# How to get the focal length of stereocalibrate?

**URL:** <https://forum.opencv.org/t/how-to-get-the-focal-length-of-stereocalibrate/11788>\
**Category:** Uncategorized\
**Tags:** calib3d\
**Created:** [January 28, 2023, 5:41am UTC](https://forum.opencv.org/t/how-to-get-the-focal-length-of-stereocalibrate/11788 "2023-01-28T05:41:43Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![ghak](https://avatars.discourse-cdn.com/v4/letter/g/a8b319/32.png) [@ghak](https://forum.opencv.org/u/ghak)\
**Post date:** [January 28, 2023, 5:41am UTC](https://forum.opencv.org/t/how-to-get-the-focal-length-of-stereocalibrate/11788/1 "2023-01-28T05:41:43Z")

</div>

Hi every one.  
I have two webcams that i calibrated to make depth estimation. when i make stereocalibrate, the intrinsic matrices of the cameras doesn’t change (even thogh the two cameras has not the same focal).  
But when i make cv2.decomposeProjectionMatrix from the projection matrix of stereorectify, i get a different focal  
can i get the new focal length directly or i’m i obliged to use cv2.decomposeProjectionMatrix ?