Is this lens distortion?


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CT 3833

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Sep 23, 2006
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#1
Hi, I noticed the top right corner of this photo has a very severe distortion. The distortion looks so strange that it seems to only occur at that particular corner, not anywhere else on the left or either side at the bottom.

Is this a lens distortion? Thanks.

 

Nov 12, 2003
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#2
i think the lack of apparent subject with the a grid or straight lines makes the effect only very visible on that corner...

The railing is also "stretched" ma.. but ya i see what you mean about the building curving...
 

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Rashkae

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Nov 28, 2005
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#3
your lens might have what is also called a centering defect. Try to take a head-on shot of a brick wall or similar uniform pattern. Try to see if the distortion is still only in that one corner
 

CT 3833

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Sep 23, 2006
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#4
i think the lack of apparent subject with the a grid or straight lines makes the effect only very visible on that corner...

The railing is also "stretched" ma.. but ya i see what you mean about the building curving...
Thanks. one point forget to mention, the building is leaning "sideway " towards to edge of the photo instead of the usual leaning "inward" towards the center of the photo. This puzzled me as well. Or my perception is wrong?

your lens might have what is also called a centering defect. Try to take a head-on shot of a brick wall or similar uniform pattern. Try to see if the distortion is still only in that one corner
Thanks. I will go test it out this weekend.
 

night86mare

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Aug 25, 2006
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#5
is this 10mm? if it happens to be an ultra wide angle most of them tend to be alright everywhere except for the extreme corners. if this is sigma 10-20 then that might explain it

yes that is lens distortion AND combination of vertical distortion
 

CT 3833

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Sep 23, 2006
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#6
is this 10mm? if it happens to be an ultra wide angle most of them tend to be alright everywhere except for the extreme corners. if this is sigma 10-20 then that might explain it

yes that is lens distortion AND combination of vertical distortion
night8mare,
no, this is the Tamron 17-50mm and I shot at 17mm wide.
 

calebk

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Jul 25, 2006
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#7
night8mare,
no, this is the Tamron 17-50mm and I shot at 17mm wide.
It leans outward because your image plane is at at angle slanting downward as compared to the vertical of the building.

Normally you'd see converging verticals near the top of the frame because you are photographing a building by slanting your camera upward to catch the whole building:

|
|
image plane \ | building
|

But in this case, your image plane (sensor) is slanted the other way

image plane /

Hope you get the drift.
 

CT 3833

New Member
Sep 23, 2006
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#8
It leans outward because your image plane is at at angle slanting downward as compared to the vertical of the building.

Normally you'd see converging verticals near the top of the frame because you are photographing a building by slanting your camera upward to catch the whole building:

|
|
image plane \ | building
|

But in this case, your image plane (sensor) is slanted the other way

image plane /

Hope you get the drift.
Caleb,
thanks for your explanation! Hope I understand your explanation correectly, in simple term, it depends on whether I am pointing my camera "more" downward or upward in relative to the building. I will go try it out. Thanks!
 

Kit

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Jan 19, 2002
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#9
Yes; to put it in simpler terms, you are pointing the camera downwards. Hence you get the diverging lines. You'll also notice that the buildings are stretched out of proportion, that's perspective distortion which is inherent in all wide angle lenses. These distortions will occur at all edges of your photos. The reason why you think you are seeing it only at the corner where the buildings are is because the vertical lines of the buildings serves as a guide and accentuate the distortions more than anywhere in the photo.
 

night86mare

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#10
night8mare,
no, this is the Tamron 17-50mm and I shot at 17mm wide.
this is the distortion chart for the lens if you use canon



doesn't look too noticeable to me.

to correct the keystone effect here, photoshop lens distort filter at +77 or +78 setting (very extreme) will give you more correct verticals. here also probably requires a bit more liquification (manual correction) to make sure everything is perfect. of course always best to compose in a way such that you avoid this because you end up degrading the image and having to crop part of it away. in this case, a rather large part:



if you need details on how to do this, you can read pages 1 to 8 from the stuff i have written here (click on link). cheers.
 

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#11
your lens might have what is also called a centering defect. Try to take a head-on shot of a brick wall or similar uniform pattern. Try to see if the distortion is still only in that one corner
Agree with this good suggestion, if wanna confirm just can shoot brick wall or maybe a piece of graph paper, the distortions can be consistently replicated that way.
 

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