Poser's typical scale is VASTLY smaller than most shape-makers. 

Here's how to get it right:

1. Bring the OBJ into Poser.  Scale it to the desired size. 

2. Save it as a prop.

3. While it's still in the scene, export a new OBJ from Poser.  (File: Export: Wavefront OBJ)

4. In the selections, uncheck everything except "As Morph Target".

5. Give this a name like "Lamp-For-MT.obj"

6. Use this OBJ to make all morphs in Blender; bring it into Blender, move vertices around, export it without any change of scale.

7. Apply these MT objects to the prop you made in Step 2. (the 'Load Morph' button on the prop panel.)

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