I had a disagreement about the correct use of a ligature and kerning in a headline and would appreciate any help in seeking insight on the issue. The issue is with the "f" and "t". One side believes using the ligature creates proper kerning throughout and the other side believes the "f" and "t" should be spaced out slightly more and separated for a better look. I know this may not be a black and white issue but again any thoughts or knowledge about the issue would be appreciated. Thanks.
ligatures are designed specifically for this. Well sometimes for stylistic reasons, but combination with "f" will often have collisions. "fi" and "fl" are the most common examples. In these cases it is generally best to use the ligatures available to you. The other option of increased kerning leaves you with unbalanced white space (In your example the space between the "f" and "t" doesn't look good to me).
This is assuming you are using a well designed typeface, with well considered kerning and ligatures and are setting your type with no increased tracking.
Take the following example, with no ligatures and no increased kerning. Hopefully everyone can agree the collisions with the "fi" and "fl" aren't good:
We can fix that by increasing the kerning between the problem pairs.
However you can see the spacing is very uneven and unbalanced:
Swap out the problem pairs for the ligatures and all those problems are solved:
The other option is to increase the tracking, so the increased spacing is more consistent. This isn't a good idea in body text but could be a good solution for headers—but that will depend on the typeface used and context.
it depends on your intentions with this typographic material.
If it is supposed to be something stylistic, condensed kerning may be an aesthetic approach to some given design choice.
but, if you want to give priority to readability, for a block of text or a headline which function is solely to convey information. The separated versions is the one you are looking for, from far away, or -in an extreme scenario- for someone with a faulty vision, it can easily be confuse with an H, fused up pieces of types may seem a minor issue, but it has its impression on typography and can have some implications depending of many circumstances: Where this text will show up, the distance x size ratio it will be normally read, if it will be printed out, the kind of print, printing surface, ink type, etc.
If you have a aesthetic reason to glue them together, it is not wrong. but if you are putting it in a block of text, go for the separated one for the sake of readability, and for letting the types breathe, so they don't seem like they're one single character.