Manfrotto 454 Micrometric Positioning Sliding Plate

Yes, the Manfrotto 454 Micrometric Positioning Sliding Plate will work with the Manfrotto 394. The bottom of the plate has a inch female thread and will work with most tripod heads and quick release plates.

The knob to adjust fore and aft positioning in the Manfrotto 454 Micrometric Positioning Sliding Plate is usually placed on the left of the camera so that you can take photos with your right hand and control the fore and aft with your left hand.

There are many remotes for the D90. This is a wired remote for the D90, http://bhpho.to/1alWxywAnd this is a wireless version, http://bhpho.to/1cm0HdBA lens ring can either be a reverse ring to attach two lenses together for macro photography or it could mean a Macro ring light.

If you are referring to connecting a camera with an Arca-type quick release plate to the top of the Manfrotto 454 Micrometric Positioning Sliding Plate, then as long as the quick release plate you own also has a female-threaded 1/4"-20 socket on the bottom of the plate, it would be compatible for your usage needs. Not all Arca-type quick release plates have 1/4"-20 threads on the base of the plate, so it will depend on your specific quick release plate as to if it would be compatible for your usage needs. If you are referring to using a separate accessory quick release clamp that is Arca-compatible, they all usually have either a 1/4"-20 or a 3/8"-16 female tripod socket on the base of the unit, so they should be compatible. If your quick release clamp uses the larger 3/8"-16 socket, you can purchase a reducer bushing such as the Oben 3/8"-16 to 1/4"-20 Reducer Bushing, B&H # OB1039, for your usage needs.

useless junk. I returned it.

The Manfrotto 454 Micrometric Positioning Sliding Plate will work equally well in either orientation.

One full rotation is 1 mm.

One end of the rail is threaded, just screw into that thread up through the rail.