I think one question could start the discussion: What is the proportion that a character should have in contrast with it main stroke or stem?

I wish it were that easy. Before one can answer the question of stroke contrast, some questions need to be answered about the intended appearance and use of the face. So, if you asked, "What should be the contrast of a boring bold san serif, for use around 24 point?", one of us could help with an approximate ratio, range, or examples of them.

You can also just look at some fonts like yours and measure them.

Hope that helps.

I found this very illuminating:
The Modification of Letterforms
by Stanley Hess © 1981 Art Direction Book Company

You can tell a question is good when the best answer is "It depends". :-)

However, a couple of Good Rules, for any text face at any target point size:
- The caps should be shorter than the ascenders (unless they're unusually narrow).
- The descenders should be shorter than the ascenders.

hhp

My personal rules...

1) try some stuff
2) learn from yourself
3) trust your gut
4) repeat

I know that the answer of this question is 'it dependes'. I ask because I think that proportion is what define a character, i.e if you fail to get a right proportion, your characters look terrible…

But now I start this discussion; I want to pick a typeface and compare two sizes: let's say FF Quadraat Regular at 6pt and FF Quadraat Regular at 24pt;

I resize them to fit in the same x and cap height.
I think the diference do not exist in this example…

But, let's discuss it
---------
Thanks
Fábio Santos

@mattmatthew I follow the same rules:

5) sometimes you need to get some expertise knowledge.

?
You're setting the same typeface (that does not have optical sizes) four times larger and then reducing it to a quarter its size, and expecting it to look different? That only makes sense for metal fonts.

hhp

That only makes sense for metal fonts.

You mean like this? ;-)


_+880_____________________________
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__++888_____+++88__________+++8___
__++8888__+++8880++88____+++88____
__+++8888+++8880++8888__++888_____
___++888++8888+++888888++888______
___++88++8888++8888888++888_______
___++++++888888888888888888_______
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_____+++++++000088888888888_______
______+++++++00088888888888_______
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________+++++++0088888888_________
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@hrant Now I see the difference :D [I'm dumb]

I make this node because I see some photos about workshops laid on proportion theme. Then, and because when I try drawing some characters at Fontlab, this kind of theme make my head pain.

So, because all of this, I make this node to see what typophiles think and know about it.

Perhaps you’ll like this interesting post quoting Frutiger on the subject of proportion. The thread itself is quite interesting as a whole.

Obvious perhaps, but originally proportion was pretty much all based on the size of your the nib on your pen. Calligraphic letters were usually about 7 nib widths high and 4 nib widths wide.

Also, didn't Gill or Frutiger say something about a percentage of black to white that seemed correct to the eye, something like 60% black to 40% white? (Those figures are probably off)