Posts Tagged ‘uv’
High-resolution photography is seemingly where it’s at in today’s day and age. NASA knows this, and as such, astrophysicists at both the Goddard Space Flight Center (GSFC) in Maryland and Pennsylvania State University have stitched together a remarkable 160-megapixel UV image of the Large and Small Magellanic Clouds — our two closest neighboring galaxies (less than 200,000 light years away). Read more…
Typical photography exists around the visible spectrum (think of the rainbow), but cameras are also able to pick up other wavelengths of radiation. Ultraviolet radiation, as the name suggests, comes after the violet section of the visible spectrum so is not visible to our eyes. However, some animals (birds, for example) are able to see UV.
UV reflectance photography essentially is recording the UV radiation which is reflected back from a UV source. A UV source emits UV radiation, and this is often referred to as UV light. However UV light does not exist, since light is visible and UV is not! UV reflectance is a fairly involved and arduous process without specialized equipment, however the results can be very rewarding.
Ultraviolet fluorescence is a mechanism in which UV radiation excites chemicals in an object and causes them to release visible light. There are many household objects which fluoresce, such as some washing detergents (anything that ‘makes your whites whiter), soda water (it contains a chemical called quinine which makes it taste bitter, and also causes the fluorescence), the dyes found in highlighters, the bacteria found on the face (which cause spots and acne), bodily fluids (including urine) and much more.
UV lens filters are a popular way to protect the front element of lenses from damage, but you should make sure you invest in a high-quality one unless you want to make a huge sacrifice in image quality. Reddit user EvilDoesIt shot the photos above comparing a cheap filter with a pricier one:
The top one is a $20 Quantaray UV filter. Bottom is a ~$70 B+W MRC UV filter. This is a more extreme example, but it shows the difference between a nice filter and a crappy cheap one. Both these shots are unedited JPEGs from my Nikon D7k with a Nikkor 17-55 ƒ/2.8 @ 1.3s ISO100.
I do realize that the top pic can be easily fixed by adjusting levels, but in my opinion, it’s always better to get the best picture you can get out of your camera before editing. [#]
His last sentence is a gem: to achieve the best images, you want to make sure you’re squeezing out the best image quality you can from each step along the way.
Image credit: Photographs by EvilDoesIt and used with permission
You may have heard that digital cameras can be made sensitive to infrared light by removing the IR filter found inside, but did you now that something similar can be done with the human eye? People who have aphakia, or the absence of the lens on the eye, have reported the ability to see ultraviolet wavelengths. Claude Monet was one such person. Carl Zimmer writes,
Late in his life, Claude Monet developed cataracts. As his lenses degraded, they blocked parts of the visible spectrum, and the colors he perceived grew muddy. Monet’s cataracts left him struggling to paint; he complained to friends that he felt as if he saw everything in a fog. After years of failed treatments, he agreed at age 82 to have the lens of his left eye completely removed. Light could now stream through the opening unimpeded. Monet could now see familiar colors again. And he could also see colors he had never seen before. Monet began to see–and to paint–in ultraviolet.
[...] With his lens removed, Monet continued to paint. Flowers remained one of his favorite subjects. Only now the flowers were different. When most people look at water lily flowers, they appear white. After his cataract surgery, Monet’s blue-tuned pigments could grab some of the UV light bouncing off of the petals. He started to paint the flowers a whitish-blue.
The lens on a human eye ordinarily filters out UV rays, so we don’t see many of the things certain animals see. For example, the males and females of some butterfly species look identical to the human eye but very different to UV-sensitive eyes — the males sport bright patterns in order to attract the females!
Glow Graffiti is an aerosol can-style light painting tool similar to the one by artist Aïssa Logerot that we featured back in September. It’s powered by a UV light rather than the interchangeable LED lights used by Logerot, but the Glow Graffiti comes with a special UV-sensitive backdrop on which paintings are visible for around 30 seconds (the kit contains letter stencils too). You can pick up a set for $39 from Photojojo or Amazon (it’s prime eligible).
One of the benefits of running a gear rental business is that you have a ton of equipment you can use for random experiments. That’s exactly what Roger Cicala, the owner of LensRentals, did with the UV filters he had on hand. One-upping the 19 filter stack we shared a while back, he mounted 50 different UV filters to a Canon 5D Mark II and 300 f/4 lens to see what the resulting images would look like.
Future generations of photographers may one day look back and wonder why we often blinded each other with painfully bright flashes of light for the sake of proper exposure.
NYU researchers Dilip Krishnan and Rob Fergus are working on a dark flash that eliminates the “dazzle” effect of regular flashes in a low-light room. They’ve created this camera rig that combines common infrared photography techniques with an ultraviolet flash that produces a dim purple glow instead.
The team placed an infrared filter on the lens of the Fujifilm S5 Pro, which is has a modified CCD sensor that specializes in IR and UV photography. To supplement existing UV light, the team created a modified filter on an external flash to emit only UV and IR wavelengths. Read more…