A full frame photo is considered to be 24 x 36mm, however most cameras use sensors of smaller sizes. When using such a camera it seems that the camera is zooming in but all it does is crop part of the image as seen here.
Different cameras have different sizes of sensors. For example, Canon's sensor size is 1.6 times smaller than full frame, Nikon and Sony are 1.5 times smaller.
Showing an example of how a camera typically crops an image
Analysis of the EXIF info in the photo
3ds Max is set to work with full frame photos, so when manually setting the camera focal length found in EXIF data, it needs to be multiplied by the crop factor (1.6 or 1.5, depending on the camera model).
Check the focal length and find out the crop factor of the camera model. The time and date when the photo was taken is used for positioning the sun in a 3D scene using the Daylight system. Create a free camera in 3ds Max and enter focal length.
Working out the focal length and crop factor
Matching render settings
The render settings in the dialogue window should be changed to match the proportions of the photograph.
Making sure the render settings match the photograph
Setting the photo background
Set the selected photo as a background using Alt+B. Select Use Files, set Match Rendering Output in the list of settings of Aspect Ratio, and then click Apply to Active View. Click OK.
Setting the photograph as a background to the viewport
The scene so far
At this stage we have a 3D scene containing the existing objects that are set on the corners of visible CamPoints, and a photo on the background of the viewport projection. Now we can move on to the Camera Match dialogue window.
Preparing to move on to the camera match dialog window
Assigning camera positions
There is a list of CamPoints and an Assign Position button in the image below. Select each CamPoint on the list, click Assign Position and try to match its location on the photo as accurately as possible. Do it with every CamPoint.
If you wish 3ds Max to calculate the focal length and create a new camera automatically, just click on Create Camera. It could be that its position won't be entirely correct though. There are 2 ways to correct it by either moving it manually or adding more CamPoints and clicking on Modify Camera.
It is highly recommended that you create a camera yourself, and manually set the focal length. Check the Freexe FOV boc and click on Modify Camera.
Assigning camera positions to the CamPoints in the scene
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