Let me begin by saying that my relationship with fountain pens goes back to the time we were allowed to use them in school (Std. 3?).
Unlike today, ball points, roller balls, etc. weren't permitted and even if they were, I would have stuck to fountain pens.
Barring a very brief period a year or two ago, I have not been a collector but have amassed a fair number over the years. Most of my school pens (primarily Camlin and Chelpark) are long gone. Ditto for those used in college. Now that I think back, we must have been amongst the last batches (class of '85) that had to draw on a drafting board and not on a computer.
When I decided to collect, I was primarily drawn to vintage fountain pens from the 1930s to 1960s but soon put a stop to that for pecuniary reasons.
Some status pens came my way early in my life and I used them for years but when they became easily recognisable in India. I put them away and mostly used Lamy Safaris.
Whilst the Safaris are good fountain pens, I wanted something better. About a year ago I decided to zero in on two fountain pens I have had my eyes on for a very long time - the Pilot Vanishing Point and the Lamy 2000.
The Pilot Vanishing Point was designed at the time of the 1964 Tokyo Olympics. Here is how it works
http://thewritingdesk.co.uk/reference.php?id=43
The Lamy 2000 was designed by Gerd A. Muller (of Braun electric shaver fame) for Lamy and it entered production in 1966. Here is an excellent review -
http://www.fountainpennetwork.com/forum ... my-design/
Both pens have largely remained unchanged, more so the Lamy 2000, for approximately 50 years and still remain in production.
The Pilot Vanishing Point allows me to continue using a fountain pen but one that has the convenience of a ballpoint. Hence, this is almost always in my shirt pocket along with a Caran d'Ache 2mm clutch pencil and a writing pad.
On days that I know I will be doing a lot of drawing and writing, the Lamy 2000 and its siblings (ball point, 4-in-1 ballpoint and 0.7mm mechanical pencil) along with the 2mm clutch pencil and pad take up pocket space. For sketches and marking on site, a Lamy Scribble (3.15mm lead), Koh-i-noor (5.6mm lead) and an old set of six clutch pencils having different coloured 2 mm leads remain in the bag. However, the pencils are another subject.
For those days that I only want to carry fountain pens and just one pencil, I ink up my Platinum #3776 Centurys in Bourgogne, Black and Chartres Blue with similar coloured inks.
My current inks are J. Herbin Perle Noir for black, Diamine Red Dragon for red, Diamine Midnight for blue and Diamine Green/Black for green. All excellent inks. However, there is no water resistance, especially from the Diamine inks. I have switched to Platinum Carbon Black as black is my primary colour and it's waterproof. I may switch to pigmented red, blue and green inks later.
The Platinum Carbon Black and other pigmented or iron gall inks are high maintenance inks and not recommended for those who do not write everyday. Nor is it recommended for those who do not clean their fountain pens regularly.
Some pics....
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There's lots more to come but I would like to hear from other members as well.
and strangely enough I was an avid collector a long while a go. 
) are a pair of gold plated Mont Blanc's (one fountain pen and one ball pen) and a silver plated Cross (fountain pen)