Welcome to "fish finder school"
Garmin 400 C
Purchase price on eBay $294, included shipping.
This model has been out about three years.
My jig on the screen, a 3/8 ounce jig with twister tail and a bit of sucker meat.
There's a little surface clutter at 12 feet, this is normal. Note in the first and fourth screen shots I am at different depths. I was fishing suspended fish there and the bottom is actually an artificial depth as the cone intercepts the slope at the first contact with the bottom. Below, there is actually six feet of water below what is shown as the bottom due to the angle of the bottom drop off angle.
A fish moves in and back out under the transducer. He came up from the bottom for a look, and went back down. The brighter red is the stronger signal, the jig is moving up and down. Note the split screen and the zoom which is set at 4X in the zoom box seen at left screen. I can move the zoom box up and down as the fish are seen suspended above.
I drop the jig and the fish comes up to visit. The jig, seen above the fish is being jigged up and down, as you can see, then dropped to the fish as he comes from the bottom, then raised again only to have the fish take a brief look, and go back down.
I drop the jig as fast as possible through the suspended fish at 40 feet to get to the larger fish off he bottom, which may be a mistake as the suspended fish many times may be the aggressive feeder. This is on a gentle slope and even the bottom fish is suspended a number of feet off he bottom.
Note at left side of zoom screen there is a fish exiting the cone angle at 52 feet. The bit lower fish is moving to the center of the cone as the signal shows more red, He was about I test depth with the jig raising it in 4 inch increments to determine where it locates on the screen. Note the jig from above is entering the zoom screen at left, and the jig has made clutter as it falls on the right side screen.
Now here's your first pop quiz, what do we have here? Fish moving out and up as the jig is out of center of the cone as it falls fast. Six fish, one jig falling from the top, swarming in and back out. Hang on to the rod.
Another group attack, moving in and up to the jig with a suspended bunch of guys all at 47 feet I was tormenting, One bottom fish came in very quick out of no where and is moving to the center of the cone on the bottom edge of the 4X screen. 
A larger fish already suspended looking over the jig drops to follow it during the tease, and a suspended fish moves across at 53 feet. There's a lurker on the bottom at 58 feet.
Five fish, one jig. One is surfacing fast on right screen,
The school moves off screen.
Right side screen, the jig is falling fast to catch the three swimmers, note the 54 foot level has one leaving the area again.
Some good action, who's on first? There's five fish, the jig is falling and being followed by the top fish coming down and in. The other four fish moved in to the jigging zone.
This is what I like to see, a pack coming to dinner.The jig is in the pack with more fish coming up to see what's going on. At the edge of 53 feet, another one turns and comes back in, the bottom one turns and comes back in, Three come in from the bottom, one larger fish crashes in and down, only to lift and leave the scene.The jig is falling at 47 feet. There are three nice fish under the cone and the lower blip at 55 has left the scene.
Professor D. Fishfinder. Note the sky is dark and blustry, the fish are active at mid day. Also note the monster fish rod is in the rack and I am using a medium rod presently. 
School's out, a limit of Flaming Gorge lake trout. 15 pound line, medium action rod, a great Okuma Magda 20 DS reel, with a line counter that is pretty handy.
Class dismissed, what's for dinner?
As a post script, the fish finder is as important a tool as the ice auger, or the sled that makes life in the cold and wind more comfortable for sustained fishing time. Believe it or not, this was mid afternoon fishing when the fish are all over the screen. the best bite comes early and late in the day except for the darker skies today.
This is my first winter to fish the lake trout exclusively, and only the tenth time out with the new fish finder. It's suggested retail price is normally $375 but through fleabay, It cost $294 shipping included.
Next class will be on the hand held sonar that saves drilling holes all over to find the depths and fish. For honors students: jigging school 101 lures and technique, There is a fee for this class ;-) JUST KIDDING, those are secrets!!!
Extra credit question, why would anyone wish to use a flasher? This model has a flasher mode and it is not much use compared to this option.
See you on the ice!