http://i615.photobucket.com/albums/t...ams/S00998.png
http://i615.photobucket.com/albums/t...s/S00998-1.png
DoubleG
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Thanks for the pics and the descriptions!
Why is the left side brighter than the right? Them little specks are hard to determine as fish. I thought just debris in the water, I have a lot to learn. 1 more question, the ditch, shouldnt it be darker to the left and right of it,like deeper water?
Even tho these shots are DoubleG's (and I'll let him interject his exact interpretation of his shots)... I will offer some insight on possible scenarios that cause SI images (or parts of SI images) to be darker or brighter....Quote:
Originally Posted by wilbur
Basic sonar function is simply a sound pulse sent thru the water which is reflected off of targets in the sonar beam shape...
The brightness of ("strength of" is a better term) any target's relection returned to the xducer can be influenced by several factors:
*Bottom/target composition-the harder the bottom/target, the better it reflects the sound pulse-the brighter the image (or part of the image)
*Water depth-the deeper the water, the more of the sound pulse is absorbed in the water-the darker the image
*Water clarity-the dingier the water, the more of the sound pulse is absorbed in the waterborne particles-the darker the image
*Sloping terrain-sloping down & away from the xducer will reflect less of the sound pulse-darker image
*Sloping terrain- sloping up & away from the xducer will reflect more of the sound pulse-brighter image
In the case of DoubleG's image where 1 entire side is darker than the other ...I would venture to guess that the left side of the boat was sloping up & away from the xducer- reflecting more- brighter.... And the left side of the boat was sloping down & away from the xducer- reflecting less- darker...
(There are few other instances where a faulty piezo element or a tilted xducer can cause images to be different in brightness left to right....but that's topics for other discussions..)
Rickie
The ditch looks perpendicular to the boat's path and not deep enough to create a shadow..(So shallow that none of the sonar pings were blocked that would create a shadow..)
Rickie
Thanks Rickie.. You hit the nail on the head with that response. I was running a ledge that was shallower on the left side of the boat and dropped off deep on the right side of the boat. So, you get strong returns on the left side and weaker returns on the right side. Also, I fish out of an aluminum boat, so it leans to one side. I adjust my transducers to account for this but it will do the same weak/strong return.
Yeah the specks are small... but crappie are not big fish. If they are scattered and feeding, they will look like the image I posted. I can verify that will a couple limits that day long lining. When you compare the specks on 2D and DI, you can tell better that they are fish.
Thanks to the both of you, You are two very intelligent people when it comes to this stuff.