Camera focus with dome

Hi guys, this morning I went to Lake Iseo to do some tests with the bluerov2, light and video tests, and as usual I came back a little disappointed by the quality of the video. It always seems out of focus, I stopped to look at a thin object of about 10cm and I couldn’t figure out what it was. I have had the rov for 6 months, I tried to change the original hd camera with a sony imx290 hd, I tried to replace 4 lenses, from the original one up to the 180 ° fisheye. Nothing always out of focus, I followed the instructions by focusing the camera at a distance of 50cm, with the dome, without the dome, with one camera and then the other, nothing to do. Today I went home and did a new experiment, I took a bucket 35cm high and filled it with water, then I put a plasticized table with letters and numbers on the bottom, I put the dome to float in the water, I took a raspberry pi 3b connected the hd camera with original lens and put it at about the distance that is in the dome when it is mounted on the rov, and surprise, i saw the table blurry, so i did the focus in the dome that floated in the water and I managed to focus on the table. So I removed the camera from the dome and the focus in the air is blurry … In practice the dome in the water changes the focus, I calculated that by focusing the lens in the air and then focusing the objective in the dome, I had to rotate the objective about 60 ° counterclockwise to have the focus in the water. Now I have to do further tests with greater distance and then try this week at the lake, but I think I am on the right path … I will keep you informed of my progress. :slight_smile:

Hi guys, as I told you, I took a container with 60cm of water, I put the dome to float and I put the HD camera inside, to get the perfect focus I had to move the lens further away reaching about 80 ° in Counterclockwise.

Ok, 2 months ago I bought the exploreHD camera With protected case up to 300mt, but unfortunately I was unable to use it because it lost the video signal when passing through the cobalt connector. So I disassembled it and inserted it in the dome of the rov, this camera has the possibility to choose 2 settings, if in HQ and therefore without loss of details because the H.264 encoding has little impact on the quality, or a less performing H.264 setting , therefore with more artifacts, but less heavy in terms of transmitted data. Unfortunately the raspberry pi 3B cannot handle the HQ coding at 100% so I have a delay of about 1 or 2 seconds in the image, with disastrous consequences in driving the Bluerov. So I have to use the least performing firmware version to drive the rov. Despite this, the exploreHD is still great, but I would like to test it in HQ. I mounted a 2.8mm lens with about 110 ° of aperture without distortion, to have more or less the same aperture as the gopro hero7 black in superview. I used the same resolution and Fps on both, leaving the basic settings and not making any corrections in post production. The only problem is youtube which further reduces the quality. I adjusted the lens by focusing on an object about 1m away from the water, and then turning it counterclockwise by about 75 °. In fact, in the image of the video out of the water you see everything slightly blurred, but then in the water the music changes. As soon as I can I will try to change the focus further, but I would say that I am on the right path. The image is much better than before, it happened to me to see an object and not understand what it was. The white balance is better in the exploreHD even if overexposed, the definition is better in the gopro, but the exploreHD is with the least performing firmware. I used 2 original bluerobotics spotlights pointed downwards, and 2 spotlights modified by me with 17 cree xlm leds and 6 red leds, for about 6000 real lumens measured by me for a total of 12000 lumens. I have also mounted 2 lasers of 1000 mW, but one of the 2 in cold water loses power, I have already ordered others. Enjoy and let me know what you think. :wink:


I had a chance to check out the footage :slight_smile:

Great to see you were able to finally get the exploreHD to work with your setup even if it required a bit of modifications! We noticed quite a lot of artifacts with the dome being used instead of a flat port especially when it comes to focus on the edges. Huge difference when it comes to color, the exploreHD with the TrueColor is definitely performing way better than GoPro. I do wonder how much sharper and less distorted the image would be if you were able to get the housing to work instead of the dome glass. Also, as you mentioned, the other firmware will make the image much sharper but at the cost of needing more processing with the Pi. Either way, very happy to see you being able to use our cameras :slight_smile:

Thanks for sharing!