Ask Mr. Smarty Plants

USDA Plant Hardiness Zone Map shows that Brooklyn is either in Zone 7a or 6b. The average minimal temperatures are 0 to 5° F for 7a and -5° to 0 F for 6b.

Acer palmatum (Japanese maple) as the name suggests is native to Asia, not North America. Since our area of expertise is plants native to North America we can't really furnish you with firsthand knowledge about the growing requirements of Japanese maple, but we're happy to point you to some information that can help you. Information from Ohio State University and The Garden Helper indicates that the Japanese maple does well in light or partial shade. Some cultivars will tolerate full sun. WorldPlants.com indicates that there are also cultivars that will do well in shade.

We are a bit more knowledgeable about Rhododendrons since there are more than 25 species native to North America and 8 of those are native to New York:

Rhododendron arborescens (smooth azalea)

Rhododendron calendulaceum (flame azalea)

Rhododendron canadense (rhodora)

Rhododendron lapponicum (Lapland rosebay)

Rhododendron maximum (great laurel)

Rhododendron periclymenoides (pink azalea)

Rhododendron prinophyllum (early azalea)

Rhododendron viscosum (swamp azalea)

All of these will grow in partial shade although several hours of sun per day will probably keep them from becoming 'leggy' and will also produce more blooms. Morning sun is preferable to afternoon sun—the disadvantage of the afternoon sun compared to morning sun is the elevated temperature that accompanies the afternoon sun. Since your area receives very little afternoon sun and temperatures are generally not extreme where you live, I would think that your rhododentrons would do fine. Here are some general tips from Flower Gardening Made Easy.

Rhododendron arborescens

Rhododendron calendulaceum

Rhododendron canadense

Rhododendron lapponicum

Rhododendron maximum

Rhododendron periclymenoides

Rhododendron prinophyllum

Rhododendron viscosum