Adjustable old film effect

We will be creating an effect that tries to fake some kind of darkening on the edge of an old film-roll and some noise.

So let's make a start with the following image:

We duplicate the layer and apply the Gaussian Blur Filter as follows:

Now we create a new white layer and apply a radial gradient to it right into the middle of the layer:

To get the right position for your gradient you should use some generated guides. Image -> Guides -> New Guide (by percent). Create two of them at 50%. One vertical and horizontal each.
Now scale the layer in width to about 160% of its size:

Apply the Curves-Tool and a Gaussian blur as follows:

Add a layer mask to our blured layer and copy the layer containing our modified gradient into it:

To get the darkening on the edges we select the whole image via Ctrl + A, select the mask, copy its content via Ctrl + C and paste it back into the image and create a new layer from the floating selection. Invert this new layer and set its mode to "Multiply".

The final step is to add some noise to the darkening layer. Therefore we will be resizing it to 50% of its size, add some HSV-Noise (Filters -> Noise -> HSV Noise):

Now scale it back to its original size but with "Interpolation" set to "None". This way the noise wont get blured and it will stay as crisp as possible.
If you like you still can add some sharpening filter to the layer with the noise.
The cool thing about this setup is that you still can choose the amount of blur and darknes by just modifying the layers' "Opacity"