Using std::async to call member function returning std::vector

I know, guys, there is s***t load of posts about std::async, but I just cant figure it out myself (for my defense I can say that today was my first day looking at whole multithread & async thing...). Here's what I have and what I want it to do - I have a camera and a projector and I want to synchronize them. They are connected so the projector signal triggers acquisition of images. HOWEVER I have to call for acquisiton start before I start displaying images via projector. I am using OpenCV as image processing/handling lib.

class Camera
{
public::
    //this one captures images till vector reaches given count of images (while loop)
    std::vector<cv::Mat> captureSetOfImages(uint count = 10)
};
class Projector
{
public:
    void start();
    void stop();
}
int main()
{
    Projector *proj = new Projector();
    Camera *cam = new Camera();
    std::vector<cv::Mat> recvimgs;
    recvimgs.reserve(10);
    auto f = std::async(&Camera::captureSetOfFrames, cam, PATTERN_10);
    proj->start();
    while(recvimgs.size() < 10)
        recvimgs = f.get();
    proj->stop();
}

I get an error:

3   IntelliSense: no operator "=" matches these operands
            operand types are: std::vector<cv::Mat, std::allocator<cv::Mat>> = std::vector<cv::Mat, std::allocator<cv::Mat>> (unsigned short)   

1. From where this unsigned short at the end of error is coming from...?
2. How can I achive this behaviour? (If the code example is not clear enough I want first to prepare for grabbing by calling Camera::captureSetOfFrames() then simultaneously call Projector::start() but knowing camera is ready for capturing, finally terminate displaying by calling Projector::stop() when all images are captured)

Hope you can figure it out!

PS: Base post which suggested me this (not working) solution How to, in C++11, use std::async on a member function?