While people have successfully caught fish since the day someone thought to chuck a spear at those strange things moving around in the water, the modern technology of fish finders has become indispensable. Even anglers in kayaks are figuring out ways to rig up a good fish finder.
It takes a lot of the guesswork out of fishing. Deposit the name, they aren’t just for finding fish, at least not directly. Fish finders are also capable of mapping the terrain underwater, which is a fantastic tool to have. It helps anglers figure out where fish are likely to hang out.
There are two primary aspects of fish finders that newbies often confuse, or simply lack a general understanding of the differences between the two—down imaging and side imaging. Down imaging vs side imaging is often a source of contention, though both have their pros and cons.
Down Imaging vs Side Imaging Sonar
Down Imaging Explained
On its face, the primary difference between down imaging and side imaging is that one offers imaging directly below your boat while the other scans water to the side. Fish finders have what is called a “transducer” and it’s the component that sends out sonar waves that bounce back, creating an image.
With down imaging, the transducer sends sonar directly down, from beneath your boat, sending back images of structures and fish directly beneath you and slightly to the sides. You get a limited view of the sides because the sonar waves form a sort of cone.
Most fish finders you find on the market are down-imaging fish finders. Down imaging is cheaper and highly effective for the price. They’re also very simple to use and set up. A common use for them is bass fishing, but they are useful in just about any format.
Pros
- Works great while moving
- Delivers fantastic, detailed environments beneath the boat
- Easy to use
- Great for deep water and structural fishing
- Less expensive
- Most including mapping and plotting
Cons
- Image quality drops while sitting still
- Catches very little to the sides
Side Imaging Explained
Side-imaging technology works just like down imaging, with a transducer that sends out conical sonar waves. With side imaging, however, the majority of the scans are to the side, or horizontal.
Side-imaging fish finders are very useful in shallow waters, where the cone is capable of covering the entire area, from the surface to the substrate. They do have trouble picking up small fish or even schools of small fish when you are on the move.
You wouldn’t want side imaging sonar if you’re looking for fishing holes or deepwater structures out in the Atlantic, Pacific, Gulf of Mexico, or large, deep lakes. Side imaging does have a huge advantage over down imaging, however.
With side imaging fish finders, you typically get back extraordinary images of everything around the boat, or at least where you are pointing the transducer. Image quality is exceptional with most devices, more so than with down-imaging fish finders.
Pros
- Quick side-images whenever you need them
- Excellent in shallow water
- Exceptional imagery
- Easy to use
- Scans wider areas
- Most include mapping and plotting
Cons
- More expensive
- Worthless under the boat
- Doesn’t work well at speeds faster than 2 knots
Key Differences
The key differences between the two lie in their advantages and disadvantages, especially when it boils down to where you are fishing and what you need.
Images
Some of this has to do with the technology (down-imaging vs side-imaging). The rest has to do with the premium level of the product. Humminbird, Garmin, and Lowrance practically own the fish finder corner of the market and they all manufacture premium devices.
The images you get back from these brands are exceptional. Both down-imaging and side-imaging produce exceptional images, with a slight edge going to the low-frequency side-imaging over the high-frequency down-imaging. However, murky water has a huge impact on side-imaging image feedback.
Quickness
Side-imaging is much faster. You can grab quick images of the area around you at the press of a button. However, even though down-imaging takes longer, you get a far more detailed understanding of what’s beneath you, including tiny fish, something side-imaging has trouble picking up.
Images While Moving
While side-imaging will capture images while moving, it is woefully behind down-imaging fish finders, the latter of which can take pristine images while moving at speed, regardless of depth.
Which is better?
Side-imaging fishfinders are better in shallow water, especially in rivers and close to the shoreline in bays or lakes. Down-imaging is better when the water is deep, you’re looking for a good fish hole, and you want to map out and discover underwater structures.
So each has its particular strong suit that revolves around the kind of fishing you want to do. However, you can have your cake and eat it too. Several Garmin, Lowrance, and Humminbird models do both side-imaging and down-imaging with the addition of CHIRP technology.
CHIRP stands for Compressed High-Intensity Radar Pulse, and it’s an exceptional technological tool in fish finders. CHIRP allows you to send out a narrow or a wide beam, entirely adjustable, with the addition of customizable frequencies, and they deliver incredible detail.
Several devices truly deliver exceptional down and side imaging, using CHIRP.
- Humminbird Helix 5
- Garmin Striker 7SV
- Lowrance Hook Reveal 7 Tripleshot
- Humminbird Helix 10
- Garmin Echomap UHD
- Humminbird Apex 19 MEGA SI Chartplotter
- Lowrance HDS 7 Live
These fish finders, and others like them, deliver both side and down imaging and the images they send back are so clear and pristine they almost look like a genuine photograph. They also include incredible chart plotting, mapping, and GPS features.
If you can get your hands on a premium fish finder that offers both side and down imaging, there is nowhere the fish can hide from you, ever.
Bottom Line
If you are forced to choose, most people choose down-imaging fish finders. They can scan just enough to the sides and cover deep areas of the water while moving at speed. If you prefer to fish in shallow waters, however, a side-imaging fish finder is the device for you.
If you have the money to throw around, you are much better off grabbing a fish finder that is capable of both down and side imaging. Or, you could always grab a down-imaging fish finder and add a side-imaging one as a backup later down the road.
Either way, you go, fish finders change the entire way you approach fishing. All of the unknowns become knowns. It’s not quite cheating, but it’s as close as you can get.
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