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Sensor and Lens

 List / Range of lens focal lengths

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Sensor and Lens

 List / Range of lens focal lengths

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Sensor and Lens

 List / Range of lens focal lengths

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In the List/Range box of the Sensor and Lens panel, you can specify a list of possible focal lengths of camera lenses or a range of focal lengths.

If a list of focal lengths is specified, then only values ​​from the list will be present in the drop-down list of the Lens focal length combobox. You will be able to set focal length out of the list, but with value out of the list, the comboboxes turn pink.

 

If a focal length range is specified, then only values within the range will be present in the drop-down list of the Lens focal length combobox. Changing focal length is allowed only within the specified range.

 

It is possible to set real angles of view for each value of the focal length in the list or for min and max values ​​of the range. If the real angles of view are set, then when all the other parameters coincide, the lens distortion modeling is automatically turned on.

 

If the List / Range and List of Resolutions strings are specified in the camera model parameters, the user only needs to select the lens focal length and resolution from the drop-down lists to obtain accurate model of camera's view area, taking into account  lens distortion and dependence of active area size of the image sensor from the resolution.

 


 

The List / Range string can be in any of the following formats:

 

1. List of focal lengths

 

F1;  F2;  F3.. list of focal lengths in millimeters separated by a semicolon.

 

Example:  2.8;4;12;18

 

2. Range of focal length

 

Fmin  -  Fmax. Minimum and maximum focal lengths divided by dash.

 

Пример: 4-6

 

3. The range of focal lengths taking into account lens distortion

 

Ar|Cr|Fmin|Ahmin|Avmin|Admin   -    Fmax|Ahmax|Avmax|Admax

 

Ar – is the Aspect ratio of the active area of the image sensor. If the ratio is 4:3, then it can be omitted.

CrCrop. If Crop = 1, then it can be omitted.

Fmin, Fmax – the minimum and maximum focal lengths.

Ahmin, Avmin, Admin – horizontal, vertical and diagonal angles of view with minimum focal length.

Ahmax, Avmax, Admax – horizontal, vertical and diagonal angles of view with maximum focal length..

 

To simulate lens distortion, you must specify one of three angles of view (horizontal vertical or diagonal). For minimum and maximum focal lengths the same type of angles should be specified.

The Lens Distortion simulation is automatically turned on when the active camera has Aspect ratio equals Ar, Crop coincides with Cr, and the focal length is in the range Fmin..Fmax.

Within the Fmin-Fmax range, the angles of view are calculated proportionally.

 

At the boundaries of the range, the accuracy of the simulation is determined only by the initial values, but within the range the actual distortion may differ.

 

4. The list of focal lengths taking into account lens distortion

 

Ar1|Cr1|F1|Ah1|Av1|Ad1;    Ar2|Cr2|F2|Ah2|Av2|Ad2;    Arn|Crn|Fn|Ahn|Avn|Adn;… A list of substrings separated by semicolons.

 

Each substring consists of the values:

 

Arn – is the Aspect ratio of the active area of the image sensor. If the ratio is 4:3, then it can be omitted..

CrnCrop. If Crop = 1, then it can be omitted.

Fn – lens focal length.

Ahn, Avn, Adn – horizontal, vertical and diagonal angles of view with focal length = Fn.

 

To simulate lens distortion, you must specify one of three angles of view (horizontal vertical or diagonal). For each focal lengths the same type of angles should be specified.

The Lens Distortion simulation is automatically turned on when the active camera has Aspect ratio equals Arn, Crop coincides with Crn, and the focal length is  higher than minimum Fn and lower than maximum Fn in the list.

Between the values of the list, the angles of view are calculated proportionally.

 

This is a more accurate distortion approximation than the range of focal lengths taking into account lens distortion. By specifying several points of correspondence between the focal length and angles, one can describe a complex dependence of angles view of a real lens and the focal length.

 

The List / Range string can be no more than 200 characters.

 

The List / Range string is included in the list of camera model parameters and can be automatically assigned to the active camera when it is assigned a model from the Table of Camera Models.

 

 

The List / Range string can be edited as plain text or using the drop-down form, which can be opened by the button in the upper corner of the List / Range box.

 

On the form, select the required tab: List, Range, List with distortion or Range with distortion.

Then select or enter the required values ​​in the boxes and click Add. The string will be automatically formed in the top box of the form.

 

To record the string to the List / Range box, click Record.

 

Clear clears the top box of the form.

 

Cancel closes the form without recording the string.