Films about the details of filming

Since you're in the midst of the '70s, these two might be of some value:

Hearts Of the West (1976) - Zane Grey-wannabe Jeff Bridges goes west in the early '30s and falls in with a low-budget film company run by harried, does-it-all exec Alan Arkin, who churns out grade-Z westerns. Andy Griffith gives a standout performance as a former performer and industry veteran dispensing sage advice to the novice. There's some subplot silliness involving two inept hoods on the trail of stolen loot, but it's overall a sweetly charming film.

Nickelodeon (1976) - This depiction of the 1910 pioneer days of film making suffered some from director Peter Bogdanovich's fall from grace after stumbles like Daisy Miller and At Long Last Love that followed his meteoric rise, but it's really much better than its reputation would suggest, and puts some of the whimsy of Paper Moon and manic energy of What's Up Doc to good use.

Both of these are affectionate valentines to making films on the fly during their respective, long-gone eras. In the documentary department are these two outstanding ones: 

Hollywood (1980) - Each episode of Kevin Brownlow's and David Gill's 13-part series for Thames Television explores specific aspects and themes relating to the pre-sound era, two of which in particular - Hazard Of the Game and Trick Of the Light - go into great nuts-and-bolts detail with regard to cinematography, special effects and stunt work. All incorporate the first-hand recollections of directors, cameramen, performers and others who were there when it all happened. Highly recommended. 

Visions Of Light (1992) - Excellently-crafted and informative look at the art and accomplishments of cinematographers across all eras of film. Another whole-hearted recommendation.   

     

You may get some ideas here:

Movies about making movies

The list in my original post is not complete. I was too lazy to keep it updated.