Hot answers tagged distortion
20
Likely culprits, in order of probability:
Bad SD card (by far the most likely).
Bad cable or card reader.
A bad connection inside the camera.
Something horribly wrong with the camera's electronics.
Something wrong on your computer.
The "bad card" scenario is, unfortunately, the most likely, and in that case the pictures are lost. If it is just the ...
16
The terms are fisheye (circular distortion) and rectilinear (straight edges).
Fisheye lenses are often unfairly branded as "special effect" lenses by some photographers, due to their near ubiquitous use in skateboarding magazines in the 90s, and the ease at which you can create unusual images when trained on nearly any subject.
However fisheyes have sever ...
15
These are known as Chromatic Aberrations or Colour Fringing. These predominantly occur around areas with high contrast such as sharp edges in photographs or around the white water bottle and dark background in your case.
A wider apeture can affect the lenses sensitivity to aberrations although certain lenses can see this "effect" vary depending on focal ...
13
It is much more complicated than that. There are 85mm prime lenses I'm aware of that exhibit some degree of barrel distortion, and barrel distortion is almost a given at the wide end of a zoom lens no matter how long that wide end is. On the other hand, at the "long" end of the Tokina 11-16mm f/2.8, you would have to be shooting brick walls to notice any ...
13
The two types of lenses you refer to are:
Rectilinear - lenses which produce straight horizontals and verticals across the image
Fisheye - lenses with circular distortion
Rectilinear lenses produce more 'natural' looking images but tend to stretch features towards the edges of the frame, so some subjects, e.g. faces, look odd. But they work well for ...
12
The lens correction software may be able to counter lens distortion and chromatic aberration distortion. Also perhaps it can counter poor contrast to some degree. But a good lens has more to offer:
Sharper image. The lens correction cannot restore image detail lost due to an unsharp lens.
Aperture. Good quality lenses typically have a larger aperture. You ...
10
I think it's more correct to say that Lightroom's lens profiles can make any lens "better." Bad lenses are still bad, good lenses are still good. The corrections Lightroom can make simply improve some aspects of image quality. Making the leap of taking a poor lens and making it good is far outside of what LR can do.
8
No, it's not all that bad. On most shots, you won't be able to tell by eye if the curvilinear distortions have been corrected for or not - you'll need straight lines adjacently parallel to each other or to edge to tell. In nature, you won't have those lines. In portraiture, it will exaggerate some parts and diminish others, but perspective distortion and ...
7
Your interpretation of distortion is correct. For an example of a lens that exhibits barrel distortion at the wide angle and pin cushion distortion at the telephoto end, have a look at the Canon 18-135mm
Tools like PTLens and Hugin perform the corrections after the demosaicing of the Bayer data. I'm not sure why this would matter?
If you're interested in ...
7
Lightroom does this for selected lenses, or you can create your own profile if your lens isn't listed.
This blog post explains how this works, both with respect to the built-in profiles, adjusting manually, or creating your own with Adobe's software utility.
7
There are a limited set of defects that can be corrected in software, lateral chromatic aberration, yes, but not longitudinal chromatic aberration. Lateral CA results in the component colours of light being displaced radially across the sensor. This can be corrected by simply warping each colour channel slightly differently. Longitudinal CA causes out of ...
7
This effect is called fisheye effect
You can either get this effect by using a fisheye lens or using photoshop. Try googling fisheye effect photoshop. I found there great tutorials there.
http://www.marcofolio.net/photoshop/create_a_fish_eye_lens_effect_in_photoshop.html
...
7
Actually to avoid distortion the opposite of what you said holds true.
Move faces or features you don't want to distort such as fingers away from the edge of the frame
Keep the lens parallel to the subject if at all possible
Step back and shoot, planning to crop to the desired framing later
Consider using the distortion to your advantage for "fun" shots; ...
6
You can use Hugin to do these types of corrections.
They also have a nice guide for lens calibration, which allows you to calibrate for the distortion of your lens, then save those settings to apply later.
6
Not only is it possible, but it's becoming commonplace. The micro-four-thirds system makes extensive use of it, and some compact cameras now do too. (I imagine that if they don't yet, most super-zooms will within a few years.) Digital Photography Review has a good article on this at http://www.dpreview.com/articles/distortion/ , and it's worth reading even ...
6
I think the distortion you are seeing is not caused by the lens, I think it's just perspective distortion.
The Canon 50mm f/1.8 has a DXOmark distortion rating of 0.2% and if you look at the actual measurements, especially the grid you will see that the distortion is very low - too low to notice in a normal picture - I don't know about the other cameras you ...
6
It's very difficult to correct by hand, but very very easy for a computer to correct, given a formula for how the distortion behaves.
The reason the Photozone review states that this distortion is difficult to detect, is that most software only offers very simple correction based on radially symmetric distortions based on simple formulas. You can usually ...
5
There is one possibility and that is an operator error. Any one of these will do it:
If you took out the card from the camera before it was finished writing. In this case your pictures are lost since they were never stored correctly.
If you took out the memory from the reader before it was finished reading (If you use Windows, you should use the ...
5
As far as free alternatives you can try Fred's defisheye script for ImageMagick, or Fulla, which is a command line tool that comes with Hugin.
Fisheye-Hemi is superior to these, though, as instead of using a standard remapping to a rectilinear projection that softens the edges and requires an aggressive crop it uses a custom mapping algorithm that preserves ...
4
Yes, distortion is the second worst type of aberration. The worst is softness.
That is why when Nikon introduced their 18-200mm lens, instead of making it extremely soft like all others of the same focal-range, they made it sharper but left in a lot more severe distortion.
Distortion is particularly bad because it is impossible to correct without losing ...
4
Most lenses have some amount of distortion, it just may not be measurable or significant.
Thom Hogan says of the f/1.4G:
Linear distortion is low (though slightly higher than the f/1.4G) and
barrel in nature. At under 0.5% it's not something I'd bother
correcting unless I had software that did automatic correction based
on EXIF data, in which ...
4
I use Gimp and the
MathMap
plugin, together with a few
scripts of mine
to convert the fisheye image into whatever projection better fits the subject: either rectilinear, stereographic, or Mercator. Mercator is my favorite: it's a kind of panoramic cylindrical projection that looks quite similar to the Fisheye-Hemi projection and is free of local distortions ...
4
As a photojournalist I must say I prefer a fixed aperture lens with some versatility, say a 2.8 24-70mm. This allows for more of the real world variables you run into. Wide angles are great for so many things, but it's so nice, especially in instances like you're describing, to zoom to 50mm and make a portrait.
However, portraits can be made with wide ...
3
No. It is not possible on the D7000.
Even though the D7000 can do it on JPEGs, it is questionable to do so on a DSLR. If you did that on the RAW preview, you would get a different image compositionally-speaking from the embedded thumbnail than the RAW.
This is a feature much better suited for SLDs and both Panasonic and Olympus have implemented it in the ...
3
What you are referring to is a chart from Azure Photonics which they call an MTF chart.
It says (see source): Distortion : <12~1% (not <12-1%)
I believe it is saying that within 12mm of the optical centre the distortion is about 1%
<12 I take to mean "within 12mm", and ~1% means "about 1%"
The chart measures the % distortion (of horizontal ...
3
Depending of the focal length of the lens e.g. 28mm, 55mm, 100mm etc. images can look distorted. As the sample below shows that an image taken with a wider angle lens with a same crop may look wider.
So a wide angle lens from a close range widens, while a longer does not.
The left is taken with a 28mm lens and the right with a 70mm lens.
I think the ...
3
As the post above says, it depends on what you shoot. I do allot of architectural and travel photography: Except where I want to use a distortion for artistic effect, I dislike any pincushion or barrel effects. Five years ago when I mainly shot landscapes it could also be a problem when the horizon was off centre, it would curve up or down. However for ...
3
One that I know of is DxO Optics Pro. I've used the trial version of this software, and it seems pretty good. Not quite enough additional value for me to get this on top of PSE at this point, but I was considering it instead of PSE for a while.
3
PTLens and Bibble can both do these, and both support MacOS. PTLens can be used as an Aperture plugin. I kind of doubt that Bibble can -- it's intended more as a direct competitor to Aperture than a plugin.
Both come with large databases of lenses and the corrections they need. Both also read the EXIF data to see what lens you were using (and in the case of ...
3
Barrel distortion is the result of lens design, regardless of focal length. The Canon 50mm f/1.4 has slight barrel distortion, that's only visible if you photograph a "straight line" at the very edges, and that is by no means a wide angle lens.
A fisheye lens is a special design created to enhance and underline barrel distortion. Canon and Nikon both make ...
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