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jbeale
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full-circle M12 fisheye lens for 1/4 inch sensor?

Tue Aug 30, 2016 3:32 am

Somewhat related to RPi camera: I'm interested in a circular fisheye lens. I know about the "fisheye" converter lenses made for mobile phone cameras, but I've never seen one that has acceptable focus near the edges of the frame. The sample photos I see have edge detail missing, they are blurry and full of color-halos around the perimeter. I believe a dedicated fisheye lens can do better.

Most of the "full fisheye" lenses in the M12 mount that I have seen are intended for 1/3-inch or larger format sensors. On a 1/4 inch format sensor such as either of the official RPi cameras use, this will not show the full 180 degree hemisphere image; it will be cropped on the edges. Does anyone know of such a lens?

As an example, here is one fisheye claiming support for 1/4 and 1/3 inch sensors. Not exactly cheap, either.
https://www.vision-dimension.com/en/len ... winkel/209 ...but this lens has an image circle of 3.4mm in diameter, meaning the 3.67 x 2.74 mm sensor on the RPi v1.3 camera would crop it significantly on top & bottom.

Here is a similar lens, the Sunex DSL218 with image circle of 3.3 mm.
http://www.optics-online.com/OOL/DSL/DSL218.PDF

EDIT: I see a 2.9mm image circle lens with f=0.98 mm advertised, Focusafe FS09818FEBMP which is $120 used and $$? new
http://www.ebay.com/itm/0-98mm-M12-0-5- ... 2497762100
http://focusafe.en.alibaba.com/product/ ... _lens.html

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Gavinmc42
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Tue Aug 30, 2016 7:40 am

I have been keeping my eye on GoPro lens and other 180-360 degree cameras.
https://360fly.com/au/
http://kodakcamera.pixpro-sp360.com/

360 degree Youtube, Facebook etc action videos are getting more common, driving the camera and lens makers.
14-16MP sensors are common now.
If they are good enough for 4K videos they should be ok for the Pi cameras?

I think GoPros are M12?
Mobile lens are getting better
https://www.dpreview.com/reviews/aukey- ... ick-review
https://www.immervisionenables.com/buil ... orph-lens/
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karrika
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Tue Aug 30, 2016 9:25 am

The 120 degree lens that is available for Pi Cam is the closest to a full circle I have at the moment.

I have a dream of creating an outdoor camera for navigation that could always see the horizon, stars, beacons, landmarks and other vehicles. It would be great to run it without moving parts. So I am also interested in buying a half circle lens with fairly good optic quality.

The distortion of the 120 degree lens is terrible. I have no clue of how accurately you could measure the height of the sun from the horizon. Or would direct sunlight make the picture unusable.

PS. yes, I know that GPS exists and would probably be the sensible solution. But I am just interested in seeing if you could create a terrestrial navigation unit with a Raspberry Pi 3, nautical chart data, nav stars tables and a camera. Like the old vikings sailed.

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Gavinmc42
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Tue Aug 30, 2016 11:16 am

Been awhile since I thought of outdoor star navigation.
I was thinking of indoor robots.
A camera with 360 degrees around horizontal and 240/180 vertical would be a useful vision system.
Pointing up, it can use ibeacon guidance and optical flow/movement detection.
On drones it points down for position holding etc.
With the H264 motion vector code it could be very useful with the quad core Pi's.
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Raspberries are not Apples or Oranges

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jbeale
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LS-40180 Fish Eye Lens for R-Pi

Fri Sep 02, 2016 3:40 pm

Here is another one I had not noticed before:
http://www.ebay.com/itm/LS-40180-Fish-E ... 1223605857

The barely-readable datasheet claims it is a f=1.05mm, f/2.0 lens with image circle of 3.8mm and achieves a field of view of 194 x 142 degrees on a sensor of 3.6 x 2.7mm size. Also, that it is suitable for a 1 Mpixel sensor. So that is not a full-circle fisheye on the RPi camera, but the lens is also pretty cheap.

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Gavinmc42
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Sat Sep 03, 2016 12:17 am

Anyone found M6 fisheye/wide angle lens?

Because of the short focal lengths using a M12 adapter, it may pay to remove the double side tape and glue the camera module to the pcb.
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jbeale
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Sat Sep 03, 2016 12:24 am

As far as I can tell, M6 is not really very standard, there is M6 x 0.35 and M6 x 0.3 and M6.4 x ? and various other things. I've never seen a fisheye type. Here are a few: http://www.megapixellenses.com/sale-807 ... art-1.html

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Gavinmc42
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Mon Sep 05, 2016 7:22 am

I think most M12 wide angle are designed for bigger sensors 1/2.3" etc.
The Pi sensors are around 6mm or 1/4" so something like these?

http://www.megapixellenses.com/sale-807 ... -lens.html
http://www.megapixellenses.com/sale-807 ... -lens.html
http://www.megapixellenses.com/sale-807 ... -lens.html
http://www.megapixellenses.com/sale-807 ... -lens.html
http://www.megapixellenses.com/sale-807 ... 10635.html
http://www.megapixellenses.com/sale-807 ... -lens.html

Can you use 1/2, 1/2.3" wide angle lens and get the same angle with a 1/4" sensor?
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jbeale
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Tue Sep 06, 2016 3:48 pm

The key is to look at the diameter of the image circle. If the image circle diameter is smaller than the shorter side of your sensor, then the sensor will capture the entire image circle. Otherwise, the sensor will crop off some part of the image circle, limiting the field of view that you would see if you had the same lens on a larger sensor. The RPi camera sensor (both v1.3 and v2.1) is a so-called 1/4" format (more accurately, it is 3.67 x 2.7 mm in size).

As far as I know, there is no M12 fisheye lens made with an image circle 2.7 mm or smaller; certainly not one with anything like 5 Mpixel resolution. The closest thing I've seen is that $120 (used) Focusafe FS09818FEBMP lens claiming a 2.9 mm image circle, which is indeed pretty close.

Then, there are some exotic M12 lenses for the 1/2.3" GoPro camera going up to 280 degrees (!) with a 4.2mm image circle. I don't know what the 180 degree image circle would be on that lens. Also, price is a bit high :-) http://www.seesense.eu/entaniya-lenses/4590337841

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jbeale
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Tue Sep 20, 2016 6:33 am

Ok, I got an OV5647 RPi-compatible board from Ebay with a fisheye lens which, though not quite "full-circle" is pretty close, and in the corners it looks like a little bit more than 180 degrees. It was this item: http://www.ebay.com/itm/271577288240 which claims to use a LS-40180 lens
http://www.uctronics.com/ls-40180-fish- ... 2074l.html

In an image taken straight up, you can see the desk surface the camera is sitting on, which is actually behind the lens: https://goo.gl/photos/gbhw9M4P7usvwGc2A

Here is a photo looking out the window: https://goo.gl/photos/z6r5wskqGHLPFiabA

Image

xuboson
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Mon Feb 06, 2017 8:28 pm

Hey jbeale, what's the difference between the camera + lens you found on ebay (http://www.ebay.com/itm/271577288240) and the Arducam (https://www.amazon.com/Arducam-LS-40180 ... B013JWEGJQ)?

They both use OV5647 sensors and LS-40180 fisheye lens. If I'm not mistaken, the arducam is said to have a FOV of 160 degree, not 180.

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jbeale
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Tue Feb 07, 2017 3:13 pm

From the Amazon link you posted to the Arducam:

Question: Can the manufacturer please post some photos taken with the camera?
Answer: As you can see the LS-40180 lens is 180 degree fisheye lens which has big distortion and dark corners, you can find the demo photos from www.arducam.com/downloads/Lenses/Fisheye/LS40180 If you need something else, please let us know.
By Arducam SELLER on January 12, 2016

xuboson
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Mon Feb 13, 2017 1:23 am

So... have you not considered the Arducam while shopping for your fisheye lens + sensor?

From what I can tell, they use the exact same lens and and OV5647 -- Have you tried to get a 185+ degree FOV with your camera sensor + fisheye lens?

I need to capture 185+ degrees, but as you mentioned, it's not really capturing the full 180. Any tips or tricks I can benefit from?

Thanks

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jbeale
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Mon Feb 13, 2017 9:45 pm

I didn't measure it exactly, but I believe the camera model I have does in fact cover more than 180 degrees if you measure across the frame diagonals. However, the RPi camera's sensor is not large enough with this lens to show you a "circular fisheye" image with 180 degrees in every direction. If you need that, I think you may have to look elsewhere (eg. USB camera, not RPi camera).

Here is one example that claims 180 (I haven't tried this one myself, but one review says works OK with R-Pi):
https://www.amazon.com/180degree-Fishey ... B00LQ854AG

By the way: I don't think there is any true-180 degree camera with really good image quality at the edges, no matter how much money you spend.

301217638
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Mon May 15, 2017 11:00 pm

Hey jbeale, I've been reading your posts on this forum and they've been very helpful for my project. I'm also looking for an M12 lens for the Rpi camera that can capture at least 180 degrees (horizontally and vertically) field of view. My search results for the M12 lenses yielded similar results as yours, I haven't been able to find one yet. I'm wondering if maybe you had some luck with this and found an Rpi lens that has at least 180x180 field of view that won't get cropped by the Rpi sensor?

I also saw the USB camera you linked earlier (https://www.amazon.com/180degree-Fishey ... B00LQ854AG). Although I'm wondering if I can use two of these at the same time with a single Rpi board or Compute Module.

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jbeale
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Tue May 16, 2017 8:17 pm

I'm not aware of any good-quality, true 180-degree FOV camera, either as an optional lens for the R-Pi camera or as a standalone USB camera.
You can try searching for example "180 degree USB" in google and see what you get. Amazon does list some USB cameras claiming 180 degrees.

The product listings I have seen include several pictures of the camera, but no pictures taken by the camera. You may ask yourself, why that is?
If the product delivered a decent quality image, I expect the seller would be willing to show the evidence.

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Gavinmc42
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Wed May 17, 2017 2:47 am

What about using a mirror?
I've seem optical flow researchers make mirrors from lathe turned aluminum bar then polished.
Just about any mirror could be made this way.

Or something like thse
https://singularityhub.com/2012/05/02/3 ... martphone/
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301217638
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Fri May 19, 2017 4:32 pm

jbeale wrote:
As an example, here is one fisheye claiming support for 1/4 and 1/3 inch sensors. Not exactly cheap, either.
https://www.vision-dimension.com/en/len ... winkel/209 ...but this lens has an image circle of 3.4mm in diameter, meaning the 3.67 x 2.74 mm sensor on the RPi v1.3 camera would crop it significantly on top & bottom.
I'm a little confused here about why the Rpi camera image sensor size is 3.67 x 2.74 mm. Isn't the Rpi camera 1/4", which is 3.2 mm x 2.4 mm (as shown here https://www.jlab.org/accel/beam_diag/vi ... r_size.gif)?

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jbeale
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Re: full-circle M12 fisheye lens for 1/4 inch sensor?

Fri May 19, 2017 5:26 pm

In a word, no. Those image sensor size categories (1/4, 1/3 etc) are not standardized, they are only approximate bins or size ranges, and each manufacturer, even each separate product has its own dimensions. There are also often 4:3 and 16:9 aspect ratio sensors, again with the same label but of course different actual dimensions. The exact numbers for the RPi v1 and v2 cameras are available at http://elinux.org/Rpi_Camera_Module

RPi v1 camera sensor size: 3.67 x 2.74 mm (Omnivision OV5647)
RPi v2 camera sensor size: 3.674 x 2.760 mm (Sony IMX219PQ)

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