I read those as Js…
Anyway, I think that you can safely add a bar provided it doesn’t extend all the way to the left (see Verdana, for example).

Oddly enough, I find myself interpreting the Js as Is more WITH the crossbar as shown in the sample. It has an oddly cursive look to it; weird at the very least. I don't get that at all with the J without the crossbar, to the point that I don't see how anyone could. There might be a cultural bias working here.

However I do appreciate having an I with serifs in an otherwise sans font, if only to reinforce distinction between it and lowercase L.

A descending hook on your cap J would allow for tighter kerning in all caps settings, resolving the white space issue, but that's not a suitable design decision for every situation.

To clarify what I mean by cultural bias: If the second pair of samples are both I, with both a hooked and straight form; the hooked form is never used in American English as anything but a J. I am not familiar with the current use of a hooked I, though I understand that the modern J is derived from that.

Thanks for your replies.

A descending hook on your cap J would allow for tighter kerning in all caps settings, resolving the white space issue, but that's not a suitable design decision for every situation.

That's true, I certainly hadn't thought of that. Truly, I'm a bit uncomfortable with a descending J.

Let me rephrase my question slightly, to avoid any confusion:

I intended to use a short, serifed J and a standard I. Will some readers (presumably when reading isolated words) mistake this short serifed J for an I drawn as it appears in Schoolbook Regular?

(I don't mean to ask about confusion between J and I when both are serifed and hooked - this is another problem/thread!)

Any native German speakers familiar with the Schoolbook styled I that is so alien to me?

(Just to clarify in the initial image the characters in all four samples are JI.)

Some thoughts regarding the initial ‘I’ with hook in these two threads on Flickr:
flickr.com/photos/hardwig/3635998322
flickr.com/photos/ninastoessinger/4879966035

Hi,

as its name implies Schulbuch/Schoolbook typefaces have been made particularly for school / educational books or are modified versions of existing typefaces – e.g. AG Schulbuch is a modified version of Akzidenz Grotesk Buch.

It’s no coincidence that this specific /I/-form reminds of Italics and/or handwriting.

In Germany, pupils were/are taught a standardised form script/handwriting (one of them is called Lateinische Ausgangsschrift, but there are several revisions).
It was assumed that seizing the letter forms pupils were used to, e.g. the one storey /a/ and the /I/ like the one you mentioned would ease the recognition of particular letters and therefore improve the overall readability and legibility for reading rookies.
Quite likely, the ‘abstract’ look of a Grotesk /I/ – a simple vertical line – was an issue, too.

The one-storey /a/ and /g/, the hooked lc /l/, the spurless G and the peculiar /I/ could also be considered an atavistic parallel to German blackletter letterforms. Even though blackletter wasn’t taught anymore in school at that time it was still way more present than it is today. And in blackletter (and therefore in Germany until WW2), the differentiation between /I/ and /J/ has not been popular till the late 19th century / early 20th century. This potential parallel might be a reason why a single-storey /a/ and /g/ and a hooked lc /l/ are still looked upon as being ‘German’ by some.
Until then, it was most common to have one glyph for both /I/ and /J/ which either sits on the baseline or drops it, but always with some kind of crossbar and in the shape of what (nowadays) most people would read as a /J/.

And, being German, I doubt that a lot of people in Germany would misread this specific one as an /I/. In a custom font I made two years ago (a Geometric Grotesk), I used a /J/ with a crossbar similar to the /I/ in Schulbuch Süd, the /I/ being a simple vertical stroke. I didn’t hear of complaints about ambiguity or the danger of confusion so far…

Thanks again for your replies, very interesting to read, both here and on Flickr, Nina's image is really charming too.

… a /J/ with a crossbar similar to the /I/ in Schulbuch Süd, the /I/ being a simple vertical stroke.

It does sound like this is an acceptable format today. Neuzeit for example uses this combination, though the J is not hooked.