cannot convert '*void(MyClass::*)(void*) to void*(*)(void*) in pthread_create function

i'm trying to create a new thread with a class "CameraManager" but i have the following error:

cannot convert '*void(CameraManager:: * )(void*) to void*( * )(void*) in pthread_create function

i defined in the cameramanager.h file:

public:
void *dequeueLoop(void *ptr);

and in the cameramanager.cpp

void CameraManager::startDequeuing(){
dequeuing = true;
dequeueThreadId = pthread_create(&dequeueThread, NULL, &CameraManager::dequeueLoop, NULL);
}

void *CameraManager::dequeueLoop(void *ptr){
while(dequeuing){
    highSpeedCamera->dequeue();
    highSpeedCamera->enqueue();
}

I don't want to declare dequeueLoop as a static function i also tried to declare dequeueLoop as a class friend function in the following way but then it doesn't have scope on class variables 'highSpeedCamera' and 'dequeuing' and the compiler also tell me that 'dequeueLoop' was not declared in this scope

to make dequeueLoop a friend function i did:

cameramanager.h

public:
friend void *dequeueLoop(void *ptr);

cameramanager.cpp

void CameraManager::startDequeuing(){
    dequeuing = true;
    dequeueThreadId = pthread_create(&dequeueThread, NULL, &CameraManager::dequeueLoop, NULL);
}
void *dequeueLoop(void *ptr){
    while(dequeuing){
        highSpeedCamera->dequeue();
        highSpeedCamera->enqueue();
    }
}

Where i'm doing wrong?