Talk:Field of View - Revision history

Beeswax: /* close focusing increases FoV */

2011-01-30T15:27:16Z

‎close focusing increases FoV

Erik Krause at 17:48, 28 January 2011

2011-01-28T17:48:57Z

Beeswax: /* close focusing increases FoV */ new section

2011-01-27T13:57:03Z

‎close focusing increases FoV: new section

Erik Krause at 10:59, 11 June 2009

2009-06-11T10:59:13Z

Rew at 21:17, 10 June 2009

2009-06-10T21:17:33Z

Rew at 21:17, 10 June 2009

2009-06-10T21:17:10Z

Rew: Created page with 'in the formula $FoV = 2 * atan \frac{35}{2 * Focal Length}$ The "35" should be some "length" because it is divided by a length, and should become unitless. Of course...'

2009-06-10T21:16:25Z

Created page with 'in the formula <math>FoV = 2 * atan \frac{35}{2 * Focal Length} </math> The "35" should be some "length" because it is divided by a length, and should become unitless. Of course...'

New page

in the formula
<math>FoV = 2 * atan \frac{35}{2 * Focal Length} </math>

The "35" should be some "length" because it is divided by a length, and should become unitless. Of course the length is the size of a standard negative: 35mm. If you want to "ignore units" as most americans like to do, it should not that "Focal length" is in mm. But more accurate is:

<math>FoV = 2 * atan \frac{35 mm}{2 * Focal Length} </math>

← Older revision		Revision as of 15:27, 30 January 2011
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	I believe this phenomenon is known (in cinematography at least) as "focus breathing". In my own limited experience, the FoV is slightly larger when close-focusing compared to infinity focus. Presumably it is more pronounced in some lens designs than others. If I understand correctly, the lens' specified focal length (eg nikon 50mm) will be correct for infinity focus, so at its minimum focusing distance the lens' FoV would be better represented by a focal length number of -say- 49.1mm ? For the purposes of lens correction calibration, would it be appropriate to compensate for close focusing by reducing the focal length variable ? or would that throw some other parameter(s) out of whack ? --[[User:Beeswax\|Beeswax]] 13:57, 27 January 2011 (UTC)		I believe this phenomenon is known (in cinematography at least) as "focus breathing". In my own limited experience, the FoV is slightly larger when close-focusing compared to infinity focus. Presumably it is more pronounced in some lens designs than others. If I understand correctly, the lens' specified focal length (eg nikon 50mm) will be correct for infinity focus, so at its minimum focusing distance the lens' FoV would be better represented by a focal length number of -say- 49.1mm ? For the purposes of lens correction calibration, would it be appropriate to compensate for close focusing by reducing the focal length variable ? or would that throw some other parameter(s) out of whack ? --[[User:Beeswax\|Beeswax]] 13:57, 27 January 2011 (UTC)
	: Exact FoV does depend on even more factors. Details are explained in [http://www.janrik.net/PanoPostings/NoParallaxPoint/TheoryOfTheNoParallaxPoint.pdf Rik Littlefield's paper about the no-parallax-point] --[[User:Erik Krause\|Erik Krause]] 17:48, 28 January 2011 (UTC)		: Exact FoV does depend on even more factors. Details are explained in [http://www.janrik.net/PanoPostings/NoParallaxPoint/TheoryOfTheNoParallaxPoint.pdf Rik Littlefield's paper about the no-parallax-point] --[[User:Erik Krause\|Erik Krause]] 17:48, 28 January 2011 (UTC)
		+	:: Thanks Erik, you've made me realise I failed to ask my question properly! I'm a Hugin newbie, and the "focal length value" I mean is that in "Hugin / Camera & Lens tab / Geometric / focal length" input ... so the question is really about how Hugin interprets this value. Is it used only to determine FOV or does it affect other calculations too ? If I tweek it to achieve a better FOV fit, will I upset something else ? My apologies for being so clumsy! [[User:Beeswax\|Beeswax]] 15:27, 30 January 2011 (UTC)

← Older revision		Revision as of 17:48, 28 January 2011
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	I believe this phenomenon is known (in cinematography at least) as "focus breathing". In my own limited experience, the FoV is slightly larger when close-focusing compared to infinity focus. Presumably it is more pronounced in some lens designs than others. If I understand correctly, the lens' specified focal length (eg nikon 50mm) will be correct for infinity focus, so at its minimum focusing distance the lens' FoV would be better represented by a focal length number of -say- 49.1mm ? For the purposes of lens correction calibration, would it be appropriate to compensate for close focusing by reducing the focal length variable ? or would that throw some other parameter(s) out of whack ? --[[User:Beeswax\|Beeswax]] 13:57, 27 January 2011 (UTC)		I believe this phenomenon is known (in cinematography at least) as "focus breathing". In my own limited experience, the FoV is slightly larger when close-focusing compared to infinity focus. Presumably it is more pronounced in some lens designs than others. If I understand correctly, the lens' specified focal length (eg nikon 50mm) will be correct for infinity focus, so at its minimum focusing distance the lens' FoV would be better represented by a focal length number of -say- 49.1mm ? For the purposes of lens correction calibration, would it be appropriate to compensate for close focusing by reducing the focal length variable ? or would that throw some other parameter(s) out of whack ? --[[User:Beeswax\|Beeswax]] 13:57, 27 January 2011 (UTC)
		+	: Exact FoV does depend on even more factors. Details are explained in [http://www.janrik.net/PanoPostings/NoParallaxPoint/TheoryOfTheNoParallaxPoint.pdf Rik Littlefield's paper about the no-parallax-point] --[[User:Erik Krause\|Erik Krause]] 17:48, 28 January 2011 (UTC)

← Older revision		Revision as of 13:57, 27 January 2011
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	: Just edit. Actually a "35mm" negative is 36mmx24mm in size. 35mm is the width of the entire film, including perforation etc. Since the formula is universal, I changed it to "size". (This error was pretty old, thanks for pointing it out) --[[User:Erik Krause\|Erik Krause]] 10:59, 11 June 2009 (UTC)		: Just edit. Actually a "35mm" negative is 36mmx24mm in size. 35mm is the width of the entire film, including perforation etc. Since the formula is universal, I changed it to "size". (This error was pretty old, thanks for pointing it out) --[[User:Erik Krause\|Erik Krause]] 10:59, 11 June 2009 (UTC)
		+
		+	== close focusing increases FoV ==
		+
		+	I believe this phenomenon is known (in cinematography at least) as "focus breathing". In my own limited experience, the FoV is slightly larger when close-focusing compared to infinity focus. Presumably it is more pronounced in some lens designs than others. If I understand correctly, the lens' specified focal length (eg nikon 50mm) will be correct for infinity focus, so at its minimum focusing distance the lens' FoV would be better represented by a focal length number of -say- 49.1mm ? For the purposes of lens correction calibration, would it be appropriate to compensate for close focusing by reducing the focal length variable ? or would that throw some other parameter(s) out of whack ? --[[User:Beeswax\|Beeswax]] 13:57, 27 January 2011 (UTC)

← Older revision		Revision as of 10:59, 11 June 2009
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	Should I just edit this into the main page, or should some discussion be held first? -- REW.		Should I just edit this into the main page, or should some discussion be held first? -- REW.
		+
		+	: Just edit. Actually a "35mm" negative is 36mmx24mm in size. 35mm is the width of the entire film, including perforation etc. Since the formula is universal, I changed it to "size". (This error was pretty old, thanks for pointing it out) --[[User:Erik Krause\|Erik Krause]] 10:59, 11 June 2009 (UTC)

@@ Line 3: / Line 3: @@
 <math>FoV = 2 * atan \frac{35}{2 * Focal Length} </math>
-The "35" should be some "length" because it is divided by a length, and should become unitless. Of course the length is the size of a standard negative: 35mm. If you want to "ignore units" as most americans like to do, it should not that "Focal length" is in mm. But more accurate is:
+The "35" should be some "length" because it is divided by a length, and should become unitless. Of course the length is the size of a standard negative: 35mm. If you want to "ignore units" as most americans like to do, it should note that "Focal length" is in mm. But more accurate is:
 <math>FoV = 2 * atan \frac{35 mm}{2 * Focal Length} </math>
 Should I just edit this into the main page, or should some discussion be held first? -- REW.

@@ Line 1: / Line 1: @@
 in the formula
 <math>FoV = 2 * atan \frac{35}{2 * Focal Length} </math>
@@ Line 5: / Line 6: @@
 <math>FoV = 2 * atan \frac{35 mm}{2 * Focal Length} </math>

Talk:Field of View - Revision history

Beeswax: /* close focusing increases FoV */

Erik Krause at 17:48, 28 January 2011

Beeswax: /* close focusing increases FoV */ new section

Erik Krause at 10:59, 11 June 2009

Rew at 21:17, 10 June 2009

Rew at 21:17, 10 June 2009

Rew: Created page with 'in the formula FoV = 2 * atan \frac{35}{2 * Focal Length} The "35" should be some "length" because it is divided by a length, and should become unitless. Of course...'

Rew: Created page with 'in the formula $FoV = 2 * atan \frac{35}{2 * Focal Length}$ The "35" should be some "length" because it is divided by a length, and should become unitless. Of course...'