What is the difference between a well constructed and a poorly constructed font?

Question

I'm speaking of both, fonts optimised for print, and fonts optimised for screens. Serif and sans-serif doesn't matter. Commercial or free — also doesn't matter.

What matters is the quality of the font. There are some fonts that you'd want to use for headings in a national newspaper or for a text in a printed book. And on the other hand there are poorly made fonts with details that a professional designer would spot and would want to avoid.

So, what distinguished a good quality font from a badly made font from a design point of view?

Answer 1

A Good font:

• Pair kernings have been addressed. How does "AV" look? Or "To"?
• The glyph box is not dramatically larger (or smaller) than the glyphs
• Glyph alignment on the baseline is correct, including adjustments for caps and rounds such as C, O, G, Q, S, etc.
• Stroke weights, thick or thin, are consistent between various glyphs, even if they have varying contrast.
• The x-height is an appropriate size compared to the Cap height. Some fonts have a drastically smaller or larger x-height.
• Proper family naming. This is a big one for me. And often a harbinger to just how much I'll use the font. I detest when a font, even a beautiful typeface, is provided in a single file for every possible weight and style variation. Rather than naming the family all the same family name the designer chose to separate each face and not provide a common family name. Thus causing each and every face variation to take up a line in font menus rather than creating a submenu under a family name. If my menus are 3-screens tall to list all 20 faces in each of only 4 fonts... well, I won't use those 4 fonts.
• Unique IDs. Often with some "hobbyist" or less experienced font creators they can edit existing fonts. Either their own or someone else's and then save as a new font. It may be more a matter of "templating" their own creations. If they create font A with all their personal metadata, they may merely open font A, insert glyphs for font B and save it as a new file. There are times where the FONTID is overlooked. This can, and will, cause font conflicts on a system. The troubling part here is you won't know there's a conflict until you install/activate the font on your system and it's conflicting "cousin". Thankfully some font management applications can check for conflicts without activating/installing fonts.

These are few factors I look at.

Then beyond that a "good" font for me has a few subjective preferences. These are merely opinions and not really a factor in technical terms:

• OpenType format with a large table of glyphs
• Multiple weights, not just the 4 standard faces (Regular, Italic, Bold, Bold Italic). I really prefer "mega", "pro" or "super" families with 15-20 face variations from condensed/compressed to black/heavy.
• I tend to prefer typefaces with larger counters and slightly larger x-heights for easier reading.

Answer 2

It really tends to come down to flow: is the spacing even? Are there uneven blobs of color where everything gets to seem too thick or thin? Do strokes feel like they narrow to join evenly on the 'm' or 'n'? Do characters like @, $ and %, the parentheses and quotation marks, complement the design, or have they been clearly borrowed in from another font, or not properly scaled to match the bold or light weights? How about accents?

This link shows you a font that deliberately breaks some of these rules (over-'constructed' characters, lumpy joins, a 'W' whose base is too narrow, etc). Tobias Frere Jones who lectures on type design at Yale has two good articles (part 1 & part 2) on mechanics of type design and how letters can look lumpy if misproportioned. Professor Indra Kupferschmid has a checklist, but it's not got any illustrations sadly. Paul Shaw's Flawed Typefaces article is very good at illustrating specific quirks in some very good typefaces that still might cause problems. Some are historically appropriate or justifiable in the name of variety, others were caused by long-gone technical limitations.

Answer 3

These are not rules, as you can find good quality free fonts as well as lousy commercial (paid) fonts, but generally a few differences:

1. The quality of details: I have seen free families from Google Fonts which have actual errors in some characters. Other times you can expect bad optical corrections, bad spacing or limited character set. More experienced type designers will generally put their effort into commercial families, whereas working with a free font, you kind of expect that's been published by a less experienced designer which may not apply all the fine tuning found in commercial work (again not a rule).
2. Number of weights: While a free font family may come in Regular and Bold, a commercial family may include alot more. Lets just look at Helvetica which has 34 different weights for sale.
3. Character set: a commercial font usually has an extended character map and is available for multiple languages, which is important for companies as they need to operate and address multiple markets, they need language specific characters.

Answer 4

One more is are the glyphs distinct enough, between "I, l, 1", "0, O", etc - especially if they are not next to each other or in an obvious context, i.e. imagine a password where there is no rhyme or reason and it could be either a number or a letter