What is Crop factor?

by Paul Carr
(London, England)

Can someone please explain to me what crop factor is or what it means. I am using a Canon 450d with a Canon 70-300mm telephoto lens. The salesperson who sold it to me told me that I was really getting 112-480mm.

What is he talking about and how do I zoom in to 480mm?

Comments for What is Crop factor?

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Crop factor and field of view
by: Stuart Moore

Smaller sensor gives narrower field of view. If you take a picture with the same lens on both a FX and a DX camera and crop the FX image to that of the DX, the picture will be identical in terms of content (including depth of field) but for resolution (having thrown away a load of pixels from the FX image).

Try reading this:
http://photo.net/

The Crop Factor of a Sensor
by: Anonymous

As mentioned, most modern DSLR's have a "crop" factor (sometimes called "FOV" for "Field Of View"), which is usually measured in relation to 35mm film. Some DSLR's are "Full Frame" (FF), meaning their sensor is almost identical in size to one frame of 35mm film; these cameras have no crop-factor.

Smaller sensors only detect the central part of the image that "FF" lenses cast; in effect, they have "cropped" (cut away) the outer portions of the frame. The effect is the same as what you get with a "digital zoom" -- you have "thrown away" the outer parts of the image the lens provides. Commonly, this crop factor is equivalent to a 1.5x or 1.6x digital zoom.

The net effect of this crop is similar to having a less-wide-angle, more-telephoto lens; thus, as the crop is relative to 35mm, some refer to the lenses themselves and (the magnification) in their "35mm-equivalent"; so (for a 1.5x sensor, a 50mm lens gives magnification equivalent to a 75mm lens).

NOTE, however, that the focal-length of the lens remains the same, and so do the characteristic perspectives of the lens, no matter the crop-factor. You will see differences between a shot on a 90mm lens with a 1.5x crop-factor body, vs. a 135mm lens on a full-frame body.

What is Crop factor?
by: Anonymous

If you compare the size of the film in a normal SLR (film is 35mm) to the image sensor in most DSLRs you?ll find that the size of the DSLRs sensor is generally smaller. If you take a photo with a smaller sensor and the same lens it will only show a smaller area of the scene.

When you enlarge images to the same size from different sensors the ones with the smaller sensors will be enlarged more ? making it seem bigger.

Generally they run from 1.6 - 2x depending.

So what you are in fact doing is multiplying your 35mm lens when using it on a digital camera.

The crop factor
by: Anonymous

Hi,

What I read into that information is that you can view up a scene and then crop it by zooming in on one part of it.

Or you can just take all the picture and crop it on you computer.

Regards
Ann

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