I have 3 of the 1970 S pennies and boy its hard to tell, Do you think the 10x mag lense is the best way to go? thanks!
The best all round is 10X but you must get used to using it - that takes time. With that said 9999 out of 10,000 1970-S cents are LGDT's and you need to learn the difference between the 2. Many even after years still cannot tell the difference The SMDT is smaller but not by much. Look at the size of the 0 - on the large date it has a little bulb at the top or a point - the SMDT does not. Get both types or photos of each in front of you and you will, (after some time) be able to tell. In all likely hood your 3 cents are LGDT's.
See http://www.cointalk.com/t93080-3/. It will tell you anything you need and probably more about the 1970-S small date.
