POTW #4: An experiment in HDRI

underexposure
middleexposure
overexposure
TonemappedImage

Finally, a POTW that isn't a macro of a small animal. This photo shows the UCC church across the street from Wilder. Briefly, this scene had a very wide dynamic range, but the dynamic range that can be captured in a single jpeg is low. To retain detail in highlights and shadows, I took 3 exposures (left, click to view larger), all the same aperture (f/8) but different shutterspeeds (1/100, 1/25, 1/6 sec) and merged them into a single image. Continue reading POTW #4: An experiment in HDRI

  

POTW #2: Dragonfly Macro

Dragonfly

This Lancet Clubtail (Gomphus exilis) was shot near Rockport, MA. Click to see a larger version; the wing detail is pretty cool. These dragonflies eat mosquitos; so they're good guys in my book, but they don't eat enough of them to totally protect the innocent nature photographer. I got pretty bit up in the wetland area where this was taken.

Another cool thing about dragonflies: they have nearly a 360 degree field of view. They use the fact that they can see behind themselves to emply a technique called motion camouflage. The dragonfly chooses a distant landmark, and as it approaches its moving prey it stays on the prey's line of sight to the landmark. That causes the prey to perceive the attacking dragonfly as stationary. The dragonfly appears to just get larger while staying in the same place until it hits the prey.

  

POTW #1: Squirrel by the Sphynx

Squirrel

Nathaniel suggested I post a photo of the week (POTW) on the blog. Here is the first, a squirrel in a tree near the sphynx. What do you think? (click image for a larger version)

technical specs:
shutter: 1/160, aperture: f/3.5, focal length: 72mm (432 mm in 35mm equivalency) distance: about 4 meters

Additional notes: In a high contrast image taken with a digital camera, it can be difficult to avoid chromatic aberration (CA), which often appears as purple fringing at the boundaries between light and dark in the image. This is caused by a few things:
1) the red and blue pixels on the CCD are more sensitive to IR than the green ones,
2) IR is focused differently than visible light by the lens
3) I think the interpolation from the RGB images probably has a hand in it too.

This image showed some CA at the lower edge of the branch and around the leaf stem in the bottom of the frame. I removed the purple fringes by desaturating magenta in the GIMP. See the before and after below (this image is also clickable to enlarge):

CA detail
Note that the "corrected" image has also had some adjustments to levels and curves.