Kratzer, Funkedup is right. Moving the viewpoint forward/backward with arrow up/down does not change the FOV. Try it on the runway, by moving the viewpoint and observing how only your plane/vehicle seems to move in relation to you. Notice that you don't loose peripheral vision.
Now, try zooming. You will see that the objects around you get bigger, but you loose peripheral vision.
I have personalized my views so that there are as little of the cockpit frames in the view as possible. Usually this can be done by moving the viewpoint forward, as close as possible to the cockpit window - "sticking your cheek against it". There is no peripheral view loss in doing so. I use full zoom out, to get the biggest peripheral vision.
Try customizing your forward view. You will surely find a suitable setting where the bulky windscreen frame of the 109 obscures the view as little as possible. You might have to compromise, to get the gunsight to appear large enough for enjoyable gunnery.
Good luck.
Camo