How to simulate a photo being taken from the photographer's POV in a film? How would I go about simulating a photo being taken from the photographers POV in a film?

I want the still to be part of the shot, with moving images before and after the still. And I want the supposed camera to be an analogue old school one.

More accurately I'd have to


superimpose an analogue style viewfinder (I could only find effects for camcorder ones so far)
simulate the closing of the iris
add a filter to make the still look more like an analogue photograph 
add a sound effect (at least that's not a problem)


Any tips on how to do this? I'm still in pre-production so all info from setting up the shot to post production would be helpful.

Relevant Equipment 
I'll be shooting with a Canon 5D MkII, 50mm prime lens
Editing in Final Cut Pro
Drawing out a viewfinder should not be a big deal. You can do this quicker than searching for one. Do it in photoshop or another decent app. Draw the lines with anti-aliasing on a transparent layer and export it as a PNG with transparency. You may want to set the layer compositing mode in FCP to be something other than the default, play around a bit.
Simulating closing of the iris is just a quick fade to black and back; the sound effect sells it.
Desaturation, the addition of grain. Don't over do it.


I would try 'pillar boxing' the viewfinder shot (4:3 inset in the 16:9 frame of the film), possibly reducing the size so it is inset from the outside frame completely (black all around in addition to being 4:3) as this will give more of the feeling of being 'inside' the camera viewfinder. Then when the taken photo is shown that is full frame. 

You may find that desaturating the viewfinder view and showing the taken photo with normal saturation does a better job of achieving what you want; this will depend on the narrative purpose of this effect.