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> Chi, the perspective and feel of the 85mm lens on any camera is > identical. That is optical physics and not open to any other > interpretation. All one is doing is cropping the image circle. If you > could sneak into the back of the 10D camera and put in a full frame > 35mm sensor, the central image would not change in any way. The only > change would be the extra image real estate around the original > limited 10D sensor.
Now what I think really happens is that a photographer using the 85mm lens with a camera with a smaller sensor steps back to include the field of view he is used to seeing with a full frame 35mm camera. This changes the image appearance making it flatter, not the lens!!
Asher
Now what I think really happens is that a photographer using the 85mm lens with a camera with a smaller sensor steps back to include the field of view he is used to seeing with a full frame 35mm camera. This changes the image appearance making it flatter, not the lens!!
Asher
The focal length of a lens depends on,apart from the lens structure, the size of the negative or sensor. Changing the light sensitive area effectively changes the focal length. Another way of saying this is changing the size of the light sensing area effectively changes the angle of view of the lens.
Asher,you are telling me something I already know,am I telling you something that you don't know ?
Asher,you are telling me something I already know,am I telling you something that you don't know ?
Wang:
Sorry, you are dead wrong. The size of the negative or sensor has NO effect on the focal lenght of the lens, or on the angle of view of the lens. It is just as Asher describes, the size of the sensor simply limits (crops) the area of the image projected by the lens. Thinks about it: if I take a photo and crop the image in processing, does this change the angle of view?
It is a bit presumptious alleging that you are telling Asher something he doesn't know, when what you are telling is plain wrong.
Respectfully
Mike.
Sorry, you are dead wrong. The size of the negative or sensor has NO effect on the focal lenght of the lens, or on the angle of view of the lens. It is just as Asher describes, the size of the sensor simply limits (crops) the area of the image projected by the lens. Thinks about it: if I take a photo and crop the image in processing, does this change the angle of view?
It is a bit presumptious alleging that you are telling Asher something he doesn't know, when what you are telling is plain wrong.
Respectfully
Mike.
Hi Mike,
My answer to your question,"Thinks ab... of veiw" is yes. The size of the sensor is an important determinant of the focal length.
Let us look at a diagram.85 mm lens has diagonal angular view of about 28 degrees,from one corner of the photo to the far corner is about 28 degrees. Images of all the objects within this angle reach the sensor. If the sensor is reduced in size,an object at the corner of the photo will not be detected by the new sensor,the angle of view is effectively reduced with the new sensor. If the conversion is 1.5,the new angle of view is about 18 degree. Even if you crop the image in processing,you effectively changes the angle of view from 28 to 18 degrees.
The new image has all the looks of the new focal length. The face looks less 3D and more compressed,there is also a decrease in the variation of the sizes of the objects in different positions from the camera.
Let us consider an extreme ex&le. With an image taken by a wide angle lens say 21mm,if you crops the images enough you can make it looks like an image from an 600mm lens,provide the first image has enough resolution for you to crop.
I am happy to go to any sites,read anything,listen to anyone if the contrary is explained to me,otherwise I am dead right and I hope that you believe I have written something which you don't know.
My answer to your question,"Thinks ab... of veiw" is yes. The size of the sensor is an important determinant of the focal length.
Let us look at a diagram.85 mm lens has diagonal angular view of about 28 degrees,from one corner of the photo to the far corner is about 28 degrees. Images of all the objects within this angle reach the sensor. If the sensor is reduced in size,an object at the corner of the photo will not be detected by the new sensor,the angle of view is effectively reduced with the new sensor. If the conversion is 1.5,the new angle of view is about 18 degree. Even if you crop the image in processing,you effectively changes the angle of view from 28 to 18 degrees.
The new image has all the looks of the new focal length. The face looks less 3D and more compressed,there is also a decrease in the variation of the sizes of the objects in different positions from the camera.
Let us consider an extreme ex&le. With an image taken by a wide angle lens say 21mm,if you crops the images enough you can make it looks like an image from an 600mm lens,provide the first image has enough resolution for you to crop.
I am happy to go to any sites,read anything,listen to anyone if the contrary is explained to me,otherwise I am dead right and I hope that you believe I have written something which you don't know.
I would have to agree with Mike and Asher (and my earlier post about the 85mm of course).
The results are perhaps most apparent with my 21mm Distagon on 20D. The beautiful perspective and visual 'feel' of the lens is not altered in photographs; you just can't see the edges!
I think the ex&le of post-cropping a photo is the easiest way to appreciate it, like taking a 36x24" print and just cutting it down to the 22.5x15" central area.
Cheers,
Matt
The results are perhaps most apparent with my 21mm Distagon on 20D. The beautiful perspective and visual 'feel' of the lens is not altered in photographs; you just can't see the edges!
I think the ex&le of post-cropping a photo is the easiest way to appreciate it, like taking a 36x24" print and just cutting it down to the 22.5x15" central area.
Cheers,
Matt
> Chi,
Unfortunately, it doesn't work like that. Yes as one get further out from the center of the lens, the angle of capture of that part only changes. However, that angle is only important for determining howe MUCH of the field observing is in the field of view to be captured.
Imagine a full size sensor when an 85mm lens is attached for a portrait. There is a head and shoulders and around it the back ground backcloth. Now the edges of that sensor are blocked with a 1-5 mm black frame directly on the sensor. With each progressively reduced central area, the actual head and shoulders is utterly unchanged. No angular changes. No contrast changes. The head and shoulders have not changed. The images printed have a smaller border of background.
That's how it is!
Asher
Unfortunately, it doesn't work like that. Yes as one get further out from the center of the lens, the angle of capture of that part only changes. However, that angle is only important for determining howe MUCH of the field observing is in the field of view to be captured.
Imagine a full size sensor when an 85mm lens is attached for a portrait. There is a head and shoulders and around it the back ground backcloth. Now the edges of that sensor are blocked with a 1-5 mm black frame directly on the sensor. With each progressively reduced central area, the actual head and shoulders is utterly unchanged. No angular changes. No contrast changes. The head and shoulders have not changed. The images printed have a smaller border of background.
That's how it is!
Asher