Some people claim that Fomapan 100 has a similar look to APX 100.
I used to hear that, but could never get that look out of it. There is a Rollei 80s which looks VERY much like apx 100 tonally, but I haven't had the chance to try it yet. I'm still using their Ortho25, and loved the R³ when it was still available.
My recommendation would be to give the 80s a go, and see how that does ya. Can't be bad.
If the lens doesn't read "ZEISS", then it just isn't.
There is a Rollei 80s which looks VERY much like apx 100 tonally, but I haven't had the chance to try it yet.
Rollei 80s has extended red sensitivity and because of this colours are rendered different than with panchromatic film. Red is very light and with a 720nm filter you can even get the wood effect.
AFAIR nobody who used both claimed that the 80s is like APX100.
Nevertheless an interesting film; I use it for IR (normal b/w is done with Acros in the 100ASA range).
APX 100 is unique in how it renders color. TMax 400 gives about the same grain and sharpness as APX 100. Use a light green filter to get as close to its color rendition as possible.
You may also wish to underexpose TMax 400 and shoot it at EI 640 or so, to resemble the shadow detail of APX 100, which had a slightly longer toe. A developer like Xtol 1+1 will serve you well with this film.
"Often moments come looking for us". - Robert Frank
"Make good art!" - Neil Gaiman
"...the heart and mind are the true lens of the camera". - Yousuf Karsh