I recently bought Nikon D7200. A good camera. But I feel a great challenge while taking a photo of a model standing in the middle of the tunnel. The tunnel is short and outside the tunnel is a picturesque lush green landscape.

• If I use in-built flash, it takes a picture of model but then washes out the tunnel's outside view with 'white'.
• If I don't use the flash, the subject comes 'dark'

What aperture is needed if the model is say 10 ft from your camera and the tunnel end is say 200 meters? What shutter speed is required? I don't want bokeh effects.