Photography & Image processing notes

Got an Old Canon Point-and-Shoot Camera? Hack It – IEEE Spectrum

A decade is a long time in technology—long enough for a technology to go from hot product to conspicuously obsolete to retro cool. In 2010, IEEE Spectrum’s David Schneider wrote about a hack to supplant the firmware in Canon point-and-shoot cameras and add new features, such as motion detection. As it turns out, at the time point-and-shoot cameras were near their zenith of popularity. Since then, while compact stand-alone digital cameras are still being made, their sales have shrunk dramatically. As the smartphone camera became the most ubiquitous type of camera on the planet, point-and-shoot cameras found themselves relegated to the back of the closet.

That was certainly the case with our Canon PowerShot S80. My wife bought it in 2008 primarily to document her paintings in between professional photo shoots, and a few years later we replaced it with a mirrorless Nikon 1 J-1 with interchangeable lenses. So when I found the S80 while decluttering recently, I wondered: Was it just e-waste now, or could it be combined with today’s technology to do interesting things?

I decided the perfect test case for my S80 was variable time-lapse photography. This is a task for which even an 11-year-old digital camera, with its larger optics, can compete with today’s smartphones on image quality. This scenario makes mobility a moot point, but the task also requires more sophistication than even CHDK—the open-source firmware replacement David Schneider wrote about in 2010—can easily offer alone.

My S80’s original firmware had a function that would take a photograph at fixed intervals of between 1 and 60 minutes, in 1-minute increments. CHDK provides a script that allows a more fine-grained increment of 1 second, but I wanted to try time-lapse photography of the Empire State Building, which we happen to have a good view of from Spectrum’s New York office. During the day, the light changes slowly, so I wanted to shoot one photo every few minutes. At dusk, however, the lighting on and around the building changes more dramatically, so I wanted photos taken at a faster rate.

The first thing was to test my camera. It’s a credit to Canon that despite years of disuse, all the parts sprang to life. The only problem was on the battery side. I had three batteries, one of which refused to charge at all, and two others I no longer trusted for a long-duration experiment, so I found a DC adapter on eBay that powers the camera from a wall socket.

Then I installed CHDK. Fortunately, this is one of those rare pieces of open-source software for which the documentation is a comprehensive and intelligible wiki. Looking up the instructions for my S80, I determined its current firmware, which turned out to be 1.00f. Only the 1.00g version is compatible with CHDK, so I followed the instructions to upgrade the factory firmware, the biggest obstacle to which was finding the right utility software to open the 7z format that the firmware file was compressed with.

A cross-platform tool called Stick makes finishing the CHDK install easy: Drop a photo taken with a camera onto the tool’s interface and it analyzes the metadata and downloads the exact version of CHDK required onto a SD card. Launching CHDK on my camera just requires putting the prepared card in and pressing the S80’s “shortcut” button.

CHDK provides an interface for remote control of the camera via the USB link normally used to download photographs directly to a PC. A number of programs can use this PTP standard, including chdkptp, which offers both a command line version and a graphical user interface (GUI) version that lets you see what is being displayed in the viewfinder screen live. One of the nice things about chdkptp is that a precompiled binary, bundled with required supporting libraries, is available for the Raspberry Pi, thus eliminating dependency hell.

I ran into two problems, which were resolved after searches of CHDK’s user forums. The first was that chdkptp couldn’t connect to the S80—a helper process on the Pi was grabbing the connection, assuming I wanted to download photos. The simplest solution was to find the offending process using a “ps -ax | grep gphoto2” command, and “kill -9” it. (This works only on a per-session basis; if you want to permanently disable the helper, you’ll have to edit some deep configuration files.)

My camera and chdkptp could now connect, but I still couldn’t actually take a photo. This was solved by writing a script with some mode commands I found on a forum. CHDK runs the script when I press the camera’s shutter, and then it is happy to accept remote commands.

To implement my variable time-lapse schedule, I wrote a short Python program on the Pi. I looked up the time of the sunset and set the Python program to check the clock. Outside a half-hour window around sunset it would take a photo every 10 minutes, and one every 30 seconds inside the window. To control the S80, I just issued an OS call to the chdkptp command line tool that connected and triggered the shutter—that is, os.system(“./ -c -eshoot”).

I left the system running from the early afternoon till dusk, and when I returned I had 113 images, which I dumped into iMovie to make a time-lapse video. Ta-da!

Now that I have my proof of concept, it would be a straightforward task to write a Python script that could download the times of sunrise and sunset and adjust itself automatically. I can also save images directly to the Pi. Then I could access and download these images remotely over a wireless network, allowing for the option of leaving the camera and Pi in place for long periods of time for truly epic time-lapse movies.

This article appears in the December 2019 print issue as “Hack Your Old Point-and-Shoot.”

Source: Got an Old Canon Point-and-Shoot Camera? Hack It – IEEE Spectrum

Got an Old Canon Point-and-Shoot Camera? Hack It – IEEE Spectrum was last modified: March 31st, 2021 by Jovan Stosic

CHDK Dummies Guide 2nd Edition

CHDK : Quick Start

If you don’t want to read this short guide, or the somewhat longer official CHDK User Manual , here’s a quick list of what you need to do to load and run CHDK.

  1. Download and install the STICK utility from this link >: STICK
  2. Run STICK to configure your SD card and install CHDK.
  3. Put the SD card’s lock switch into the “locked” position and put the card into your camera.
  4. Start your camera normally. You should see the red CHDK logo appear for a few seconds.
  5. Press the defined <ALT> key  for your camera to enter CHDK mode. The <ALT> key is usually either the PRINT or PLAY button. However, some cameras use the DISP, VIDEO, HELP or FACE buttons so you might have to try different buttons to find the right one.
  6. Press the MENU button in <ALT> mode to access the CHDK configuration menus.  Press the FUNC/SET button to bring up the scripting menu.
  7. Press the shutter button in <ALT> mode to run the currently loaded script.
  8. Exit <ALT> by pressing the <ALT> button again. Override settings and onscreen display option will now enabled while you are back in normal Canon mode.

Source: CHDK Dummies Guide 2nd Edition | CHDK Wiki | Fandom

CHDK Dummies Guide 2nd Edition was last modified: March 31st, 2021 by Jovan Stosic

Understanding Metering and Metering Modes

Understanding Metering and Metering Modes

Every modern DSLR has something called “Metering Mode”, also known as “Camera Metering”, “Exposure Metering” or simply “Metering”. Knowing how metering works and what each of the metering modes does is important in photography, because it helps photographers control their exposure with minimum effort and take better pictures in unusual lighting situations. In this understanding metering modes article, I will explain what metering is, how it works and how you can use it for your digital photography.

When I got my first DSLR (Nikon D80), one of my frustrations was that some images would come out too bright or too dark. I had no idea how to fix it, until one day, when I learned about camera metering modes.

1) What is Metering?

Metering is how your camera determines what the correct shutter speed and aperture should be, depending on the amount of light that goes into the camera and the sensitivity of the sensor. Back in the old days of photography, cameras were not equipped with a light “meter”, which is a sensor that measures the amount and intensity of light. Photographers had to use hand-held light meters to determine the optimal exposure. Obviously, because the work was shot on film, they could not preview or see the results immediately, which is why they religiously relied on those light meters.

Today, every DSLR has an integrated light meter that automatically measures the reflected light and determines the optimal exposure. The most common metering modes in digital cameras today are:

  1. Matrix Metering (Nikon), also known as Evaluative Metering (Canon)
  2. Center-weighted Metering
  3. Spot Metering

Some Canon EOS models also offer “Partial Metering”, which is similar to Spot Metering, except the covered area is larger (approximately 8% of the viewfinder area near the center vs 3.5% in Spot Metering).

You can see the camera meter in action when you shoot in Manual Mode – look inside the viewfinder and you will see bars going left or right, with a zero in the middle, as illustrated below.

Nikon Viewfinder

If you point your camera at a very bright area, the bars will go to “+” side, indicating that there is too much light for the current exposure settings. If you point your camera at a very dark area, the bars will go to the “-” side, indicating that there is not enough light. You would then need to increase or decrease your shutter speed to get to “0”, which is the optimal exposure, according to your camera meter.

A camera meter is not only useful for just the Manual Mode – when you choose another mode such as Aperture Priority, Shutter Priority or Program Mode, the camera automatically adjusts the settings based on what it reads from the meter.

1.1) Problems with Metering

Camera meters work great when the scene is lit evenly. However, it gets problematic and challenging for light meters to determine the exposure, when there are objects with different light levels and intensities. For example, if you are taking a picture of the blue sky with no clouds or sun in the frame, the image will be correctly exposed, because there is just one light level to deal with. The job gets a little harder if you add a few clouds into the image – the meter now needs to evaluate the brightness of the clouds versus the brightness of the sky and try to determine the optimal exposure. As a result, the camera meter might brighten up the sky a little bit in order to properly expose the white clouds – otherwise, the clouds would look too white or “overexposed”.

What would happen if you added a big mountain into the scene? Now the camera meter would see that there is a large object that is much darker (relative to the clouds and the sky), and it would try to come up with something in the middle, so that the mountain is properly exposed as well. By default, the camera meter looks at the light levels in the entire frame and tries to come up with an exposure that balances the bright and the dark areas of the image.

2) Matrix / Evaluative Metering

Matrix Metering or Evaluative Metering mode is the default metering mode on most DSLRs. It works similarly to the above example by dividing the entire frame into multiple “zones”, which are then all analyzed on individual basis for light and dark tones. One of the key factors (in addition to color, distance, subjects, highlights, etc) that affects matrix metering, is where the camera focus point is set to. After reading information from all individual zones, the metering system looks at where you focused within the frame and marks it more important than all other zones. There are many other variables used in the equation, which differ from manufacturer to manufacturer. Nikon, for example, also compares image data to a database of thousands of pictures for exposure calculation.

Matrix Metering

You should use this mode for most of your photography, since it will generally do a pretty good job in determining the correct exposure. I leave my camera metering mode on matrix metering for most of my photography needs, including landscape and portrait photography.

3) Center-weighted Metering

Using the whole frame for determining the correct exposure is not always desirable. What if you are trying to take a headshot of a person with the sun behind? This is where center-weighted metering comes in handy. Center-weighted Metering evaluates the light in the middle of the frame and its surroundings and ignores the corners. Compared to Matrix Metering, Center-weighted Metering does not look at the focus point you select and only evaluates the middle area of the image.

Center-weighted Metering

Use this mode when you want the camera to prioritize the middle of the frame, which works great for close-up portraits and relatively large subjects that are in the middle of the frame. For example, if you were taking a headshot of a person with the sun behind him/her, then this mode would expose the face of the person correctly, even though everything else would probably get heavily overexposed.

4) Spot Metering

Spot Metering only evaluates the light around your focus point and ignores everything else. It evaluates a single zone/cell and calculates exposure based on that single area, nothing else. I personally use this mode a lot for my bird photography, because the birds mostly occupy a small area of the frame and I need to make sure that I expose them properly, whether the background is bright or dark. Because the light is evaluated where I place my focus point, I could get an accurate exposure on the bird even when the bird is in the corner of the frame. Also, if you were taking a picture of a person with the sun behind but they occupied a small part of the frame, it is best to use the spot metering mode instead. When your subjects do not take much of the space, using Matrix or Center-weighted metering modes would most likely result in a silhouette, if the subject was back-lit. Spot metering works great for back-lit subjects like that.

Spot Metering

Another good example of using spot metering is when photographing the Moon. Because the moon would take up a small portion of the frame and the sky is completely dark around it, it is best to use Spot metering – that way, we are only looking at the light level coming from the moon and nothing else.

Some DSLRs like the Canon 1D/1Ds are capable of multi-spot metering, which basically allows choosing multiple spots to measure light and come up with an average value for a good exposure.

5) How to Change Camera Metering Mode

Unfortunately, this varies not only from manufacturer to manufacturer, but also from model to model. On the Nikon D5500, for example, it is done through the menu setting (Info button). On professional cameras such as the Nikon D810 and Nikon D5, there is a separate button on the top left dial for camera metering. Changing metering on Canon cameras also varies from model to model, but generally it is done through a key combination (“Set” button), camera menu or a dedicated metering button close to the top LCD.


Understanding Metering and Metering Modes was last modified: September 10th, 2017 by Jovan Stosic


In photography, bokeh (originally /ˈbkɛ/,[1] /ˈbk/ boh-kay — also sometimes pronounced as /ˈbkə/boh-kə,[2] Japanese: [boke]) is the aesthetic quality of the blur produced in the out-of-focus parts of an image produced by a lens.[3][4][5] Bokeh has been defined as “the way the lens renders out-of-focus points of light”.[6] Differences in lens aberrations and aperture shape cause some lens designs to blur the image in a way that is pleasing to the eye, while others produce blurring that is unpleasant or distracting—”good” and “bad” bokeh, respectively.[7] Bokeh occurs for parts of the scene that lie outside the depth of field. Photographers sometimes deliberately use a shallow focus technique to create images with prominent out-of-focus regions.

Bokeh is often most visible around small background highlights, such as specular reflections and light sources, which is why it is often associated with such areas.[7] However, bokeh is not limited to highlights; blur occurs in all out-of-focus regions of the image.

Source: Bokeh – Wikipedia

Bokeh was last modified: September 25th, 2017 by Jovan Stosic


RawTherapee is a cross-platform raw image processing program,[2] released under the GNU General Public License Version 3. It was originally written by Gábor Horváth of Budapest, Hungary, before being re-licensed as free and open-source software in January 2010.[3] It is written in C++, using a GTK+ front-end and a patched version of dcraw for reading raw files. It is notable for the advanced control it gives the user over the demosaicing and developing process. The name used to stand for “The Experimental R

Source: RawTherapee – Wikipedia

Raw Therapee Manual_en

RawTherapee was last modified: September 25th, 2017 by Jovan Stosic



From Wikipedia, the free encyclopedia
Mamiya Digital Imaging Co., Ltd.
Camera and lens manufacturer
Industry Digital imaging and photography
Founded May 1940
Headquarters Tokyo, Japan
Key people
Seiichi Mamiya, founder
Products Cameras, Optical and other products
Number of employees
Parent Phase One
Website Mamiya Japan
Mamiya Leaf

Mamiya Digital Imaging Co., Ltd. (マミヤ・デジタル・イメージング マミヤ・デジタル・イメージング ー株式会社?, Mamiya Dejitaru Imejingu Kabushiki-gaisha)[needs IPA] is a Japanese company that manufactures high-end cameras and other related photographic and optical equipment. With headquarters in Tokyo, it has two manufacturing plants and a workforce of over 200 people. The company was founded in May 1940 by camera designer Seiichi Mamiya (間宮精一) and financial backer Tsunejiro Sugawara.


A Mamiya C3 twin lens reflex, from 1962.

Mamiya originally achieved fame for its professional medium-format film cameras such as the Mamiya Six and the Mamiya Press series. It later went on to develop the industry workhorse RB67 series, the RZ67 and the twin-lens reflex Mamiya C-series, used by advanced amateur and professional photographers.

Many Mamiya models over the past six decades have become collectors’ items. The earliest Mamiya Six medium-format folding camera, the 35 mm Mamiya-Sekor 1000DTL, the lightweight 35 mm Mamiya NC1000, the 6×6 cm medium-format C series of interchangeable-lens twin-lens reflex (TLR) cameras, and the press cameras of the Super/Universal series are highly valued. Mamiya also manufactured the last models in the Omega line of medium format cameras.

Mamiya entered other business markets over time by purchasing other companies.[1] Until 2000, it made fishing equipment such as fishing rods and fishing reels. In 2006, the Mamiya Op Co., Ltd., Inc. transferred the camera and optical business to Mamiya Digital Imaging Co., Ltd. The original company, doing business as Mamiya-OP, continues to exist and makes a variety of industrial and electronics products. It also makes golf clubs, golf club shafts and grips, and golf balls through its subsidiaries Kasco and USTMamiya.[2]

In 2009, Phase One, a medium format digital camera back manufacturer from Denmark, purchased a major stake in Mamiya. In 2012, Phase One combined Mamiya and another subsidiary, Leaf Imaging, created a new, worldwide Mamiya Leaf brand to integrate both companies’ product lines into one complete medium-format digital camera system offering. The re-branding offers a streamlined product development and establishment of a more efficient customer sales and support base.

135 film[edit]

Mamiya started manufacturing 135-film cameras in 1949, with 135-film point-and-shoot compact cameras being introduced later. The excellent Mamiya-35 series of rangefinder cameras was followed by the Mamiya Prismat SLR in 1961 and the Mamiya TL/DTL in the mid-to-late 1960s. The SX, XTL and NC1000 were other 135-film SLR camera models introduced by Mamiya. One of Mamiya’s last 135-film SLR designs was the Z-series. The original entry-level ZE model was an aperture-priority-only SLR; the ZE-2 added manual exposure; the ZE-X added shutter priority and full program automated mode, and (with a dedicated flash and an EF-series lens) focus-priority flash exposure). In these models the aperture ring had no direct connection to the diaphragm, allowing the camera body to override the set aperture, and the lenses could communicate a considerable amount of information to the camera body via electrical contacts on the mount.

The Mamiya ZM, introduced in 1982, was essentially an advanced version of the ZE-2, with some of the features of the ZE-X. It was the last Mamiya 135-film camera produced. It had an aperture-priority automatic time control, based on center-weighted TTL readings, an automatic shutter-speed range from 4 seconds to 1/1000, and a manual range from 2 seconds to 1/1000. Visual and audio signals indicated over- or under-exposure, pending battery failure, or excessive camera shake. Metering modes, shutter release, self-timer, manual time settings and the ergonomics of the camera body were also improved.

In 1984 Osawa, one of Mamiya’s major distributors, filed for the Japanese equivalent of bankruptcy and, soon after, Mamiya discontinued 135-film camera production to focus on the medium-format professional market.

Medium format[edit]

Mamiya made a series of square format twin lens reflex (TLR) throughout the middle of the twentieth century. These were developed into the C cameras (C2, C3 through to C330s) which have interchangeable lenses as well as bellows focus.

In 1970, Mamiya introduced the RB67 6×7 cm professional single lens reflex (SLR). The RB67, a large, heavy, medium-format camera with built-in closeup bellows was innovative and successful. Previous medium-format professional cameras used the square 6×6 cm format which did not require the camera to be rotated for photographs in portrait orientation, problematical with large and heavy cameras when tripod-mounted. The RB67 had a rotating back which enabled photographs to be taken in either landscape or portrait orientation without rotating the camera, at the expense of additional weight and bulk. The RB67 soon became widely used by professional studio photographers. The 6×7 frame was described as being ideal, as the 56mm x 67mm negatives required very little cropping to fit on standard 10″ x 8″ paper.

When comparing the RB67 to full frame 135 cameras there is a so-called “crop factor” of a half. That means the standard 35mm frame has “half” the diagonal of the 67 (though the ratio is different) but a quarter the area. This effects the focal length of lenses so that to get an equivalent field of view on a 35mm camera you need half the focal length. There is a similar effect on the depth of field of a particular aperture, so a 90mm f1:3.5 on the RB67 is equivalent to using a 45mm f1:1.8 on 35mm full frame.

In 1975 Mamiya started to offer the M645, a camera with 6×4.5 cm frame, allowing 15 shots on a standard 120 roll film becoming the first MF camera to offer that format size also known as the 645 format.

The RB67 was followed by the more advanced RZ67 6x7cm frame format camera in 1982. These cameras established Mamiya as a major medium-format professional camera manufacturer, together with Hasselblad, Rollei, Bronica and Pentax.

In 1989, Mamiya introduced the Mamiya 6 and Mamiya 7 (6x6cm and 6x7cm, respectively) rangefinder cameras, compact and quiet cameras which are reputed for the extremely high optical quality of their lenses.

In 1999, Mamiya presented the Mamiya 645AF, a 6X4.5 frame SLR camera with interchangeable lenses and film backs, auto focus and an integrated prism visor that would be the base platform for the Mamiya 645AFD film and digital back cameras.

Digital products[edit]

Mamiya introduced the Mamiya ZD, which was a compact medium-format camera, in 2004. Rather than taking the form of a digital back solution, it was all built into one unit, much like a 35mm camera. This camera utilized the Mamiya 645AF lenses and had a resolution of 22mp. The solution had technical difficulties and became delayed. At the same time, Mamiya also announced a ZD back which had the same specification but was intended to be used with the Mamiya 645AFDII / AFDIII. The ZD back was even more delayed and, once it was introduced, it was already outdated.

In 2009, the Mamiya M Series digital backs were released (M18, M22 and M31) all featuring high pixel counts with large CCDs and compatibility with the Mamiya 645AFD range and RZ/ RB series (via specially manufactured adapters). All the backs are compatible with 4×5 inch view cameras. In the final quarter of 2009, Mamiya released its Mamiya 645DF camera, the latest and digital-only version of the famed 6×4.5 format AF camera series. The Mamiya 645DF has many improved features including mirror-up delay, lack of shutter lag, AF preference with priority on speed or precision, and compatibility with the new leaf shutter lens range (Mamiya Sekor AF 80mm, 55mm and 110mm D lenses with in-built leaf shutters). With these lenses attached, flash synchronizations speeds of up to 1/1,600 of a second are achievable, although the camera can also be programmed to use the focal plane shutter even if a leaf shutter lens is attached. 2010 saw the release of 3 Mamiya DM Systems (Mamiya DM33 System, consisting of a 645DF camera body and 33MP digital back, the Mamiya DM28 System, consisting of a 645 AF III camera body and 28MP digital back, and the Mamiya DM22 System, consisting of a 645 AF III camera body and 22MP digital back. A new logo and webpage were also launched.[3]

Mamiya America Corporation[edit]

In the United States, the trademark for “Mamiya” is not owned by the original company in Japan but rather by a wholly separate entity called Mamiya America Corporation (“M.A.C.”). As such, All products that bear the name “Mamiya” are controlled by M.A.C. and has resulted in a considerable rise in retail pricing when comparing the same products to ones sold outside the United States. As of 2014 MAC group no longer manages the Mamiya brand in America, all sales, service and support was transferred to Phase One who already owned a large portion of Mamiya.


For a detailed list of current and historical products, see List of Mamiya products.

6×4.5 cm format[edit]

  • The M645 (discontinued) was manufactured from 1975 to 1987. This was the first model to offer a 6×4.5 cm frame.
  • The Mamiya 645 Super (discontinued) was manufactured from 1985 to 1993. This was a new camera with a moulded plastic shell on a diecast metal frame. Its features are as for the M645 1000s (indeed it is able to use the same lenses and film cartridges). It added removable film backs, whereby a dark-slide could be inserted and the back removed mid-roll.
  • The Mamiya 645 Pro (discontinued) was manufactured from 1993 to 1998.
  • The Mamiya 645 Pro-TL (discontinued) was first released in 1997.
  • The Mamiya 645E (discontinued) was first released in 2000. Entry-level camera, non-interchangeable back, popular among beginners.
  • Mamiya 645DF+ — modular DSLR medium-format camera; also available as the Phase One 645DF

6×7 cm format[edit]

Source: Mamiya – Wikipedia

Mamiya was last modified: September 25th, 2017 by Jovan Stosic

Back-illuminated sensor

Back-illuminated sensor

From Wikipedia, the free encyclopedia
For the lighting design practice, see Backlighting (lighting design). For backlights in liquid crystal displays, see backlight.

A back-illuminated sensor, also known as backside illumination (BSI or BI) sensor, is a type of digital image sensor that uses a novel arrangement of the imaging elements to increase the amount of light captured and thereby improve low-light performance. The technique was used for some time in specialized roles like low-light security cameras and astronomy sensors, but was complex to build and required further refinement to become widely used. Sony was the first to reduce these problems and their costs sufficiently to introduce a 5-megapixel 1.75 µm BI CMOS sensor at general consumer prices in 2009.[1][2] BI sensors from OmniVision Technologies have since been used in consumer electronics from other manufacturers as in the HTC EVO 4G[3][4] Android smart phone, and as a major selling point for the camera in Apple’s iPhone 4.[5][6]


A traditional, front-illuminated digital camera is constructed in a fashion similar to the human eye, with a lens at the front and photodetectors at the back. This traditional orientation of the sensor places the active matrix of the digital camera image sensor—a matrix of individual picture elements—on its front surface and simplifies manufacturing. The matrix and its wiring, however, reflect some of the light, and thus the photocathode layer can only receive the remainder of the incoming light; the reflection reduces the signal that is available to be captured.[1]

A back-illuminated sensor contains the same elements, but arranges the wiring behind the photocathode layer by flipping the silicon wafer during manufacturing and then thinning its reverse side so that light can strike the photocathode layer without passing through the wiring layer.[7] This change can improve the chance of an input photon being captured from about 60% to over 90%,[8] with the greatest difference realised when pixel size is small,[citation needed] as the light capture area gained in moving the wiring from the top (light incident) to bottom surface (paraphrasing the BSI design) is proportionately smaller for a larger pixel.[citation needed] BSI-CMOS sensors are most advantageous in partial sun and other low light conditions.[9] Placing the wiring behind the light sensors is similar to the difference between a cephalopod eye and a vertebrate eye. Orienting the active matrix transistors behind the photocathode layer can lead to a host of problems, such as cross-talk, which causes noise, dark current, and color mixing between adjacent pixels. Thinning also makes the silicon wafer more fragile. These problems could be solved through improved manufacturing processes, but only at the cost of lower yields, and consequently higher prices. Despite these issues, early BI sensors found uses in niche roles where their better low-light performance was important. Early uses included industrial sensors, security cameras, microscope cameras and astronomy systems.[8]

Industry observers[who?] noted that a back-illuminated sensor could theoretically cost less than a similar front-illuminated version. The ability to collect more light meant that a similarly sized sensor array could offer higher resolution without the drop in low-light performance otherwise associated with the megapixel race. Alternatively, the same resolution and low-light capability could be offered on a smaller chip, lowering costs. Key to attaining these advantages would be an improved process that addressed the yield problems, largely through improving the uniformity of an active layer on the front of the detectors.[8]

A major step in the adoption of BI sensors was made when OmniVision Technologies sampled their first sensors using the technique in 2007.[10]These sensors, however, did not see widespread use due to their high costs. Sony’s work on new photo diode materials and processes allowed them to introduce the first consumer back-illuminated sensor as their CMOS-basedExmor R” in August 2009.[1] According to Sony, the new material offered +8 dB signaling and −2 dB noise. When combined with the new back-illuminated layout, the sensor improved low-light performance by as much as two times.[1]

Competitors followed suit, and by the end of the year most companies were offering a version in their high-end products. OmniVision has continued to push the technology down their product lines. By contrast, the iPhone 4s employs a sensor manufactured by Sony. Another example is the HTC EVO 4G[4][3] which equipped with an 8 megapixel, 1.4 µm pixel BSI sensor from OmniVision. In 2011, Sony implemented their Exmor R sensor in their flagship smartphone Sony Ericsson Xperia Arc.[11]

In January 2012 Sony developed the back-side illuminated sensor further with Stacked CMOS,[3] where the supporting circuitry is moved below the active pixel section, giving another 30% improvement to light capturing capability.[12] This was commercialized by Sony in August 2012 as Exmor RS with resolutions of 13 and 8 effective megapixels.[13]

In September 2014 Samsung announced the world’s first APS-C sensor to adopt back-side illuminated (BSI) pixel technology.[14][3] This 28-megapixels sensor (S5KVB2) was adopted by their new compact system camera, the NX1, and was showcased along with the camera at photokina 2014, held in Cologne, Germany, 16 to 21 September.

On 10 June 2015 Sony announced the first camera employing a back-side illuminated full frame sensor, the α7R II.[3]


Source: Back-illuminated sensor – Wikipedia

Back-illuminated sensor was last modified: September 25th, 2017 by Jovan Stosic

What is Composition in Photography?

What is Composition in Photography?

With the first article in our new Mastering Composition series, it is only fitting that we start off by discussing the very definition of our main topic. In this article for beginner photographers, I will outline the general meaning of the term “composition” in art. I will also briefly discuss the goal of composition, define what a good composition is and why it is such an important part of any work of art. At the end of the article I will provide you with a simple question that is also a hint on what is to come in future articles.

What is Composition in Photography

1) General Definition of the Term

The term “composition” applies not only to visual arts, but to music, dance, literature and virtually any other kind of art. In certain contexts, such as writing, this term may not be as widely used, but is just as valid nonetheless. In general, the term “composition” has two distinctive, yet related meanings.

First and foremost, “composition” describes placement of relative objects and elements in a work of art. Consequently, composition is a key aspect of a good work of art. There is hardly a way to overemphasize the importance of composition. Any aspiring artist ought to give composition of his work a lot of attention. A good composition is one that has just enough detail. Too few elements is bad because it robs the work of art of necessary detail that makes correct interpretation possible. It also ruins the balance of an image. And too many elements can be very distracting as well. Good composition requires good balance. It is best to make sure all the elements present are necessary for the idea or story you are trying to pass on.

In some cases, composition can mean the work of art itself and is a synonymous to that term. For example, when talking about a specific installation or dance, a phrase “This composition…” can be used. Such a definition also widely applies to music (creators of which are known as composers) and paintings.

2) What is Composition in Photography?

Now that we know the general definition of the term “composition”, it is not too hard to figure out its meaning in photography. Simply put, composing an image means arranging elements within it in a way that suits the core idea or goal of your work best. Arranging elements can be done by actually moving the objects or subjects. A good example for this case is portrait or still life photography. Street photography involves anticipation, since the photographer doesn’t usually have the choice of moving his subjects himself, but has to wait for them to take the most suitable position within the frame. Another way of arranging elements is by changing your own position. Such a way is appropriate in circumstances that do not allow the photographer to physically move anything, like landscape photography.

Composition is a way of guiding the viewer’s eye towards the most important elements of your work, sometimes – in a very specific order. A good composition can help make a masterpiece even out of the dullest objects and subjects in the plainest of environments. On the other hand, a bad composition can ruin a photograph completely, despite how interesting the subject may be. A poorly judged composition is also not something you can usually fix in post-processing, unlike simple and common exposure or white balance errors. Cropping can sometimes save an image, but only when tighter framing and removal of certain portions of the image is the correct solution. That is why giving your choice of composition plenty of thought before capturing an image is a step of utmost importance.

Street Photography in Vilnius

Focal length, aperture, angle at which you choose to position your camera relative to your subject also greatly affects composition. For example, choosing a wider aperture will blur the background and foreground, effectively lessening the importance of objects placed in there. It will also more often than not result in more noticeable corner shading (vignetting), which will help keep viewer’s eye inside the frame for longer. On the other hand, closing down the aperture will bring more objects into focus which, in turn, may result in better image balance. How so? Well, “sharper”, more in-focus objects may attract more attention than a blurry shape, but not always (see image sample below). An experienced photographer will use all the available means to achieve the desired result. It is worth noting that de-focusing objects in the foreground or background does not negate their contribution to overall composition of the image. Simple shapes, tones, shadows, highlights, colors are all strong elements of composition.

Take a look at the below image. Despite the fact that part of a wall showing in the foreground is completely out of focus, it is the most vivid part of the photograph as well as being quite bright. For this reason, it attracts our attention much more than the main subject (man with the tea cup and his Siberian Husky hiding in shadows). The bright yellow rectangle is the first thing you see when you glance at the photograph. A good and obvious way to fix this would be to reduce the vividness and luminance of yellow using Lightroom’s HSL panel (although I actually like the contrast between the two parts of the photograph):

Street Photography in Vilnius_1

We will discuss color, tone and other composition elements in more detail in upcoming Mastering Composition series articles.

Composing an image eventually becomes a very natural process. With enough practice – mind you, there can never be too much of such a thing – you will not even have to think about the placement of those elements. Your subconscious will do it for you. Your fingers will dial correct settings, your eye will guide the framing. Poor composition will instantly appear unnatural and just plain wrong to you. The more experience you have, the better choices you will make. Best way to grow as a photographer is not to rush your decisions and not trust your subconscious unquestionably, but to learn new ways of composing your image. Not that you shouldn’t trust your guts – you should, of course. But make sure to also give it some thought, experiment, take a few shots and analyze them during post-processing. See what works best, try to understand why and then experiment some more.

3) The Goal of Composition

One may assume that a good composition is one that is most pleasing to the eye. Consequently, the goal of good composition ought to be showing your subject or object in a flattering, aesthetically pleasing manner. But such opinion is a little superficial. Not every work of art is supposed to be pleasing or beautiful to the viewer. Some artists try to express different, stronger ideas and their subject, as well as composition choices help achieve that. For example, if an artist wants the viewer to feel uncomfortable or nervous, he will choose a composition that is least “natural” and come up with something unexpected and shocking. A good example of such work is war photography, where photographers often try to help the viewer feel how terrifying and destructive war is. On the other hand, an artist may portray war victims in a very flattering and disturbingly beautiful way. By doing so, he would emphasize war’s ugly nature in a grotesque and sarcastic manner. So, in the end, the goal of a good composition is to help express the idea of the artist by necessary means.

4) Assignment for Beginners

This simple assignment is for beginner photographers, who would like to actively learn along with other readers and participate in creation of these articles.

  • Name basic varieties (or simply “types”) of composition you are familiar with. Make sure to list just one variety and try not to repeat those that have already been named by someone else. Best if you don’t use Google – test yourself and wait for the upcoming articles patiently 🙂 The following image is a hint for one of the most obvious basic compositions types.

Street Photography in Vilnius_2

Good luck!

Source: What is Composition in Photography?

What is Composition in Photography? was last modified: July 13th, 2017 by Jovan Stosic