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Zoom reach on crop sensors
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Jan 11, 2019 09:39:39   #
DebAnn (a regular here)
 
I understand that zoom lenses "reach" further on crop sensor cameras. Does a zoom lens specifically designed for a crop sensor camera have that effect? For instance, does a 55-250 mm zoom made for a crop have an effective reach of around 400 mm? Or does that only apply to lenses that work on both full frame and crop?

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Jan 11, 2019 09:54:37   #
lsaguy
 
I'm going to go out on a limb here just to see if I understand this. Hoggers, feel free to correct me if I'm wrong (like you'd need my encouragement :-})
Putting an FX lens on a DX camera doesn't change the "reach" at all. Think of the field of view (FOV) of any lens as a conical area with a defined base length. What the FX lens does on a DX camera is give the effect of decreasomg that base to that of a, roughly, 1/3 bigger lens.
To put numbers on it. If an FX lens of, say, 300mm focal length, the base of the cone is 100 feet. Put that lens on a DX camera and the smaller sensor cuts down that base to 66 feet, the base of the cone of an FX lens of 400mm.
And now to be graded on my understanding of this phenomenon.....

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Jan 11, 2019 10:04:15   #
Linary
 
DebAnn wrote:
I understand that zoom lenses "reach" further on crop sensor cameras. Does a zoom lens specifically designed for a crop sensor camera have that effect? For instance, does a 55-250 mm zoom made for a crop have an effective reach of around 400 mm? Or does that only apply to lenses that work on both full frame and crop?


Any lens on a camera with a sensor smaller than full frame will produce a cropped image. On a Nikon AP-S camera body a 300mm lens will produce an image which has the same field of view of a 450mm lens on a full frame camera. This is not magnification, this is cropping.


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Jan 11, 2019 10:06:01   #
bsprague (a regular here)
 
If we had switched to some concept like "field of view" when we shot film, it would make more sense.

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Jan 11, 2019 10:08:50   #
Mac (a regular here)
 
lsaguy wrote:
I'm going to go out on a limb here just to see if I understand this. Hoggers, feel free to correct me if I'm wrong (like you'd need my encouragement :-})
Putting an FX lens on a DX camera doesn't change the "reach" at all. Think of the field of view (FOV) of any lens as a conical area with a defined base length. What the FX lens does on a DX camera is give the effect of decreasomg that base to that of a, roughly, 1/3 bigger lens.
To put numbers on it. If an FX lens of, say, 300mm focal length, the base of the cone is 100 feet. Put that lens on a DX camera and the smaller sensor cuts down that base to 66 feet, the base of the cone of an FX lens of 400mm.
And now to be graded on my understanding of this phenomenon.....
I'm going to go out on a limb here just to see if ... (show quote)


What you say is basically correct.
On Nikon cameras the crop factor is 1.5 so a 300mm lens on a DX camera would give an equivalent angle of view of 450mm.
This is not limited to FX lenses on DX cameras. Focal length is constant, so a 300mm DX lens would also give an equivalent angle of view of 450mm.

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Jan 11, 2019 10:09:41   #
Linary
 
bsprague wrote:
If we had switched to some concept like "field of view" when we shot film, it would make more sense.


When you were shooting film, did you ever use a "half frame" camera, and did the apparent extra reach or cropped field of view come into play?

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Jan 11, 2019 10:16:43   #
Longshadow (a regular here)
 
Linary wrote:
Any lens on a camera with a sensor smaller than full frame will produce a cropped image. On a Nikon AP-S camera body a 300mm lens will produce an image which has the same field of view of a 450mm lens on a full frame camera. This is not magnification, this is cropping.


So if you crop saving the center of an image to the dimensions of the original image , it is not "effectively" zooming in? If you have a lens and zoom in, are you not cropping the original "wide" image?
Is "zooming" in not magnifying? Consider the definition of "magnify".

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Jan 11, 2019 10:17:14   #
bsprague (a regular here)
 
Linary wrote:
When you were shooting film, did you ever use a "half frame" camera, and did the apparent extra reach or cropped field of view come into play?


When shooting film, I had two systems. One was 35mm Nikon rectangle and the other was 2 1/4 inch square Mamiya twin lens. To get what was thought to be a "normal" field of view, a 50mm lens was appropriate on the Nikon. If I recall correctly, it was an 80 mm lens on the Mamiya.

So, in that sense, the Nikon that has morphed from film to digital and called "full frame" was really the "cropped" camera.

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Jan 11, 2019 10:28:34   #
Linary
 
bsprague wrote:
When shooting film, I had two systems. One was 35mm Nikon rectangle and the other was 2 1/4 inch square Mamiya twin lens. To get what was thought to be a "normal" field of view, a 50mm lens was appropriate on the Nikon. If I recall correctly, it was an 80 mm lens on the Mamiya.

So, in that sense, the Nikon that has morphed from film to digital and called "full frame" was really the "cropped" camera.


I agree with you about the lenses. I used the Rollie 35mm with a 50mm lens and Yashica 2 1/4" with an 80mm or sometimes 135mm lens, and cannot ever remember anyone discussing the extra reach or image cropping. It was just something we all knew and took into account when choosing a camera for the day.

Everything seems to be more complicated now, yet there is no difference in the technology or the physics involved. Nowadays, I look through the viewfinder and either take the photo or change the lens (or even the zoom which I did not have in the film days).

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Jan 11, 2019 10:36:19   #
Linary
 
Longshadow wrote:
So if you crop saving the center of an image to the dimensions of the original image , it is not "effectively" zooming in? If you have a lens and zoom in, are you not cropping the original "wide" image?
Is "zooming" in not magnifying? Consider the definition of "magnify".


I concede to your argument, you are in effect, zooming in.

I would much rather zoom using a full frame body and a zoom lens, than use a crop sensor body to achieve the same result. This argument probably does not stand up when the image quality of a modern camera is taken into account, but I'm old fashioned

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Jan 11, 2019 10:44:27   #
Mac (a regular here)
 
DebAnn wrote:
I understand that zoom lenses "reach" further on crop sensor cameras. Does a zoom lens specifically designed for a crop sensor camera have that effect? For instance, does a 55-250 mm zoom made for a crop have an effective reach of around 400 mm? Or does that only apply to lenses that work on both full frame and crop?


The lenses don't reach farther, but they give an angel of view of a longer lens.
This will apply to all lenses, those lenses designed for crop sensors and those designed for both.

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Jan 11, 2019 10:44:32   #
DebAnn (a regular here)
 
I knew this would get more technical than I need. So I'm simplifying the question. If I use my Canon 70D camera (crop) with a 70-300mm lens and shoot a photo of a lion that's in the distance, will I get a closer-looking shot than if I used the same lens on my Canon 6D II? Yes or no?

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Jan 11, 2019 10:46:53   #
DebAnn (a regular here)
 
Thank you Mac. That's the answer I was looking for. Your post crossed time-wise with my latest post.
Mac wrote:
The lenses don't reach farther, but they give an angel of view of a longer lens.
This will apply to all lenses, those lenses designed for crop sensors and those designed for both.

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Jan 11, 2019 10:48:42   #
Mac (a regular here)
 
DebAnn wrote:
Thank you Mac. That's the answer I was looking for. Your post crossed time-wise with my latest post.



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Jan 11, 2019 10:49:25   #
Longshadow (a regular here)
 
Linary wrote:
I concede to your argument, you are in effect, zooming in.

I would much rather zoom using a full frame body and a zoom lens, than use a crop sensor body to achieve the same result. This argument probably does not stand up when the image quality of a modern camera is taken into account, but I'm old fashioned


I don't use a crop sensor to achieve that result, I use a crop sensor body because that's what I have.
Sometimes I wish my 18 would really be an 18.

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