The terms "whole frame" and "partial frame" (often referred to as "full-frame" and "half-frame" or "cropped frame") in photography primarily relate to the size of the camera's image sensor and how it affects the field of view and image capture. Here's a breakdown:
Understanding Image Sensor Size
The core difference lies in how large an area the sensor captures when an image is taken. This directly impacts the final look and feel of a photograph.
Full-Frame Cameras (Whole Frame)
- Sensor Size: A full-frame camera features an image sensor that is approximately the same size as a 35mm film frame (36mm x 24mm).
- Field of View: Because of its larger sensor, a full-frame camera captures a wider field of view at a given focal length compared to cameras with smaller sensors.
- Image Characteristics: Full-frame cameras generally excel in low-light conditions and can produce images with shallower depth of field (blurry backgrounds) more easily.
- Reference: As noted, a full-frame camera sensor has the same dimensions as a 35mm film frame.
Partial Frame Cameras (Half-frame or Cropped Frame)
- Sensor Size: Partial-frame cameras have image sensors that are smaller than a 35mm film frame. Common sizes include APS-C and Micro Four Thirds.
- Field of View: These cameras capture a narrower field of view compared to a full-frame camera, effectively "cropping" the image. This crop factor changes depending on the specific sensor size.
- Image Characteristics: While having smaller sensors can offer certain advantages, such as portability and often lower prices, they are usually not as capable in low-light and typically produce images with deeper depth of field.
- Example: A half-frame camera, as stated in the reference, has a smaller sensor that crops the image.
Key Differences Summarized
| Feature | Full-Frame Camera | Partial-Frame Camera |
|---|---|---|
| Sensor Size | Roughly 36mm x 24mm (35mm film frame equivalent) | Smaller than a 35mm film frame |
| Field of View | Wider at the same focal length | Narrower (cropped) at the same focal length |
| Low-Light Performance | Generally better | Generally less capable |
| Depth of Field | Shallower depth of field more easily achieved | Deeper depth of field typically |
| Size & Cost | Generally larger and more expensive | Generally smaller and more affordable |
Practical Implications
- Focal Length: With a partial-frame camera, you need to consider the crop factor when determining the actual field of view of a lens. For example, a 50mm lens on an APS-C camera might have the equivalent field of view of a 75mm or 80mm lens on a full-frame camera.
- Lens Compatibility: Some lenses are designed specifically for cropped frame cameras and might not be fully compatible with full-frame bodies.
- Image Quality: While full-frame cameras tend to have better image quality overall due to their larger sensors, modern partial-frame cameras offer excellent performance as well.
Conclusion
In summary, the terms whole frame and partial frame indicate the size of the image sensor in a camera, with full-frame using a sensor equivalent to 35mm film and partial-frame using a smaller sensor. This difference significantly impacts the field of view, image characteristics, and overall performance of the camera.
