Transparent ink pen?

[Vay]

HI, I am just starting to draw with pens. I need transparent ink pens that I can easily carry with me, so no dip pens (No, I don't mean invisible ink pen, I have lots of those that I threw away). I am currently using some cheap ink pen that has inconsistent ink flow and is really dark. I want to get a pen with less opaque ink, preferably having not a scratchy tip and have replaceable ink cartridges. I have thought about purchasing Rotring rapidograph pens, but Does the Rotring rapidograph pens come in varying opacity ink cartridges? I never got a rapidograph pen before and they are pretty expensive. Would you recommend rapidograph pens in general?

I have dip pens that I can use the ink combined with water to make less opaque lines, but they are really scratchy, so it damages the paper. The non-scratchy versions are felt tipped right? But I don't think they come in less opaque, do they?

[s.ketch]

If you want something less opaque try graphic markers instead of pens.

[arenhaus]

Yep, try markers.

Or a water brush filled with diluted ink.