[Elphel-support] Wide angle high resolution lens for Elphel 353L

[Jan Blažíček]

Hello everyone,

I hope you're well. I have a question regarding lens recommendations for Elphel 353l cameras. I have been able to find a couple of tips around your support list and your blog, but a lot of the samples are dead links / lenses are discontinued etc. I haven't been able to find anything close to my specification requirements for quite a while, so I am turning to you with a new thread.

Basically, we're using a pair (or more) 353Ls in a stereo application. The cameras are synced, use a very narrow horizontal ROI, something along the lines of 2592 x 96 px in the middle of the sensor. I am working on a stereo matching application which could handle the high FPS from the camera as we need to build a depth map as close to real time as possible. The cameras are fine for that even though one seems to have misaligned sensor, which makes it a pain to focus.

The problem is that the application requires the cameras to scan a large horizontal surface, around 2.5 m from a short distance, about 1 m away from the target. Looking at the other threads, that would mean:

f = 5.8 mm * (1 m / 2.5 m) ~ 2.32 mm

HFOV = 2 * atan(2.5 m / 2) ~ 102 deg

We currently have a set of Kowa 3.5 mm lenses, which are not working out. We need something with a bit wider HFOV and built for higher resolution cameras, which is hard to come by. We can fiddle with the setup a bit, so the camera - object distance is not set in stone, but I thought maybe you guys may have some concrete tips for a good lens / manufacturer? Fujinon is sadly out of my current budget. I found a Theia technologies SL183 that does look fine on paper, but the sample shots they have sent me look barely usable as far as distortion and softness goes.

A good resolution and low distortion is more important than wide angle in this case, I'd settle for ~90+ degrees HFOV if there was nothing available. I am also not really set on varifocal / monofocal as long as it has good optics.

Thank you very much for any help you may be able to provide and have a great day,

Jan B.
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