My mother used to have a Canonet GIII QL17, and I've decided to buy a couple for sentimental reasons more than anything else -- one for me and one for my sister (who's currently without any cameras). Anyhow, in doing a bit of Web research, I've found that these cameras were designed for the 1.35v mercury cells that are no longer available in the US, and I'm wondering what others have found to be good replacements. Are 1.5v silver oxide or alkaline cells good enough, or do they result in too much exposure error? (I expect that both I and my sister will shoot mainly print films, not slides.) If the error for using, say, a 1.5v silver battery is predictable, how much should the ASA speed be adjusted to compensate? (I gather alkaline cells' voltage varies over their lifetime.) Is it worth the extra cost for a WeinCell battery? The MR-9 adapter looks interesting, but is hideously expensive (it costs more than a used Canonet on eBay). Thanks for any tips.