anti-alisasing not working for far objects?

I’m new to Unity3d and I have problem with aliasing on far objects.

I’m using Syphon to send my rendered scene to madMapper to distribute the scene on 3 video projectors projecting on different screens.
Because MadMapper only takes one input texture, I need to capture my entire scene with only 1 far camera. I’m using triple HD resolution for the width ( 5760) and 1440 for the height (my project works with a ratio of 4:3). I put these values in Render width-Height of the Syphon server texture custom resolution script.

Looking at the objects zoomed 3 times (the zoom used at the end on one of the video projectors), they have aliasing (see the image attached).

The shader used on these objects is transparent/specular. The objects look sharp when they are big or close to the camera.

All the quality settings are set to hi.

Do you have any hint for the newbie I am please?

Are you certain you can only use a single camera to send the output to Syphon? It might be possible to have multiple camera’s next to each other so their combined resolution sums up to 5760x1440 with the help of viewport rect.

I think that option is not possible because the Syphon script is attached to a camera and output what this camera looks at…

An idea would be to use different cameras and capture their texture to planes and then using a last camera with the syphon script looking at these planes to output the result. But it’s about the same, I have to put the camera far enough to view all the planes…

still looking for a solution