I was a fan back in the days when the band wasn't yet famous.

在这个乐队还没出名的时候，我就是他们的歌迷。

《牛津词典》

I popped into the fan club.

我迅速进入了歌迷俱乐部。

youdao

Are you a computer fan? I am a computer fan.

你是电脑迷吗？我是电脑迷。

youdao

I always like the name Reagan and I'm kind of a Ronald Reagan fan, so,voila,here she came along.

VOA: special.2009.07.06

So, many of you are new to the Boston area, now I still realize, and I want to let you know it's not required that you be a Red Sox fan to be at MIT.

你们中很多人新来到波士顿地区，现在我仍认识到，我想让你们知道在麻省理工学院,不一定必须做一个红袜队的球迷。

麻省理工公开课 - 化学原理课程节选

I've seen an episode. I thought it was okay. I'm not as big a fan of it as seemingly everyone else is.

我看过一集。我觉得还可以。不过我不像其他人那么着迷。

就业很难 - SpeakingMax英语口语达人

If I was a fan, I'd be very disenchanted.

WSJ: No. 5 Georgetown pulls away from Cincy at Big East

Mr. Kumar: I'm not an F1 fan, and especially I wasn't an F1 fan when we did this.

WSJ: Tata Unit Seeks Profile Boost Via F1 Deal

If I was an Astros fan, I wouldn't despair.

NPR: How Two Baseball Teams Got Their Dubious Records