Some Hubble tuning-fork galaxies only reveal their true morphology in near-IR. This is particularly so for galaxies with a large dispersion in stellar ages and spatially-distinct stellar populations, such as in spiral galaxies. However, such galaxies which undergo a morphological metamorphosis from the WFPC2 to NIC3 images are rare; most retain the same appearance in all wavebands, or are too compact for the structural parameters to be determined. Once the morphological k-corrections have been accounted for, it appears that the fraction of true irregulars does increase at faint magnitudes/high-z. Finally, the deep near-IR data shows that there is no significant evolution in the incidence of barred spirals with redshift: their apparent scarcity in the optical is a band-shifting effect on the older stellar population of their bars. A more detailed description of this work is given in Bunker, Spinrad & Thompson (1999).
Acknowledgments I wish to thank my collaborators on this program, Hyron Spinrad and Rodger Thompson. We are grateful to Ray Weymann and Lisa Storrie-Lombardi at OCIW for organizing an enjoyable and timely workshop on photometric redshifts, and thank Daniel Stern, Leonidas Moustakas and Mark Dickinson for useful discussions. A.J.B. acknowledges by a NICMOS postdoctoral research fellowship, supported in part by NASA grant NAG5-3043. The observations were obtained with the NASA/ESA Hubble Space Telescope operated by the Space Telescope Science Institute managed by the Association of Universities for Research in Astronomy Inc. under NASA contract NAS5-26555.