Blog Archives

Sensors: CCD vs. CMOS

3/26/2016

How These Digital Sensors Work

This video to the left gives a very basic visual demonstration of the differences between each sensor. CCD sensors work in rows while the CMOS sensors register individual information at each pixel and then shuffle the information to a master unit. Look below for more information about each sensor.

CMOS Senors

Complementary Metal Oxide Semi-Conductor
Widely used in consumer grade cameras
Note: Every pixel has its own reader, which registers the exposure and then all the readers sent to one master unit at a time to create the overall exposure for the picture.

CCD Sensors

Charged Coupled Device
Used in larger format cameras
No wide use in consumer cameras
Note: Every row of pixels has a storage element for the electrons. In this storage unit, after every picture is taken, photons release electrons, which are then counted in the storage unit to calculate exposure.

Errors with Sensors and the Real Differences

There are issues with digital sensors such as motion fragmenting and rolling "jelly" shutter effects. Make sure you're using the right sensor for your project. For example, if you're going to film quite a lot of motion where the camera itself is moving around then you may want to use a CCD sensor camera. However, if you're not doing much movement and the camera will be locked down with a relatively static frame then CMOS sensors will work just fine.

NOTE: Make sure to do the right research before you begin your project to make sure you get the results you desire. There are hundreds of brands and cameras out there. Make sure you know what you're using and why you're using it.

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Multiple Exposure Photography

3/26/2016

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Controlling exposure in photography is challenging for some students to wrap their minds around. There are three settings that work together to control motion, light, depth of field, and quality of the overall image.

Shown in the image to the right:

Aperture - Depth of Field
Shutter Speed - Motion
ISO - Image Quality

Mastering Shutter Speed

Mastering ONE LONG Exposure

Review content and examples on http://www.photomatters.org/multiple-exposure

Math required to take a photograph with multiple exposures
Black room or space without light
Camera settings (10+ second shutter, aperture to capture motion, low ISO)
Lighting instruments (flashlight, phone light, flash, lights flicked)
Choreographed movement for subject
Covering for camera vs. uncovered camera between shots

Note: The information presented at the above mentioned example (shown left, here) encourages the use of a strobe flash to achieve the shown effect. However, a strobe flash is not required. Students should instead focus on the use of a manual shutter using a black card or even the photographer's hand to block light as the subject moves to each position.

Examples Images and the Math Used

The technical elements are shown at the right. Note the four separate positions without blur in between. The photographer did a 25 second long exposure (for both examples shown above) with 4-5 seconds per position. He then covered the lens for a second to allow the model to transition to the next pose. Repeat.

This student used a motorized board to move himself forward without having to change positions. He chose to leave the shutter open during transitions to create the streak. You can tell where he held still for longer because his image is much clearer. He shot with a 15 second exposure for all the images shown above.

These images were done with glow stick rings around the subject's hands. He shot with 10 second exposures and moved his quickly and in repeated motion. The shutter was open the entire time without manual shutter (hand/card).

The photographer used a laser light strapped to a light stand. Then four students held mirrors in a square. The settings varied only slightly. For the most part, the photographer used 10 second exposures to capture the laser. Longer exposures did not yield better results.

Water slows dye down substantially already, but by using a slow shutter the photographer was able to capture stronger and richer swirls of the two separate colors. These images were shot with a 25 second exposure with a 500 watt tungsten light to the right with a white umbrella. Aperture set f22.

The shot with all three boys was done with each boy present for 2-3 seconds with a split second of transition for them to move out of and into position. The photograph capped her hand over the lens to act as a manual shutter as each boy moved. This prevented any motion blur.

The photographer set the shutter to a 30 second exposure, pausing for 5 seconds at each position. The then varied between caping his hand over the lens and not to create the streaks. The final images are from an un-choreographed light saber battle with a 10 second exposure.

The photographer used a glow stick to wave behind a static subject for 15 seconds. The student's face in the background can be seen when he holds in one position too long while waving the glow stick as the glow lights up his face as well as the subject.

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Developing Film

3/25/2016

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Depending on the type of film you've shot and the type of developer you're using, you will need to develop your film for longer or shorter periods of time. Below is a development chart for most of the major types of film based on Kodak D-76 developer. If you cannot find your film on this then search around online.

Film Type Developer Dilution ISO 35mm 120 Sheet Temp.