  We present observations of fields containing eight recently discovered binary
millisecond pulsars using the telescopes at MDM Observatory. Optical
counterparts to four of these systems are detected, one of which, PSR
J2214+3000, is a novel detection. Additionally, we present the fully
phase-resolved B, V, and R light curves of the optical counterparts to two
objects, PSR J1810+1744 and PSR J2215+5135 for which we employ model fitting
using the ELC model of Orosz & Hauschildt (2000) to measure the unknown system
parameters. For PSR J1810+1744 we find that the system parameters cannot be fit
even assuming that 100% of the spin-down luminosity of the pulsar is
irradiating the secondary, and so radial velocity measurements of this object
will be required for the complete solution. However, PSR J2215+5135 exhibits
light curves that are extremely well constrained using the ELC model and we
find that the mass of the neutron star is constrained by these and the radio
observations to be greater than 1.75 solar masses at the 3-sigma level. We also
find a discrepancy between the model temperature and the measured colors of
this object which we interpret as possible evidence for an additional
high-temperature source such as a quiescent disk. Given this and the fact that
PSR J2214+5135 contains a relatively high mass companion (greater than 0.1
solar masses), we propose that similar to the binary pulsar systems PSR
J1023+0038 and IGR J18245-2452, the pulsar may transition between accretion-
and rotation-powered modes.
