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11-13-2012, 11:10 PM   #1
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Perspective correction

Will a lensbaby be of any use to correct keystone effect on close ups of buildings?

11-13-2012, 11:25 PM   #2
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To correct perspective you will want a lens that can Shift.

To my knowledge, all the Lensbabies only have a function to allow Tilt.


Perspective control lens - Wikipedia, the free encyclopedia



Tilt will just allow you to change the depth of field (although, from the images I've seen, Lensbabies seem to make images unnatural and crap in general)
11-14-2012, 12:10 AM   #3
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It would be much easier to do in post-processing. All the major image editors have perspective correction tools that are easy to use.
11-14-2012, 01:28 AM   #4
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You need shift lenses. Try first with software if it's only slightly correction needed.

The options are:
- Pentax K 28 shift,
- Olympus 24mm shift or 35mm shift, and change mount (leitax).
- Zeiss Distagon 35mm shift, and change mount (leitax).
- Medium format Pentacon Six lenses with shift adapter.

Nikkor PC 28/3.5 also fits with Pentax body, but it's not click in (force fit).
It fits tight with a 6-8mm turn, so if you use it, be very careful.

11-14-2012, 10:33 PM   #5
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Keystone is caused by the rules of perspective and is the result of tilting your camera upwards to shoot a tall object. To avoid keystone, you must keep the film plane parallel to the plane of your subject. A shift lens will allow you to do this while still getting the top of your subject in the frame. Unfortunately, you need a fairly wide FOV to make a shift lens work for you and even 28mm is not really wide enough for APS-C.

The most flexible solution is a view camera. Check out this PDF for a more detailed description on how to do perspective and focus control using camera movements (tilt/shift/swing).

http://paulturounetblog.files.wordpress.com/2007/08/view-camera-movements.pdf
  • Change the plane of the film/sensor relative to the subject to change the perspective
  • Change the plane of the lens relative to the subject and film/sensor to manage the plane of focus (Scheimpflug...love that word...)
  • Change the position of the lens relative to the subject to change the spatial relationship of objects in the frame


Steve


(...is really needing to get the Chamonix out in the field again...)


Last edited by stevebrot; 11-14-2012 at 10:47 PM.
11-14-2012, 10:41 PM   #6
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QuoteOriginally posted by mdave13 Quote
It would be much easier to do in post-processing. All the major image editors have perspective correction tools that are easy to use.
What he said...though there may be some loss of subject and/or detail.


Steve
11-14-2012, 11:00 PM   #7
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Just want to point out that the "distortion" is actually natural, and if you correct it so the building sides are perfectly parallel, it will look odd to the eye. Your brain expects the building to taper, so you should leave some in.
11-14-2012, 11:16 PM   #8
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QuoteOriginally posted by SpecialK Quote
Just want to point out that the "distortion" is actually natural, and if you correct it so the building sides are perfectly parallel, it will look odd to the eye. Your brain expects the building to taper, so you should leave some in.
True, every time I see an image (be it an actual shift, or software) that's been corrected, I always think it looked better without the adjustment.

edit:
Of course, now that I'm looking for an example on google, only ones that look good are coming up....


Last edited by hks_kansei; 11-14-2012 at 11:29 PM.
11-15-2012, 12:59 AM   #9
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QuoteOriginally posted by hoanpham Quote
Medium format Pentacon Six lenses with shift adapter.
Unfortunately and for an unknown reason, the shift adapter for Pentacon six lenses seems to be discontinued and is very difficult to find nowadays, while the tilt adapter is still widely available from a number of sources.

Cheers!

Abbazz
11-18-2012, 09:46 AM   #10
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With all the pixels in modern cameras, I consider a (good) wide lens and cropping to be the best shift solution.
11-18-2012, 10:13 AM   #11
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QuoteOriginally posted by drougge Quote
With all the pixels in modern cameras, I consider a (good) wide lens and cropping to be the best shift solution.



...and a good ultra-wide is cheaper and easier to use than a shift lens!


Steve
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