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13

I have not used Fulla myself but pulled this information together from various internet resources. First you need to install Fulla, which is included in the Hugin package. sudo apt-get install hugin-tools Fulla is able to read in correction data from the last open-source PTLens database, available here. You have to point Fulla to the PTLens database ...


9

All lenses create a circular image, it's just that most of them have an image circle large enough that it covers the entire sensor. Vignetting at wide apertures is a manifestation of the image circle encroaching on the corners of the sensor as the circle edge is not as sharp as it would be with a narrower aperture. With a fish-eye lens, the image circle is ...


8

For an image like that, a "fisheye" lens was used. This is a specialized lens that covers an extreme wide angle. What can a fisheye lens be useful for?


8

I found this simple command with just rewrite all your gopro pics: mogrify -distort barrel "0 0 -0.3" *.JPG More information about imagemagick command can be found on http://www.imagemagick.org/script/command-line-options.php#distort The method Barrel has the following arguments: A B C [ D [ X , Y ] ] An explanation how to set this four coefficients ...


7

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 ...


6

The difference between a wide angle fisheye lens and a wide angle rectilinear lens is equal area projection versus straight line projection. Uncorrected, they will both demonstrate field curvature. All simple lenses will demonstrate field curvature based on the angle of view the lens provides. Of course the sensor/film size is also involved in the angle of ...


6

It will work as expected. Any fisheye that projects a circular uncropped image on an EF-S camera does so also when attached to an EF-M mount with an EF/EF-M adapter. Correspondingly, the image of a full-frame circular fisheye gets cropped like it would with an EF-S camera. The sensor size being the same (APS-C), any adapted lens functions optically exactly ...


5

The fisheye "effect" is dependent only on the angle between the camera and subject, it is thus totally independent of distance. What you might be noticing is that a fisheye lens bends all straight lines unless they pass through the exact centre of the image. In some natural scenes the horizon will be the only straight line in the image, thus if you happen ...


5

Wow, answered my own question: There is a switch on the fisheye lens labeled "LIMIT" which will lock the maximum zoomed out state of the lens to a point where no negative space is captured on non-full-frame sensors. When this LIMIT switch is in the non-active position, the lens does not impose any artificial limits and the you are free to capture a ...


5

A fish-eye lens is not just a lens with a very short focal length, it also has a specific distortion (cf. fish-eye projection vs. rectilinear projection). So while you can use a full-frame fish-eye on an APS-C body, it will still be a fish-eye lens.


4

You don't even need an expensive fisheye lens to produce this effect. The linked image is a series of multiple shots and stitched in Photoshop http://www.panoramio.com/photo/41726629?tag=best You can see more images like this at http://www.panoramio.com/user/221285


4

This is actually all the same lens. Samyang makes them and they are sold under different brand names. The identical nature of the first two is kind of apparent from the specs, but actually the "6.5mm" is too — and apparently there's also a Vivitar 7mm. (See this web page for more.) All of these companies have names which were historically legit camera gear ...


4

Consider this review of the Canon 8-15 f/4L USM fisheye, which can shift from circular at 8mm to diagonal at 15mm. Yes, it's circular because the lens's entire image circle is inside the area of the sensor, rather than covering the entire sensor. I'm not sure there's going to be an entire explanatory webpage other than Wikipedia on this, because it's such a ...


4

You can do it in the GoPro software: https://gopro.com/help/articles/How_To/How-Can-I-Remove-the-Distortion-Fisheye-Effect-in-GoPro-Studio


4

The fisheye effect does not come from the wide focal length, but it comes from using a lens that is not rectilinear. A rectilinear lens is one that, despite the focal length, will still ensure that there is no barrel or pincushion distortion: that all straight lines remain straight, not curved. Technically, it ensures that the image is the image that would ...


4

If you want Hugin to auto-recognize and correct for the lens, then probably the right tag to use is Samyang 8mm f/3.5 Fish-Eye CS, because this is the entry in the lensfun database, which is now integrated into Hugin use. In the slr-samyang.xml file the entry is: <lensdatabase version="1"> <lens> <maker>Samyang</maker> ...


4

Michel Thoby's webpage has the following formula for the equal-area projection: r = 2 f sin(θ/2) where r is the distance from the centre in the projection plane of a point that is visible under angle θ. (image source) For 10 mm focal length this gives r = 2 * 10 mm * sin(π/2 / 2) = 14 mm for the radius of the 180-degree image circle. This roughly ...


4

The link below reviews a Canon 8-15mm lens. It shows sample images from various focal lengths on both full frame and cropped sensors. According to these images, yes indeed will see the full circle when shooting at 8mm on a full frame camera. http://www.lenstip.com/311.1-Lens_review-Canon_EF_8-15_mm_f_4_L_Fisheye_USM_Introduction.html Here is the ...


4

With the full-frame camera, should I expect to see the entire circular image? It depends on what focal length you've set the lens to. The EF 8-15mm f/4L USM fisheye is unique in being circular at the wide end (at least on full frame it is), and diagonal at the "tele" end. Where you are in the zoom range determines how much of the frame is covered by the ...


4

Unlike "normal" (rectilinear) lens, there are many types of fisheye lenses, using different projections. The same focal length (f) can give different image size and/or different distortions, depending on the type. Example: Assuming your 8mm lens uses the most basic equidistant fisheye (180° degrees field of view = -90°..+90°) R = f · θ 8mm · π/2 ≈ 12....


4

The EF 8-15mm f/4 L Fisheye lens has a gel filter holder in the rear of the lens. Gel, or other very thin media, can be cut to fit this holder. Gel ND filters are not as easy to find as they once were, but are still available from specialty companies such as B&H. Here's a list of the Canon lenses with a 31mm rear gel filter holder: EF 8-15mm f/4 L ...


4

What you're probably looking for is a circular fisheye lens for APS-C. Fisheye lenses come in one of two types: circular or diagonal. Circular ones put the entire image circle inside the frame of the sensor, while diagonal ones are more traditional and project an image circle large enough to cover the entire sensor and yield a rectangular image. Keep in ...


3

Let's think about what's happening here. The adapter essentially reduces the focal length by about 60%, giving a wider field of view. It's an oversimplification, but let's stick with it for brevity. Say you have a prime lens with a fixed focal length of 50mm. With the adapter in place, it now has the field of view equivalent to a 20mm lens. With your ...


3

The field of view would be the same as an equivalent focal length, but fish eye can go wider than a flat lens. There is only so much distortion you can remove however. By nature of the way the light paths travel, there is going to be some roundness to the image. It's the same problem as projecting a round globe on to a flat map. You can distort the image ...


3

I doubt there's a hardware solution to this, and if there were one, it's likely to cause a decrease in image quality. Software is your solution, here. From the DJI website for the Phantom 2 Vision minidrone: A lens profile released by Adobe for DJI Phantom 2 Vision's camera can be used to remove lens distortion DJI keeps it here: http://download.dji-...


3

On an SLR, since the image is transmitted by the attached lens regardless of whether you use the optical viewfinder or live view, both live view and the optical viewfinder will show what the sensor sees, including the effect of any filters or modifiers attached to the lens. Indeed, live view is a feed directly from the sensor. Not all viewfinders offer 100% ...


3

As with any lens on a dSLR, the viewfinder and liveview will show you any lens effects. The lightpath into the camera travels through the lens first before it is reflected by the mirror up into the viewfinder, or (in liveview as the mirror is locked up) before it hits the sensor to be turned into image signals that are sent to the LCD. So however the lens ...


3

Looking at the specs of the DJI Phantom 3 and 4, the lens is described as: FOV 94° 20 mm (35 mm format equivalent) f/2.8 Focus at ∞ The Phantom 2 on the current DJI website comes with a GoPro Hero4 Black, which (if you're shooting 16x9) has a 118.2º HFOV (the narrower fields of view settings are done by cropping). So, I'd say that, no, it's ...


3

Largely it depends on sensor size. 4.5mm is for APS-C but there are shorter ones, even less than 1mm, for smaller sensors. The issue for a rectilinear lens is that as the angle-fo-view gets wider, the construction becomes more and more difficult. Remember that a rectilinear lens must preserve straight lines and so the optics will get more complex and ...


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