Hi everyone!
Could someone explain to me the difference between “focus on” and “focus in on”.
Yesterday I stumbled upon the verb “focus in on something”, and for some reason it stuck with me, why is that “in on”?
I looked up for any other examples on ReversoContext AI and there were a lot of them. Looks like it’s a common thing.
But I grasped no difference. Is that a kind of further intensification or what? Longman and Webster have just the “focus on” one.
As a native English speaker, they both convey the same meaning to me. The “in” is redundant. It’s like saying “often times” instead of just saying “often”.
Thanks a lot!
I shouldn’t rely on AIs so much 
I believe there are slight differences between the two. Here are some example sentences that have come to mind;
COMPARED TO;
Either can be used in either sentence. However as a native English speaker the “in on” is more directly attributed toward the subject matter.
Also, I think “focus in on” is more common with the “ing” suffix, for example;
I’m focusing in on my inner struggles at the moment.
IN SUMMARY;
“Focus on” is a lot more common in the present, whereas “focus in on” is more applicable to something specific; like a skill.
It’s interesting, thank you so much!
But hey, you native speakers, you’re going to confuse me even more. Is it because I’m Russian? 
Whould you argue with @Ryanaissance to distill the truth?
I can’t comment on the UK, but at least here in the US you will hear both. As Oz234 has said, there will be no misunderstanding if you substitute one for the other. Perhaps there is a subtle extra emphasis on the subject by adding the “in”, but perhaps not. The extra “in” sounds redundant to me, but maybe there are others who do hear an extra emphasis.
Out of curiosity, I brought this up with a few people yesterday. One person thought maybe there is a difference, but he could’t pinpoint it. Every else thought they were the same.
The takeaway is, I think, that if there is a difference, most people will not be aware of it.
I like it. I found also such explanation:
That is nearly the same as the Oz234’s point. Although, he just suspects as Oz234 just believes.
I’ve found this an interesting, because of the different opinions amongst natives. In Russian there are two (three) phrases that mean the same, in order from the general to the particular:
Сосредоточиться на проблеме - > (Сфокусироваться) → Заострить внимание (на отдельном нюансе этой проблемы)
So you can"Сфокусироваться" on a problem as well, but often it means “to stop being distracted” or “перестать отвлекаться”. That’s why in the brackets.
A sentence that highlights the different meanings of these phrases is, “Instead of focusing on the big picture, I think we should focus in on this specific problem.”
The emphasis can also be conveyed instead of adding “in” by stressing “this”, or whatever particular it is that needs emphasizing.
In writing its harder to indicate where the stress lies. Italicizing the emphasis works, but adding the “in” does the job as well. I still maintain that the “in” is redundant, as context should tell you where the emphasis is anyway.
It almost feels like it had the implication of zoom in on the problem, like literally using the camera and zooming in to see more detail. Or there is also the expression zero in on something, which has a similar meaning so it looks almost like the extra preposition might be adopted from that expression.
Thank you for the response!
I guess that’s right. Since there is no dictionary that has this term, while natives have a slightly different sense of it.
Just found on Quora: