Quick question about crop bodies/lenses
Discussion
Hi all
Selling some gear on eBay and just been asked a question by someone that to me reads like they think buying an EF-S type lens over an EF (sorry for the canon talk, but I mean a lens made for the crop bodies) lens for a crop body camera (20D) will give them the proper focal length. I.e. buying a 35mm EFS lens for a crop body, will give them 35mm on that camera, where as a 35mm EF lens would be cropped.
As far as I was aware, the crop factor applies regardless as it is a feature of the camera not the lens.
So...
35mm EF lens on a FF camera gives you a 35mm shot ( well the field of view will)
35mm EF lens on a crop gives you a shot equal to having a 56mm lens on a FF camera. This is because the imaging circle is much larger than the sensor and the sensor is taking only the middle square of the image. It is cropping out the centre, giving you a narrower field of vision and hence the effect of being zoomed in further.
35mm EF-S on a FF won't work because mechanically it would get in the way of the mirror mechanism on a FF camera
35mm EF-s on a crop body, still gives you that effect of being zoomed in, ie equivalent field of vision as a 56mm on a full frame, but what I was confused about was the imaging circles. The EF-S lens produces a smaller imaging circle to match the smaller sensor, this makes the lens more compact and cheaper to make.
But in order for this to make sense in my head, the smaller image circle must essentially be a circular crop of the larger imaging circle produced by a EF lens. What I mean is, the EF-S imaging circle iS NOT a magnification of the EF imaging circle ( ie they don't both contain all the same features of a scene).
This way a subject in the middle of an EF lens is the same size as the middle of an EF-S lens if you simply focused them both onto a wall or something.
Is that right? Or have I just told some poor guy on the internet a load of hogswill?
Selling some gear on eBay and just been asked a question by someone that to me reads like they think buying an EF-S type lens over an EF (sorry for the canon talk, but I mean a lens made for the crop bodies) lens for a crop body camera (20D) will give them the proper focal length. I.e. buying a 35mm EFS lens for a crop body, will give them 35mm on that camera, where as a 35mm EF lens would be cropped.
As far as I was aware, the crop factor applies regardless as it is a feature of the camera not the lens.
So...
35mm EF lens on a FF camera gives you a 35mm shot ( well the field of view will)
35mm EF lens on a crop gives you a shot equal to having a 56mm lens on a FF camera. This is because the imaging circle is much larger than the sensor and the sensor is taking only the middle square of the image. It is cropping out the centre, giving you a narrower field of vision and hence the effect of being zoomed in further.
35mm EF-S on a FF won't work because mechanically it would get in the way of the mirror mechanism on a FF camera
35mm EF-s on a crop body, still gives you that effect of being zoomed in, ie equivalent field of vision as a 56mm on a full frame, but what I was confused about was the imaging circles. The EF-S lens produces a smaller imaging circle to match the smaller sensor, this makes the lens more compact and cheaper to make.
But in order for this to make sense in my head, the smaller image circle must essentially be a circular crop of the larger imaging circle produced by a EF lens. What I mean is, the EF-S imaging circle iS NOT a magnification of the EF imaging circle ( ie they don't both contain all the same features of a scene).
This way a subject in the middle of an EF lens is the same size as the middle of an EF-S lens if you simply focused them both onto a wall or something.
Is that right? Or have I just told some poor guy on the internet a load of hogswill?
http://www.cambridgeincolour.com/tutorials/digital...
Not sure I would point a potential buyer to this article unaccompanied but it does rehearse the various points that lens and sensor combinations bring up.
Not sure I would point a potential buyer to this article unaccompanied but it does rehearse the various points that lens and sensor combinations bring up.
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