coleman florescent lantern output?

I've got an 8D Coleman florescent lantern. It is the one that looks rather like a white gas style one with a red top and the place where the fill port would be is a yellow nightlight. It has a high and a low setting and I believe it uses a 15 watt ccfl bulb. I don't really notice much output difference between high and low. I do know that it has lasted two camping trips, running several hours each of two nights now, on the same set of batteries (running on low since, as I said, I really don't see much output difference).

Anyways, does anybody know what the actual light output of this lantern is and what sort of reasonable runtime I should expect from it using 8 D cell alkalines (and would NiMH Ds give me any better runtime)?

http://www.coleman.com/coleman/colemancom/detail.asp?product_id=5312-702&categoryid=1045

About 30 hours on Low and 18 on High. it is about 400 lumens.

Blacklight, I just bought a Coleman Micropacker lantern with a Cree LED. Looks slick. Bought it for a gift, so can't really unpack and test it. The packaging says 65 lumens for 8 hours, or 13 hours on low.

Can you tell me what the lumen output is on low?

Is it a fully regulated light? (suspicious because it runs on 3 AA's)

Thanks.