Mega di/si vs 455

[Jhawknseattle]

What is the range limit on the effectiveness of mega imaging? No matter how much I play with the settings, I cannot see fish in 30+ feet of water on mega downimaging, which also includes seeing fish in the water column near the bottom on side imaging. When I change the sonar to 455 the fish absolutely pop on the unit. Is there a possibility my unit is defective, or is it just not good at seeing fish or other similar small objects close to the bottom in 30+ feet. Here's an image from today in close to 50 feet. With mega down imaging these fish did not show up on down imaging, only 2d, but once I changed to 455 they all showed up.

[Wayne P.]

800 kHz has a thinner Imaging pulse than 455 kHz, and 1.2 MHz has a thinner Imaging pulse than 800 kHz.
Sooo using 455 kHz creates a blurrier/larger image and that is why you can see small stuff better.
The MEGA frequency gives you the sharp detail.

2D sonar's coverage is a LOT larger so "stuff" is within its coverage for a longer period of time---even more blurry.

With 2D and DI, everything is size relative to the depth.

[Wayne P.]

You can see the dots on DI and SI that correspond to the very exaggerated fish arches on 2D.

[Tone357]

Don't get stuck on wanting to use Mega for everything. I use 455 for most side imaging duty to actually see fish. And try turning your chart speed up to 9 or 10. It makes a major difference in whether you see fish or you don't see them. And don't forget about 800 MHz as well. There is nothing wrong with your unit. Look at it as using a hammer when you need a wrench. You have to use the right tools for the situation.

[Jhawknseattle]

Don't get stuck on wanting to use Mega for everything. I use 455 for most side imaging duty to actually see fish. And try turning your chart speed up to 9 or 10. It makes a major difference in whether you see fish or you don't see them. And don't forget about 800 MHz as well. There is nothing wrong with your unit. Look at it as using a hammer when you need a wrench. You have to use the right tools for the situation.

I was wondering about turning up the chart speed. Might try that.

[Jhawknseattle]

800 kHz has a thinner Imaging pulse than 455 kHz, and 1.2 MHz has a thinner Imaging pulse than 800 kHz.
Sooo using 455 kHz creates a blurrier/larger image and that is why you can see small stuff better.
The MEGA frequency gives you the sharp detail.

2D sonar's coverage is a LOT larger so "stuff" is within its coverage for a longer period of time---even more blurry.

With 2D and DI, everything is size relative to the depth.

I appreciate all the help you've given me. I used mega imaging all summer targeting rock piles and weedlines anywhere from 20-30 feet. When I fished those targets, I never looked for fish, but just for the structure I was looking for and did real well. This fall however, fish are not hanging on structure, I've been finding them on small humps in 35-45 feet of water. This has made finding fish much more important since I'm looking for these schools on humps, before I fish. Mega imaging has just not been working in this case. I've been playing around with frequencies and settings and have found 455 to be the most helpful. I just can't get my mega imaging to show fish, and right now that's what I'm needing it to do.

[Tone357]

The most important parameters in actually seeing fish are, chart speed, sensitivity, range and contrast. In that order. Either one can cancel out the others.

[Jhawknseattle]

The most important parameters in actually seeing fish are, chart speed, sensitivity, range and contrast. In that order. Either one can cancel out the others.

I just can't seem to get mega sonar dialed in to see fish like I can with 455 frequency. I keep 2d up with down imaging because I don't trust my mega down imaging. I finally went back to 455 and while I'm not getting the clearest picture nor taking full advantage of the capabilities of my unit, I'm seeing fish, and catching those fish. I just wish I could get mega settings dialed in so I can get the benefits it gives with structure detail, along with it showing those smallies on the bottom.

[Tone357]

I just can't seem to get mega sonar dialed in to see fish like I can with 455 frequency. I keep 2d up with down imaging because I don't trust my mega down imaging. I finally went back to 455 and while I'm not getting the clearest picture nor taking full advantage of the capabilities of my unit, I'm seeing fish, and catching those fish. I just wish I could get mega settings dialed in so I can get the benefits it gives with structure detail, along with it showing those smallies on the bottom.

What's more important? Seeing fish? Or seeing them with Mega? I look at it as you're trying to turn a bolt with a screwdriver. For me, Mega works well for seeing structure. The other frequencies are better for seeing fish. You have to decide what you want to see, then adjust your units accordingly!

[Jhawknseattle]

What's more important? Seeing fish? Or seeing them with Mega? I look at it as you're trying to turn a bolt with a screwdriver. For me, Mega works well for seeing structure. The other frequencies are better for seeing fish. You have to decide what you want to see, then adjust your units accordingly!

And that's I think the conclusion. I wanted to make sure I wasn't missing a setting or doing something wrong on mega imaging. I would absolutely rather see fish than structure, but it seems with mega especially at that depth you kind of need to make a choice. Thanks for the input really appreciate it.

[Tone357]

And that's I think the conclusion. I wanted to make sure I wasn't missing a setting or doing something wrong on mega imaging. I would absolutely rather see fish than structure, but it seems with mega especially at that depth you kind of need to make a choice. Thanks for the input really appreciate it.

[SLYDoggie]

I troll for Stripers so am only interested in the water column and I rarely use Mega. I probably use 455Khz 99% of the time. It does a much better job of fish returns in the water column.

I've attached a couple of screen captures I took yesterday afternoon as I was trolling. I've attached the Mega 360 image and the companion SI/DI/2D which I snapped close to the same time. As you can see, I was picking up fish down to the maximum 80' depth I had my 2D/DI set to. I probably wouldn't have picked up many (if any) of these using the Mega setting.

You can also see the Thermocline "shading" on the DI from about 40' to 60'. I don't know if the Mega setting would have picked that up either.

Bottom line, Mega is good at bottom and structure detail but isn't the best if you are more interested in the water column and things at a distance.

[Dale Hollow Nut]