I have a tech. question, I'm in the process of buying a new Lowrance,ELITE 7 depthfinder, Which transducer should I get, I read the ducers job but it seens to me I can't get DSI if I go with the 50/ 200 the 83/200-433 something or other, I assume is the ducer with down image right? or what---- I mainly troll Lake Onterio for lakers,salmon ect (over water 300ft) fish usually 100- 150ft down then I do alot of trolling for Walleyes over 80ft of water, fish usualley 45-60 ft down, then I come to Lake Erie and fish waters 30ft or less, now I know of guys that can see their rigger ball and can watch the fish come to the lure and back off out of the screen, Which ducer are they using 50/ 200 or 83/200 any input would be great THANKS GUYS PAP