In the SI view below ...:
#2 is obviously closer to the boat than #3 ...
So explain why would #3 give a better return than #2 if #3 is farther away ...??
Attachment 275074
Rickie
Printable View
In the SI view below ...:
#2 is obviously closer to the boat than #3 ...
So explain why would #3 give a better return than #2 if #3 is farther away ...??
Attachment 275074
Rickie
#3 is out in the meat of the SI beam. The #2 is in the marginal fringe area directly under the boat. I am curious why #2 doesn't give as much relief to where you can see that the block is elevated in the DI image. I guess if you are shooting across the top at an angle you get some shadowing and the unit sees it as raised up, whereas if you are directly over the top it cant really tell that there is a difference between the top of the block and the lakebed. I guess that one could just be all silted in also, the portion that laps over from the bottom contour looks like it is a little softer.
I GO OVER SUNKEN BOATS OFTEN AND ALWAYS GET BETTER PIC TO SIDE WITH SI,STRONGER SINGAL TO SIDE THAN STRAIGHT UNDER BOAT PLUSE SI TAKES A BETTER PIC OF OBJECT ON ANGLE WHERE IT CAN PASTE IT IN BETTER,EVEN A PAINTER CAN PAINT A BETTER PIC OF BOAT ON ANGLE BETTER THAN SIDE WAYS
I agree with both above. But since this was taken with an onix, I'm going to say it is sunk in softer bottom further as seen in the 2D view. But I don't understand why it shows up so curved on DI view?
PONTOON,ON DI, ONIX OR NOT ,DRAW A FLAT PIC AND SO CORNERS ARE FARTHER AWAY AND SO MUST BE DRAW DOWN HILL FARTHER FROM DUCER BUT IN LINE WITH REST OF CONCRETE SLAB,IF YOU WOULD PAINT A OVERHEAD PIC OF SLAB YOU ALSO WOULD HAVE TO PAINT THAT WAY,ON FLAT OBJECTS IT IS THE ONLY WAY TO DO IT,I AGREE ONE SLAB IS DEEPER IN THE MUD
Here's a better shot of those concrete slabs.they have cables attached,that hold the floating docks in place...http://i826.photobucket.com/albums/z...psrfx9v28a.jpg
I like the way Orange worded his answer ... #3 is out in the meat of the SI beam. The #2 is in the marginal fringe area directly under the boat.
The SI sound pulse is strongest along its "Main Axis" ...which is 30° from horizontal ...
Above and below this 30° - the sound pulse is attenuating (getting weaker) ...
Attachment 275075
So like Gene mentions ... Better SI pix will come from objects that are off to the side a little in the stronger part of the SI beam sound pulse ...
Good job again guys ... :ThumbsUp
Cool pic kosmo ...
Rickie
KOMOS,THAT IS A GREAT PIC,FROM ONIX? DID IT DRAW OUT THOSE DOCKS LIKE THAT OR DID YOU PASTE SOME OF IT IN?WOULD LOVE TO SEE CAMERA PIC OF THAT BIG DOCK,AGAIN IF ALL THAT IS JUST SI ,DON'T SEE HOW YOU GOT SUCH A PIC UNDER THAT DOCK
That's all Onix.I'll be down that way today.I'll see if I can get you a video,to look at (maybe)Quote:
Originally Posted by genec
So if using 800 MHz looking for bottom structure is the rendered DI almost useless? Can you miss things directly under the boat on SI completely?
orangeagent,if the item is strong enough and nothing blocking view unless you went too fast it will pick it up even straight under boat,unless too small .under the boat is closer and do not need as strong of a signal as outward longer signal would need,imo
I asked because that image of the beam shapes made it look like 800khz stops well short of the vertical center line. Wasn't sure if I should do 2d and SI combo instead of the triple view when using that frequency. I like the DI view as well as 2d, even though it isn't as clear as my dedicated DI I still find myself much better able to figure out fish sizes and structure shapes.
except for true di,the di you would be seeing is from your si,and if si did not see it di could not see it
The 800kHz has definitive side lobes that continue past vertical under the boat (as seen in the diagram) ...Quote:
Originally Posted by OrangeAgent
Attachment 275076
There are several factors of Sonar frequency that come into play when deciding which frequency to use ...
*800kHz will be more detailed with less range (as depicted below - the outer edges of the 800kHz are getting darker quicker) ...
*455kHz will be less detail with more range (as depicted below - the outer edges of the 455kHz are brighter but the entire SI is less detailed) ...
Attachment 275077
Rickie
That is great info, I have seen that screen shot floating around the net but never with a good explanation to go with it. I was thinking that the 800kHz was just a narrower beam so you lost some of the upper part of the water column at the edge of the range but had more detail of the bottom.
So if I am going under a bridge with a span between the pilings of say 80 ft, if I use 800khz and a 50ft range I will still see the tops of the pilings but with super detail? I will have to take a sd card with me next time I go out I have been scanning these monster schools of shad and fish under some bridges I fish often.
I find bridge pilings to be very challenging ...depending on the size of the pilings ...Quote:
Originally Posted by OrangeAgent
The shadow will be more noticeable than the piling itself because of the way SI paints vertical structure in the SI image ...
Please post pix of both frequencies of your bridge pilings when you capture them ...
Rickie