Object Calculator

The Object Calculator is accessible from Tools tab.
Related videos:
The Object Calculator is combination of built-in data bases and formulae that allow computing various parameters of your imaging setup (like FOV, CFZ, size, resolution etc.) without need to enter "hard to find data". It also can help to export the FOV size to your Planetarium application for easier target selection and frame orientation (see Planetarium section). 
APT contains one database with all Canon EOS and Nikon models and their specifications. Also it has database with many deep sky objects in the Object Browser. Combining them it is possible to see what is you Field-Of-View (FOV) size, the size of an object in pixels or to see how big the object will be into your frame!
Object Calculator
On camera connection APT will automatically select the Canon EOS or Nikon model (or the option "CCD/CMOS Camera") in the list box "Camera". Also you can select any model if you want to make a comparison. The other value you have to enter (for CCD/CMOS there is need to enter the sensor and pixel size one time only) is the telescope or lens focal length.
Click on Recalc button will make the calculations and print the results (and the sensor properties) in the Log panel. If you select an object from the Object Browser, or if you enter object size in arc-minutes, there will be information about the expected size in pixels too.
Here is sample with selected M78 (from the Object Browser) for QHY22 CCD camera and focal length 1000mm:
And the same calculation for EOS 6D:
Also in the main screen Preview Area you will see how big the object will be into your image:

Camera Model

1. Camera Model
The list of all Canon EOS and Nikon models plus possibility to select a CCD/CMOS. The Canon EOS/Nikon model or the CCD/CMOS option is automatically selected when connection is established.


2. Recalc
Makes new calculation with the current camera model, focal length and object size.
If you use the Shift+Click on the Recalc button (or Alt+W shortcut), APT will collect information about the FOV size, the current telescope coordinates (if connected), the rotator position (if connected) and then to send it to the connected Planetarium application to show you where the telescope is pointed in a bigger context. If there is no telescope or rotator connection it will still show the FOV size.

Focal Length

3. Focal Length
Enter the focal length of your telescope or lens to use for calculating the Field Of View (FOV) and the resolution arc-second per pixel. If you are using Canon/Nikon lens, APT will read the current lens focal length after each exposure and will update this value automatically.
The button "..." allows creation/selection of different profiles. When Focal Length control is focused you can use arrow up/down keyboard keys to scroll through the profiles you have defined.

Scope Diameter

4. Scope Diameter
Enter the diameter of your telescope or lens to use for calculating the Critical Focus Zone (CFZ). Requires the Focal Length to be populated too.


5. Size
Enter the Object Size that you want to use for the calculations. The values are in arc-minutes. You can enter something like 10x5 for oval object or just 11 for circular object.
If you enter 12.5x7 it will draw an ellipse tilted by the diagonal "lower left - upper right". If you enter 7x12.5 it will draw the same ellipse, but tilted by the diagonal "upper left - lower right". In order to see the object outline, you have to select a camera model, enter focal length, object size and to click on “Recalc” button. If you change any parameter, click again on the “Recalc” button to recalculate and re-draw the object.
To hide the outline use the Target button in the Main screen.
If you want quickly to change the ellipse orientation double click in the edit box and APT will switch from 7x12.5 to 12.5x7.

CCD params

6. CCD params
These are the CCD/CMOS camera parameters used to calculate the Field Of View (FOV) and the resolution arc-second per pixel. They are need only when you use CCD/CMOS camera.

Object Browser

7. Object Browser
Opens the Object Browser in order to select an object. On object selection it size will be automatically populated in the Object Size field.

CCD Profiles

8. CCD Profiles
CCD Profiles allow to store the parameters for two CCD/CMOS cameras and later to switch fast between them. To store a profile, enter the CCD/CMOS parameters, hold the Shift key and click on the buttons "1" or "2". To load a profile just click on the desired button. Profile loading also makes automatically the calculations made the Recalc button.

Ringy Thingy

9. Ringy Thingy
Ringy Thingy is an innovative way to edit numeric values using only mouse or touch pad. See details and animation how to use it in the Application Interface notes.