You can freely change the size of the image in the viewfinder by using the wide-angle / telephoto zoom lever

Wide-angle End - Press the zoom lever to the wide-angle side. The lens is set to 28mm wide-angle. This gives you a a wide field of view, suitable for taking group or landscape pictures

Telephoto End - Press the zoom lever to the telephoto side. The lens is set to 70mm telephoto. This makes the image larger, suitable for taking portraits.