reflected -x = colour X is partially absorbed We are always applying a judgement call as to how much we think a particular colour is absorbed or reflected by any subject. But for a simple diagram, it's best not to overthink it. Human-Invisible Colour Notation: UVcolorName Any combination of one reflected RGB colour and reflected UV is a human-invisible colour, of course. I've been writing names of these human-invisible colours using a compound colour name: UVred for +R-G-B+UV, UVgreen for -R+G-B+UV, UVblue for -R-G+B+UV, and so forth. This or similar naming is common in the scientific literature. In the diagram I've indicated these human-invisible colours by adding patterning to the underlying reflected colour. This is not particularly scientific, but it serves the purpose. (We could alternately add fine striping or even use contrasting colours not in the animal's spectrum.) Assumptions The bee has green, blue and ultraviolet visual receptors, so how does it see a color such as reflected yellow? In additive light, reflected yellow may be a combination of reflected red and green light with blue absorbance, +R+G-B. But yellow may also have its own reflected wavelength, not a combination of red & green. For this diagram I have simplified the matter by assuming that both reflected +R+G-B yellow and a yellow wavelength would stimulate only the bee's green receptor. Other colors are treated similarly: reflected yellow wavelength or yellow as +R+G-B = +G, green to the bee reflected violet wavelength or violet as +r-G+B = +B, blue to the bee reflected orange wavelength or orange as +R+g-B = +g, dark green to the bee reflected brown wavelength or brown as +r+g-B = +g, dark green to the bee reflection of all RGB wavelengths +R+G+B = white = +G+B, cyan to the bee magenta which can only be +R-G+B = +B, blue to the bee Diagram First row, left: Human Vision This is how we humans would see a flower such as a Sunflower which has yellow or orange-tinged yellow rays and a dark brown central disk. First row, center: Camera Vision, UV-only This is the flower as seen by a UV-capable camera fitted with a UV-pass (only) filter on the lens. In only UV light, the flower ray tips reflect UV and the bases of the rays absorb UV. The flower's central disk also absorbs UV. Any color seen in a UV photograph is false colour which is a by-product of the fact that the UV light passes through the dyes of a Bayer filter and is thus recorded in the camera's color channels. The key point to make is that strongly reflected UV is recorded as whites or very light greys or very bright false colours in such a photograph while absorbed UV is recorded as blacks or dark greys or very dark false colours. Moderately reflected (or absorbed) UV is of course somewhere in between these two extremes. First row, right: Camera Vision, UV/B/G filter stack If the lens is fitted with a filter stack which passes large amounts of reflected UV together with small amounts of reflected blue and reflected green light, then we begin to take a step in the direction of emulating trichromatic UV/B/G bee vision. This filter stack maintains the areas of UV absorbtion and UV reflection seen in the UV-only photograph, but there may alterations in the tonality in UV absorbing areas if such areas happen to reflect some blue or some green as a component of the flower colour. Be sure to note that with this filter, the colours recorded by the camera should also be considered false colours because we cannot know exactly how the UV signals will combine with any blue and green signals when passing through the camera's Bayer filter. Another assumption here is that in order to correctly derive any blue and green colours passed under the UV/B/G filter stack, we must make a white balance setting either in the camera or in the raw file converter. The white balance setting would affect both actual colors and false colors. The flower's dark brown central disk reflects small amounts of red and green light while absorbing UV and blue light. After passing through the UV/B/G filter stack, passing through Bayer filter and being subjected to a white balance adjustment, the reflected light is recorded as a dark green. The flower's yellow ray bases reflect red and green light while absorbing UV and blue light. After passing through the UV/B/G filter stack, passing through Bayer filter and being subjected to a white balance adjustment, the reflected light is recorded as a slightly brighter green. CHECK THIS The flower's yellow ray tips reflect red, green and UV light while absorbing blue light. After passing through the UV/B/G filter stack, passing through Bayer filter and being subjected to a white balance adjustment, the reflected light is recorded as bright yellow. Second row, left: Bee Trichromatic UV/B/G Vision To step to a better colour modeling of bee vision, we must consider how to handle UV-reflecting areas recorded under the UV/B/G filter stack. Remember, from above, that when UV is reflected along with some other RGB colour, we have the human-invisible colours like UVblue, UVgreen or UVcyan. And remember that we are assuming for simplicity that reflected yellow stimulates the bee's green receptor. Thus UVyellow will be considered as UVgreen. There is more than one way of modeling, for example, a bee's UVgreen. In this diagram I've chosen to add a kind of patterning to the areas which reflect both UV and green. This modeling might fail with any subject which has similarly patterned areas! But so far, for flowers, we are OK using this.

Here once more is my (recently often seen) Bouquet which was so vibrant in Visible light. And here is the reflected UV Bouquet in monochrome so as not to be confused by any false colours. As a reference, I also extracted the reflected Red, Orange, Yellow and Green from the Bouquet. (There is no reflected Blue, Magenta or Cyan in this scene.) Red Orange Here is the Green component of the reflected-Orange. Approximately. Yellow Green Bees have receptors for UV, Blue and Green. I figure that we'll give the Bee the benefit of the doubt and assume that it can see a bit of Yellow or Yellow-Green, too. (Seem to recall that from all my reading last year.) Any flower in this Bouquet which absorbs UV and reflects blue/cyan/green/yellow will appear to the Bee to be blue/cyan/green/yellow and thus easily emulated by - you guessed it - blue/cyan/green/yellow in my Bee Vision Bouquet. For any UV-absorbing, red-reflecting flower, I'll assume the Bee will "see" black/grey tones because no visual receptors are stimulated. For an orange-reflecting flower, I'll assume the Bee can detect the green component so orange flowers will appear greenish or yellow-green to the Bee. But, how to model the UV-reflecting areas on the flowers which also reflect one of the RGB colours or combinations? For example, the orange Lilies in this bouquet are a combination of red-reflection, green-reflection and UV-reflection in some combination. To the Bee, these Lilies are "UVgreen" (maybe a little bit UVgreen/yellow.) UV-Green is a real colour to the Bee, but to us it is an imaginary colour. So I decided to paint any UV-reflecting areas of the Bouquet with a Motley Color Mix such as is never seen on a real flower in order to startle us into recognizing that the Bee sees UV reflecting areas very differently from the way we do. So what do you think? I had fun. Bee Vision Bouquet This will click up to a larger size in an expanded browser. Here is an unresized crop from the sunflower rays and mum rays whose tips and petals are UV-reflecive and yellow-reflective. This is an unresized crop from the orange-reflective and UV-reflective lily petals.

EDITOR'S NOTE: The other thread had gotten long enough. Some good things were learned there! I have some additional work with these filter stacks to post so we can continue to discuss the "ideal" bee vision filter stack. Of course, I doubt there is an ideal filter stack for this kind of work, but we will enjoy talking about it. :) Discussion: UG5 + IR-Cut Filter Stack, Part 1 I made some UvGB photos of a red Gerbera Daisy using my Hoya U-330 UV-pass filter stacked with different S8612 IR-blockers. Some little breezes were encouraging the flowers to dance, so I stayed at f/8 instead of my usual f/11. The filter stack which worked best to block red in the UvGB photographs was the Hoya U-330 stacked with two S8612 IR-Blockers, 1.75 mm and 2.0 mm in thickness. Shots were made of white reflective standards and a CC Passport in order to create visible, UV and UvGB colour profiles in Photo Ninja. Some of that is lost after resizing and embedding an sRGB profile for online display. Equipment: D600-BB + UV-Nikkor 105/4.5 + Sunlight Visible Reference[ f/8 for 1/10" @ ISO-400 with Baader-UVIR Cut Filter ] UV Reference[ f/8 for 1.3" @ ISO-200 with BaaderU UV-Pass Filter ] Equivalent to f/8 for 1/1.6" @ ISO-400. UvGB[ f/8 for 1/10" @ ISO-400 with Hoya U-330 UV-Pass (1.5 mm) + S8612 IR-Block (1.75 mm)] UvGB[ f/8 for 1/10" @ ISO-400 with Hoya U-330 UV-Pass (1.5 mm) + S8612 IR-Block (2.0 mm)] UvGB[ f/8 for 1/10" @ ISO-400 with Hoya U-330 UV-Pass (1.5 mm) + S8612 (1.75mm) + S8612 IR-Block (2.0 mm)] Two S8612 filters.