Wide Angle & Lens Correction in PS

[Thlayle]

Randy, I have a 10-20mm I use on my D7000, and a 16-35mm on my D600. I shoot wide angle pans all the time for you shot I would have likely used 3 shots and stitched in Photoshop which does an excellent job by the way. Now I shoot almost all my stuff with the camera set in Portrait mode, now I use a L-bracket so that I can quickly change from landscape mode to portrait in a matter of seconds.

Cheers: Allan

Thanks, Allan. I have heard of the L-brackect usage in this forum before, perhaps in a comment by Manfred(?). Is there a more specific name for it? It's an offset, isn't it, that helps with the perspective issues in rotating the lens for images to be taken for stitching together?

-Randy

[Thlayle]

I very rarely correct for pronounced wide-angle barrel distortion (I'll correct more if it's slight or pincushion), but I'm an eccentric when it comes to this kind of thing, as I like fisheyes and often shoot 360x180 panos from fisheye images and do weird remappings, so distortion is a friend to me. I've occasionally defished, but as you note, often it's simply not worth the real estate loss. And I rarely shoot architecture.

When I shoot rectilinear UW with my Oly 9-18 (I'm on four-thirds, so that's only an 18-36 equiv.), I'm generally not correcting at all. I don't mind the leaning verticals.

(9-18 @9mm)


And if I do mine, I can try hoofing it out and zooming in.

Very nice & thanks, Kathy. I see what you mean & I am generally finding these sorts of framings to work for me without trying to correct for the angular effects on the uprights in the images. I'm shooting a lot with my fixed length 14mm, 'hoofing & zooming' doesn't come into it so much for me.

-Randy

(9-18 @18mm instead)

[Thlayle]

Used Hugin to fix your image. Just a fast way not pefect. Loaded your image then preview and adjusted it and converted it one minute not perfect but nearly. check Hugin
Shooting a lot 14mm full frame and using a manfrotto three way geared head to get the camera absolutly straight. Also using the camranger to frame the picture.
You have a crop sensor so it's 22mm on a full frame so good enough for stitching.http://s8.tinypic.com/2nks6mo_th.jpg

I see that worked great, no lost real estate to speak of either. Looks like Hugin is a worthwhile option. Right now, I'm thinking I should set aside the Adaptive Wide Angle filter, at least for now. It works well but is more time consuming & definitely seems to relate to losing more of the picture edges in the processing.

I think there are better perspective correcting tools for my purposes in Photoshop and Lightroom that I need to get familiar with. Maybe I will eventually see a proper niche for the application of the Adaptive Wide Angle filter.

-Randy

[Polar01]

There is no special name for an L-bracket other than L-bracket now there are a number of different makers of them. The one I use and I believe Manfred also is made by Really Right Stuff. They are not universal as each is made for that make (mine Nikon) and model D7000 or D600. so one for a D7000 will not fit a D600 correctly, also you have to use their ballhead and/or clamp (I use their quick release clamp on my Feisol Tripod and ball head.
I am putting a link to the Really Right Stuff site, also checkout the pulldown "Be an Expert", some good general info on choosing a tripod and heads.

http://www.reallyrightstuff.com/s.nl...code=46&key=fr

Cheers: Allan

[ajohnw]

I did this one from three 9mm m 4/3 portrait shots just as a trial and used Fotoxx to stitch them automatically. I picked the shot because of the lighting differences just out of curiosity. I'd say it covers about 2 of what ever 18mm FF covers in that orientation. Cropping always looses some. The near pillar was only a couple of metres away from me. I've lost some of the fence on the right hand side and some of the one on the left.



There is some near distortion on the pillar but the other was sloping. I couldn't specify the focal length correctly which might have caused that. it wont currently allow less than 24mm to be set.

I also sat on the edge of this and did a 180 degree one with my feet nearly in the view of the one taken directly ahead. As I suspected it produced an odd effect. The shape is really parallel sides with curved ends. Unfortunately 2 people down in it were lost.



I haven't tried feeding them through Hugin yet. I have used that for correctly complex distortion on a street shot.

John
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[Shadowman]

Sometimes the distortion is made more apparent by too many leading lines or patterns.

[ajohnw]

This what Hugin did to it. It's changed since I last used it and easier to select the projection. Advanced needs to be selected to set the control points. I never looked at the expert panel which I assume allows further adjustments. It calculated the max crop and is as large as it can be.



There is still a bit of keystone/tilt so I should have used more control points but sometimes it's easier to finish that sort of thing off with a direct correction for that.

John
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[loosecanon]

I use the same lens sold here as Samyang .
If you look on Adobes website you can find the profile that will correct the unusual maustache distortion that the lens generates,
There as also profiles elsewhere on the web. You don't need to worry about the camera used for the profile, it is the distortion to be corrected.
The procedure to get the profile into lightroom is easy once you understand it (cannot remember at this moment) is all online.
It does solve a problem.

[Shadowman]

This what Hugin did to it. It's changed since I last used it and easier to select the projection. Advanced needs to be selected to set the control points. I never looked at the expert panel which I assume allows further adjustments. It calculated the max crop and is as large as it can be.



There is still a bit of keystone/tilt so I should have used more control points but sometimes it's easier to finish that sort of thing off with a direct correction for that.

John
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The excessive cropping is what stopped me from using the distortion feature in LR or PSE, makes composing the image up front so much more important.

[Thlayle]

I use the same lens sold here as Samyang .
If you look on Adobes website you can find the profile that will correct the unusual maustache distortion that the lens generates,
There as also profiles elsewhere on the web. You don't need to worry about the camera used for the profile, it is the distortion to be corrected.
The procedure to get the profile into lightroom is easy once you understand it (cannot remember at this moment) is all online.
It does solve a problem.

Wow: I didn't think of that possibility, that I might get the lens profile to work with in Photoshop. I'm working with the CC subscription, so I wonder if that will work for me. Giving it a try....

[ajohnw]

The excessive cropping is what stopped me from using the distortion feature in LR or PSE, makes composing the image up front so much more important.

That's basically why I just took a couple to see what happened. That way when I choose to take one seriously I might have some idea how much extra to frame.

I've no interest what so ever in getting into package merits again. People will use what they use and that's that. In some respects I am some times surprised that people jump in defending Adobe after fashion as if there just can't be any alternatives.

John
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[Manfred M]

Frankly, I do almost all my distortion correction by hand; using the Photoshop skew and scale functions (under the Transform tab). That way I can control the amount of material that I lose in the edit. The automated functions crop to maintain the aspect ratio and avoid any areas missing pixels.

I find that sometimes I can get a superior composition by either changing my aspect ratio or rebuilding some of the missing material using either the clone or content aware functionality. I might also choose to merely reduce the distortion, rather than to eliminate it to get a composition that works.

The issue with any automated function is that one gives up control for simplicity. In my experience, I prefer being the one to make the compositional calls, rather than trusting the software to get it right.

[ajohnw]

I often use that sort of method as well Manfred. Similar method and a different cheat in the bottom left corner, not completely done and could have been cropped a little more really.

The top of the pillars wont correct. I suspect that is down to some other correction that has already been applied.




ProPhoto image was posted.

John
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[inkista]

Hmm. Have you guys tried using horizontal/vertical/straight line control points in Hugin?

One small note. Samyang is the company that makes the 14/2.8. And the number of brands their lenses are known by includes Rokinon, Vivitar, Bower, Phoenix, Pro Optic, Walimex, and probably half a dozen others. Roger Cicala charmingly calls these "Rokibowyang" lenses.

Nice sphericals in the link, did you use special camera or software? I have one of those Theta360 cameras that provides the software to view.

No special camera. Just a fisheye lens (either my Sigma 8mm f/3.5 EX DG circular fisheye on my Canons or my Rokinon 7.5mm f/3.5 fisheye on my Panasonic mft cameras), and then stitched with either PTMac or PTGui. The Theta360 looks like fun! 360 video is not something I can do with my method. And it's certainly more convenient than having to drag out a tripod and pano head and do multiple shots and then stitch by hand. But the 6MP resolution of the Theta360 is the sticking point for me. My stitched panos typically are web-delivered at 3000x6000 (18MP) for virtual viewing, and that still looks kinda low-res to me.

Very nice & thanks, Kathy. I see what you mean & I am generally finding these sorts of framings to work for me without trying to correct for the angular effects on the uprights in the images. I'm shooting a lot with my fixed length 14mm, 'hoofing & zooming' doesn't come into it so much for me.

[grin]. True. But maybe someday you'll get an ultrawide zoom. I never did for my Canons, but when I moved to mft, and i found I could get the 9-18 for $400 refurbed...

[loosecanon]

The distortion given by the samyang 14mm is complex, and not easy to correct, but with the profile someone else has done all this complex work. The distortion is not a simpe stright line correction.

[Shadowman]

[QUOTE=ajohnw;472918]That's basically why I just took a couple to see what happened. That way when I choose to take one seriously I might have some idea how much extra to frame.

I've no interest what so ever in getting into package merits again. People will use what they use and that's that. In some respects I am some times surprised that people jump in defending Adobe after fashion as if there just can't be any alternatives.

John

It takes a bit of experimentation with the capture and post processing to get both functions to mesh well. I tend to take the UWA lens on long trips more often than I would a one day venture. I also tend to hold off on post processing UWA shots as I know a bit more effort will be involved.

[ajohnw]

I have a suspicion that using lens correction before correcting in say Hugin can cause problems. Not entirely sure but suspect the problem with the top of the pillars is down to that.

The tutorial Kathy linked to may be out of date. Hugin is basically a panorama application correcting for distortion and exposure variations. The other application she mentions is similar.

Distortion on Hugin is fixed by adding horizontal and vertical reference lines to the image. It initially throws up 2 copies of the same image. One point is marked in the left hand view and the other in the right hand via left mouse button clicks. It may find the right hand one automatically. It gives a magnified view to aid location. When happy a right click causes it to load the data. If the final image is a panorama the next step is to select the next image in the left (??) hand view and select alignment points in the same way. This is to speed up processing as it will also align and scale as needed in software. I have another package that aligns automatically but it takes some time.

It will correlate reference point and indicate if the ends are only loosely related but will still work with them. On the shot posted it's probably unwise to use the columns as references as they might be tapered. Wall features and the windows are unlikely to be.

It has 3 interfaces. The simple one that comes up initially, advanced and sort of super user one. The basic usage is the same in all cases. There is still a need to select rectilinear for a normal projection in the stitcher panel before doing anything else. It reads lens data from the files exif. There are now help pop ups on most if not all features.

John
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[inkista]

Hugin is basically a panorama application correcting for distortion and exposure variations...

Basically, but not completely.

You can completely correct the mustache distortion of the 14/2.8 using Hugin. "Calibration" in Hugin/Panorama Tools is basically building a lens profile for correction. This is why PTLens existed before Adobe thought to put lens profiles into their software. Panorama Tools includes lens correction.

Distortion on Hugin is fixed by adding horizontal and vertical reference lines to the image.

No. Perspective and position are corrected by the horizontal and vertical control points. Distortion correction is done with the straight line control points, where you place points along a line that is curved in the image, but is actually straight. The tutorial I pointed to was basically just for perspective correction. Lens calibration would be here.

[ajohnw]

Distortion correction is done with the straight line control points, where you place points along a line that is curved in the image, but is actually straight. The tutorial I pointed to was basically just for perspective correction. Lens calibration would be here.

Where are these points added Kathy? I missed that. On Linux there is what appears to be a separate application - Hugin Calibrate Lens. Also Hugin batch and Hugin Panorama Creator. I've not noticed any facility to correct curvature in the latter one.

John
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[inkista]

Where are these points added Kathy? I missed that.

Same window as the regular control points. Best reference I can find is this one, for PTGui, but Hugin should be similar:

http://www.erik-krause.de/index.htm?...distort_en.htm

I've never needed to do it, and I prefer Lightroom profiles for ease-of-use .

OK. Took a quick look in Hugin. Where you select vertical/horizontal under Mode, it looks to me like the "Add new line" choice makes SL control points.

On Linux there is what appears to be a separate application - Hugin Calibrate Lens.

Yes. PTLens is probably the first GUI I know of that was specifically geared towards lens correction tasks. Hugin can be a somewhat cryptic interface.

Also Hugin batch and Hugin Panorama Creator. I've not noticed any facility to correct curvature in the latter one. ...

Different interfaces for different tasks. Hugin's ability for you to get to some of the CLI stuff can be more than a little hidden--hence the wide plethora of UIs folks write to make certain tasks easier.