Saturday, November 15, 2014

Kenko 1.4x Extender Tradeoff

After having used the Kenko 1.4x extender this afternoon, I started wondering if that had been a good idea. Am I better using the tele-extender to increase resolution or am I better simply enlarging the image? This evening, I setup a test chart, placed at 30' from the camera, and used the Canon EF 100-400mm f/4.5-5.6L IS with and without the extender. After importing the images into Photoshop, I enlarged the images taken without the extender by 140%. This gave both sets of images the same pixel resolution.

The results are shown below (you may want to click on the images to view a full-sized version). Not unexpected, the image quality is degraded by introducing the extender, whose optics are not as good as the lens. For the coarse details, the image quality is better with the enlarged, 400mm image, both in terms of sharpness and contrast. For fine-grained detail, however, the story is not so simple. The contrast is still better at 400mm but, a some point, the details are simply too fine to resolve at 400mm.

Not sure exactly how this applies to a bird image. I am thinking that for the Brown Booby images, where pixelation was noticable, I was better off using the extender. For the Osprey shots, I am not sure.

With Kenko, 560mm f/8, original resolution
Without Kenko, 400mm f/8, image size increased in Photoshop by 1.4x to match pixel resolution
Without Kenko, 400mm f/5.6, image size increased in Photoshop by 1.4x to match pixel resolution

Hunt for the Brown Booby

On a rare bird alert from eBirds, we went to the Bob Wentz Park on Lake Travis early last Saturday afternoon, looking for a Brown Booby that had been seen repeatedly around Windy Point. We hiked around the perimeter of the exposed land south of the park since most of the recent sightings had been towards the dam.

Google map with annotations
We saw a large raft of mixed duck species, a large number of coots, and a few cormorants. We even saw a formation of Sandhill Cranes flying over head. However, we were disappointed not to see the Booby. We may have been at the park too late in the day.

This morning, we got up early and returned to the park before 9:00 am, despite the cold and dreary weather. Danielle suggested we stay at the parking lot which overlooks the area and scope the area first. We immediately saw three Ospreys soaring to the south. Within ten minutes, Danielle spotted the Booby north west of the park in the direction of the marina.  It was identifiable in the binoculars but a bit out of reach for a decent photograph.


Despite the distance of over 2000, the Brown Booby was clearly recognizable with its strongly demarcated white breast and belly and huge webbed feet. The bird was plunge diving from a low height. As it fished, it slowly drifted further up-river and we lost track of it after about 30 minutes. It is hard to imagine what this bird is doing in Lake Travis in central Texas as it is a tropical bird which spends most of its time at sea, coming to nest on tropical islands during breeding season.

Canon 7DII, EF 100-400mm f/4.5-5.6L IS + Kenko 1.4x - ISO-1600, 560mm, f/8, 1/1000 sec

The Ospreys continued to soar in our vicinity and we were able to get some close views.

Canon 7DII, Canon EF 100-400mm f/4.5-5.6L IS + Kenko 1.4x - ISO-1600, 560mm, f/11, 1/1250 sec
Canon 7DII, Canon EF 100-400mm f/4.5-5.6L IS + Kenko 1.4x - ISO-1600, 560mm, f/10, 1/1250 sec
Canon 7DII, Canon EF 100-400mm f/4.5-5.6L IS + Kenko 1.4x - ISO-1600, 560mm, f/10, 1/1250 sec
Canon 7DII, Canon EF 100-400mm f/4.5-5.6L IS + Kenko 1.4x - ISO-1600, 560mm, f/16, 1/1250 sec

Sunday, November 9, 2014

Sandhills are Migrating

This weekend, we went birding at Bob Wentz Park on Saturday and Pedernales Falls SP on Sunday. At both locations, we saw migrating flights of Sandhill Cranes. Here is the formation seen from the bird blind at Pedernales Falls SP.


Yellow-Rumped Warbler at PFSP

While on our quest for the Dusky-capped Flycatcher, one of the first birds we saw at the Pedernales Falls SP bird blind was this Yellow-rumped Warbler.  This is only the second one I have seen, the first one being at the pond at Balmorhea SP.

Canon 60Da, EF 100-400mm f/4.5-5.6L IS, 400mm, f/5.6, 1/400 sec, ISO-400

Dusky-capped Flycatcher at Pedernales Falls SP

We went to Pedernales Falls SP this afternoon in search of a reported Dusky-capped Flycatcher. The Travis Audubon Society Rare Bird alert had first reported a sighting Oct. 25, and the most recent sighting was yesterday. The range maps in our bird guides show this species only in South East Arizona, the Davis Mountains, and the Lower Rio Grande Valley, and then only in summer. Seeing one in Central Texas in November would indeed be a rare sight.

We stayed at the bird blind from 13:30 to 17:00 and got our best view of the likely bird around 14:30. We also heard the quiet, plaintive, falling peee-uur call that would be consistent with this species, though not at the same time as we saw the bird. We observed the bird in the low trees between the gate and the newer of the two bird blinds as well as from inside the blind itself. We gathered our notes and pictures to compare against the bird guides.

The pictures below show two key field marks that support this as a Dusky-capped Flycatcher rather than one of the other similar Myiarchus sp. common in this area. First, note the strong rusty edges on the tail feathers and, importantly, the lack of rufous color on the underside of these tail feathers. In addition, note the edges of the secondaries in the second picture. These are clearly rufous edges rather than the white edges seen on the other species.


Canon 60D, EF 100-400mm f/4.5-5.6L IS, ISO-800, f/5.6, 1/640 sec, Flash

Canon 60D, EF 100-400mm f/4.5-5.6L IS, ISO-800, f/5.6, 1/1000 sec, Flash


Wednesday, November 5, 2014

Danielle Raises a Monarch Caterpillar

This year, we planted a number of Tropical Milkweed plants in the yard to provide food for Monarch butterflies and their caterpillars. We started seeing Monarchs in the yard during October.


On Oct 22, Danielle found this caterpillar on the plants and brought it, and some milkweed, into the house to keep it safe from birds.


A few days after she brought it in, it formed a chrysalis at the top of the terrarium. Over the two weeks it slowly developed, darkening, and eventually becoming transparent and releasing its butterfly today on Nov 5.





Things started to go wrong at this point. The butterfly broke out of the chrysalis on its own but was not able to hold on. Several times, Danielle picked it up and placed it carefully on a branch to hang while its wings formed and stiffened.




Though the wings did eventually fully "inflate," the butterfly kept losing its perch. Much to our distress, it did not survive long enough to fly away. Upon further reading, Danielle concluded that this outcome is consistent with parasitization by the protazoan Ophryocystis elektroscirrha (OE)

Monday, November 3, 2014

Fun Images from Airplane

Here are some fun pictures I took with my phone while on the airplane to and from Deanna's memorial service.  On the out to Las Cruces, I took this shot showing the oil field activity around Toyah, TX. These were mentioned as a serious source of light pollution on my last visit to the McDonald observatory. I can see why - fracking as far as the eye can see.


As I took off from El Paso on the way back, I got this aerial shot of the airport, including my brothers out-bound plane which was boarding.


Finally, on my second leg, I looked out the window and notice that the engine cowling was polished metal. Waving my hands, I found that I could pick out my own reflection. Perhaps the first selfie taken through an airplane window.