When it comes to transducers on fishing electronics, there are single frequency transducers and dual frequency transducers. Single frequency transducers are used for lakes, while dual frequency is used when you are fishing in deep water. In deep water, the higher frequency transducer on a dual transducer fish finder is the one that shows all the fish.
You can also get display screens on marine electronics with many different resolutions. Of course, the higher the resolution, the better the image. Color screens are better viewed in direct sunlight. The overall size of the monitor may be anywhere from four to seven inches, measured on the diagonal. Generally, the more power your fishing electronics come with, the better are the results, even in still or shallow water. Depth penetration is related to the quality and the power of the transducer. Better transducers penetrate the water best. Saltwater and muddy water will limit the depth to which your fish finder will penetrate.
Norcross makes a portable fish finder with many new marine electronics features including several sensitivity settings and a mountable and side scanable sonar sensor. To use it, you need to power it on, toss the floating sonar sensor overboard and get instant fish, depth, weed, and contour readings on the handheld monitor device. It updates depth readings four times per second for high accuracy, and you can have the information displayed in meters or feet. The LCD display blocks glare with Polarized VirtuView technology and SoftGlow backlighting. It comes with an audible fish alarm and provides accurate measures of weed height.
Eagle makes a line of inexpensive to mid-range fishing electronics that are boat mounted. Some of them have grayscale screens, and some are color. The color monitors are easier to read in bright sunlight. These fish finders start at below $100.
Humminbird is also a popular brand for marine electronics. Though they, too make inexpensive fish finders, they also have some more gadgety models, too, such as a combination wristwatch / fish finder, and specialized fish finders for ice fishing.
Lowrance is considered one of the better providers of marine equipment, including fish finders. They feature bigger monitors and higher resolution than other brands, though they, too, have a couple of more affordable models, and even one model that is specially designed for ice fishing.
Marine electronics for fishing include GPS systems and other devices that combine multiple features. You can buy a fish finder for 100 dollars and you can spend several hundred, too. Your specific needs and budget will determine which type of marine electronics for fishing will best suit your needs.