Hi Snowdrop.
I also have a 705. When I first started, I made up a little card with the numbers I had obtained doing air tests for the various coins. I tried to dig according to the numbers, 36 for a new penny, 42 for an old one, 32 for a $1 etc. Now I dig anything that gives a clear or sharp signal, and a lot of other stuff as well. Mostly I know what the machine says it is, especially the common stuff such as the old and new pennies, 1c and 2c and $1 and $2. But, the numbers do vary depending on the soil composition and probably a lot of other stuff I don't know about.
You won't know what the uncommon stuff is, until you dig it. And rings and half-crowns are not common, hence I dig most things. For the first few outings, I suggest you take a little notebook. Record the number off the target, dig it, then record what it is. You will soon see a pattern and will also see that the same target will have more than one number, especially with regard to different locations. After a while you can guess what the target will be before you dig, then dig it and see how often you are correct.
I started running the machine discriminating out- 8-6-4-2 and 48, and haven't changed it. I very rarely dig a target to find it is ferrous, but some of the old bent nails fool me every time. I started using the 4 tone setting and that is still what I use. I use sensitivity around 20 - 23.
I haven't used anything else and am pretty happy with it as a dirt fishing machine. Get a couple of sets of rechargables and it will be a cheap pastime.
