Even if you have a good command of using f-stop numbers and properly exposing photographs, you might not understand the math behind why f-stop numbers are what they are. Here’s a simple (albeit math-filled) explanation by Dylan Bennett of what f-stop is, including a simple trick you can use to memorize the f-stop scale.
Posts Tagged ‘exposure’
Adam Dachis over at Lifehacker offers a simple method for correcting underexposed photo with any image editor that supports layers, inversion, and Overlay blending mode. Simply create a duplicate later, invert it, set the blending mode to Overlay, and then adjust the opacity to suit your taste. While it’s certainly not a pro photography trick — other techniques including adjusting the curves and levels may be better — it’s a quick and easy tip that may be good to know.
On January 1st of last year, photographer Michael Chrisman began shooting a solargraph by placing a pinhole camera in the Port Lands of Toronto and aiming it at the city’s skyline. Over the next 365, the rising and setting sun slowly exposed the photo paper inside. The total exposure time? 31,536,000 seconds. Instead of developing the image using traditional darkroom chemicals, he instead used a scanner to capture the extremely overexposed image — destroying the original image in the process — and ended up with the photo you see above. Those yellow lines you see in the sky shows the gradual shifting of the sun’s path over the course of 2011.
(via Toronto Star)
Image credit: Photograph by Michael Chrisman and used with permission
This might look like some kind of microscopic organism, but it’s actually a high-speed photograph of a nuclear explosion. It was captured less than 1 millisecond after the detonation using a rapatronic camera, which is capable of exposure times as brief as 10 nanoseconds (one nanosecond is one billionth of a second). The photograph was shot from roughly 7 miles away during the Tumbler-Snapper tests in Nevada (1952). The fireball is roughly 20 meters in diameter, and three times hotter than the surface of the sun.
Kaufmann’s Posographe is an intricate pocket-sized mechanical calculator invented back in the 1920s. Measuring 13x8cm and filled with tiny scribblings, the device allowed photographers to approximate the exposure values they needed by simply sliding around six small pointers.
“Exposing to the right” is a well-known rule of thumb for maximizing image quality by pushing exposure to avoid noise, but the equation is changing as the quality of image sensors continues to improve. Ctein over at The Online Photographer writes,
In theory, you can still use the dubious right-hand rule. Just be careful to never blow out any pixels.
[...] Unless you’re sure you’re dealing with a low contrast subject, pushing your exposure to the high side makes it likely you’ll blow highlights. If you’re trying to improve your odds of getting a good exposure, pulling away from the right is a much smarter thing to do. If you know your subject is really high in contrast, pull far, far away from the right. Keep those highlights under control and let the shadows go where they may.
[...] Just, whatever you do, don’t expose to the right unless you’re absolutely positive there are no highlights to get blown. It was a questionable rule to begin with; these days I call it downright dangerous.
‘Expose to the Right’ is a Bunch of Bull [The Online Photographer]
Want to challenge yourself by shooting manually without a light meter? Head on over to eBay and pick up a Johnson “Standard Exposure” Calculator for less than $10. Released in the late 1940s, it’s a simple rotary device that lets you calculate the proper exposure by choosing the current scene, weather, exposure time, and film speed. Find more about these exposure calculators over on photomemorabilia. You can also check out the Exposure-Mat for a printable card that helps calculate exposure too.
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…
It’s the end of an era. Photojournalist Steve McCurry has developed the last roll of Kodachrome film produced by Kodak.
National Geographic has been following the final journey of the last Kodachrome roll ever since Kodak’s announcement last year that it would retire Kodachrome. Kodak has been manufacturing Kodachrome since 1935.
McCurry developed 36 slides on Monday at Dwayne’s Photo Service in Parsons, Kansas, which is the last labs to process the film type. The final images were shot in New York City, but the last three frames were taken in Parsons.
If you’ve got undeveloped canisters of Kodachrome of your own, Dwayne’s will develop them only through December of this year.
(via Associated Press)
Image Credit: Old Kodachrome canisters by Ryan Sahb
On the same day I was experimenting with the light painting I described in a post yesterday, I also fiddled around with long exposure portraiture. I had my buddy Aaron pose for me at his desk in near darkness. The only sources of light in the room were his laptop screen, a few LED flashlights that I placed on his desk in various directions, and a lighter that Aaron held in his hand.
Here’s the original, unedited photograph that resulted:
It was taken with a 10 second exposure at ISO 100. It was probably a mistake to use such a low ISO, since I could have gotten the same exposure with less time if I had used a higher number. Every time the ISO number doubles, the shutter speed is cut in half for the same exposure (assuming aperture is kept constant). This is pretty intuitive, since if you double the sensitivity of your film, you’ll only need half as much time to expose it with the same amount of light.
Keeping the aperture at a constant f/8, here’s what the difference would have been.
ISO 100 – 10 second exposure
ISO 200 – 5 second exposure
ISO 400 – 2.5 second exposure
ISO 800 – ~1.25 second exposure
ISO 1600 – ~.75 second exposure
Luckily, Aaron was able to hold still enough to not appear too blurry in the photograph, making it acceptable when viewed at a normal web resolution. If it were to be blown up or printed, the faster shutter speed would have helped a lot.
Here’s a crop showing the different small sources of light that I used to illuminate the scene:
What I found interesting about lighting up the scene this way was that each of the sources of light were a slightly different color temperature, giving the scene an interesting look in terms of colors and lighting.
During post processing, I increased exposure a little, did a little recovery, added a splash of fill light, and pushed contrast up a little. Here’s the final image (hover over it to compare it to the original):
If you’re looking for something new to learn and photograph, try your hand at taking longer exposure portraits with unconventional sources of light. Just find a friend that can hold still!