Help with distortion with a 10-20mm lens

Pentaxbuff · 01-02-2008, 23:46

Ok, I have this new Sigma 10-20mm lens ... just got it yesterday!
I have taken a few (several) photos and the results are rather surprising, which I expected in a way. I.E.: very wide angle of view and distortion at the very widest focal.
I have included a couple of samples here to share with the pros!
One big question renains: how do we correct the "leaning" of the church in that first picture? I have browsed through the Help section of PS and found some stuff on perspective, distortion, vanishing point, etc... but seems quite complex.
Anyone suggesting a quicker and not-so-difficult way to adjust the "leaning"?

Photo 1:

Photo 2:

This one I like ...it was obviously taken straight on at a higher focal.
I did, of course, lean again to the right on that second shot! Guess it,s back to the straightening tool!

stupot · 02-02-2008, 00:22

try Rob Barron's tutorial on converging verticals

Converging Verticals - 2 quick ways to cure them!

**Dabhand16** · 02-02-2008, 00:23

There are two ways of dealing with converging verticals.

One is to use the transform tool to drag out the image, the second is to use the lens distortion tool.

Whichever one you use, you will find that you will run out of space at the top of the image before you can get anywhere near where you want to be, although the second shot will probably be OK as there is plenty of room at the top.

Trick is to leave the space there when you take the picture.

Also in PS, leave a little convergence in the final image as if you go for absolutely vertical verticals, it can often look wrong

silkstone · 02-02-2008, 00:31

Please forgive this crude effort but I don't want to fire up the Windows machine right now so I've tried this on the Gimp for the first time - not very good but it gives a rough idea.

P.S. You don't say that you allow image edits so I'll get rid of this if you object.

**Dabhand16** · 02-02-2008, 00:39

Good one Paul - but the proportions don't look right. Church and tree should be higher?

The correction has compressed the image vertically.

silkstone · 02-02-2008, 00:44

Fussy, fussy...

Perspective corrections do tend to compress one way or the other, so you can resize (without maintaining aspect ratio) to correct. This one is horribly crude but it was just intended to give an idea of what could be done. Normally I'd correct the RAW using Bibble and the Percy plugin, which gives a huge amount of control over perspective and lens distortion.

**Dabhand16** · 02-02-2008, 00:46

Pentaxbuff · 02-02-2008, 18:45

Thanks to you too, Stupot.
I found the tutorial, using the "Distort" procedure, and it has worked great! I kept a bit of "distortion" ... after all, this was taken with a 10-20mm lens.
The only problem was with the second solution, using the Crop tool ... when I clicked on it, there was no "perspective" button to click on.
Other than that, I have learned two neew tricks today, thanks to all of you PS Pros!
Cheers!

Pentaxbuff · 02-02-2008, 18:54

Dabhand, I did get around with the Transform/Distort tool and it does work quite well.
Also, I gave a try with the lens distortion filter, and that also works, however, as you said, there was little left of the canvas at the bottom, so the cropping made the pic a tad smaller. I'll make sure to leave plenty of space when taking the photo with that lens.
As always, you guys are terific with the help!
Cheers!

Pentaxbuff · 02-02-2008, 18:56

Silkstone, that was a pretty good edit and , no, I don't mind at all.
This actually helps tremendoulsly.
You mention the plug-ins: correct the RAW using Bibble and the Percy plugin, can you download that directly as a freeware?
I'd like to see what it is capable of.
Thank you for the info!
Cheers!

_MB_ · 02-02-2008, 19:10

That distortion's called volume anamorphosis distortion - you can fix it in DxO optics but only if you have it loaded with the right lens module, which you can get as a free demo, but not for Pentax unfortunately

silkstone · 02-02-2008, 19:51

Quote:

Originally Posted by Pentaxbuff

Silkstone, that was a pretty good edit and , no, I don't mind at all.
This actually helps tremendoulsly.
You mention the plug-ins: correct the RAW using Bibble and the Percy plugin, can you download that directly as a freeware?
I'd like to see what it is capable of.
Thank you for the info!
Cheers!

You can have a 30-day trial of Bibble Pro, but unfortunately that won't help with perspective correction without the Percy plugin which costs (not very much).

See Bibble Labs - Professional Photo Workflow Software for Bibble, and Bibble Plug-ins from Sean M Puckett - Nexi for Sean's plugins. Some of these have free versions, but not all.

Although Bibble can be used with JPGs, it is really intended as a RAW processor/converter.

stupot · 02-02-2008, 20:06

Quote:

Originally Posted by Pentaxbuff

Thanks to you too, Stupot.
I found the tutorial, using the "Distort" procedure, and it has worked great! I kept a bit of "distortion" ... after all, this was taken with a 10-20mm lens.
The only problem was with the second solution, using the Crop tool ... when I clicked on it, there was no "perspective" button to click on.
Other than that, I have learned two neew tricks today, thanks to all of you PS Pros!
Cheers!

Hey no probs Pentax, but its Rob that deserves the thanks as he was the one who put the hard work in.

slipstream · 03-02-2008, 16:07

Try keeping your camera as close to 90deg to the ground as possible, ie keep the lens straight to the ground. The more you angle the lens up or down, the more distortion you will get. I learnt this with my Tokina 12-24.

01-02-2008, 23:46	#1 (permalink)
Pentaxbuff Getting Comfy Join Date: Oct 2007 Location: Québec, Canada in a small town reputed to have the second most beautiful sunsets in the world! Posts: 175	Help with distortion with a 10-20mm lens Ok, I have this new Sigma 10-20mm lens ... just got it yesterday! I have taken a few (several) photos and the results are rather surprising, which I expected in a way. I.E.: very wide angle of view and distortion at the very widest focal. I have included a couple of samples here to share with the pros! One big question renains: how do we correct the "leaning" of the church in that first picture? I have browsed through the Help section of PS and found some stuff on perspective, distortion, vanishing point, etc... but seems quite complex. Anyone suggesting a quicker and not-so-difficult way to adjust the "leaning"? Photo 1: Photo 2: This one I like ...it was obviously taken straight on at a higher focal. I did, of course, lean again to the right on that second shot! Guess it,s back to the straightening tool!

02-02-2008, 00:22	#2 (permalink)
stupot Forum Regular Join Date: Aug 2005 Location: Corfe Mullen, Wimborne, Dorset Posts: 1,316	Re: Help with distortion with a 10-20mm lens try Rob Barron's tutorial on converging verticals Converging Verticals - 2 quick ways to cure them!

02-02-2008, 00:23	#3 (permalink)
Dabhand16 Pixalo Crew Join Date: Jun 2006 Location: Dunstable Bedfordshire UK Posts: 8,915	Re: Help with distortion with a 10-20mm lens There are two ways of dealing with converging verticals. One is to use the transform tool to drag out the image, the second is to use the lens distortion tool. Whichever one you use, you will find that you will run out of space at the top of the image before you can get anywhere near where you want to be, although the second shot will probably be OK as there is plenty of room at the top. Trick is to leave the space there when you take the picture. Also in PS, leave a little convergence in the final image as if you go for absolutely vertical verticals, it can often look wrong __________________ Graham

02-02-2008, 00:31	#4 (permalink)
silkstone Feet under the table Join Date: Jan 2005 Location: Silkstone Common, Yorkshire, UK Posts: 3,380	Re: Help with distortion with a 10-20mm lens Please forgive this crude effort but I don't want to fire up the Windows machine right now so I've tried this on the Gimp for the first time - not very good but it gives a rough idea. P.S. You don't say that you allow image edits so I'll get rid of this if you object.

02-02-2008, 00:39	#5 (permalink)
Dabhand16 Pixalo Crew Join Date: Jun 2006 Location: Dunstable Bedfordshire UK Posts: 8,915	Re: Help with distortion with a 10-20mm lens Good one Paul - but the proportions don't look right. Church and tree should be higher? The correction has compressed the image vertically.

02-02-2008, 00:44	#6 (permalink)
silkstone Feet under the table Join Date: Jan 2005 Location: Silkstone Common, Yorkshire, UK Posts: 3,380	Re: Help with distortion with a 10-20mm lens Fussy, fussy... Perspective corrections do tend to compress one way or the other, so you can resize (without maintaining aspect ratio) to correct. This one is horribly crude but it was just intended to give an idea of what could be done. Normally I'd correct the RAW using Bibble and the Percy plugin, which gives a huge amount of control over perspective and lens distortion.

02-02-2008, 00:46	#7 (permalink)
Dabhand16 Pixalo Crew Join Date: Jun 2006 Location: Dunstable Bedfordshire UK Posts: 8,915	Re: Help with distortion with a 10-20mm lens

02-02-2008, 18:45	#8 (permalink)
Pentaxbuff Getting Comfy Join Date: Oct 2007 Location: Québec, Canada in a small town reputed to have the second most beautiful sunsets in the world! Posts: 175	Re: Help with distortion with a 10-20mm lens Thanks to you too, Stupot. I found the tutorial, using the "Distort" procedure, and it has worked great! I kept a bit of "distortion" ... after all, this was taken with a 10-20mm lens. The only problem was with the second solution, using the Crop tool ... when I clicked on it, there was no "perspective" button to click on. Other than that, I have learned two neew tricks today, thanks to all of you PS Pros! Cheers!

02-02-2008, 18:54	#9 (permalink)
Pentaxbuff Getting Comfy Join Date: Oct 2007 Location: Québec, Canada in a small town reputed to have the second most beautiful sunsets in the world! Posts: 175	Re: Help with distortion with a 10-20mm lens Dabhand, I did get around with the Transform/Distort tool and it does work quite well. Also, I gave a try with the lens distortion filter, and that also works, however, as you said, there was little left of the canvas at the bottom, so the cropping made the pic a tad smaller. I'll make sure to leave plenty of space when taking the photo with that lens. As always, you guys are terific with the help! Cheers!

02-02-2008, 18:56	#10 (permalink)
Pentaxbuff Getting Comfy Join Date: Oct 2007 Location: Québec, Canada in a small town reputed to have the second most beautiful sunsets in the world! Posts: 175	Re: Help with distortion with a 10-20mm lens Silkstone, that was a pretty good edit and , no, I don't mind at all. This actually helps tremendoulsly. You mention the plug-ins: correct the RAW using Bibble and the Percy plugin, can you download that directly as a freeware? I'd like to see what it is capable of. Thank you for the info! Cheers!

02-02-2008, 19:10	#11 (permalink)
_MB_ Forum Regular Join Date: Mar 2007 Location: Northumberland, UK Posts: 826	Re: Help with distortion with a 10-20mm lens That distortion's called volume anamorphosis distortion - you can fix it in DxO optics but only if you have it loaded with the right lens module, which you can get as a free demo, but not for Pentax unfortunately

03-02-2008, 16:07	#14 (permalink)
slipstream Quite Chatty Join Date: Nov 2007 Posts: 65	Re: Help with distortion with a 10-20mm lens Try keeping your camera as close to 90deg to the ground as possible, ie keep the lens straight to the ground. The more you angle the lens up or down, the more distortion you will get. I learnt this with my Tokina 12-24.

03-02-2008, 17:13	#15 (permalink)
Rob Barron Loves the place Join Date: Sep 2006 Location: Poole, Dorset Posts: 5,174