Creating custom lenses for PhotoVista Panorama

ISeeMedia PhotoVista Panorama comes with a number of pre-defined lenses so that you can just select the camera/lens you used and don't have to worry about anything else.

Lens selection in PhotoVista Panorama 3

However, if PhotoVista Panorama doesn't have a preset lens definition that matches the equipment you are using, you can create your own. There are two ways of doing this:

  • Use the "custom" option from lens settings in PhotoVista
  • Use a text editor

In PhotoVista version 1.0.1 it is possible to add a lens definition for the ultra-wide 8mm fisheye lens in order to create spherical panoramas. However in version 1.32 (and all versions since then) additional changes were made that prevent ultra-wide angle lenses from working properly.

Using the Custom Lens Settings interface

Defining a custom lens in PhotoVista Panorama 3

To enter your own lens type you need to choose between setting the focal length, portrait field of view (the FOV for the longest edge of the picture), or landscape field of view (the FOV for the shortest edge of the picture). Whichever you choose, when you alter the value the other values will automatically be calculated for you. Also make sure the film format is correct and select 'fisheye' if you used a fisheye lens.

If you use a film camera it is extremely likely that the settings for your scans will be different from the lens (see the digitising article). If so you should click "fine tune settings" to let PhotoVista analyse the pictures and see if it can find a slightly better setting (you must have at least 3 pictures loaded to be able to do this).

PhotoVista restricts the lenses that you can define using the Custom Lens Settings dialogue - if you find you cannot define your lens, then you should try defining it using a text editor instead (see below).

Using a text editor

In the folder where PhotoVista is installed there is a sub-folder lenses. In here you will find all of the pre-defined and user-defined lenses that you see in the main lenses window of PhotoVista. All these files are text readable. Open one of them in a text editor such as NotePad or WordPad on a Windows PC and you will see something like:

PVLens 1
mode fov_portrait
format 35mm
focal_length 8.00
fov_portrait 180.00
fov_landscape 180.00
fisheye 1
default_rotation 0
manufacturer unknown
description Use this setting for full circular 180 degree fisheye

Here's the explanation of each of the lines you see above:

PVLens always '1'
mode focal_length for 'use focal length'
fov_portrait for 'use portrait FOV'
fov_landscape for 'use landscape FOV'
format film format: either 35mm, APS_Classic, APS_HD, APS_Panorama
focal_length Focal length in mm
fov_portrait Vertical field of view of a portrait picture, i.e. the field of view on the longest side of the picture
fov_landscape Vertical field of view of a landscape picture, i.e. the field of view on the shortest side of the picture
fisheye Whether the lens is a fisheye lens: 1 for 'yes' and 0 for 'no'
default_rotation Normally 0 or omitted completely. To pre-rotate all images 90 degrees, set this to 90. (optional)
manufacturer Name of the lens manufacturer (optional)
description Lens description (optional - this appears in the main lenses window)

It shouldn't make any difference which mode is selected, since field of view and focal length are interrelated and one can be calculated from the other for a given image size. To calculate the field of view or focal length of your lens, use the lens calculator.

If you are using a digital camera and you want to create a lens definition using a text editor as shown here, be sure to check the specification of the lens with the manufacturer. You need to specify the "35mm equivalent" focal length which is not always what is written on the lens itself.

Once you have finished creating your lens, save it using a filename (without extension such as .txt) in the lenses folder. When you re-start PhotoVista you should see the lens (the screen-shot below shows a lens I called "my Lens").

Custom lens listed in lens chooser in PhotoVista Panorama 2

If you use Windows NotePad you will not be able to stop it saving the lens as, for example, 'my Lens.txt'. You will have to remove the '.txt' manually if you want to, otherwise that will appear in the lenses window (but the new lens definition will still work).