I'll need vs. I'll be needing

[Natalia]

Imagine a situation where  a friend of mine is going for a trip. Now she is in the act of packing,  and she put my camera to her bag.  The thing is, I will also need the camera later on, so which of the following tenses should I use? And what is the main difference between them?
1)   I’m sorry, but I will need this camera.
2)   I’m sorry but I will be needing this camera.

[Daniel]

need = more general, more common
be needing = emphasizing the ongoing need in the future

However, "be needing" can also be used sometimes with a sort of casual flavor, specifically with that phrase-- "no, don't take that, I'll be needing it later!". But it's still not very common.

[Natalia]

So we empahsise the ongoing need in the future - OK,  and isn't it that by using "will be ~ing",  we also want to be less direct and more polite?

[Daniel]

No, I don't think so. Maybe in some contexts, but not in all.

It's almost like the specific phrase "I'll be needing that" means "I will start needing that in the future", suggesting you do not need it now or do not obviously need it now.

But in general the -ing in the future just emphasizes the action is ongoing. It's almost never necessary.

This specific phrase is a little unusual, so the best way to learn it is:
1. Understand the basic idea of -ing as 'ongoing'.
2. Look up examples of this phrase (and others!) in use.

The "meaning" to a native speaker is just the sum of all times they've heard the phrased used. What you're lacking is that experience, so if you want to know the "meaning", you just need to see more examples. You're beyond the basic "rules" at this point.

[Natalia]

I agree. The best way to learn the language is through practice. Anyway, thank you for your explanation, I'll remember that.