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Tuesday, March 11, 2008

Digital Formats


Find the "right" format for you

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Digital Formats
Because both of the flowers shown in this article were very close to ground level, the articulating LCD monitor on the Olympus E3 allowed for accurate composition of the shots.
It’s interesting to me as an observer of digital photography’s evolution that few people seem to discuss formats. I’m talking about digital formats based on the size of the sensor. In film, we used to talk about formats all the time: 35mm, 645, 6x6, 6x7, 4x5 and so on. Each of these formats has advantages and disadvantages for the nature photographer. Digital is very similar. There are different-sized image sensors that have advantages and disadvantages for photographers.

I hear many photographers talk about digital format as if there was only one format, full frame. Full frame means full-frame 35mm, so it’s a bit of a misnomer. If we looked at the comparison of digital to film, what’s really full frame? Medium-format film is certainly bigger than 35mm, so would that be a fuller frame?

The reality is that we have different formats for digital based on the size of the image sensor. It’s important to keep these sizes in mind because they affect what an image looks like and what we can do with a digital file. For our purposes, we can break down formats for D-SLRs into four groups, starting from larger to smaller:

1. Large- and medium-format (bigger than 35mm)
2. Full frame (35mm size)
3. APS-C (smaller than 35mm; the size of APS-C film)
4. Four Thirds format


One thing to remember when discussing these formats is that technology is continually changing. A disadvantage today, such as higher noise for a certain format, might be meaningless next year.

Large And Medium Format. It’s hard to say exactly how larger-format sensors will affect digital photography. Some people feel that the image quality of smaller sensors will get so good that these larger sensors never will be needed. Other photographers feel that there are real advantages to having a physically larger sensor in the way the camera can be set up for use, such as view camera-style equipment. In addition, there may be limits as to what can be done with small lenses designed for smaller formats even if the sensors themselves can handle high resolution.

Advantages: A large sensor easily captures extremely fine detail for a scene. Large sensors can be used with medium- and large-format cameras, allowing you to use lenses designed for them. There are some high-quality lenses available for this type of camera. In addition, it’s theoretically easier to build a view camera with a larger-format sensor. Larger sensors tend to have much less noise compared to smaller sensors, so large-format sensors are typically noiseless. Finally, a larger sensor has the potential for capturing a wider range of color and tonalities, so that it can have a higher bit depth for its image files.

Disadvantages: The biggest disadvantage for a large digital format is in the cost of the sensors. Large-format sensors are expensive to produce today. Slightly smaller medium-format-sized sensors are still pricey, though not as much as large format. Larger formats require bigger camera bodies that are less portable in the field, and their sensors typically require more power as well. Larger formats also make longer focal-length lenses act like wider-angle lenses compared to smaller formats. That makes telephoto images harder to get because you see more of a scene with any given focal length. In addition, lenses require a large image circle to cover a large sensor, which can add expense and weight to a lens.

Full Frame (35mm Size). One thing that has confused the formats issue in this type of camera is that full-frame and APS-C formats fit inside basically the same type of cameras. You can’t tell the difference between two cameras of these different formats if you just see the camera’s silhouette. The result is that the same lenses are used for both formats, but the lenses act differently within the image area of each‚ yet these formats are just as different as 645 versus 6x7.

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