New Fuji Lens for newborn

I've been photographing my baby since he was born with XT1, XT2, and iPhone. He's just walking now. Once the baby is 3months the wiggle will get you and the f1.4 lenses focus too slow and the depth of field is too small anyway. Get close in with 23mm f2, 35mm f2, heck even get in close with 18mm.  As soon as baby starts moving you will want fast focus of the new f2 lenses or the pro zooms. Getting in close to baby and close the ground with 23mm f2 works great - babies head & face proportions are different than a child or adult, so I find that shorter focal lengths work well. At 90mm my babies head looks way huuuuge. A bit of perspective distortion from a wide angle to have a big face and small body, a hand close to the lens, or a toe reaching out can be really fun. Also to capture the interaction you need some space that a portrait lens won't give you. And, they turn and lean and roll and just plain jump around so quickly that framing wide and cropping in post is a good way to go.

I also used the 23mm f1.4. Fantastic lens, fast focus. But really that weight and cost isn't really worth it. The bokeh on a close subject is a bit nicer than the f2, but there's very little in it, and f1.4 really is only good for a stationary subject anyway.

Fleeting expressions are magical if you can capture them, so you can use a tele and just cover the face, cropping the head. One of my best was using the 55-200 with a close focus tube, manual focused, but baby was sleepy so it was a rare posing moment. But you can also just crop those in post if you don't mind the drop in pixel count. (55-200 is good for outdoors, but indoors its slow to focus. Not recommended for babies.)

I've also found that I need to shoot at at least 125 or faster to suppress babies motion blur, so f2 without stabilization beats f3.5 with IS. 1/60s doesn't cut it.

Where my 18-55 shines with baby is video. f5.6, fix the focus plane (actually on the XT2 I can reposition using the joystick and refocus with a half press and it turns out OK) and film. Don't forget, 1/30 or 1/60s for video. You will want an ND filter if you want to shoot video outside. I have a 6 stop and it works OK for CA sun.

One more tip - framing: its great to include the arms / hands etc when a kid or adult are holding the baby, showing that connection.