  The behaviors of null geodesics in the spherical symmetric black holes in
Einstein-Maxwell-dilaton (EMD) theory with coupling function
$f(\Phi)=e^{-2\alpha \Phi}$ are meticulously analyzed. We investigate the
effects of coupling constant $\alpha$ on the effective potential of photon
trajectories within three ranges, namely $0<\alpha <1$, $\alpha =1$ and $\alpha
>1$. We find that the thicknesses of lensing and photon rings are smaller at
larger $\alpha$ and fixed electric charge in the unit of mass $q$, whereas they
are larger at fixed $\alpha$ and larger $q$. Remarkably, the behaviors of
photon trajectories are found to be more interesting when $\alpha>1$. Namely,
the radius of the black hole shadow $R_\text{s}$ becomes to be smaller than the
photon sphere radius $r_\text{ph}$ when $\alpha > 1$ and $q>q^*$. Moreover,
$R_\text{s}$ goes to zero as $q$ saturates the extremal limit, beyond which the
photon orbit becomes absent. %This tends to be consistent with the result of
Wilczek. Furthermore, we construct the optical appearance of black holes
surrounded by optically and geometrically thin accretion disks with three
emission models. Our results indicate that the observed flux originating from
the lensing and photon rings exhibits suppression as $\alpha$ increases, while
it undergoes amplification with the increasing parameter $q$.
