question: Why does the picture in the view finder and the final photo change when we rotate out cameras from vertical to horizontal ?? I mean, camera lenses are circular.. it shouldn't make any difference as to the way we hold our phones..
comment: Lenses are circular, but it is largely unimportant in how they are shaped. All the lens does is focus light onto a sensor, which is actually capturing the image. Sensors come in all sizes, but stick to a few aspect ratios. The one in your phone is probably 16:9 or a similar size. That size sensor results in that ‘shift.’
passages: Section::::Reception.:Technical problems.:Antenna.
  
  Shortly after the iPhone 4 was launched, some consumers reported that signal strength of the phone was reduced when touching the lower left edge of the phone, bridging one of the two locations which separates the two antennas, resulting in dropped calls in some areas with lower signal reception. In response, Apple issued a statement advising that customers should "avoid gripping [the phone] in the lower left corner" when making or receiving a call.
   BULLET::::- As the viewfinder of a TLR camera requires the photographer to look down toward the camera, it is inconvenient to frame a photo with a subject that requires the camera to be positioned above the photographer's chest unless a tripod is used. In these cases, the camera may be positioned with the lenses oriented horizontally. Due to the TLR's square format, the composition need not be altered.
   The distance of the exit pupil from the sensor plane determines the range of angles of incidence that light will make with the sensor. Digital image sensors often have a limited range of angles over which they will efficiently accept light, especially those that use microlenses to increase their sensitivity. The closer the exit pupil to the focal plane, the higher the angles of incidence at the extreme edges of the field. This can lead to pixel vignetting. For this reason, many small digital cameras (such as those found in cell phones) are image-space telecentric.
  
  Section::::See also.
  
  BULLET::::- Transmittance
   In some situations, a camera may be connected directly to the base mount. This is more common with monopods, where a separate head may not be necessary. In these cases, and for times when a smaller tripod head is being connected to the legs, the connection is often made using a 1/4-20 screw, rather than a 3/8-16 screw.
  
  Section::::Head mounts.
   Most current photographic lenses are designed to minimize field curvature, and so effectively have a focal length that increases with ray angle. Lenses of short focal lengths (ultra wide, wide and normal) below 50 mm typically suffer more from field curvature. Telephoto lenses typically have very little or no visible field curvature. The Petzval lens is one design which has significant amount of field curvature; images taken with the lens are very sharp in the centre, but at greater angles the image is out of focus. Film cameras, may be able to bend their image planes to compensate, particularly when the lens is fixed and known. This also includes plate film, which could still be bent slightly. Digital sensors are difficult to bend, although experimental products have been produced. By 2016 the only consumer cameras featuring curved sensors were "selfie" Sony Cybershot KW-1 and KW-11. Large mosaics of sensors (necessary anyway due to limited chip sizes) can be shaped to simulate a bend over larger scales.
   There are two ways to attach your camera to a monopod. The first is to screw the monopod's screw thread directly into the camera body. This is fine if you're using a fairly small, light lens.
  
  If you're shooting using a long, heavy telephoto lens, it's better to use a tripod mount ring. This fixes the monopod to the lens rather than the camera body, giving better balance and stopping the monopod from rotating in your hands as you try to position it.
   There are also a number of add-on camera modules for smartphones, they are called "lens-style" cameras (lens camera or smart lens). They contain all the essential components of a digital camera inside a DSLR lens-shaped module, hence the name, but lack any sort of viewfinder and most controls of a regular camera. Instead, they are connected wirelessly and/or mounted to a smartphone to be used as its display output and operate the camera's various controls.
  
  Lens-style cameras include:
   Picture orientation is recorded such that photos (but not videos) are always right-side-up, and are cropped on their ends if being viewed in the opposite orientation from which they were taken. However, the phone only recognizes upright (portrait) and rotated onto its left side (landscape), and does not recognize right-side or upside-down orientation. When put this way or flat on a table, it uses the previously recognized orientation. When entering text messages (or any other text such as address book), the phone uses the standard dialpad and iTap when upright, while it uses a small QWERTY virtual keyboard layout while on its left side. The rotation function is controlled by an accelerometer.
   Section::::Camera phone.:Orientation.
   Smartphones can usually not fixed on a tripod, which can make problems at filming or at taking pictures with long exposure times.
  
  Section::::Laws.
   This requires that the image circle of the lens be larger than is required to cover the film without use of movements. If the lens can produce a circular image just large enough to cover the film, it can't cover the bottom of the film as it rises. Consequently, lens coverage must be larger to accommodate rises (and falls, and shifts).
   BULLET::::- Camera facing away: This position automatically starts the camera application to take pictures or create videos. If the phone's video player application is being used, twisting to this position automatically changes the video to horizontal full screen mode, and it is possible to stand the 5700 on its side in this position so it is easier to watch videos.
  
  BULLET::::- Camera facing forward: This position automatically starts the camera application and is intended for self-portraits and for videophone calls. This position lets the phone be laid down horizontally on its side for hands-free use of the video camera.
   BULLET::::- Sony Clie PDA (various PEG-XXXX models)
  
  BULLET::::- Sony PlayStation Portable camera
  
  BULLET::::- Game Boy Camera which swivels horizontally for self-portraits
  
  BULLET::::- Veo SD camera for Toshiba e805 pocket pc
  
  BULLET::::- Notion Ink Adam
  
  BULLET::::- Asus M50VM laptop computer
  
  Section::::List of other devices with swivel lens.:Cellphones.
  
  BULLET::::- LG CU500
  
  BULLET::::- LG VX7000
  
  BULLET::::- Nokia N90
  
  BULLET::::- Samsung V200, SCH-U740
  
  Section::::List of other devices with swivel lens.:Cellphones with pseudo swivel lens.
  
  Some cellphones have lens that rotate and allow users to take self-portraits but are limited in the angles where the camera can take pictures. 
  
  BULLET::::- Samsung SPH-A900
   A camera's angle of view depends not only on the lens, but also on the sensor. Digital sensors are usually smaller than 35 mm film, and this causes the lens to have a narrower angle of view than with 35 mm film, by a constant factor for each sensor (called the crop factor). In everyday digital cameras, the crop factor can range from around 1 (professional digital SLRs), to 1.6 (consumer SLR), to 2 (Micro Four Thirds ILC) to 4 (enthusiast compact cameras) to 6 (most compact cameras). So a standard 50 mm lens for 35 mm photography acts like a 50 mm standard "film" lens on a professional digital SLR, but would act closer to an 80 mm lens (1.6 x 50mm) on many mid-market DSLRs, and the 40 degree angle of view of a standard 50 mm lens on a film camera is equivalent to a 28–35 mm lens on many digital SLRs.
   New trends for smartphone displays began to emerge in 2017, with both LG and Samsung releasing flagship smartphones utilizing displays with taller aspect ratios than the common ratio. These designs allow the display to have a larger diameter, but with a slimmer width than 16:9 displays with an equivalent screen size. Another trend popularized that year were displays that contained tab-like cut-outs at their top-centre—colloquially known as a "notch"—to contain the front-facing camera, and sometimes other sensors typically located along the top bezel of a device. These designs allow for "edge-to-edge" displays that take up nearly the entire height of the device, with little to no bezel along the top. This design characteristic was popularized by the Essential Phone (which featured a circular tab for its camera) and iPhone X (which used a wider tab to contain a camera and facial scanning system). In 2018, the first smartphones featuring fingerprint readers embedded within OLED displays were announced, followed in 2019 by an implementation using an ultrasonic sensor on the Samsung Galaxy S10.
   In 2019, Samsung announced the Galaxy A80, which has only rear cameras. When the user wants to take a selfie, the cameras automatically slide out of the back and rotate towards the user.
  
  Section::::Manufacturers.
  
  Major manufacturers of cameras for phones include Toshiba, ST Micro, Sharp, Omnivision, and Aptina (Now part of ON Semiconductor).
  
  Section::::Social impact.
  
  Personal photography allows people to capture and construct personal and group memory, maintain social relationships as well as expressing their identity. The hundreds of millions
   Section::::Hardware issues.:iPhone 6 Plus camera issues.
  
  It was reported that the optical image stabilization systems on some iPhone 6 Plus models were faulty, failing to properly stabilize when the phone is being held perfectly still, leading to blurry photos and "wavy"-looking videos. The optical image stabilization system was also found to have been affected by accessories that use magnets, such as third-party lens attachments; Apple issued advisories to users and its licensed accessory makers, warning that magnetic or metallic accessories can cause the OIS to malfunction.
   The exact shape of this region varies depending on what kind of camera lens is being simulated, but typically it is a frustum of a rectangular pyramid (hence the name). The planes that cut the frustum perpendicular to the viewing direction are called the "near plane" and the "far plane". Objects closer to the camera than the near plane or beyond the far plane are not drawn. Sometimes, the far plane is placed infinitely far away from the camera so all objects within the frustum are drawn regardless of their distance from the camera.
   In Figure a) below (images are upside down, as a photographer would see them on the ground glass of a view camera), the lens is in the “normal” position. Notice that much of the unwanted foreground is included, but not the top of the tower. In Figure b), the lens has been shifted up: the top of the tower is now inside the area captured on film, at the sacrifice of unwanted green foreground.
  
  Section::::Movements.:Shift.
   As an alternative visualization, consider the points X, O & O that form a plane called the "epipolar plane". The epipolar plane intersects each camera's image plane where it forms lines—the epipolar lines. All epipolar planes and epipolar lines intersect the epipole regardless of where X is located.
  
  Section::::Epipolar geometry.:Epipolar constraint and triangulation.
  
  If the relative position of the two cameras is known, this leads to two important observations:
   Post-processing can be done with image editing software. This normally involves cropping the image to a square and straightening it. The cropping is necessary because in most cases the (normally square) viewfinder image covers only about 25- 50% of the area of the (normally rectangular) digital picture.
  
  Additionally some photographers prefer to 'flip' the TtV image so that it is no longer a mirror image, especially if the image contains lettering.
   Competitors followed suit, and by the end of the year most companies were offering a version in their high-end products. OmniVision has continued to push the technology down their product lines. By contrast, the iPhone 4s employs a sensor manufactured by Sony. Another example is the HTC EVO 4G which has an 8 MP, 1.4 µm pixel BSI sensor from OmniVision. In 2011, Sony implemented their Exmor R sensor in their flagship smartphone Sony Ericsson Xperia Arc.
   Section::::Models.
  
  Section::::Models.:Mamiya Press.
  
  The original Mamiya Press was introduced in 1960 with the M-type back attachment system. It came with a 90 mm lens and has a bellows mechanism on the back that allows up to 15 degrees of tilt and 31 mm of extension.
  
  Section::::Models.:Mamiya Press G.
  
  The Press G, introduced in 1963, is identical to the original except for the G-type back attachment system, which is compatible with Graflex Speed Graphic cameras.
  
  Section::::Models.:Mamiya Press S.
   While programs such as Adobe Photoshop have new features that allow users to stitch images together, they only support "rectilinear" types of stitching. Photoshop cannot produce them as quickly or accurately as stitching software programs can such as Autodesk Stitcher. This is because there is sophisticated math and camera-lens profiles that are needed to create the desired panorama image which is based on your camera's depth of field (FOV) and the type of lens used. Cameras such as the Nikon D3 or D700 have a full frame digital SLR cameras, whereas the Nikon D90 or Canon T2i (Rebel line of Digital EOS cameras) have a smaller sensor. When full frame digital SLR cameras are used with a fish eye lens such as a Sigma 8mm F/3.5, a full circular image is captured. This allows you to shoot 2 or 3 shots per view to create a 360 X 360 stitched panoramic image. When used with a non full frame digital SLR camera like the Nikon D90 or Canon digital Rebel and similar cameras, 4-shots are required with the camera in the portrait position. The resulting image will have the left and right sides cropped off each of the 4 images and each of the four corners, creating a rounded image.
   The MFT design standard also specifies multiple aspect ratios: 4:3, 3:2, 16:9 (the native HD video format specification), and 1:1 (a square format). With the exception of a few MFT cameras, most MFT cameras record in a native 4:3 format image aspect ratio, and through cropping of the 4:3 image, can record in 16:9, 3:2 and 1:1 formats.
  
  In addition, all current Micro Four Thirds cameras have sensor dust removal technologies.
  
  Section::::Lens mount.
  
presuppositions: If lenses are circular, then rotating a cell phone from vertical to horizontal should not effect the photo. 
corrections: It is the sensor that is responsible for the image aspect ratio, not the shape of the lens.
raw_presuppositions: If lenses are circular, then rotating a cell phone from vertical to horizontal should not effect the photo.  It shouldn't make any difference in the way we rotate our phone cameras in changing the appearance of the final photo.
raw_corrections: It is the sensor that is responsible for the image aspect ratio, not the shape of the lens. It is the sensor that is responsible for the image aspect, not the shape of the lens.