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Zoom reach on crop sensors
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Jan 13, 2019 08:11:23   #
Longshadow (a regular here)
 
frankraney wrote:
1/300.... A 300mm lens is a 300mm lens. Lenses are measured in mm, from the optical center to the sensor.


Yes, for JUST the lens, standing alone.

Put it on two different size sensor cameras and it becomes effectively something different on each. 300 on FF and (300*CropFactor) on the other. Then you should use 1/(300*CropFactor) as the starting point for the shutter for hand held.

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Jan 13, 2019 08:24:25   #
Longshadow (a regular here)
 
frankraney wrote:
Jim, The lens length is 300mm, so why go to 1/450. The rules of this is 1/mm. The crop factor is only a comparison between a crop sensor and a ff sensor.....a 300mm on a crop sensor is like a 450 on a ff...or another way to put it, to take a shot with a ff 450mm and crop it down. A 300mm designed for a crop sensor is 300mm, and a 300mm on a ff is 300mm.

Am I all wet?


Think you got it backwards above. A 300 on a FF is like a 450 on a 1.5x crop; 480 on a 1.6x crop.
And yes, use 1/(LensMM*CropFactor) with CropFactor=1 for FF.

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Jan 13, 2019 10:07:40   #
DaveyDitzer (a regular here)
 
Please define "more reach". If the same subject is shot from the same distance, it is not "magnified" by the crop factor. it just fills more of the frame.

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Jan 13, 2019 10:23:18   #
frankraney (a regular here)
 
Bill, I don't think so....a 300 on a crop sensor(1.5) is like a 450 on a full frame.

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Jan 13, 2019 11:10:09   #
LWW (a regular here)
 
DaveyDitzer wrote:
Please define "more reach". If the same subject is shot from the same distance, it is not "magnified" by the crop factor. it just fills more of the frame.


And the difference between magnification and filling more of the frame is what?

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Jan 13, 2019 11:39:10   #
Longshadow (a regular here)
 
DaveyDitzer wrote:
Please define "more reach". If the same subject is shot from the same distance, it is not "magnified" by the crop factor. it just fills more of the frame.


ergo, more reach. (closer in)

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Jan 13, 2019 11:40:52   #
Longshadow (a regular here)
 
frankraney wrote:
Bill, I don't think so....a 300 on a crop sensor(1.5) is like a 450 on a full frame.


Sorry, miss-read.

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Jan 13, 2019 12:44:37   #
frankraney (a regular here)
 
Longshadow wrote:
Sorry, miss-read.


no Problem, I've done that numerous times..

Jim straightened me out on the above...I understand crop factor etc (or at least I thought I did) But I never read or thought about the crop sensor affecting the 1/MM.....(1/mm*cf)....

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Jan 13, 2019 13:20:19   #
nadelewitz (a regular here)
 
Longshadow wrote:
The lens focal length itself does not change, the effect depends what camera you put it on.

Well, doesn't a longer-focal-length lens have more reach???


Well, no, the effect of a lens does not change depending on what camera you put it on. What changes is how much of the lens's field of view is recorded by a smaller sensor.

And yes, a longer focal-length lens has more reach. So what? That's not what is being discussed here.

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Jan 13, 2019 13:28:51   #
Longshadow (a regular here)
 
nadelewitz wrote:
Well, no, the effect of a lens does not change depending on what camera you put it on. What changes is how much of the lens's field of view is recorded by a smaller sensor.

And yes, a longer focal-length lens has more reach. So what? That's not what is being discussed here.


1 - Isn't that change in field of view perceived as zooming in?

3 - Then what is?

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Jan 13, 2019 14:05:18   #
nadelewitz (a regular here)
 
Longshadow wrote:
1 - Isn't that change in field of view perceived as zooming in?

3 - Then what is?


1. That's the perception, which is an erroneous assumption. On a crop-sensor camera you are just SEEING the narrower, cropped field-of-view that a longer lens would see.
The lens is still projecting the same area into the camera, but the small sensor just gets a smaller central area.

3. What is what?

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Jan 13, 2019 14:20:45   #
Longshadow (a regular here)
 
nadelewitz wrote:
1. That's the perception, which is an erroneous assumption. On a crop-sensor camera you are just SEEING the narrower, cropped field-of-view that a longer lens would see.
The lens is still projecting the same area into the camera, but the small sensor just gets a smaller central area.

3. What is what?

Okay. So there is no real or apparent zooming with a crop sensor?
I've been calling these variable-field-of-view lenses by the wrong name?

That's not what is being discussed here.
What is then?

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Jan 13, 2019 15:28:48   #
LWW (a regular here)
 
Q - How many angels can dance on the head of a pin?

Q - Is the pin an English Whitworth size pin?

Q - Is it an American Standard size pin?

Q - Is it a Euro Metric size pin?

Q - What is the crop factor of the shadows from smallest to largest?

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Jan 13, 2019 15:29:55   #
Longshadow (a regular here)
 
LWW wrote:
Q - How many angels can dance on the head of a pin?

Q - Is the pin an English Whitworth size pin?

Q - Is it an American Standard size pin?

Q - Is it a Euro Metric size pin?

Q - What is the crop factor of the shadows from smallest to largest?



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Jan 13, 2019 15:51:23   #
PHRubin (a regular here)
 
LWW wrote:
Let’s say both sensors were 24 MP just of different sized sensors. The FF, to get the same FOV, would be cropped down to 16mm(MP) while the APS would maintain the full 24 MP.


It is worse than that, the image is cropped both in length and width.
A Canon APS-C sensor is 329mm² while a FF is 864mm². 24*(329/864) = 9.14 MP.
For Nikon it is almost as bad: 24*(380/864)=10.56 MP

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