Cinematography

Cinematography scope: Media, especially the electronics media has become quite a vast domain of learning as well as jobs today. The considerations of abroad or national are gone because the digital revolution has trespassed the boundaries.
Cinematography has not just remained restricted to films and entertainment anymore. The scope of cinematography is quite big all around. There are projects that are done on a global level and even for a certificate course, the scope remains good. As cinematography is learning the camera its direction and uses, photography -still or motion - hence the career prospects are always there. The course can work winners for those who have been searching for an opportunity to learn the nuances of cinematography work. The certificate course, however, shall be done preferably from an acknowledged and recognised the place.
Film, TV and New Media Production - Overall, there is no difference in the domains mentioned.
As a Mass Communication Expert, I shall not appreciate the submission that each of these categories mentioned is different from each other, they complement each other.

Documentary production/cinematography is a specialisation domain, and there may be many things that you will need to keep learning along with the production learning.
The suggestions that I can make are:
1 A degree in a popular language that could be used in your work place
2 Content writing and proof reading
3. Web development and digital marketing
4. Music and sound mixing basics/audio production
5. Advertising and public relations management
The decision depends on how much time you get free from the work of learning documentary production. When you say that you are learning the production of documentary, I take it as a comprehensive work that is itself a time-taking thing and might not allow you to venture for more.
Read the related question which gives a similar solution:
https://ask.shiksha.com/what-parallel-courses-can-i-pursue-with-a-certificate-course-in-radio-jockeying-for-better-career-prospects-qna-4393561

The cinematography is all about the art as well as skills to make the best of camera and place for the shoot of a film. This skill is possessed by those who have sharp minds, quick hearts and minds and strong observation skills. The essentials of becoming a cinematographer are so complex and elite that we can not think of acquiring them in isolation. A distance mode degree for the sake of making an educational qualification and eligibility may be fine but someone to be called a cinematographer just because a degree or certificate was done via distance mode, that is not praiseworthy.
It is not worth pursuing a certificate from distance learning in India or from anywhere because this 'media' thing needs real learning which is more than the classroom. Such learnings and experiences come when the cameraman gets time to learn the nuances and advanced things at a dedicated place.
If we allow distance learning to run and sell such a course and people start doing the same, it will be tough for the field of videography and photography or even film-making to get people who actually know what to do.
Creative aspects of learning are developed when a class meets. Hence, we may not suggest a total distance mode course in camera works or lighting or direction or even acting. Practical learning has to be there, at any cost.
It is not worth doing any course which needs professional competence which is developed by personal contact with the institution and in regular classes.
Read the following:
https://ask.shiksha.com/what-are-the-career-prospects-in-india-and-abroad-for-certificate-course-in-cinematography-qna-4393195
https://ask.shiksha.com/is-it-worth-to-pursue-a-certificate-course-in-videography-from-distance-learning-in-india-and-why-qna-4392997

Media, especially the Electronic Media has become quite a vast domain of learning as well as jobs today. The considerations of Abroad or national are gone because the digital revolution has trespassed the boundaries. Cinematography has not just remained restricted to films and entertainment anymore. The scope of Cinematography is quite big all around. There are projects that are done on global level and even for a certificate course the scope remains good. As cinematography is learning the CAMERA it's Direction and Use, Photography -Still or Motion - hence the career prospects are always there. The course can work winners for those who have been searching for an opportunity to learn the nuances of Cinematography work. The Certificate Course, however, shall be done preferably from an acknowledged and recognised place.