uplander
TPF Noob!
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I've been thinking about this for some time. This statement is out there all the time, "A 400mm lens on a 1.6 crop factor sensor is equivalent to a 640mm on a full size sensor".
I believe this is a true statement when you are comparing field of view which is expressed in angle. So what you have is a lens that projects the same size image but because the sensor sizes are different the smaller sensor captures a smaller portion of the image which results in a narrower FOV. The image isn't any different it's just that the smaller sensor captures less of it, hence the narrower FOV.
I believe stating that a 400 mm lens on a 1.6 crop sensor becomes a 640mm lens is misleading. One tends to think it makes the lens more powerfull in magnification which isn't true. I would think the magnification is the same unless there is some difference in the distance from rear element to the sensor.
So if that distance is the same ( I would tend to think it is ...I may be wrong though) Then the only difference is the amount of the image projected by the lens each respective sensor catches. So then the area of the image each sensor captures are exactly the same in image size and quality except the crop sensor records less of it ( IE the bordering edges)
Hence I think that a 400mm lens is a 400mm lens despite what body it is on. Or in other words saying it is the equivalent of a 640mm on a 1.6 crop factor sensor is a bunch of hooey! A 400mm lens on a crop body does not get you any closer to your subject than a full size body
Unless.....you start looking at the amount of pixels in each sensor or lets just say does having more pixels/cm2 will give you better resolution when you crop and in effect give you more magnification which is a whole another can of worms. So maybe we should just stay and debate the first part of this post.
I got a feeling this should be interesting if you really put some thought into it.
Discuss!!!:mrgreen:
I believe this is a true statement when you are comparing field of view which is expressed in angle. So what you have is a lens that projects the same size image but because the sensor sizes are different the smaller sensor captures a smaller portion of the image which results in a narrower FOV. The image isn't any different it's just that the smaller sensor captures less of it, hence the narrower FOV.
I believe stating that a 400 mm lens on a 1.6 crop sensor becomes a 640mm lens is misleading. One tends to think it makes the lens more powerfull in magnification which isn't true. I would think the magnification is the same unless there is some difference in the distance from rear element to the sensor.
So if that distance is the same ( I would tend to think it is ...I may be wrong though) Then the only difference is the amount of the image projected by the lens each respective sensor catches. So then the area of the image each sensor captures are exactly the same in image size and quality except the crop sensor records less of it ( IE the bordering edges)
Hence I think that a 400mm lens is a 400mm lens despite what body it is on. Or in other words saying it is the equivalent of a 640mm on a 1.6 crop factor sensor is a bunch of hooey! A 400mm lens on a crop body does not get you any closer to your subject than a full size body
Unless.....you start looking at the amount of pixels in each sensor or lets just say does having more pixels/cm2 will give you better resolution when you crop and in effect give you more magnification which is a whole another can of worms. So maybe we should just stay and debate the first part of this post.
I got a feeling this should be interesting if you really put some thought into it.
Discuss!!!:mrgreen:
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