Tuesday, November 24, 2009

Northern Bobwhite

Northern Bobwhite, adult male, TX in April

I was on a ranch in Raymondsville TX looking for Ferruginous Pygmy-Owl when a small covey of Bobwhites dropped into the feeder. In NJ (where I've seen precisely one) the birds are skittish but they were obviously not feeling threatened and used to the human activity in this area. They weren't totally tame, and sped up as they walked past me. I ended up lying on the grass shooting the quail hand-held with the 1D Mark III as they wandered past me or fed on grain. This is always a little more exciting in a region that has fire ants, but I got away with it this time.

Thursday, October 22, 2009

Short-billed Dowitcher

Juvenile, NYC in September

This is a classic juvenile Short-billed Dowitcher shot from a low angle (lying in the mud) at Jamaica Bay WR toward sunset. This was shot with the digital Rebel XTi, which doesn't always produce exceptional images but does well on well-lit subjects at low ISO.

Wilson's Phalarope

Tuesday, October 13, 2009

Tests on 5D Mark II settings

Prompted by discussions with a friend concerning his new 7D I did the following tests on my 5D Mark II :

1. Default Picture Code settings do not affect RAW file appearance in Lightroom. Not a great surprise this, since RAW files are supposed to evade most or all processing policies that effect in-camera JPG files. I shot an IT8 target with RAW+JPEG. Of interest was that there was some difference in color reproduction in the reds between "Faithful" and "Neutral" in the JPGs.

2. High ISO Noise Reduction settings do affect RAW appearance. This test was shot against a defocussed white wall (i.e. "featureless" image) at 2 stops underexposure at ISO 1600. There was a marked difference in appearance of the JPG files, with much less evident grain in Standard and Strong settings than at Low or Disabled. Standard was fairly close to Strong. This pattern was also evident in file sizes (more noise = larger files). For the RAW files there was a subtle difference for the same shots - more or less invisible for the lower ISO (400?) that I tested the previous evening but just visible at ISO 1600. I did not test sharpness reduction, but that's the usual trade-off. Canon, however, in this document, indicate that Adobe Camera Raw ignores this setting.

3. Noise patterns at all ISOs. Everything from 100 to 3200 in 1/3 stop increments with the same -2 stop underexposure as the previous test. Notably, stops 1/3 below the "standard" ones showed less noise, but also a little more exposure. In fact for ISO 160 the featureless noise shots perhaps showed nicer noise appearance than ISO 100. The 5D Mark II has this tendency to produce grid noise artifacts at lower ISOs. The ISO 1/3 stop above the standard ones fared least well. This pattern has been commented on previously at the Dpreview.com forums, and despite the high bs level much of the content in those forums, it appears to have a basis in fact.

Central Park, October 6th

Black-throated Blue Warbler (first fall male)

Scarlet Tanager (first fall male - notice the molt limits in the coverts)

Thursday, September 3, 2009

More megapixel obsessions

Starting this May I largely stopped using the professional level EOS-1D Mark 3 and have subsequently mostly used the EOS-5D Mark 2. The autofocus performance of the latter is quite a lot worse, particularly in flight, but I had found that the images were noticeably sharper in some instances and generally had more "pop". I still use the 1D3 for flight shots.

I process RAW in Lightroom so in principle things will be normalized but there is a real difference in image quality. The 5D2 has many more pixels (21.1 Mpix vs 10.1), and more per square mm since the 1D3 pixel density is equivalent to 10.1*1.3*1.3 = 17.1 Mpix. The factor of 1.3 comes in because the APS-H sensor on the 1D3 is smaller than the full frame 5D2. The 5D2 appears to be sharper even on a per-pixel basis probably because of a weaker aliasing filter.

Enter the newly-announced Canon 7D which is the common APS-C sensor size (1.6x crop factor) and 18 Mpix. Running the numbers the 7D pixel density is equivalent to 17.9*1.6*1.6 = 45.8 Mpix on a full frame size. No, that's not a typo. It has twice the pixel density of the 5D2 and almost 3x that of the 1D3. You can't ignore that.

There will be the usual concerns about noise level at higher ISOs, and how much actual sharpness you can realize off any lens combination. If you shoot the 17-40/4L wide open the actual resolution of the lens is worse than that of the chip. However the supertelephotos that I use have a lot of inherent sharpness. Some of that sharpness is lost when using the 1.4x teleconverter - it's not difficult to see that in test shots but I can also see it in real life photos in the rare situations when I get to take the 1.4x off.

Which brings me to the thing that most excites me about the 7D - thinking about the number of megapixels on the subject using different lens combinations. This is the same thing as considering pixel density, but adding in a factor for focal length conversion. The equation normalized to full frame is pretty simple:

Effective pixels = Mpix * chip-factor * chip-factor * focal-length-factor * focal-length-factor

Chip factors are 1.0 for the 5D2, 1.3 for APS-H like 1D3, 1.6 for APS-C like 7D. Focal length factor is normalized (i.e. 1.0) to a 700mm f5.6 which is what I use with the 500mm/f4L + 1.4x. (Edit: updated for a 16 mpix APS-H EOS-1D Mark IV, aka 1D4).

These are in Mpix on a "subject" of the same nominal size, so bigger = better.

1D3 1D4 5D2 7D
500mm 8.7 13.9 10.8 23.4
600mm 12.6 20.2 15.5 33.6
500+1.4x 17.1 27.4 21.1 45.8
800mm 22.3 35.7 27.5 59.8
600+1.4x 24.6 39.4 30.3 66.0

The absolute #s are not relevant because you couldn't image a subject with that many Mpix on it, but the relative numbers hold. I could shoot with the bare 500mm f4 on the 7D and have more pixels on a subject than the same subject with the 500mm+1.4x on the 5D2. Depending on how much these lens combinations outresolve the 7D sensor, and issues with the aliasing filter, the 7D could resolve as much as twice as much detail as the 5D2 for telephoto-type subjects where the subject does not fill the frame. The 5D2 still wins for landscape subjects where the 1.6x crop factor on the 7D kills the widest focal length one can achieve.

Apart from sharpness the wider apertures of bare lenses w/o teleconverters allow lower ISOs or faster shutter speeds to be used in dark conditions. As the analysis indicates it's worth taking a very hard look at this camera for bird subjects because there might be a substantial effective resolution gain. Remains to be proven, however, as many factors can come into play to degrade image quality.

Update: the general vibe on the Dpreview forums is that the 7D has lower image quality than the 5D Mark II - this not really being a surprise since it was packing nearly as many pixels into a far fewer chip. It also has less latitude for overexposure (perhaps as much as a stop). It seems there is still no free lunch for smaller pixels. Since the 1D Mark IV has smaller pixels than the 5D Mark II, it will be interesting to see comparative reviews of the latest 1D series increment.

Thursday, August 27, 2009

Red-necked Phalarope, Jamaica Bay WR

Pretty much the only thing I photographed in a relatively brief visit to the East Pond ahead of two days of scheduled rain. This is an adult in basic plumage.

Monday, June 22, 2009

Upland Sandpiper

Sheyenne National Grasslands in the vicinity of the Nature Conservancy's Brown Ranch, ND. I think this swath of wetland was actually owned by the Nature Conservancy.

Thursday, June 18, 2009

Dusky Grouse

Dusky Grouse (formerly Blue Grouse) at Grand Teton National Park in Wyoming, June 2009. This rather tame male was sheltering from the periodic drizzle under an evergreen at dawn, but also singing with a series of almost inaudibly low-frequency hoots. In dark conditions this was taken without the teleconverter at ISO 1600 at something absurd like 1/30th at f4. Nevertheless only required only moderate work with Noise Ninja to get a decent result.

Tuesday, June 16, 2009

Gray Jay

Shoshone National Forest in Wyoming, to the east of Yellowstone National Park and to the west of Beartooth Pass.

Monday, June 15, 2009

Black Rosy-Finch

Adult Black Rosy-Finch in breeding plumage, feeding on a snow field at the east (MT) side of the eastern summit of Beartooth Pass. There were about 30 of them milling around. The following morning there were none here or anywhere along Beartooth Highway.

Mountain Bluebird

The male of a fairly cooperative pair at Makoshika State Park at Glendive, MT on the MN-ND-WY trip.

Sunday, June 14, 2009

Nelson's Sharp-tailed Sparrow

They are never supposed to be this cooperative, but this adult male Nelson's Sharp-tailed Sparrow (now called Nelson's Sparrow) was singing on the reed-covered fence line at Lostwood National Wildlife Refuge. Probably helped that at the time there were two males there, so competition for this small piece of habitat was relatively fierce.

Saturday, June 13, 2009

Brewer's Blackbird

One of the few cooperative ones from the MN-ND-WY trip, roadside at Lords Lake National Wildlife Refuge near Bottineau, ND

Saturday, May 30, 2009

Willow Flycatcher

Adult male Willow Flycatcher, Franklin Twp, NJ in May. Several areas in Franklin hold them, at least in part because Franklin Twp makes some effort to keep a fair amount of open space. Some of these grasslands are invaluable for declining birds like Grasshopper Sparrow and Bobolink, although Willow Flycatcher is a little more versatile and not under quite so much pressure as those two specialists.

Tuesday, May 19, 2009

Golden-winged Warbler

Adult male, NY in May. Rapidly declining under the twin pressure of habitat loss and hybridization with the more dominant Blue-winged Warbler, there are still a few pockets of this species to be found in the north-east.

Sunday, April 26, 2009

Bay-breasted Warbler

Very early but not totally unprecedented, this adult male Bay-breasted Warbler was seen on April 26th in Central Park. This species is more commonly associated with being found in the warbler weather of May 10th or later.