How do i increase ROM for Dips?

Hey, i dont have any rings but i do have a set of chairs where i regularly do dips.

When i take a video i see that my elbows are actually slightly behinds rather than pointing out.

But when i look at videos, i see alot of gymnasts able to go all the way down, they can touch the bar with their shoulders. I can only go to about 90 degree or so untill it starts to hurt a bit.

So how do i get lower? Any tips or anything.

Also what do you guys think of psudo planche pushups (basically hip pushups)?

thanks again

Basically unless you are super tight and can go no further down because of this, in time you'll be able to go lower when you get stronger.

Probably strength then