Monthly Archives: July 2007

Peering at the Golden Gate

I celebrated Julian’s 10th birthday a bit early yesterday with Julian and his grandparents (they won’t be around on his actual birthday). We had a very nice dinner at Skates (for his desert, Julian had Chocolate Decadence cake with a candle). Then we walked out on the Berkeley Pier.

I exposed this image for 25 seconds so I could stop the lens down as far as possible (to f/25). My idea was to get the Golden Gate Bridge in focus at infinity, using the high depth-of-field to also maintain clarity in the pier’s wood railing.

Posted in Landscape, Photography, San Francisco Area

Taming Extravagant Dynamic Range

At the end of June this year, the full moon rose in the eastern sky at about sunset (although by July 2 after dark). This cosmologic timing gave me the chance to consider extravagant dynamic range. In other words, what can you do with captures in which the dynamic range is simply too great to process for both bright areas and dark areas?

It’s always best to start with the best capture possible. This is less of a tautology than it seems, and is often ignored by photographers who think Photoshop can fix anything.

In fact, post-processing can fix many problems with the range of an exposure. But the contrast between a bright full moon and a landscape at dusk (or in darkness) is immense (see the photo below). As a first pass, a full moon nicely lit by reflected light from the sun at ISO 100 should expose properly at about 1/250 of a second and f/8. An evening landscape might properly expose at ISO 100 at 15 seconds and f/4 (if it is a cityscape with some ambient sunset light remaining) to 30 seconds and beyond if it is a true night landscape.

Tower of the Moon 2

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This extravagant dynamic range is greater than you’ll find in most photographic situations, and well beyond the capabilities of RAW multi-processing. RAW processing gives you -4 stops to +4 stops in dynamic range, although this entire eight f-stop range is not usable due to factors like noise introduction (it takes considerable Photoshop skills to even get close).

Back of the envelope, the eight f-stop theoretical range within a single RAW exposure proves a dynamic range of 2^8 (or 128). As I just noted, this entire range is not practically usable. In contrast, the dynamic range between bright moon and night sky is about 3,000 (the number you would need to multiply 30 seconds at f/4 to get to 1/250 of a second at f/8). It’s easy to see that you can’t expose a single digital RAW capture for both ends of this 3,000:1 ratio.

But wait! Isn’t there a good solution to this problem using HDR (High Dynamic Range) merging tools? A Merge to HDR Automation ships with Photoshop that will automatically blend a whole exposure range of different captures of the same subject. If this interests you, you might want to consider a speciality tool (it comes standalone or as a Photoshop plugin), Photomatix, which uses tone mapping to create HDR blends of multiple exposures (and does a rather better job than the Photoshop automation). And, no, this is no panacea that deals with the problem in extravagant dynamic range between moon and night sky.

There’s some concern that HDR blends tend to look artificial. Leaving this aesthetic issue aside, there’s a bigger technical issue when it comes to the moon in the night sky. Namely, at least some of the exposures involved are going to be lengthy, probably well over a second. This time lapse means that you can’t take static multiple images (the moon will move from one farme to the next), and the HDR blend will not appear seamless.

Another post-processing technique to consider using with the bright moon and dark landscape is to simply fire off two exposures, one for the moon and one for the landscape, and combine them. For the record, this can be done with film as well as digital. And the problem here is that except in really unusual circumstances the results will look highly artificial.

So what is to be done? Photographers must fall back metaphorically on the cunning of the coyote and wolf, animals that enjoy the moon, and seek images that create attractive “natural” renditions of the dynamic moon-landscape spread within a single RAW capture. One strategy: employing softness so that is OK for the moon to lose details in the highlights (this is what I used in the photo above).

Another tactic: photograph the moon and landscape early enough so the dynamic range isn’t so extravagant (but things are clearly tending towards dusk). This may only give you a narrow time window of a couple of minutes, and it requires the right moon-rising time, but works for the photo below:

Rose Moon Rising

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Posted in Photography

Serpent Mother

Matt and Amy and their kids came down from Placerville to go to the Fire Arts Festival at The Crucible in Oakland. After a nice dinner, Julian and I joined them at the festival.

It was great to see so many people being creative and having fun, well, just for the fun of it. I decided to see how well my long exposure digital night techniques would work on the fire creatures.

Julian and my favorite was the Serpent Mother by the Flowering Lotus Girls, shown above before full night and below with a BART train and (far below) in flames with the Serpent Mom’s egg.

Fun with Fire 1

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Serpent Mom and Bart

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Serpent Mother and Egg

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Posted in Bemusements, Photography

Moonshine

At two minutes, this exposure was smack dab in the middle of the dynamic range for capturing bright moonlight. In other words, the exposure should be (and indeed was) “correct” with a roughly equal distribution of dark, middle, and light tonalities and appropriate rendering for each.

If you look closely, particularly in the larger size, you can see that this was a long exposure at night: witness the star trails. But in most ways the digital capture shows a scene with as much vivid detail as a daytime capture.

Other issues: I’m not sure how I feel about the optical artifacts (generated by the internals of my lens) around the moon. The moon is actually a more concentrated light source than the sun, you’d never see quite the targeted beam effect from sunlight. Moonlight is a bit lower in color temperature than sunlight, and you can see the difference on the hillside on the left. And the glow at the edge of the horizon from urban lights is a purely night phenomenon.

Here’s another image captured looking in the same direction from Arch Rock.

Related story: Taming Extravagant Dynamic Range.

Posted in Digital Night, Landscape, Photography, Point Reyes

Does a Cerclage Cause Blondness?

Phyllis sent Dr. Michael Katz, the high-risk ob-gyn whom we credit with the safe birth of our younger two sons, the photos of Mathew on his third birthday.

Dr Katz’s response: “thanks for the update. Is that hair color because of the cerclage or the medications?” (If you are lucky enough not to know what a cervical cerclage is, here’s a definition, and here’s part of our story.)

I love Phyllis’s reply to Dr. Katz. Here it is.

Hmm…the data is entirely inconclusive…if you compare the three test subjects (all male):

— Julian, age 10 in two weeks (alas no cerclage and no medication)
— Nicky, age 5 1/2 going on 15 (cerclage, bedrest, and lots of medication)
— Mathew, recently 3 and very proud of it (cerclage and some medication):

Brothers

You will see that there appears to be no correlation whatsoever in terms of hair color and cerclage/medication used. To further study this hypothesis, a new control group (with one member) would have to be formed and again tested with the cerclage/medication hypothesis. Unfortunately the continuation of this study seems unlikely: Tired test mama says: “three boys are enough!” Crazed test Dad says “Another baby? With another husband!”

We’re so proud of our three boys, they are all so different and all so wonderful! Thank you for helping us have such a great family!

Posted in Kids, Photography

Mathew on His Third Birthday

We celebrated our youngest member, Mathew, and his third birthday yesterday at home with his siblings and grandparents (above). I managed to take his portrait between strenuous bouts of cupcake eating, candle blowing out, and present opening.

This morning we were at another party for Mathew at his pre-school, Step One, where Mathew wore a Thomas-the-Tank-Engine crown (below).

Mathew on His Third Birthday 2

Here are all of our family at the Step One party for Mathew:

Family

I don’t feel I can take as much time post-processing photos of my kids as I can with photos that I’ll publish in books or sell as prints, but here are some general tips for kid photography.

Get down on level with the kids. Make the same effort to connect with a child who is your subject as you would with an adult whose portrait you are creating. Connection is easier to accomplish when you are down on the floor with the kid rather than way up there like some giant.

Consider boosting the ISO rather than using flash. This makes your photography less disruptive than with a flash going off in everyone’s face, and avoids problems with redeye and blown-out highlights, while still allowing you to capture motion. (And kids are constantly in motion.) ISO 640 is a good light sensitivity setting for indoor candid photos of kids.

Use noise reduction software in post-processing (Noise Ninja works well for this).

In the photos of Mathew, I reduced the noise on a Photoshop layer, masked the layer, and painted in his face. I did the same thing with a bit of luminance sharpening, using the Unsharp Mask on the L channel in LAB mode. This selective noise reduction and subtle sharpening creates a kind of halo effect around the face of the child. Sharpening only the luminance channel in a photo creates a more flattering and less harsh effect than using Photoshop’s Smart Sharpen filter. Selective layer masking restricts the effect to the child’s face.

Last, but not least, I candidly confess that I cloned the cupcake and cinnamon toast off Mathew’s face, and enlarged the catch lights in his eyes.

Most important of all, in Mathew’s words, “Me had good birthday!”

Related story: Dropped in His Tracks.

Posted in Kids, Photography

Blue Velvet Sunset

This photo shows the head of the Point Reyes peninsula peering out at sunset from under formidable cloud cover. The point of a photograph like this is not to show fine-grain detail. (Or, should I say, “fine-noise” detail?)

With an eight second exposure and clouds scuttling in the wind, the motion will definitely soften ocean and sky. So my intent is to render an expressionistic image, closer to a water color than a conventional photo.

Taken from Arch Rock at the very end of sunset, this photo reminds me that freedom of the night means not just the photography of digital night. Freedom of the night also implies the ability to photograph until the very end of sunset. And walk home safely through the long tunnel of the night.

Posted in Landscape, Photography, Point Reyes

Golden Gate Bridge from Fort Baker

The evening looked to have some fog over the Golden Gate, but I decided to try my luck. I grabbed a quick take-out burger, ate it at the trailhead, slung my pack on, and set off up the Coastal Trail behind the bridge.

Slacker Ridge was covered in fog. Down around the other side of the headlands, the ridge line above the Waldo Tunnel saw cold air blowing hard across, pushing the fog line. At first I though there was a chance for a photo, but pretty soon I felt like an arctic explorer in my down jacket and balaclava. Pretty silly a couple of miles from San Francisco. But then, you know what Mark Twain is supposed to have said about summer in San Francisco.

The bridge was pretty much buried in fog, and it was getting darker. Then I got a bright idea. I looked down at Fort Baker in Sausalito. It was still clear of the clouds.

I headed back along the trail and up and over to my car, shed my hiking boots, and drove down to the Fort Baker waterfront. On an abandoned road that crumbled to an end above the sea, in the gathering darkness, I exposed this image of the bridge against the fog, with the lights of Seacliff behind. It was pretty dark, and it took a thirty second wide-open exposure to capture the detail and blue sky shown in this image. A couple of seconds later the cloud cover was across, and the world had gone to black.

Posted in Landscape, Photography, San Francisco Area

Estero by Starlight

A recent hike along the Estero Trail in Point Reyes ending in night: starlight on Drakes Estero. Venus was so comparatively bright (the middle right) that the highlights of this nightime photo are blown out. You can dimly see the Drakes oyster beds in the middle left of the photo.

Posted in Digital Night, Landscape, Photography, Point Reyes

Estero at Low Tide

My nephew Peter, a strapping 25-year-old from Minnesota, and my friend Mark and I went for a sunset-to-night hike on the Estero Trail on Point Reyes. The trail crosses Drakes Estero, and then heads up a bluff. From the top of the bluff, we could see the sunset reflected in the channels and patterns of the low tide.

In this image, I used a circular polarizer with my camera on a tripod to bring out the colors.

Posted in Landscape, Photography, Point Reyes

Half Dome Follow-Up

The San Francisco Chronicle ran a front page story today, Danger on the Dome about the dangerous hike up Half Dome in Yosemite.

You can read a partial account of my recent hike up Half Dome and thoughts about the matter in my blog story Snakes and Ladders. Another post, Star Vortex, includes additional links to all my recent stories about Half Dome.

There are various conflicting values at play here. It’s sad to find people putting themselves in harm’s way because they don’t understand wilderness travel and risks. But the wilderness is supposed to be a bastion of freedom, and I’m opposed to unnecessary restrictions.

All that said, I don’t see why anyone would want to subject themselves to the zoo on the cables on a weekend. It’s not what I consider a wilderness experience (and the crowding adds greatly to the danger). My hike shows that with a little creative trip planning it is perfectly possible to visit Half Dome safely, avoiding the crowds.

Here’s the moon shadow cast by Half Dome from its summit:

Moon Shadow of Half Dome

Posted in Photography, Yosemite

Flower at the Center of the Universe

I’ve called this photo composition Flower at the Center of the Universe. To create the photo composition, I used layers and layer masking in Photoshop to combine Papaver Fireworks with the image below.

The bottom image is itself a photo composition I’ve called Infinite Vortex, consisting of four copies of Star Vortex, rotated and combined. Two copies of the combined Star Vortex images at different magnifications are superimposed on themselves.

I combined layers of Papaver Fireworks at two different magnifications with the Infinite Vortex composition, taking advantage of the fact that when you blend layers using Screen mode black (the background color of the Papaver Fireworks) disappears.

All a long way from the night sky at the top of Half Dome. But bear in mind: creativity is play.

Infinite Vortex

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Posted in Photography, Photoshop Techniques

Star Vortex

This is a very long time exposure taken from the top of Half Dome. It was around 1AM. I pointed the camera straight up towards the sky facing north. Here’s what I wrote in my diary:

I am taking photos after midnight, the camera on tripod open for half an hour at a shot. It is cold. Not so much my torso, but my legs and feet. I look around and see mosaics in the rock of Half Dome. This cannot be true. Looking close by flashlight, taking care not to disturb the sky exposure, I see the “mosaic” is made of lines of frost, the moisture gathered out of the air.

It is so cold I can’t sit or lie down. I must pace, it seems forever. I have a small, flat area I know it is safe to pace. Like Gandalf on the top of Orthanc. When my batteries are gone, photography is over.

For the story of how and why I was on Half Dome at night, see Yosemite Valley from Half Dome, Moon Shadow of Half Dome, Snakes and Ladders, Half Dome by Starlight, and Midnight Rambles.

Posted in Digital Night, Photography

White Balance and the RAW Landscape

Mark and I went back out to Arch Rock last night. It was a little earlier than my last hike out there, so I was able to work my way down the little canyon and across a couple of rock faces to the beach, where I photographed the arch in Arch Rock in the gathering dusk. Of course, I also photographed the moon on the beach, and other aspects of this grand scene. On our way back through the long foot-pounding miles of the tunnel of a trail under the dark trees we talked about RAW captures, white balance, and landscape photography.

Through the Arch

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It’s well known that one of RAW capture’s great virtues is the ability to correct exposure in post-processing. Within each RAW capture there’s a theoretical eight f-stop range of possible exposures that can be processed out of the raw data (if you excuse the pun). Processing at the limits of this range does introduce problems, such as excess noise, into an image. But still, the potential exposures inherent within each RAW capture do give opportunities for correcting poor initial exposures, and for extending the dynamic range of images. An example of extended dynamic range means to be able to see detail in shadow areas that would normally be black in an image exposed for bright sunshine.

That said, it’s best practice not to presume on the kindness of RAW. You should expose each image in-camera as accurately as possible. This avoids potential problems and gives you more options when you do post-process the RAW.

Even when a photo of mine was exposed properly in the first place, like the image above at ISO 100, 2.5 seconds, and f/4, I almost always end up combining from three to five different versions of the RAW capture using Photoshop layers, masking, and layer blending modes. The 2.5 second time exposure accounts for the soft effect in the clouds and water.

White balance refers to the color temperature of the light used in a photograph. It is measured in Kelvin degrees. The photograph above is lit by a combination of ambient sunlight (generally 5200 degrees Kelvin, but a little warmer in the photo of the arch because the sun was setting, so maybe 5800 degrees), and moonlight (roughly 4300 degrees Kelvin).

You can measure the color temperature of light under controlled circumstances, for example, in a photography studio. If you’ve measured the temperature of the light, you can dial it into your camera. In theory, this leads to an accurate color rendition of your subject.

As a practical matter, it is pretty impossible to measure light temperature in field conditions like I encountered in the photo of the arch. Not only did I have to do a bit of the mountain goat thing to even get in range for the photo, I also had only a short amount of time to make my exposure before I lost the light.

So the best practice is to leave White Balance set to Automatic. This means that your camera will make some attempt to measure the light temperature, and associate this reading with the image. But associating a White Balance measurement with a RAW image doesn’t actually change the image data itself because the White Balance data is simply set in a tagged text file associated with the RAW file. You can change the White Balance to any Kelvin number you think is appropriate when you convert the image in post-processing. You can do this using a slider, and visually inspect the impact of the change on your photo.

If you really want to get tricky, you can process different versions of a single RAW capture using different white balances. For example, I processed the water within the arch at 4300 degrees Kelvin (moonlight) and the clouds at 5800 degrees Kelvin (sunset).

As with differing exposure values from a single RAW capture, versions from a single RAW capture that use different white balances are combined in Photoshop as layers using masking and your choice of blending mode.

Posted in Landscape, Photography, Photoshop Techniques

Yosemite Valley from Half Dome

This is a 9 1/2 minute exposure taken from the top of Half Dome a little after midnight in mid-June. The camera was pointing west towards Yosemite Valley. You can see the moon setting, along with the time-exposure trails of stars.

It amazes me, as you can see from this photo, that so many lights are on in Yosemite Valley at midnight. I’m also surprised at the ambient light cast by the valley tents and hotels up the rocks walls that line the valley. I also would not have expected to clearly see the night lights of the cities of the California valley, like Merced, from Half Dome.

I’m surprised at the vibrant red of lichen on the rock fin that is part of Half Dome. This color is far brighter by moon-and-star light than in daylight.

As the night deepened and got colder, the air got clearer and the stars like diamonds towards the wilderness in the High Sierra. Back towards civilization (as in this photo) there were more lights. Perhaps it is not surprising that Yosemite Valley is in the direction of civilization.

For more of the story of how and why I made this image, see Moon Shadow of Half Dome, Snakes and Ladders, Half Dome by Starlight, and Midnight Rambles.

Posted in Digital Night, Landscape, Photography, Yosemite