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<h1 id="firstHeading" class="firstHeading">Hugin Camera and Lens tab</h1>
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<p>The <b>Camera and Lens</b> tab looks a lot like the <a href="Hugin_Images_tab.html" title="Hugin Images tab">hugin Images tab</a>, except that the lens settings can be edited here.
As in the Images Tab, multi-selection can be used to change the parameters for multiple images.
</p><p>Panorama Tools and <a href="Hugin.html" title="Hugin">hugin</a> allow the usage of images shot with different lenses and settings inside the same project.
Each image is associated with a lens number.
All images that share the same lens number use the same lens type, and may be forced to share the same lens parameters.
</p><p>The <b>Load lens...</b> and <b>Save lens...</b> buttons allow you to keep calibrated lens profiles. Once a set of lens parameters has been obtained through lens calibration it shouldn't vary much for future projects. The advantage of this is that if only positions are being optimised in the <a href="Hugin_Optimizer_tab.html" title="Hugin Optimizer tab">hugin Optimizer tab</a>, then as few as two or three <a href="Control_points.html" title="Control points">control points</a> are needed per image pair.
</p><p><b>Load EXIF</b> examines the selected image file and tries to determine the <a href="Field_of_View.html" title="Field of View">Field of View</a>
of the photo by reading embedded <a href="EXIF.html" title="EXIF">EXIF</a> data, note that this currently only works for
<a href="JPEG.html" title="JPEG">JPEG</a> images. The same function is performed when initially adding photos so you only need
this button to reset the <b>Field of View</b> if it has since changed.
</p><p>By default, every photo in a project is assigned to <i>lens number</i> <b>0</b>. If you are including
pictures taken with a different camera, a different lens or at different zoom settings; then
you need to assign a <i>new lens</i> for these pictures by clicking the <b>New Lens</b> button.
Assign additional photos to this <i>lens number</i> with the <b>Change Lens...</b> button.
</p>
<a name="Geometric" id="Geometric"></a><h2> <span class="mw-headline"> Geometric </span></h2>
<p>The Panorama Tools <a href="Lens_correction_model.html" title="Lens correction model">lens correction model</a> has enough parameters to model most photographic images, these parameters can be set manually here in the <b>hugin Camera and Lens tab</b> or calculated automatically in the <a href="Hugin_Optimizer_tab.html" title="Hugin Optimizer tab">hugin Optimizer tab</a>.
</p>
<a name="Lens" id="Lens"></a><h3> <span class="mw-headline"> Lens </span></h3>
<p>The most important parameters are the <b>Lens type</b> and the <b><a href="Field_of_View.html" title="Field of View">hor. field of view</a></b>.
hugin supports the following projections in input images:
</p>
<ul><li> <b><a href="Rectilinear_Projection.html" title="Rectilinear Projection">rectilinear</a></b> This is the projection used by most cameras. It keeps straight lines straight. The maximum horizontal field of view is 180 degrees (for an image of infinite size, that is).
</li><li> <b>Panoramic</b> is used by panoramic cameras, such as the Horizon, Roundshot and Spheron cameras. This projection is also called <a href="Cylindrical_Projection.html" title="Cylindrical Projection">Cylindrical Projection</a>.
</li><li> <b>Circular fisheye</b> This is projection is used by <a href="Fisheye_Projection.html" title="Fisheye Projection">fisheye</a> lenses. If the image is circular, or the corners of the image are black, use this type of fisheye lens. A circular crop in the <a href="Hugin_Crop_tab.html" title="Hugin Crop tab">Hugin Crop tab</a> can be used for cutting away the edge borders.
</li><li> <b>Full frame fisheye</b> Exactly the same projection as above, but the crop option will crop to an rectangle instead of a circle. This should be used for full frame fisheye images.
</li><li> <b>Equirectangular</b> A full spherical <a href="Equirectangular_Projection.html" title="Equirectangular Projection">Equirectangular Projection</a> image. Usually these are created as the result of the stitching process, but sometimes it is useful to be able to reload a finished panorama to extract further images.
</li></ul>
<p>After the lens type has been specified, an estimate for the horizontal <a href="Field_of_View.html" title="Field of View">Field of View</a> (HFOV) is required.
The HFOV specifies the horizontal opening angle of the image in degrees.
Since most photographers are more familiar with <a href="Focal_Length.html" title="Focal Length">Focal Length</a> as a measure for the HFOV, it can be entered into hugin, and hugin will compute the HFOV from it.
For this calculation the actual focal length and the <a href="Crop_factor.html" title="Crop factor">crop factor</a> of the camera are required.
If the 35mm film equivalent focal length is known, a crop factor of 1 should be used.
</p><p>In case of <a href="JPEG.html" title="JPEG">JPEG</a> images, hugin can usually automatically calculate the HFOV based on the <a href="EXIF.html" title="EXIF">EXIF</a> information.
</p>
<a name="Radial_Distortion.2C_Image_Center_Shift_and_Image_Shearing" id="Radial_Distortion.2C_Image_Center_Shift_and_Image_Shearing"></a><h3> <span class="mw-headline"> Radial Distortion, Image Center Shift and Image Shearing </span></h3>
<p>Usually lenses do not project images exactly according to the selected projection type, but suffer from distortions.
In many cases the distortions are acceptable for single image shots, but they need to be corrected when stitching a panorama.
The <b>a</b>, <b>b</b> and <b>c</b> parameters are used to remove that distortion.
They are applied radially from the image center, which can be moved by changing the <b>d</b> and <b>e</b> parameters.
These <b>a</b>, <b>b</b>, <b>c</b>, <b>d</b> and <b>e</b> parameters are the basis of the panotools <a href="Lens_correction_model.html" title="Lens correction model">lens correction model</a>.
</p><p>Scanned images might also suffer from image shearing. This can be corrected using the <b>g</b> and <b>t</b> parameters.
</p><p>The distortion parameters usually vary with the focal length, and to a lesser degree with the focus.
The <b>link</b> checkbox indicates whether the parameter is linked or not.
A linked parameter is forced to the same value for all images with the same lens number.
This is the default for the HFOV and distortion parameters.
If a parameter is not linked each images is allowed to have individual values for the respective parameter.
This is useful if a different zoom or focus setting has been used for some images.
If scanned images are used, they are usually not perfectly centered, and each image should have individual <b>d</b> and <b>e</b> parameters.
</p>
<a name="Photometric" id="Photometric"></a><h2> <span class="mw-headline"> Photometric </span></h2>
<p><a href="Hugin.html" title="Hugin">hugin</a> models the <b>photometric</b> parameters of a lens/camera combination in a similar way to the <a href="Lens_correction_model.html" title="Lens correction model">lens correction model</a> for <b>Geometric</b> parameters. These parameters can be set manually here in the hugin <b>Camera and Lens tab</b> or calculated automatically in the <a href="Hugin_Exposure_tab.html" title="Hugin Exposure tab">hugin Exposure tab</a>.
</p>
<a name="Exposure_and_Color" id="Exposure_and_Color"></a><h3> <span class="mw-headline"> Exposure and Color </span></h3>
<p><b>Exposure (EV)</b>, EV stands for <i>Exposure Value</i>, setting it to <i>0</i> (zero) will
result in <a href="Hugin.html" title="Hugin">hugin</a> applying no exposure change to the photo.
</p><p>EV is a standard photographic scale, each increase or decrease by one unit will change the
exposure by the equivalent of one <i>f-stop</i> (ie. halving or doubling the exposure).
</p><p>Very often, different photos in the same project, even those with the same <i>lens number</i>,
will require a different <b>Exposure</b>. This could be because the photos were taken
with a different shutter-speed or simply because the light changed between shots, if so
uncheck <b>Link</b> here before optimising exposure in the <a href="Hugin_Exposure_tab.html" title="Hugin Exposure tab">hugin Exposure tab</a>.
</p><p>The <b>Red multiplier</b> and <b>Blue multiplier</b> settings are used to account for changes
in <b>white balance</b> (also known as <i>colour balance</i> or <i>colour temperature</i>) between
photos. Setting them both to <i>1</i> will result in no <i>white balance</i> change (the numbers
are relative to the green channel which stays unaltered).
</p><p>As with exposure, different photos in the same project are quite likely to require different
<i>white balance</i>. Typically this will be caused by variations in lighting conditions between
shots - For example a cloudy scene will contain considerably less <i>red</i> light than the same scene
under direct sunlight, so uncheck <b>Link</b> here before optimising <b>White balance</b>
in the <a href="Hugin_Exposure_tab.html" title="Hugin Exposure tab">hugin Exposure tab</a>.
</p>
<a name="Vignetting" id="Vignetting"></a><h3> <span class="mw-headline"> Vignetting </span></h3>
<p><a href="Vignetting.html" title="Vignetting">Vignetting</a> is dependent mainly on your lens and the <i>aperture</i>. Usually the
centre of the image is brighter with a falloff towards the edges. The three
numbers here represent a polynomial curve used by <a href="Hugin.html" title="Hugin">hugin</a> to correct vignetting.
</p><p>You are not expected to guess these values, they are generally loaded with a lens
profile or calculated from two or more overlapping photos in the <a href="Hugin_Exposure_tab.html" title="Hugin Exposure tab">hugin Exposure tab</a>.
</p><p>Set the values to <i>0,0,0</i> for no vignetting correction.
</p><p>Usually all photos taken with the same <i>lens</i> will have the same vignetting, keep
<b>Link</b> checked to ensure <b>hugin</b> applies the same vignetting correction to all
photos with the selected lens number.
</p>
<a name="Vignetting_Center_Shift" id="Vignetting_Center_Shift"></a><h3> <span class="mw-headline"> Vignetting Center Shift </span></h3>
<p>The centre of <a href="Vignetting.html" title="Vignetting">vignetting</a> is rarely the exact centre of the photo. The two numbers
here indicate the position of the vignetting centre. The scale is in pixels, with
<i>0,0</i> indicating the centre of the photo. The values are independent of the <b>d</b>
&amp; <b>e</b> parameters which specify the origin for projection and geometric distortion.
</p><p>As with other lens parameters, this <b>Vignetting Center Shift</b> can be optimised in
the <a href="Hugin_Exposure_tab.html" title="Hugin Exposure tab">hugin Exposure tab</a>. Keep <b>Link</b> checked to ensure <a href="Hugin.html" title="Hugin">hugin</a> applies the same
vignetting centre to all photos with the selected lens number.
</p>
<a name="Camera_Response" id="Camera_Response"></a><h3> <span class="mw-headline"> Camera Response </span></h3>
<p>The <a href="Camera_response_curve.html" title="Camera response curve">camera response curve</a> is used both for mapping the images to a linear
colourspace when creating <a href="HDR.html" title="HDR">HDR</a> output, and for normalising the colourspace
for internal vignetting, brightness and colour corrections when creating
'normal' <b>LDR</b> output.
</p><p><a href="Hugin.html" title="Hugin">hugin</a> uses the EMoR response model
from the Computer Vision Lab at Columbia University which simplifies the full
response curve to these five empirical coefficient numbers. You are
not expected to guess these values, they are generally loaded with a lens
profile or calculated from two or more overlapping photos in the <a href="Hugin_Exposure_tab.html" title="Hugin Exposure tab">hugin Exposure tab</a>.
</p><p>Set the five numbers to <i>0,0,0,0,0</i> to use a generic response curve or change the <b>Type</b>
to <b>Linear</b> to indicate that your input photos have a <i>scene-referred</i> or <a href="HDR.html" title="HDR">HDR</a>
response.
</p><p>Keep <b>Link</b> checked to ensure <b>hugin</b> applies the same
response curve to all photos with the selected lens number.
</p>
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