Lightnings taking a ride

by ceinmart

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23

Likely culprits, in order of probability: Bad SD card (by far the most likely, especially with cheap cards). Bad cable or card reader (more common than you might think). Something wrong on your computer (many things can go wrong!). A bad connection inside the camera. Something horribly wrong with the camera's electronics. The "bad card" scenario is, ...


19

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 ...


17

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.


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 ...


14

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 ...


11

It's not so much a defect as a property of wide-angle lenses: they distort things on the sides. This distortion is why they are not recommended for portraiture. Of course, the very same distortion is what gives wide-angle its power, making it great for photographing interiors (making them look larger) or when going for an "artsy" effect.


10

You can correct lens distortion in post, but you do so at the expense of some of that higher resolution. Roger Cicala of LensRentals.com says in a blog post where he tests the uncorrected and post corrected resolution of an EF 24-105mm f/4 L lens at 24mm: But when someone wants to argue that they buy a lens with high distortion because it has higher ...


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 ...


8

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 ...


8

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; ...


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

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

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

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 ...


7

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 ...


7

from http://wiki.panotools.org/Lens_correction_model The actual lens correction parameters a, b and c which are used to correct for barrel distortion, pincushion distortion and even wavy distortion. The a and c parameters control more complex forms of distortion. In most cases it will be enough to optimize for the b parameter only, which is good at ...


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 ...


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

One possibility is 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 'Disconnect Removable Device' ...


6

The first and third photos exhibit barrel distortion which is normally to be expected at 18mm when using an 18-55mm zoom lens. Software correction can help, but for best results you need software that includes a custom profile of that particular lens on that particular camera. There are also some perspective issues in shots #1 and 3, which are related to the ...


6

Two things common to Wide angle lenses can do this, barrel distortion and perspective distortion. For barrel distortion, when pulling in a very wide amount of information from off axis, light gets distorted based on how extreme of an angle it is coming in at because the lens can't completely correct for how far off the lens axis the light is. On the ...


5

I had similar issues with images on my Nikon D70. Occasionally the camera showed a 'CHA' error message, images written to the card were corrupt (but could be resurrected by a data recovery tool). As it turned out my camera has contact problems at the CF card slot. Sometimes reinserting the memory card helps, sometimes I have to use contact spray to get my ...


5

That is what a JPEG image looks like when the file is corrupted. By corrupted, I mean a data corruption problem: one or more bits in the file are not what they should be - zeroes becoming ones or vice versa. JPEG is a lot more susceptible than any uncompressed format as a single wrong bit may affect the entire rest of the picture from that point onward, ...


5

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 ...


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 ...


5

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 ...


5

It's all about relative distances. Wide angle lenses don't distort, take a photo from the same distance as you'd use a 50mm lens and crop, and you'll see none of the trade mark wide angle look. When you get close to fill the frame, features that stick out such as noses are relatively much closer to the camera than the rest of the face so they appear much ...


5

There are several problems transforming the curvilinear perspective of the wide angle GoPro lens to a rectilinear one. The transformation stretches the image in certain areas and compresses it in others. This lowers the image quality as new pixels are created as approximations and interpolations from the information in the original image. There is also a ...



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