Converging verticals - DPChallenge Forums

06/07/2004 03:07:28 PM · #1

Ok, I took a few pics of an old abbey,problem, converging verticals.
Is it something I have to live with or is there any special way of taking these shots?

example

Some of the shots are worse than this,I can straighten one vertical but it just throws out the next.
Thanks,
Paul.

06/07/2004 03:13:43 PM · #2

I think this is a factor of the lens being barrel shaped.
Someone can correct me if I am wrong.
Your lens was most likely at the widest focal length? (rather than zoomed)....

Ecce_Signum

Canon EOS-5D Mark II

Canon EF 28-135mm f/3.5-5.6 IS USM

06/07/2004 03:16:48 PM · #3

Originally posted by KarenB:

I think this is a factor of the lens being barrel shaped.
Someone can correct me if I am wrong.
Your lens was most likely at the widest focal length? (rather than zoomed)....

Sounds right to me Karen. I'm sure I've read about tools that can be used to fix this??? Have you tried layers and straightning each side seperately? not quite sure how you wouild accomplish this but it might be fun trying :)

Tallbloke

Canon EOS-350D Rebel XT

06/07/2004 03:17:39 PM · #4

Had a VERY quick tweak in photoshop using "Distort"

Any better?

Steve

dacrazyrn

Nikon D300

Nikon AF-S DX NIKKOR 18-200mm f/3.5-5.6G ED VR II

06/07/2004 03:33:57 PM · #5

Wouldn't Perspective in PS fix that also? Since it converges at the top?

jmsetzler

Sony Alpha a6000

Sony 16-50mm f/3.5-5.6 E-mount

06/07/2004 03:36:22 PM · #6

This is not barrel distortion.

What is happening here is that the lens surface is not parallel to the verticals in the shot. It's perspective distortion. Anytime you are photographing verticals and you don't want this type of convergeance, you must make sure your camera is pointing straight and level.

With an SLR camera, you can buy the tilt/shift lenses that allow for correction of this. You can also shoot with a large format camera that allows you to manipulate the angle of the film plane to compensate for it as well.

Sony 16-50mm f/3.5-5.6 E-mount

06/07/2004 03:37:49 PM · #7

cool. thanks john. do you have an example of barrel distortion for comparison?

jmsetzler

Sony Alpha a6000

06/07/2004 03:41:21 PM · #8

Originally posted by KarenB:

cool. thanks john. do you have an example of barrel distortion for comparison?

Here is some barrel distortion compliments of Dr. McGregor :)

06/07/2004 03:41:26 PM · #9

John, I even used the grid to line up the shots and to me they were bob on.
Some interesting comments here thanks guys,
Steve, thanks for the try, but it looks a little skew on the end column.

just saw the example John, exactly like some of my others.

Message edited by author 2004-06-07 15:42:32.

06/07/2004 03:56:42 PM · #10

What do you reckon guys ?
I had a go at Tracy's suggestion.

Canon EF-S 18-55mm f/3.5-5.6

06/07/2004 03:57:59 PM · #11

looks good to me :)

KaDi

Canon EOS-300D Rebel

06/07/2004 04:31:11 PM · #12

I had to give it a try, too.
In PhotoShop: Image > Transform > Distort
Then move the reference point to the top center.
Draw the bottom left in appx 5% and the bottom right appx 10%
Had to crop it square, so some loss of image.

What do you think?

06/07/2004 04:36:47 PM · #13

very similar result KaDi, thats 2 ways of doing it,
This is why I like this site so much,I can't think of one of my questions that has not been answered,and hopefully helped others as well.
Thanks KaDi

Ecce_Signum

Canon EOS-5D Mark II

06/07/2004 04:44:52 PM · #14

Jeez, so many windows open to see the same pic!

Have to agree the last two look pretty fine, anybody gonna do a tutorial for us all?

06/07/2004 04:54:37 PM · #15

Originally posted by Ecce Signum:

Jeez, so many windows open to see the same pic!

Have to agree the last two look pretty fine, anybody gonna do a tutorial for us all?

I don't think I have the expertise to do that yet Andi,
I only followed the ps help file, seems pretty straight forward using the crop/perspective tools, dragging handles and all that.I did increase my canvas size to save losing any of my example.

Ecce_Signum

Canon EOS-5D Mark II

Canon EF 70-200mm f/2.8L IS USM

06/07/2004 04:59:36 PM · #16

Ah, no probs Paul, have saved this thread in my favourites, am sure I'll be back to it one day :)

EddyG

Canon EOS-1D Mark II

06/08/2004 07:41:39 AM · #17

Originally posted by KarenB:

do you have an example of barrel distortion for comparison?

I found a really good example of barrel distortion while browsing through Digital Camera Resource:

Notice how everything "bows out" instead of having straight lines? That is "barrel distortion" (when everything "bows in", it is called "pincushion distortion"). This type of distortion is caused by the lens design and not by the angle of the camera to the subject like the "converging verticals" problem. (This example is from the Panasonic DMC-FZ10, which has a 12X zoom lens, so it isn't too surprising that this lens has "shortcomings". All lenses are a trade-off.)

Message edited by author 2004-06-08 07:42:22.

Canon EF 70-200mm f/2.8L IS USM

06/08/2004 08:17:53 AM · #18

Originally posted by EddyG:

Originally posted by KarenB:
do you have an example of barrel distortion for comparison?

I found a really good example of barrel distortion while browsing through Digital Camera Resource:

Notice how everything "bows out" instead of having straight lines? That is "barrel distortion" (when everything "bows in", it is called "pincushion distortion"). This type of distortion is caused by the lens design and not by the angle of the camera to the subject like the "converging verticals" problem. (This example is from the Panasonic DMC-FZ10, which has a 12X zoom lens, so it isn't too surprising that this lens has "shortcomings". All lenses are a trade-off.)

:( broken link

EddyG

Canon EOS-1D Mark II

06/08/2004 08:31:12 AM · #19

Darn. I hate when that happens. Here is another example, also from the DMC-FZ10. Maybe this link will work? Obviously, this is a rectangular map, so it demonstrates the problem of "barrel distortion" pretty well. =]

I also found this glossary defintion of barrel distortion on DPReview which also has an example photo.

Message edited by author 2004-06-08 08:34:27.