
Throwing a rectangular lens over our logo would work in some instances, but the lens would affect any background objects that might be present in a drawing. We'd have to create a very precisely shaped lens to achieve the desired effect on just the logo.
A simpler method is to group and duplicate the collection of objects comprising our logo. Then, apply a single solid fill and single outline color to the duplicate group. If we want a watermark we might choose white for both. If we want a tint, we might choose some other color(s). For illustration purposes we used a white fill, and light gray outline.
Then, simply blend the original and color-modified groups. You can usually setthe number of blend steps low, since ultimately you are going to pick just one of the resulting blend steps as your Watermark or Tinted object. In our example we used just two blend steps. You may need to specify a few more steps to produce the desired intensity/tint.
Once you get a blend step that fits your needs, simply separate the Blend, ungroup the intermediate steps and choose the one you want. The rest can be deleted. Now you’ve got one group of objects that can be sized, moved, or whatever; without having to worry about the complexity an accompanying lens would add.
In version 7, you now have color adjustments that can accomplish the same thing. Couple this with more flexible transparency, and you can really go to town!