I can assure you it does not have 1800 lumens. Real lumens is probably around 1000 on High lamp mode, when the lamp is new.Well the HD33 has only 1800 lumens. Isn’t this much brighter?
If you were to compare what the manufacturer claims, the UHD50x has "3400" and your unit 1800.
To see what the actual brightness of a particular unit is, looks at reviews that measure it.