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crop factor?
Can someone please explain what crop factor meaning 1.5x ? I know the more pixels you have the better crop factor you have. Thanks...

Comments (8)

Rntbot wrote:.

Can someone please explain what crop factor meaning 1.5x ? I know themore pixels you have the better crop factor you have. Thanks..

Firstly, it should be emphasised that crop factor has nothing at all to do with the number of pixels..

The concept is probably more useful to some people than others. To those who have spent years using 35mm film cameras and become familiar with the way that different lenses behave on that system, it is perhaps most useful..

Since many DSLR cameras have a sensor size smaller than the film camera, the image can be regarded as a cropped section from the centre of the frame..

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

35mm film uses a 24 x 36 mm frame size, a DSLR with a sensor of 18 x 24 mm is said to have a crop factor of 1.5..

This idea can be useful in comparing the angle of view of lenses across different systems. For example a 200mm telephoto lens, when used on a digital camera with a 1.5x crop factor, would have an angle of view the same as a 300mm lens on 35mm film.Hope this helps,Peter..

Comment #1

As well as the answer above There are some point and shoot cameras that have a function which will crop the images in camera..

For instance the Panasonic FZ 50 has 10 meg at 12X zoom but if you set it to 3 meg then it will crop the centre 3 meg of the picture giving an enlargement of 21X..

You can do this on a computer but it is alot simpler to let the camera do the work..

Comment #2

Peter.

Very good explanation....of crop factor.I like your image, film and sensor together.Clear and concise..

Ed..

Comment #3

Ed Grenzig wrote:.

Peter.

Very good explanation....of crop factor.I like your image, film and sensor together.Clear and concise..

Ed.

Thanks. I should give credit for the image to Vincent Bockaert.http://www.dpreview.com/...learn/?/Glossary/Camera_System/sensor_sizes_01.htm..

Comment #4

Sherwoodpete - did you notice not once in your reference from dpreview is the term crop factor used..

We are both saying more or less similar things, I think this sums it up a little more clearly than yours and adds important points regarding the image circle you failed to mention..

I'd argue you have defined the term focal length multiplier or an effective focal length equivalency factor as opposed to crop factor.

Crop factor more accurately is a term used to describe the portion of the image circle used by the sensor. a 35mm based lens design casts image circle that can be fully utilized by a 35mm sensor..

With the advent of the DSLR there were a lot of 35mm form factor lenses out there with their given image circle. plug a smaller than 35mm sensor behind the image circle of a 35mm form factor lens and now you are indeed "cropping" the available image circle to something less than what is produced by the lenses optics..

This is where the equivalency factor(focal length multiplier) comes in to compare the effective focal lengths of a 35mm based lens on a 35mm sensor and on a camera with less than a 35mm sensor, i.e. 1.3x, 1.5x, 1.6x, & 2x(olympus lenses are size matched to the sensor using the full image circle available with no "cropping").

Taking Olympus' lead you now find canon and nikon produce smaller format lenses that are image circle matched to sensor size, i.e. not having the "extra" image circle area that the 35mm format lens provided. at that point their is no "crop" involved as the image circle and the sensor are matched..

When image circle and sensor are matched you are left to use the equivalency factor(or focal length multiplier) to compare effective focal lengths of one sensor size format to another, not a "crop factor" as you inferred..

For corrected reference;.

Http://www.digital-slr-guide.com/crop-factor.html.

E1 w/ grip, e510, e300 w/ grip, 8mm FE, 14-54mm, 35mm, 50mm, 40-150mm,50-200mm, fl-50, fuji - 6800..

Comment #5

Freealfas wrote:.

For corrected reference;.

Http://www.digital-slr-guide.com/crop-factor.html.

Also here's a link regarding "Focal Length Multiplier", (I missed this previously)http://www.dpreview.com/.../?/Glossary/Optical/Focal_Length_Multiplier_01.htm..

Comment #6

Freealfas wrote:.

I'd argue you have defined the term focal length multiplier or aneffective focal length equivalency factor as opposed to crop factor.

A focal length multiplier is used for digicams. There is no cropping. It's a small lens matched to a small sensor whereas 35 mm (full frame) is a large lens matched to a large sensor..

Crop factor is a term used for Dslrs where the same lens gives a different field of view than 35 mm due to the smaller sensor capturing only a crop of the image circle produced by the lens, not the entire image circle as 35 mm or a full frame sensor would with that lens. Technically a rectangular section of the image circle is what is recorded. A cropped sensor system uses a smaller rectangle than 35 mm and therefore records only a portion of of what the larger sensor can..

The numbers with both are focal length mulitpliers and the same term is often used for both but it can't be called a crop factor with a digicam...

Comment #7

Wmsson wrote:.

A focal length multiplier is used for digicams. There is no cropping.It's a small lens matched to a small sensor whereas 35 mm (fullframe) is a large lens matched to a large sensor..

OK, I'm with you through there....

Crop factor is a term used for Dslrs where the same lens gives adifferent field of view than 35 mm due to the smaller sensorcapturing only a crop of the image circle produced by the lens, notthe entire image circle as 35 mm or a full frame sensor would withthat lens. Technically a rectangular section of the image circle iswhat is recorded. A cropped sensor system uses a smaller rectanglethan 35 mm and therefore records only a portion of of what the largersensor can..

While commonly thrown around I'd argue cropped sensor is a misleading term at this point as one sensor isn't cropping another sensor hence the more accurate term focal length multiplier being termed to compare the two to get an effective focal length of one vs. another..

Arguably if a sensor is using a "cropped" portion of an available image circle as would be the case of a 35mm format lens being used on a smaller than 35mm sensor based camera then the term "crop factor" is appropriate..

The numbers with both are focal length mulitpliers and the same termis often used for both but it can't be called a crop factor with adigicam..

It can't be used on a camera that has a lens matched to it's sensor period regardles of it being a dslr or otherwise as there is no "cropping" occurring anywhere in the relationship of lens to sensor per say..

E1 w/ grip, e510, e300 w/ grip, 8mm FE, 14-54mm, 35mm, 50mm, 40-150mm,50-200mm, fl-50, fuji - 6800..

Comment #8

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