WESTERN VIEWS AND EASTERN VISIONS -- At the National Museum of History and Technology through January.

Generations of explorers who brought back tales of the vast and rich American West found hardly anyone would believe them.

Sophisticated Easterners, particularly the congressmen who held the national purse strings, were skeptical of the sketches and paintings from the Western expeditions because they knew how the artist's hand can enhance a scene that doesn't satisfy his eye.

The impasse was not broken until pioneer photographers, who had learned how to take their clumsy and fragile equipment into the field during the Civil War, produced stunning but believable views of the fabulous frontier. Then the troops rode and the wagons rolled to the triumphant and tragic "winning of the West."

"Western Views and Eastern Visions," at the National Museum of History and Technology, presents 170 of those photographs in a new exhibition that illustrate both the strengths and the weaknesses of the medium then and now: A picture often is worth ten thousand words; photographs can lie; and a picture does not necessarily speak for itself.

Curator Eugene Ostroff raided archives, museums and libraries from coast to coast to assemble the beautifully mounted and understated exhibition. Like fine paintings and photographs draw the viewer again and again to compare the various processes and techniques. As many as four versions of the same scene are offered to illustrate the vagaries of pencil, pen, brush and camera. The technical explanations are excellent.

But one comes away wishing the notes told more, both about the photographers and but the pictures. All of those men suffered, and some of them died. Many kept diaries describing their adventures and trials, and reports were published by most expediions; the Smithsonian pictures would benefit from more quotations from such sources.

The frustrating lacocnism is illustrated by the stereographic photo of Fred Loring, a young assistant whose face shows character beyond his year, standing with his mule, "Evil Merodach." Two days later, we are told -- only -- he was killed by Indians. What was he like? How did he come to die? Whence the mule's singular name?

Curator Ostroff, conducting a preview, pointed out two faces playfully inserted in W.H. Holmes's sketches of Pike's Peak. The little gags, unmentioned in the notes, do not appear in the final work, but the artist snuck anoter one in. It would make the exhibit even more engaging to draw the visitor's attention to such things.