Hey Preacher,
This is basically a repost of my answer to someone else with this question earlier.
Hope this helps.
Well they're a couple differences between the A520 and A610, i'll start with the most obvious one.
* A520 is 4 megapixels as opposed to the A610's 5 megapixels.
Higher megapixels don't necessarily make one camera better than the other, but gives you some flexibility when it comes to cropping pictures and making prints of them.
* A610 has a greater optical zoom range, 4x. More importantly though and the clincher for me is that it uses the new digic II processor as compared to the older DIGIC processor in the A520. Improved battery life, faster focusing... generally the camera would feel a lot faster.
* Macro mode is better in this camera I believe, might be important if you were taking closeups of nudibranchs or christmas tree worms or whatever.
Quoting liberally from dpreview here
http://www.dpreview.com/reviews/canonA620/
To put it simply I just think it's a better all round camera. But it would only be better to you if the improvements are worth the extra money to you.
Both have manual controls..
If your budget permits I'd definitely go for it, it lists for about $265 at most sites, but if you wait and shop carefully you should be able to find it for less than that
Anyway I'd suggest reading through some of the old topics in this forum or even doing a search you'll find a lot more info!
Check out this page for examples of pics the camera can take topside..
http://www.pbase.com/cameras/canon/powershot_a610
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