How check wide angle for distortion

Started May 3, 2012 | Discussions
kaedepics
Regular MemberPosts: 273
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How check wide angle for distortion
May 3, 2012

Just got the da ltd and have been out and about snapping anything in view trying to get used to using a WA. After looking through the results there are 4

images that seem to show quite a bit of distortion so I was wondering if anyone could tell me the best method for checking the lens?

The images in question are below. I have also included 2 images that seem Ok. All hand held

Marc Sabatella
Veteran MemberPosts: 6,677
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Re: How check wide angle for distortion
In reply to kaedepics, May 3, 2012

It's not clear which of these you think show too mich distortion and which you think do not. They all look pretty normal for the DA15 to me - whch is to say, less distortion than virtually any other lens of that focal length ever designed, but of course more than a "normal" lens. Only the third of your sample looks a little unusual, but it's hard to say without kmowing exactly what we ae looking at.

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Gerry Winterbourne
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Re: How check wide angle for distortion
In reply to kaedepics, May 3, 2012

You don't need to check your lens for distortion because it has it. So do all other lenses: it's a fact of photographic life. If it bothers you all you need to do is remove it. With your K-5 you can let the camera do it if you shoot in JPG (although it slows down file transfer time). Shooting raw you can do it in PP: some software uses individual lens profiles, some you have to do manually.

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Gerry

First camera 1953, first Pentax 1985, first DSLR 2006
http://www.pbase.com/gerrywinterbourne

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kaedepics
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Re: How check wide angle for distortion
In reply to Gerry Winterbourne, May 3, 2012

Thanks for the replies. I just imagined that the images were distorted more on one side of the other. I think the image taken of a grid on my computer screen shown below demonstrates that it certainly was only in my imagination.

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Gerry Winterbourne
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Re: How check wide angle for distortion
In reply to kaedepics, May 3, 2012

kaedepics wrote:

Thanks for the replies. I just imagined that the images were distorted more on one side of the other. I think the image taken of a grid on my computer screen shown below demonstrates that it certainly was only in my imagination.

Yes, unless you can position yourself absolutely dead on to the subject the distortion always looks different from side to side and top to bottom.

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Gerry

First camera 1953, first Pentax 1985, first DSLR 2006
http://www.pbase.com/gerrywinterbourne

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Rod McD
Senior MemberPosts: 1,897Gear list
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Re: How check wide angle for distortion
In reply to kaedepics, May 3, 2012

Hi,

This follows on from the thread on this topic the other day........ If you have a look at the shots of the lady with the baby in the pram with the background of city buildings, the top line of the building guard rail passes pretty much through the centre of the image and is rendered as perfectly straight. It's the shots with the grid lines that show some curvature at the edge of the image.

As the other respondents have said, you can't 'check' this (except by observation of your images). It's normal for a DSLR lens, and wide ones in particular, but the 15mm Limited has less than most. If you check your K5 manual you'll find the instructions to set the camera to correct this in its jpegs, but as they've also said, it will require longer camera processing time. Or you'll have to tackle it in PP.

What you decide to either 'live with' or correct is really a matter for your personal taste. And this might be dependent on the type of image you're printing. If it's deep in the background of a family group or portrait, it may not be noticed or matter. If it's for an architectural brochure, it might be sacrilege not to correct it!

Cheers, Rod

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Canon PowerShot G1 X Pentax K-5 Fujifilm X-T1
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