Leica M8, but I forget the settings he told me.
In suits made for the mass market, average fits and builds are studied, coats and trousers adjusted and mean proportions decided upon to averagely fit the biggest average of people.
A primary form of determining this is in the difference in inches between chest and natural waist measurement, a number most often referred to as the drop. This measurement will determine what size trouser will accompany a jacket in suits sold as a set, and will also affect the amount of waist suppression seen in the cut of the jacket.
An industry standard for the western market is a drop 6 - 6 inches between the chest and natural waist. On a suit cut to a Drop 6, a size 40 jacket will have size 34 trousers, a 42 carries a 36, a 44 - 38. Jackets would be cut with room through the body and into the quarters to fit a person with those proportions, making a standard fit for a mean average of figures.
Suits cut with a more athletic wearer in mind, generally high fashion, tend to have much higher drops. It stands to reason that the younger, more image conscious customer will have a more athletic figure, which in men usually means a slim waist to a fuller chest and shoulders. Here we might find differences as much as 8 inches, or a Drop 8.
Conversely, suits cut for an older market, or with a fuller figure in mind, may go down to a Drop 4, where the waist is creeping ever higher to equal it's girth to the chest. Although for both extremes we can see much bigger measurements on the actual body, it is usually kept to the lowest common denominator for reasons of sell through. Although I have met many a body builder with a 10 inch drop or more, actually retailing suits to these proportions would so narrow your market share to make it business suicide.
In fitting a suit off the rack, it is important that we don't err too far from classic drop 6 proportions - an off the rack suit that may have a 6 inch drop in the jacket paired with a trouser 10 inches smaller will give the impression of a scrawny lower half and an upper body ready to tumble over due to it's visual weight. Likewise a jacket worn with trousers 2 inches smaller than the chest will make a leg so full, and a seat so prodigious that the vents would never close and the jacket look dwarfed in proportion.
Although a wise man once told me that a well fitted suit is all about the superstructure, most men still seem to over-compensate for their self perceived flaws or virtues. Often we find shorter customers cutting their jacket hems to bum freezer length, making the proportions and button position on the jacket all wrong and the line of the suit stunted and erratic. Likewise the very slim customer will often try to squeeze into the smallest available suit, remembering their previous frustrations at suits far too big. But a small man in an overly tight suit often looks effete, and even smaller as a consequence.
So the moral of the story is; Fit will always be fit is fit. Too big isn't correct fit, nor is too small, too long or too short. We see the range from 5 to 7 inches in drop as correct, and following these proportions will keep you looking good. Keeping your actual figure there is not quite as easy though, as I am increasingly starting to realise.....