Thread: Down Imaging vs Side imaging vs neither

I run a 998 c si on the console and a 598 c si on the front. I use the 998 c si on the console and it really cuts down on the guess work but up on the bow I hardly every us the di or si. I really like the 2D sonar up front but that is just me.

Originally Posted by CrappiePappy

This is a true DI image :



Granted, it's from a DI only unit ... but, the information on the image is more defined than a tilted upright SI to DI image. IMHO, that is.

... cp

What you showed is a true SI image! True DI never show shadows and details on the bottom even a bit aside. The screenshot was taken above a very step (inclined) bottom, DI beam sees only one side like SI beam. This is why you see these tree shadows. On leveled bottom one will see nothing with dedicated DI.
Most of all those advertising DI images of leading sonar companies with nice shadows on bottom were done above sunken mountings.
Only Humminbird SI provides true vision under the boat. IMHO

Originally Posted by Vik3

What you showed is a true SI image! True DI never show shadows and details on the bottom even a bit aside. The screenshot was taken above a very step (inclined) bottom, DI beam sees only one side like SI beam. This is why you see these tree shadows. On leveled bottom one will see nothing with dedicated DI.
Most of all those advertising DI images of leading sonar companies with nice shadows on bottom were done above sunken mountings.
Only Humminbird SI provides true vision under the boat. IMHO

I respectfully disagree :

IMHO .... mine can't be a "true SI image" .... as it was taken with a Lowrance Elite 5 DSI unit. It only does DI ... no 2d, no SI, as it only has a dedicated crystal for DI imaging.

I get "shadows" on some of my screen shot images, as shown here :




But, not all of them will have "shadows" .... possibly because of the bottom contour beneath the cover being imaged, or maybe the depth

Normally I would get images that look like this :



... cp

Originally Posted by CrappiePappy

It only does DI ... no 2d, no SI, as it only has a dedicated crystal for DI imaging.




Normally I would get images that look like this :



... cp

Dedicated crystal for DI imaging is absolutely the same as dedicated crystal for SI imaging - it depends only of how it looks at the bottom perpendicular or at angel. If you incline DI crystal or bottom it becomes SI. Your last screenshot is a real dedicated DI image - misture of the left and right parts of 60 degree beam, no shadows and any details on the bottom.
Here are two screenshots of the same piece of bottom , first is with dedicated DI and the second with inclined DI:







Which one is more informative?

I do not know why people trying to put SI beam vertically and to get DI imagies. To me DI imagies theirs lower part look unplesantly poor, but with inclined beam they look alive.

VIC,WHAT DO U MEAN ,INCLINE DI

Vic3 ... I believe the rolling bottom image with shadows (inclined DI) is a result of direction of travel over a uneven, angled, or humped/ridged bottom, and the flat bottom image w/o shadows is the result of exactly that ... a flat bottom of equal depth during the time the image takes to travel across the screen.
I say that because of this image, which was taken on a 45deg sloping bank that I was cutting across (deep to shallow) at about a 45deg angle ... and you can see how the "inclined" bottom effect shows up on the image. It may look similar to a DI from SI conversion image, but that's where the similarity ends, since I have no SI capability (other than the similar shape of the sonar ping) :



I understand the concept that SI & DI sonar pings are both narrow fan shaped bands, and thus they kind of do the same thing ... just with the SI difference being a wider degree of coverage and thus a greater distance reach. I just think my DI unit gives better images than the DI from SI conversion ... even though I'm pretty sure that I don't have my unit settings dialed in for maximum clarity of the images, since I've set it to where it is now & left it that way. The images I've posted were taken while actively fishing, so I didn't take time to fool with changing any settings for a clearer or more more detailed screen shot image.

All things being equal, I think we're both kind of saying the same thing ... just with differing terminology. And so to keep this discussion from becoming a HB vs Lowrance debate, I concede that if DI sonar in SI units had a dedicated crystal for the DI, separate from the SI conversion software, it would be the best of both worlds. Then there wouldn't be any need for a 2d sonar capability, at all IMHO. (but that's a whole other discussion matter )

... cp

Originally Posted by genec

VIC,WHAT DO U MEAN ,INCLINE DI

Gene ... I think he's referring to the image of the bottom looking like the side of a "hill" (an incline) rather than a "flat" bottom surface (narrow strip of bright color with no shadows present).

Being that his DI images are SI images converted/rotated, they give the same inclined image (rolling hills effect) that show on either side of his SI screen. Some of my DI images give that same "inclined" bottom effect, due to the DI & SI sonar both being narrow fan shaped pings, and thus give similar images on bottom contours that are not relatively flat.

... cp

Originally Posted by CrappiePappy

I concede that if DI sonar in SI units had a dedicated crystal for the DI, separate from the SI conversion software, it would be the best of both worlds.

Latest Humminbird ONIX units already have a dedicated crystal for the DI, and now they have the same quolity DI imaging like DSI, LSS, DI units have.

But just compare side by side if the dedicated DI down imaging is better than dedicated SI down imaging:








Again, dedicated down imaging of all known conars is a mix of left and right parts of the wide DI beam - lots of details

desiappier.