Anyone no what's causing this dark area? This is 800kHz on 998...http://i826.photobucket.com/albums/z...sjbjo6nfj.jpeg
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Anyone no what's causing this dark area? This is 800kHz on 998...http://i826.photobucket.com/albums/z...sjbjo6nfj.jpeg
Looks like you have some interference on the right side, at the boat.
Softer bottom shows up as darker then hard bottom.
Pete
Quote:
Originally Posted by ShilohRed
Agree. Soft bottom is dark. Hard bottom is lighter.
Sent from my iPhone using Tapatalk
I agree with ya'll about there being a soft bottom.But why does only happen on the 800kHz, not 455kHz. ?Quote:
Originally Posted by kfi
Here it is again.this is on the onix..http://i826.photobucket.com/albums/z...pshb0udugx.jpg.....http://i826.photobucket.com/albums/z...psvrkrdh5h.jpg
Why are the depths different? Are these different locations?
I would say ,that most likely possibly could be:RoflQuote:
Originally Posted by Cane Pole
That dark area runs the length of the shotQuote:
Originally Posted by Cane Pole
This one looks like the "Ghost Lines" phenomenon when SI piezoes and a DI piezo are transmitting in the same xducer housing ...
http://i477.photobucket.com/albums/r...ps6mb2pcuv.jpg
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This one looks like the DI transmitter is shut off and only the SI piezoes are transmitting ...
http://i477.photobucket.com/albums/r...psotxfkemn.jpg
Rickie
http://i477.photobucket.com/albums/r...psgvshkuwc.jpg
The SI slice beam sound pulse is strongest along its "Main Axis" and weaker at the outer fringes of the SI slice beam directly under the boat ...
http://i477.photobucket.com/albums/r...pskwnh5zhd.png
This weakening of the outer fringes of the SI slice beam will be more evident with the 800kHz simply because higher frequency sound wave attenuates (absorbs into the water) quicker than lower frequency ...(leaving less energy to be reflected off actual targets - especially in the outer fringes of the SI slice beam) ...
Rickie
Well done rickie.sounds like lower frequency would be best used,all the time.But look at that first picture that I posted again.on the left side,were the structure is.look at how well the fish stand out,were the weaker part of the 800kHz beam is being absorbed into the bottom.notice how bright the fish(air bladder makes a hard return) returns are in comparison to the dark bottom.If this were a 455kHz si or even a 360 image.the stronger bottom return from the lower 455 frequency would make the fish hard to see.higher frequency, not only produces sharper images, but also can ,in some instances make fish stand out,on side imaging and hopefully,someday humminbird will add some form of a high frequency chirp to 360.Quote:
Originally Posted by rnvinc
I run SI a little darker when looking for fish to allow the fish return to stand out better against a darker bottom ...Quote:
Originally Posted by kosmo
http://i477.photobucket.com/albums/r...psfbc4ce68.jpg
I run SI a little brighter when looking for structure ...
http://i477.photobucket.com/albums/r...HBpngat120.jpg
Setting the unit and never touching anything is under-utilizing the features these units are capable of ...
Rickie
Good example,rickie:ThumbsUp. I would like to try 360 out on a higher frequency tho.455 seems harder to distinguish fish from bottom.lower the Sensitivity on 455.loose botton and fish, raise sensitivity,bright bottom,but hard to see fish. (Those last two picture that rickie posted,look like 800.the first picture looks like more of a softer bottom than that second one
Those shots are most likely 800kHz ...Quote:
Originally Posted by kosmo
My fishing methods lean toward seeing more detail right at the boat ...
I use 455kHz in new water looking for new structure ...
Rickie
I have never seen anything like this. It looked like a reverse course to me with the round thingies on right vs left and the similar depth change pattern in reverse. So, how was I or anyone else supposed to know?Quote:
Originally Posted by kosmo
May be a case of the Babinet principle in ur picture.:dono Of course Rickie is right about beam concentration.:ThumbsUp
Dang Tom ... I had to look that one up ...Quote:
Originally Posted by Cane Pole
https://en.m.wikipedia.org/wiki/Babinet's_principle
Your knowledge of theory is amazing ...
:ThumbsUp
Rickie
Those two pictures had the di piezo turned off.one picture is 800,the other is 455.the first picture that I posted is from a 998 that has no di piezo. It is set on 800.This picture is from my Onix.si and di are both set to 800.fish show really well in the dark area..http://i826.photobucket.com/albums/z...pspdumbs4p.jpg.Quote:
Originally Posted by rnvinc
Here's one with side imaging set to 455.this picture was taken the same day and close to the same spot as that one above,just set to different frequency. On the picture that on 800.I could keep turning the Sensitivity up and thaT dark area would still be dark,but the fish returns would get even brighter than they show there.455 would just wash the fish out as the Sensitivity go's uphttp://i826.photobucket.com/albums/z...ps8ntvuv1d.jpg
The dark stripe in the 800kHz SI images could also be the "null sector" in the 800kHz beam form ...
http://i477.photobucket.com/albums/r...pshmz3szda.jpg
(notice the 455kHz in the beam form diagram above doesn't create a "null sector")...
http://i477.photobucket.com/albums/r...psvvw0fp4t.jpg
Rickie
I would like to see humminbird add the 800kHz chirp to the 360.I believe that I could use the null area to my advantage. http://i826.photobucket.com/albums/z...ps16mexdtt.jpg
Interesting thought there kos ... very interesting ...Quote:
Originally Posted by kosmo
Rickie