Wednesday, October 21, 2009

Black card photography Part I

Sunrise and sunset are the two most favorable themes for photographers because of its rapidly changing hues and great color saturation. But they are also one of the difficult themes to master in photography. The difficulty lies on how to get a balanced exposure in a great dynamic range of luminance between the lightest (the sun) and darkest (the foreground) areas of the image. Often times you either get a silhouette against the golden hue horizon or a clear shot of the foreground but an overexposed background. Thanks to modern technologies, there are many ways to overcome the exposure dilemma in a high contrast environment such as the High Dynamic Range Imaging (HDRI), active D-lighting built in cameras, multiple exposure on the same image, gradient Graduated Neutral Density (GND) filters application and black card photography, etc. Each technique has its pros and cons but that's not the focus of this entry.

Silhouette with correct background exposure (left) V.S a clear foregroung but an overexposed backgroung (right)

It is said that the black card photography is a unique photography developed in Taiwan. Basically, black card photography uses a black card (could be anything that is dark with a characteristic of not refecting lights) to shelter the brighter area of an image allowing the darker area a longer exposure and the result is a balanced exposure. Compare to gradient graduated ND filter application and HDRI, black card photography can handle a greater dynamic range of luminance and it can be done without computer software post-editing which usually disqualifies a great photo from a photo contest. To get a balanced exposure in a high dynamic range of luminance environment with black card photography the first step is to set the metering mode to spot and measure the exposure at bright and dark areas of the scene respectively. Lets use this photo as an example:

The exposure for the sky was measured 3 secs and 13 secs for the ground with F stop 8 (it was the smallest aperture I got on sony F717) in the spot metering mode. So I set the shuttle speed to 13 secs, F stop at 8, and focus to manual as the black card may change the focal point. The camera was mounted on a tripod, self-timer was on to minimize a blurry image from shaking the camera while pressing the shutter. Then I put a black card close to the lens and adjusted the position through viewfinder as the image below:

Once the shutter was opened, I kept shaking the black card up and down a bit to prevent the formation of a black card sheltered line like in the image below. Ten seconds later, I removed the card from the lens and let the whole image be exposed for another 3 secs until the shutter closed.

By doing so, the sky was exposed for 3 secs and the ground for 13 secs and as a result, a balanced image exposure was captured.

Here are some photos that were taken by black card photography

  1. Set F stop to 16-22 to get a greater depth of field (DOF)
  2. Use Manual mode and set the shutter speed to "Bulb" rather than exact time. The reason to do that is because when you have a longer exposure it is easy to make a mistake by counting too quickly or too slowly. By using "Bulb" mode, you control the shutter that avoids under/over exposure after removing the black card.
  3. Curve the black card to match the geography when the horizon is not a simple line.
  4. Use an ND filter to earn a longer exposure time if it is too short (especially for a sunrise image)


Thank you so much for correcting my mistake and sharing great tips in the comment section, Craig.

GND filter is indeed an easier way to deal a high dynamic range luminance environment and the result usually satisfying. However, lets take the most commonly seen GND8 filter in photo stores (ND=8) for example, the difference between the darkest part to the transparent part is 3 F-stops but that's not enough to handle the contrast between the bright and the dark areas in many sunrise/sunset scenes. Of course, apply multiple GND filters can solve the problem but it might also worsen the image quality as most of the GND filters are made of plastic. Moreover, given the property of graduated decreasing darkness of a GND filter, it is easy to get an uneven exposure in the bright area on the scene (darker on the top) if the bright area has a similar exposure value (EV). ( Example: notice a grafuated darkness from top to bottom on the image that applied a Gradual Grey2 (ND8))

Even though HDR has been accepted in many reputable photo contests, it seems to me most photo contests in Taiwan still have some issues about it. HDR is the easiest way to create a well balanced exposure image in a high contrast environment. The Photomatix Pro has a high reputation in making a HDR image, download the trial version here if you are interested. Stuck in Customs has stunning HDR photos and HDR tutorial.

It is highly recommended to set focus to manual when using a black card. The concern is not because the focal point might change during the exposure; depends on compositions, sometimes the black card covers 2/3 of the lens which can be a problem when the focus is set to auto. Thank to Craig's reminder, positioning the focal point at 1/3 of the scene in front gives you the rear 2/3 scene in an acceptable focal range, it's a great tip for manual focusing. If you are interested in how to set your focal point to get a greatest DOF, try to understand the concept of hyperfocal distance and Mountain Storm Fine Arts provides a great tool to calculate a hyperfocal distance. If you have a Windows Mobile phone, you can download WinMoDof, which is a useful free application that calculates the DOF and hyperfocal distance.

It's not necessary to set shutter speed to Bulb (the pics in the article weren't set to Bulb as Sony F717 has no such feature, you can download the pics for EXIF info). The reason that I highly recommended to set shutter speed to Bulb in black card photographing even when the exposure is under 30 secs is to minimize the effect of counting error. The error is inevitable and it gets bigger with a longer exposure time. Back to my example, the proper exposure for the sky and mountains were 3 and 13 seconds respectively. If the shutter speed was set for 13 seconds and I started to shake the black card while counting to 10 but I counted it too fast, so I removed the black card at 8 seconds which gave the sky a 5 seconds to expose, as a result, an overexposed sky would be captured; if I counted the time too slow, lets say the exact time I counted to 10 was 12 seconds that left the sky only 1 second to get exposure, an underexposed sky would be captured. When I set the shutter speed to Bulb, despite the counting error, I would get the whole image either overexposed or underexposed a bit rather than a partial over/under exposed image. With a Raw format, it's easy to compensate a 3EV over/under exposed image in the camera. Of course, if you are using a GND filter as mentioned by Craig, a proper metering will negate the need for counting.

Often times I got this question: should I expose the whole image first then cover the bright area with a black card when it got a proper exposure time or the other way around as I introduced in this article? The problem is if you let the whole image expose first then cover the black card it's difficult to place the card at a proper position. I meant to write a complete guide to black card photography but I only got a DSLR a few months ago and I simply didn't have the time to take photos for a such big topic. This article is the basic concept and practice of black card photography and all photos were taken by sony F717 which limited applications of a black card. How to use a black card in complex light sources environment and photographing fireworks with a black card will be the part II coming soon.

Monday, October 12, 2009

A non-scientific publication for the very first time

Last year, I got an email from Oxford University Press asking for permission to use one of my Dalat photos, Copyright permission request, and here is the result! I wonder if I can find a print in Taiwan?

Thursday, October 08, 2009


I've never thought about going to Changhua for a day trip as the only scenery there that I can recall is the giant buddha in Bagua Shan. As I screened my photos trying to select some of them that fit my 2010 calendar theme: of human constructions, I couldn't find enough photos that I liked. Then I saw a photo of the Fan-Shaped Wheelhouse in Changhua, which is the only wheelhouse for trains that is still operating in Taiwan, so I made a day trip to Changhua and discovered that the city has more than a wheelhouse and a giant buddha to offer. Take a look at the tourist map made by Changhua City Gorvernment for more information.

The Fan-Shaped wheelhouse is connected to the Changhua train station, however its entrance is loacated about 700 meters north of station (No. 1, Changmei rd, Sec. 1; opening hours 08:00-12:00, 13:00-17:00; Mon-Sun, Tel: 886-47-244537; free entrance). One must exchange ID and fill out the visitors log at the left side of the entrance before entering. A free group tour can be arranged by calling in advance. The wheelhouse is where technicians fix and maintain the electronic and steamed train engines. A bridge of rotatable rail aligns train engines that need maintenance to a radial rails network, each rail leads to a garage and the 12 garages are arranged in a fan-shaped and that's how it got the name. Since 1998, the number 12 garage accomodates the oldest steamed train engine, CK101, in Taiwan that was built in 1907 and had stopped traveling in 1979 while the railway system was gradually electrified. There is another steam train engine, CK124, also parked in the fan-shaped garage attracting steam train afficionados nationalwide here for their pilgrimage.

Buried in my fading memories, Bagua Shan Scenic Area to me was just a temple with a big Buddha in front of its courtyard. I arrived in Changhua on a Saturday night and was not ready to settle down in a hotel so I drove around and found that the Bagua Shan Scenic Area was even more beautiful than I remembered. A restaurant (Gua Shan Yue Yuan, 卦山月圓) on top of the hill serves BBQ meals for 2-6 persons and various dishes in a garden with a view of the city lights as a background, making it a great place to have dinner.

The highlight of the Bagua Shan Scenic Area is the landmark of Changhua city which is a giant Buddha statue. Inside the statue are displays of stories from buddhism. A wooden platform provides the best 180 degree panoramic view of Changhua City. The giant buddha, probably is the biggest in Taiwan, overlooking the city also has a 9 dragons fountain in the center of its plaza and miles of trekking paths along the surrounding hill. It seems to be a good idea to go later in the day to get a sunset picture and enjoy the night view with a BBQ dinner at the restaurant.

I did some research online before the trip and found a hand made noodle house in FuXing township, Changhua County. It's a traditional san-ho-yuan (三合院) style building with a big square in the center of the complex where they can hang the freshly made noodle in the sun before packing. It would be a great cultural experience to see the traditional way of making noodles and a great theme for photography, however, the day I visited Changhua was raining so I gave up this site and went to my next destination. Here is some information about this place if you are interested: address: No.9, Lane 129, Fuxing Rd., Fuxing Township, Changhua County; Tel: 04-778-3133; Geotage: Lat:24.047111, Lon:120.426167, the best time of visit: 10:00-13:00.

First Tainan, Second Lugang and Mengjia the third (一府 二鹿 三艋舺) is a Taiwanese adage that tells a chronological development of Taiwan from south to north during the Ching dynasty. Lugang was the second largest city in Taiwan, as a result the high density of historical sites in Lugang is one of the reasons that attracts tourists flooding in and why the name Lugang overshadows Changhua. In fact, many people don't know Lugang is actually one of the many townships of Changhua, well I admitted that I was one of them before. The historical sites in Lugang are free access to the public and are all located in walking distance. The Tienhou temple (Matsu temple) is the center of tourists attraction, most people take it as a start point to other sites such as old market street, half-side well and 9 turns lane, etc. Walking in these renovated historical sites with the crowds was a journey back in time that offers a glance of those opulent old days in Lugang, but I couldn't stand the crowds and the only place that I was comfortable with was the Longshan temple. Without a flood of tourists, the wooden temple still keeps its dignity and serves the locals as an spiritual asylum. Exploring every corner of the temple at a leisurable pace, feeling its age from the fading gilding roof, it was a peaceful visit. For more information, visit Lugang township official website or Ugo's Taiwanese Secrets Lugan entry.

Lugang not only has a bunch of historical sites but also has 3 museums located in Changhua Seafront industrial park (free entrance), about 7 km away from the Tienhou temple. Show Chwan Health and Medical Science Museum, exihibits modern medical instruments and a series of anatomical diagrams of human body (No.6, Lugong Rd., Lugang Township; opening hours: 08:00-17:00, Mon-Sun; Tel: 886-4-7813888 ext. 71190) whereas the BRAND'S Health Museum has a skywalk that allows visitors a glance of the BRAND'S production line (No.18, Lugong Rd., Lugang Township; opening hours: 09:00-17:00, Tue-Sat; Tel: 886-4-7810077, a reservation is needed).

I visited the Taiwan Glass Gallery which is sponsored by the Taiwan mirror Glass Enterprise Ltd. It's a 2 level building, the ground level is the office, gift shops, tourists rest area and half of the building is deserted space. A fortified glass staircase next to the office leads to a tunnel that connects to the exihibion hall on the second level. The floor of the tunnel was made by merging 3 pieces of 8mm thick fortified glass together that can support 1000 kg in weight, the images of galaxies were embedded into the arch ceiling glass along with different pattern glasses in different lighting on the right, the dreamy glass tunnel certainly elevated my expectation of the gallery that was dampen by the look of the ground level. On the other side of the tunnel, a bright broad exhibition hall unfolded, I couldn't stop taking photos of those delicate creations and had a great time wandering in a maze that was made of mirror. A high tech eletronic curtain was able to transform a transparent glass into a ground glass, I would like to build a house with this kind of glass. I kept runing back and forth at the two ends of a tube that consists of 3 mirrors, sticking my head in the end of the tube, triangle shape in one end and round shape in the other, to create my unique kaleidoscope patterns. The only part I gave up on trying to see was the golden tunnel because of the huge queue. (Address: No. 30, Lugong S. 4th rd., Lugang Township; Geotag: lat: 120.3954, lon: 24.0687; Opening hour: 08:00-18:00, Mon-Sun; Tel: 886-4-7811299 ext. 266; a reservation is needed for a group size over 20)

On my way back to Tainan, I stopped by the Wanggong fishing port for a sunset picture. There were a bus load of photographers taking position for the view already when I arrived at the port. I took my time circumnavigating the area, from food stalls to the octangle lighthouse tower that was colored black and white stripes. Wooden platforms were built along the coastline reaching out to the sea for tourists watching the sunset. The blue bridge connects 2 sides of the port as a guardian watching over the peace of the port. I waited patiently for the bridge to light up but it didn't. It was 15 mins to 19:00, photographers were all boarding a bus so I asked one of them and realized the lights of the bridge would only be turned on for special occasions such as new year. With disappointment, I packed my gadgets and ended my day trip in Changhua.