10-05-11, 10:04 PM | #1 |
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Down Imaging versus Side Imaging
I get asked many times about which is better. To me Down Imaging with it's limited coverage area is less attractive than Side Imaging...One reason: Coverage Area. And most importantly Coverage Area away from the boat.
Down Imaging has benefits and is a great step to transition from Traditional 2D Sonar to High Frequency Sonar but both 2D Sonar and Down Imaging lack the coverage area of Side Imaging. 2D - 200kHz Sonar is 20 Degrees or 1/3 of Depth 2D - 83kHz Sonar is 60 Degrees of about equal to Depth DI has different coverage. DI from SI has three user adjustable widths: Narrow, Medium and Wide. Narrow is close to the 200kHz or 1/3 of Depth Medium is close to the 83kHz or Equal to Depth Wide is wider than both and close to 1.5 times the Depth. In Down Imaging/2D models the coverage area varies by frequency: 800kHz is approximately equal to Depth 455kHz is approximately 1.5 times the Depth. With Side Imaging the user selects the amount of Area of Coverage in the Menu. So you can view how much bottom and to the side coverage out to 240' to each side for a total of 480' of coverage...no matter the depth. This is the power of Side Imaging. Here are a couple examples of the exact same structure showing the additional data that DI does not provide. Down Imaging: Side Imaging: --- But Can DI tell you Direction? Just like 2D sonar you cannot tell which side of the transducer the data came from... But Side Imaging I can tell which side of the transducer the data comes from... This image is marked up to show where SI shows the blocks versus DI that has no ability to tell which side Hope this helps understand the features and advantages and the differences. |
10-05-11, 11:00 PM | #2 |
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I see your point and I'm sure with enough on the water practice someone could learn to interpret the SI images, but the DI is so much more intuitve (to me anyway). I can clearly see a good fish at 15' just above the bottom in the 1st DI pic. Trying to find that fish on the SI screen is tough for me. If I do most of my fishing in 20' or less (usually 5-15') and I put out a buoy as soon as I see that arch then continue about a casts length away and cast back toward it, I can imagine that within 2 or 3 casts I could drop a worm on his head. Don't get me wrong I love technology, I've been using DF's since the first HBird super 60 but for a casual shallow water fisherman I have trouble justifying the $.
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10-06-11, 09:15 AM | #3 | |
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10-06-11, 12:08 PM | #4 |
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It's about time management. I feel recreational anglers have less time to enjoy fishing. Do your prefer Casting or Catching? If you prefer Catching fish and have limited time and side imaging can maximize your precious time on the water wouldn't that add extra value? Being able to locate the fish before you cast is one of the huge advantages and the time savings for fishing in areas that will produce the highest odds of sucess.
Is the fish you talking about in the first image right above the laydown? That one is on the right side of the transducer jsut above the laydown if you look in Side Imaging shot. |
10-06-11, 12:54 PM | #5 |
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I am with Doug on the time management issue.
As someone with woefully lacking spare time (especially when I stupidly try to maintain about 20 different hobbies), I prefer to at least feel like I know what I'm doing out on the water. If money isn't too big of an issue, I'd say SI is a no-brainer. Heck, it's even interesting to look at even if you're not on the fish that day. You can see some very cool things down there. I don't catch a lot, but it's not for lack of locating and marking structure and cover. I figure (hope? ) at some point it's really going to pay off.
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10-06-11, 01:18 PM | #6 | |
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10-06-11, 01:27 PM | #7 | |
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10-06-11, 02:08 PM | #8 |
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Believe me. I overthink everything. I try to break everything down wayyy more then I need to but its just the way I am. I want to know everything about it so I can get better at whatever it is and you find that you usually will. However treating me like a 5 year old works well too. LoL.
I've only had my units since this summer and am still learning myself. I however could not imagine ever trying to fish without them again. The SI is really easy to read if you look at the color variations for deep, flat or shallow bottom contours. For me the video on youtube where the guy takes an actual print and folds it to show you how to interpret the image was priceless. Once I saw that image it was very clear to me how to view the water table and bottom. Keeping the setting between 100' - 125' out is the key to seeing more on your screen. Also a key thing is going slow enough and keeping your chart speed at the same. If I set my chart speed at 2.5 and I run between 2 & 3 mph then when I see anything at the top of my screen I know that its directly behind my boat about 4' - 6'. Then you can view it with DI for a better look. I think the transition from 2D to DI is pretty straight forward. I do however find myself generally using the SI at the console to search for cover, structure and depth changes then I only use for the most part 2D/DI view at the bow. SI while using the trolling motor surely has some benefits but not like the DI.
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10-06-11, 08:00 PM | #9 |
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Handlebars...that was my Video Clip I did explaining the technology: http://youtu.be/3xe6pLPdMKc
Ok here is the 1st 2 images I've tried to intrepret and show the relationship between the DI and SI images. I tried to circle in different colors the items seen in Down Imaging Where they actually are in Side Imaging. Does this help? Any more question let me know. |
10-06-11, 08:10 PM | #10 |
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So, a quick question, when looking for a DI sonar you want to get one with the highest frequency, so you have the largest coverage? Part two, and this is to Handlebars specifically, you use a DI up front and a SI at the console, I'll make it easy...why? To me it seems like you might want to use it the opposite way, since the transducer for the console isn't exactly center of boat, and the trolling motor usually is, and you really fish from up front, so it seems like you would want that expanded info while fishing.(?) Thx.
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10-06-11, 08:16 PM | #11 |
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Oh man, Mr. Vahrenberg aka imonbass. Its a pleasure to meet you. I never put the two together.
That really is a great video. It makes it very clear, especially when you use the 3D image with the barge to show depth. I wish you would come draw colors on my screen so I can see all the things I'm missing. LoL! It is definately a learning curve but I get a tremendous more out of it then I ever did 2D. The best thing about the new units for me is the actual screen size. Don't see as good as I used to and always had trouble with the 2" - 4" screens. They are so bright and clear. Are there ever any seminars around the country for folks to goto maybe put on by Humminbird or yourself? @Dog: Well where my transducer is mounted I know that it is 6" to the right of center which is really not enough of a difference off center to matter for the application. I have used alot of bridge pylons and fish attractors to figure out exactly where something is according to my boat & chart speed. I use the SI for more at the console while motoring around looking at the bottom structure and cover. I do sometimes use the dual screen view with SI/DI if I'm looking over a particular area. I usually just use the quick buttons to change the views from one to another so I can use the full screen size cause my eyes aren't as good as they used to be.... I may have misspoke b4 I can't remember exactly what I said, you know that selective memory my wife says I have lol, but both of my units have SI/DI function so I switch it up but I end up using 2D/3DI more up front but I have only been using them for a few months so I am still in the learning stage. I do however like the view that I get from the side instead of straight down. What I like today I may very well change completely tomorrow. So do I have a real good reason to answer your question, na probably not except I dunno what the hell I'm doing but it is alot of fun! That probably don't make much sense so now ya know me. lol. thx Thanks
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10-08-11, 10:50 PM | #12 |
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Makes perfect sense, but what finder has dual DI/SI may I ask?
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10-09-11, 10:23 PM | #13 |
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10-09-11, 10:52 PM | #14 |
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Ive always considered those that operate at three frequencies to be beyond a down imager and into a sidefinder yet like entry level.
Your correct the 798 and higher have switchfire capabilities that is because with four one of them is the narrow and the next widest just has two more that look to the sides,so even the most expensive has the di built in so to speak. But the simple piranha,and 100 thru 300 with all those inbetween are true di that do nothing else cost very lil as well. That to me is a true di as it does nothing else. My 785c2i and a 755 have three freq and sees 90 deg and 1 1/2 times the depth considering main channel is 60 ft thats a bit over each side,and far out.past where many can cast. At a basic 20 deg simple di costing a hundred buck,or more with each freq added more features. For running the di is much friendlier to me,for idling around looking at structure the wider or sf,for pure fish finding just the di or a pure sf single beam like bottom line,but that may be me old school,old and not desiring change or having the time to earn a degree. Have both Last edited by lilmule; 10-09-11 at 11:00 PM. |
10-09-11, 11:09 PM | #15 | |
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Mule, I believe you may be confusing two technologies, someone correct me if I am wrong but all the units you have listed above have 2D sonar, DI is a much newer technology and offers much wider views in very shallow water. 2D sonar is dependant upon water depth to provide much of a coverage area.
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10-10-11, 01:37 AM | #16 | |
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10-10-11, 06:21 AM | #17 |
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Then its the terminology thats confusing as di = down imaging and the cheapest one made is a basic di as that is all it does 20 deg then with added 60 coverage( a few oddballs with less deg) with units costing a little more,after that come 90 deg and 180 which while they can look down also look to the sides.
So the term is being loosely applied to three beam,which in truth is more multi than omni. Not being nitpicky just somewhat behind the times,an adjustable wrench however is not always a cresant wrench.One is a name brand not a type but attached to all,doesnt make it true. I concede that in the future a misnomer is being applied. |
10-10-11, 10:18 AM | #18 |
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Well I think the question is answered dog.
I am not a guru when it comes to electronics at all. As stated I've only had mine since the summer and am still reading and learning on/off the water all the time. Now about the terminology no matter whose brand one would use or the names they would call it I don't think we can take away the fact of what it does. I own Humminbirds. They were my choice after many months of reading, asking questions & reading reviews. I have a 1198c si at the console and a 998c si at the bow. They both have SI (side imagaing), (DI (down imaging), 2D (what I refer to as standard sonar). They can of course be viewed in different configurations which you all know. IMO whether a unit has DI exclusively or in conjunction with other technologies I don't see how or why it would be considered different or unequal. I am a little confused when you say the term is being "loosely applied". I am under the impression that when I look on my screen and I see 3 different views of which I am told are SI, DI & 2D unless what you are talking about is something that I am not familiar with considering not having many different units. I have never used too many old finders in the past. I used an old Garmin 160c for the last 12 years or so. I purchased a 385i humminbird which is 2D sonar w/ switchfire and quite honestly I hated it. I did not have great readings from it but the biggest downfall for me was the 3.5" screen size. My eyes aren't the best in the world so the determining factor for me was screen size which is the main reason I got the larger units. These new units are the best thing as far as I am concerned. I don't know everything and am always willing to analyze, break down, ask questions, listen and learn so I am looking forward to being a long term solid member of this forum and learning all that I can from all of you veterans in these threads. Carry on...... thx
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10-10-11, 11:23 AM | #19 |
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Well in the old days 2d was down imaging as works down and where its now applied can also work to each side,Im guessing somewhat 3d depending upon model.
Thats what confused me down imaging applied to one that actually sees a great deal to each side,so in effect sort of a trademark not a truth as sees or lives in both worlds. For actual usage prefer my tri beam and dual beam even my omni beam. But no matter im sure they dont depend upon sales to those on ss,as a top of the line unit sf would cost three months income. That and being old fashioned I operate an old scout being omni at 3-5 deg one side only and it shows no structure at all as has built in filter,just fish,and a very long ways out to 220 ft can pick up bass sitting under the lip of a barge or by a bridge abutment. One thing I am curious about,while they give great detail the sf,and one could put put around for days in wonderment.Here on ky lake its not the stump thats so important but what is on a ledge like a mussel bed,do they show or can one tell if one is looking at a mussel bed. Guess im behind the times and will most likly stay there. To me that is di,a wide is just that wider and dual beam,tri and quad being sf the latter being a full sf.But thats just to me not to evryone it seems. Go to the hummingbird store outlet type in down imaging everything from a simple piranha up is listed including the high end units as they have that simple feature built in,as one of even a four freq unit is but 20 deg.And even an expesive unit while it may have more pixels and show more items is covering same area a $100 unit is when in true di. Last edited by lilmule; 10-10-11 at 11:38 AM. |
10-10-11, 12:01 PM | #20 | |
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2D Sonar is Traditonal Sonar that the beam travels in a Cone Shaped Pattern. It's also Low Frequency 200 kHz, 83 kHz There is a 2D Technology called QuadraBeam that uses 455 kHz but the cone angle is still wider and not the high frequency/high detail that Down Imaging Produces. It shoot two 35° beams to the right and left to produce 90° of total coverage with the traditional 2D sonar. So you get twice the depth coverage. Down Imaging uses a very narrow band (Front to Rear) of High Frequencyu Sonar 455 or 800 kHz to build the image and get more "picture" like images. Side Imaging uses the very narrow band but is sent farther out the sides and increased coverage area not limited like Down Imaging or 2D Sonar to under the boat. You can also tell direction right and left of the transducer. If you want to learn more about coverage areas I did a video clip at a Seminar that goes in-depth into the differences of all 3 Sonars to help you better understand: http://youtu.be/sq74UJaNMSs Last edited by DougV; 10-10-11 at 12:23 PM. |
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10-10-11, 12:18 PM | #21 |
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Here is some Shell Bed Images:
Here is a cool feature on Side Imaging...you can change the color Pallete to a Special App color where red is the strong returns and green is the weak returns. Makes Shell Beds stand out like ....well take a look. |
10-10-11, 12:20 PM | #22 |
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I have the manuals that show that area nicely,as well as their own online pics from bird,understand the difference between omni ,dual ,tribeam and quad and their coverage areas.Just not the understanding of what was, now is quite different in reference to a model,rather than a deg or freq showing bottom coverage.
And in my own defense can understand it if one says dual beam,tri beam,to me old fashioned di is omni and that first 20 deg,maybe it was improvements that allowed di with additional coverage wider at speed dunno. Trademarks tend to change like wide side,wide view,guess that was one of them I concede. But question most pick up various bottoms like clay sand,etc and hardness will a tri or quad beam pick up mussel shell beds and can one tell if it does? Believe it or not an old Pirhana can,nothing certain but shows same as a rock strewn bottom,check with treble hooks and spot on either those or fist sized rock. Shute your to quick and have what i asked up thanks |
10-10-11, 12:55 PM | #23 | |
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10-11-11, 08:02 PM | #24 |
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Before I checked this thread, I was watching the KVD's Boat thread, and KVD answered the question for me, but thanks guys. After all this, I have come to the conclusion that I should just jump right to an SI unit and skip the 570 to 596 models that are DI(and 2D) only. Guess I better strart saving!
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07-26-12, 11:40 AM | #25 |
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why don't the pictures show up on this post
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