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Question about camera moving vs. focal length
Posted: 24 June 2014 06:06 PM   [ Ignore ]   [ # 16 ]
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I’m guessing that its somehow a fundamental mistake and won’t be fixed before V5.0.

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Posted: 25 June 2014 12:55 AM   [ Ignore ]   [ # 17 ]
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I’m not seeing what you are in DS4.6 at 50mm but my focal distance is not set to 200 something either.

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Exile, Drows Walk: A Tale of Jaderail starts here. Free pulp fiction at its Fantasy best, Updated 2/3/14.
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Posted: 25 June 2014 03:49 AM   [ Ignore ]   [ # 18 ]
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This is what I get with Render Dimension set to 10:1 with 50mm Focal Length camera. 

Note that the 10:1 render dimension setting has effectively reduced camera focal length to 5.53mm. 

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50mm_from_3m_10x1.JPG
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Posted: 25 June 2014 03:59 AM   [ Ignore ]   [ # 19 ]
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And this with Render dimension set to 1:1 with 5.53mm Focal Length camera (extreme wide angle).

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5.53mm_from_3m_1x1_.JPG
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Posted: 25 June 2014 04:23 AM   [ Ignore ]   [ # 20 ]
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Jaderail - 25 June 2014 12:55 AM

I’m not seeing what you are in DS4.6 at 50mm but my focal distance is not set to 200 something either.

Focal distance is not part of the problem.  In the scene above,  the camera focal distance is set to 300 (focused on corner of small blue cube).

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Posted: 25 June 2014 09:27 AM   [ Ignore ]   [ # 21 ]
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Render dimension set to 1:1 with 50mm Focal Length camera.

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50mm_from_3m_1x1_.JPG
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Posted: 25 June 2014 02:20 PM   [ Ignore ]   [ # 22 ]
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edited and removed by user

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Posted: 25 June 2014 03:09 PM   [ Ignore ]   [ # 23 ]
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linvanchene, at last a photographer.  The bug seems to effect all focal lengths.  The 10:1 render dimension was an extreme example, with render dimension set to 2:1, 50mm focal length is effectively reduced to 31.59mm.

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2x1_50mm.JPG1x1_31.59mm_.JPG
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Posted: 25 June 2014 05:49 PM   [ Ignore ]   [ # 24 ]
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Posted: 25 June 2014 06:25 PM   [ Ignore ]   [ # 25 ]
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linvanchene - 25 June 2014 05:49 PM

The question is: Was this bug introduced in one of the last updates or did we all just not notice for a very long time?

Looking back I thought that it might have first appeared with the 4.6 release.  But I’m now thinking it was the 4.5 release. 

 

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Posted: 27 June 2014 06:37 AM   [ Ignore ]   [ # 26 ]
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Here’s a list of render dimensions with the approximative focal length correction.

2:1 multiply focal length by 1.579
3:1…........................................2.370
4:1…....................................... 3.172
5:1…....................................... 3.971
6:1…....................................... 4.770
7:1…....................................... 5.561
8:1…........................................6.329
9:1…....................................... 7.142
10:1…..................................... 7.936

Most of the error is removed at any reasonable focal length (8mm to 800mm).  As linvanchene pointed out though, for composite work focal length needs to be precisely matched.

Edit:- The above only works between focal lengths of 40 to 50mm.

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