bmurphy
Posts: 6
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Alternative to 6mm Lens

Fri Jun 26, 2020 6:33 pm

I'm extremely pleased with the 16mm C-mount lens. I've been able to take some extraordinary pictures with it when the lighting is just right, but the FOV is too small and I don't always want to zoom in so close.

The 6mm lens on the other hand, I'm not as pleased. I've gotten some good closeups and it gets the job done, but it's a struggle to use, the FOV is a little too large for my tastes, and I don't much care for the fisheye distortion.

I'm looking for a lens that sits somewhere between these two. I'd like one with a wider FOV than the 16mm lens that I can take closer (but not too close) pictures without the distortion of the 6mm lens. Something that's a little bit more like a traditional camera without zoom.

Any suggestions?

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darkskyseeker
Posts: 40
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Re: Alternative to 6mm Lens

Sun Jun 28, 2020 8:33 pm

bmurphy wrote:
Fri Jun 26, 2020 6:33 pm
I'm looking for a lens that sits somewhere between these two. I'd like one with a wider FOV than the 16mm lens that I can take closer (but not too close) pictures without the distortion of the 6mm lens. Something that's a little bit more like a traditional camera without zoom.
I'd like to hear what is suggested as your issues reflect mine. Although, I am having great success with the 6mm.

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HermannSW
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Re: Alternative to 6mm Lens

Sun Jun 28, 2020 10:17 pm

bmurphy wrote:
Fri Jun 26, 2020 6:33 pm
I'm looking for a lens that sits somewhere between these two. I'd like one with a wider FOV than the 16mm lens that I can take closer (but not too close) pictures without the distortion of the 6mm lens.
All FOVs stated here are horizontal.

FOV of Raspberry 16mm lens is 30°, of 6mm lens is 63°.


I got quite some M12, CS and C mount lens samples from Lee from Arducam for testing.
I like most (sofar) 35mm lens, but 10° FOV is not what you want.

Among the C, CS and M12 mount lenses I have, these are in 30°..63° range:
31° https://www.uctronics.com/arducam-31-de ... amera.html
80°-32° https://www.uctronics.com/arducam-c-mou ... amera.html
120°-38° https://www.uctronics.com/arducam-c-mou ... amera.html
50° https://www.uctronics.com/arducam-50-de ... amera.html
50° https://www.uctronics.com/arducam-m12-l ... apter.html

I did test M12 lens kit here:
viewtopic.php?t=249483#p1674141

And 4-12mm varifocal C-mount lens here:
viewtopic.php?f=43&t=278434

8mm lenses post:
viewtopic.php?f=43&t=272658&p=1680918#p1680918


I have a cheap 12MP rated CS-mount lens with slightly more than 44° FOV as well.
jbeale calculated that it should be 8.3MP effectively for the HQ camera:
viewtopic.php?f=43&t=272658&start=75#p1656823


I can take photos with some of those lenses in case you want, and let me know how (distance, scene, ...).


https://stamm-wilbrandt.de/en/forum/20200605_140143.jpg
20200605_140143.10%.jpg
20200605_140143.10%.jpg
20200605_140143.10%.jpg (23.38 KiB) Viewed 612 times
https://stamm-wilbrandt.de/en/Raspberry_camera.html
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/raspiraw
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/github_repo_i420toh264

bmurphy
Posts: 6
Joined: Tue Jun 23, 2020 11:35 pm

Re: Alternative to 6mm Lens

Mon Jun 29, 2020 2:17 am

Ooh, thanks for the links. I'll spend some time reviewing your tests tomorrow.

I recorded a parade today, I tried both the 6mm and the 16mm and settled on the 16mm. I'm having trouble getting as good of an image out of the 6mm. Today there was a washed out haze in the middle that I couldn't get rid of while using the 6mm. The colors don't look as good and everything seems to have some kind of ugly grain to it. I'm not sure if I have any pictures/footage from this afternoon with the 6mm, I was short on time so I couldn't investigate like I would have liked.

I'll try to find some time this week to do a side-by-side comparison of the two, get more concrete examples of what's frustrating me. It's entirely possible I'm just using it wrong.

W. H. Heydt
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Location: Vallejo, CA (US)

Re: Alternative to 6mm Lens

Mon Jun 29, 2020 5:27 am

A bit of history... A "normal" lens for still photography has a focal length equal to the diagonal of the image area. For a 35mm still camera, that works out to about 43mm focal length. In actual practice, the usual "normal" lens for 35mm work is 50mm. For cine work, the field of view in generally about half that for still work. For 16mm cine, a "normal" lens is 25mm focal length. C-mount is used extensively in 16mm cine cameras. Major mail order (or, these days, web order) companies are likely to have a tremendous variety of C-mount and CS-mount (used in video) lenses, both new and used.

So...some of it comes down to what you're shooting. You'll want longer lenses for shooting video than you will for stills.

(I"m a bit of an outlier on this as I much prefer long lenses for still work. My longest from 35mm camera days has a focal length of 600mm. I've seen pictures of 2500mm lenses...)

bmurphy
Posts: 6
Joined: Tue Jun 23, 2020 11:35 pm

Re: Alternative to 6mm Lens

Thu Jul 02, 2020 2:33 pm

I haven't had a chance yet to do a side by side comparison, but I have been re-reading the Raspberry Pi High Quality Camera thread, and this comment in particular captures the issues I'm having with the 6mm lens to a T:

viewtopic.php?f=43&t=272658&start=50#p1656279

mark79
Posts: 16
Joined: Thu May 23, 2013 3:50 pm

Re: Alternative to 6mm Lens

Thu Jul 02, 2020 6:35 pm

HermannSW wrote:
Sun Jun 28, 2020 10:17 pm
bmurphy wrote:
Fri Jun 26, 2020 6:33 pm
I'm looking for a lens that sits somewhere between these two. I'd like one with a wider FOV than the 16mm lens that I can take closer (but not too close) pictures without the distortion of the 6mm lens.
All FOVs stated here are horizontal.

FOV of Raspberry 16mm lens is 30°, of 6mm lens is 63°.


I got quite some M12, CS and C mount lens samples from Lee from Arducam for testing.
I like most (sofar) 35mm lens, but 10° FOV is not what you want.

Among the C, CS and M12 mount lenses I have, these are in 30°..63° range:
31° https://www.uctronics.com/arducam-31-de ... amera.html
80°-32° https://www.uctronics.com/arducam-c-mou ... amera.html
120°-38° https://www.uctronics.com/arducam-c-mou ... amera.html
50° https://www.uctronics.com/arducam-50-de ... amera.html
50° https://www.uctronics.com/arducam-m12-l ... apter.html

I did test M12 lens kit here:
viewtopic.php?t=249483#p1674141

And 4-12mm varifocal C-mount lens here:
viewtopic.php?f=43&t=278434

8mm lenses post:
viewtopic.php?f=43&t=272658&p=1680918#p1680918


I have a cheap 12MP rated CS-mount lens with slightly more than 44° FOV as well.
jbeale calculated that it should be 8.3MP effectively for the HQ camera:
viewtopic.php?f=43&t=272658&start=75#p1656823


I can take photos with some of those lenses in case you want, and let me know how (distance, scene, ...).


https://stamm-wilbrandt.de/en/forum/20200605_140143.jpg
20200605_140143.10%.jpg

do you have any sample images with the 2.8-12mm lens at 2.8mm (or any other wide or ultra-wide angle lens with minimal barrel distortion) ?

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HermannSW
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Location: Eberbach, Germany
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Re: Alternative to 6mm Lens

Thu Jul 02, 2020 8:02 pm

mark79 wrote:
Thu Jul 02, 2020 6:35 pm
do you have any sample images with the 2.8-12mm lens at 2.8mm (or any other wide or ultra-wide angle lens with minimal barrel distortion) ?
I just did capture with 35mm lens and 50× zoom lens in series, in this posting you can see setup on 1st floor window sill:
viewtopic.php?f=43&t=278860#p1689478

I removed zoom lens, and switched 35mm lens with 2.8-12mm varivocal lens.
It is getting dark (street lights are on, 10pm here right now).
So I took a photo with 2.8mm and maximal aperture for getting much light.
I used raspistill's "--focus" feature for focusing, more than 4000.
Here is 8.1MB 12MP image captured with "raspistill -o tst.jpg":
https://stamm-wilbrandt.de/en/forum/var ... erture.jpg
Same photo scaled to 15% for attachement here:
varifocal_2.8mm_maxAperture.15%.jpg
https://stamm-wilbrandt.de/en/forum/varifocal_2.8mm_maxAperture.jpg
varifocal_2.8mm_maxAperture.15%.jpg (49.76 KiB) Viewed 434 times

The video in this posting shows going from 12mm focal length to 2.8mm in small steps, so you can get an idea of distortion:
viewtopic.php?f=43&t=278434


Form testing Arducam M12 lens kit for HQ camera, here you can see different amounts of barrel distortion for 50°, 70°, 90° and 130° M12 lenses:
viewtopic.php?t=249483#p1674386
Image
https://stamm-wilbrandt.de/en/Raspberry_camera.html
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/raspiraw
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/github_repo_i420toh264

mark79
Posts: 16
Joined: Thu May 23, 2013 3:50 pm

Re: Alternative to 6mm Lens

Thu Jul 02, 2020 8:19 pm

HermannSW wrote:
Thu Jul 02, 2020 8:02 pm
mark79 wrote:
Thu Jul 02, 2020 6:35 pm
do you have any sample images with the 2.8-12mm lens at 2.8mm (or any other wide or ultra-wide angle lens with minimal barrel distortion) ?
I just did capture with 35mm lens and 50× zoom lens in series, in this posting you can see setup on 1st floor window sill:
viewtopic.php?f=43&t=278860#p1689478

I removed zoom lens, and switched 35mm lens with 2.8-12mm varivocal lens.
It is getting dark (street lights are on, 10pm here right now).
So I took a photo with 2.8mm and maximal aperture for getting much light.
I used raspistill's "--focus" feature for focusing, more than 4000.
Here is 8.1MB 12MP image captured with "raspistill -o tst.jpg":
https://stamm-wilbrandt.de/en/forum/var ... erture.jpg
Same photo scaled to 15% for attachement here:
varifocal_2.8mm_maxAperture.15%.jpg


The video in this posting shows going from 12mm focal length to 2.8mm in small steps, so you can get an idea of distortion:
viewtopic.php?f=43&t=278434


Form testing Arducam M12 lens kit for HQ camera, here you can see different amounts of barrel distortion for 50°, 70°, 90° and 130° M12 lenses:
viewtopic.php?t=249483#p1674386
Image

thank you for sharing these. do you have (or know of) any wide or ultra-wide lenses that don't have barrel distortion?

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HermannSW
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Location: Eberbach, Germany
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Re: Alternative to 6mm Lens

Thu Jul 02, 2020 8:40 pm

mark79 wrote:
Thu Jul 02, 2020 8:19 pm
do you have (or know of) any wide or ultra-wide lenses that don't have barrel distortion?
Sorry, no.
https://stamm-wilbrandt.de/en/Raspberry_camera.html
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/raspiraw
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/github_repo_i420toh264

bmurphy
Posts: 6
Joined: Tue Jun 23, 2020 11:35 pm

Re: Alternative to 6mm Lens

Thu Jul 16, 2020 1:24 am

I got a new 35mm lens from Amazon and ran some tests tonight comparing the 6mm, 16mm, and 35mm lenses. I've also gotten better at focusing (still working on iso/color/exposure, etc.) so the 6mm is looking a bit better, especially after post-processing to remove the distortion.

I'm still not entirely satisfied with it, but I'm feeling a little better. I'll run some additional tests tomorrow when I have good lighting and post those.

There's a big jump in quality between the 6mm and 16mm lens. I'm going to keep my eye open for a quality and reasonably priced lens with minimal distortion in the 6mm to 8mm range.

This is the 35mm lens I purchased:

https://www.amazon.com/gp/product/B0773 ... UTF8&psc=1

So far I really like it. I can't wait to try it during the day. Seems like it's really good value for the money ($33).
Last edited by bmurphy on Thu Jul 16, 2020 3:04 am, edited 1 time in total.

W. H. Heydt
Posts: 12604
Joined: Fri Mar 09, 2012 7:36 pm
Location: Vallejo, CA (US)

Re: Alternative to 6mm Lens

Thu Jul 16, 2020 2:59 am

mark79 wrote:
Thu Jul 02, 2020 8:19 pm
thank you for sharing these. do you have (or know of) any wide or ultra-wide lenses that don't have barrel distortion?
The term you want is "rectilinear", as in "rectilinear fisheye". I have a 19mm (intended for 35mm still work) that is 180' FOV across the diagonal and is rectilinear.

bmurphy
Posts: 6
Joined: Tue Jun 23, 2020 11:35 pm

Re: Alternative to 6mm Lens

Thu Jul 16, 2020 3:29 am

This lens looks intriguing:

https://www.arducam.com/product/arducam ... length-af/

I'm curious to see if anybody has experience with that one.

Hermann, I see you have the 8mm lens post linked. I'll be reviewing that, you may have covered this lens in your post.

mark79
Posts: 16
Joined: Thu May 23, 2013 3:50 pm

Re: Alternative to 6mm Lens

Thu Jul 16, 2020 3:59 am

W. H. Heydt wrote:
Thu Jul 16, 2020 2:59 am
mark79 wrote:
Thu Jul 02, 2020 8:19 pm
thank you for sharing these. do you have (or know of) any wide or ultra-wide lenses that don't have barrel distortion?
The term you want is "rectilinear", as in "rectilinear fisheye". I have a 19mm (intended for 35mm still work) that is 180' FOV across the diagonal and is rectilinear.

yes, i'm looking for rectilinear wide or ultra-wide angle (non-fisheye) lenses for the HQ camera, preferably with little to no barrel distortion, and preferably that would also work well for near infrared photography. hopefully good options at reasonable prices will turn up as we explore what's available.

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HermannSW
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Location: Eberbach, Germany
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Re: Alternative to 6mm Lens

Thu Jul 16, 2020 6:54 am

bmurphy wrote:
Thu Jul 16, 2020 3:29 am
This lens looks intriguing:

https://www.arducam.com/product/arducam ... length-af/

I'm curious to see if anybody has experience with that one.

Hermann, I see you have the 8mm lens post linked. I'll be reviewing that, you may have covered this lens in your post.
Sorry, I posted photo of lenses I got from Lee above scaled to 10%, but provided 100% link as well:
https://stamm-wilbrandt.de/en/forum/20200605_140143.jpg
In top "C mount" row I have 5mm and 12mm, no 8mm C mount lens.
https://stamm-wilbrandt.de/en/Raspberry_camera.html
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/raspiraw
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/github_repo_i420toh264

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