Question on Lenses.

Lola

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Dash Cam
Mobius, A119
@Dashmellow I have been been emailing Edmond's about a 12mm lens for dash cam use. One of there technicians emailed me this question that confused me! He asked, how far did I want to go with IR ?
This confuses me. If a lens is IR corrected isn't that enough?
I explained in another email (the first) that I wanted the best video I could get at a reasonable price. I also asked why it was practically impossible to find a M12 type lens of 12mm with a aperture of 1.6 or lower, he didn't answer that.
Is there something wrong with my question?
 
I guess he is asking what types of IR light you want to see? That is, how far into the IR band you want the lens to be able to focus correctly.

I suspect you don't want any IR light, you actually want an IR filter to remove the IR light.
 
Probably people used to handle CCTV lenses that all are IR pass as on CCTV cameras there are a active IR block filter in the mount so you can block IR in daytime and let it thru in night time to get use if IR illumination by the camera or other source.
 
@Dashmellow I have been been emailing Edmond's about a 12mm lens for dash cam use. One of there technicians emailed me this question that confused me! He asked, how far did I want to go with IR ?
This confuses me. If a lens is IR corrected isn't that enough?
I explained in another email (the first) that I wanted the best video I could get at a reasonable price. I also asked why it was practically impossible to find a M12 type lens of 12mm with a aperture of 1.6 or lower, he didn't answer that.
Is there something wrong with my question?

The sensors in our dash cams are sensitive to the near Infra-Red spectrum as well as the visible spectrum. IR starts at 700 nm (nanometers or nanometre) and for photography extends to about 1,000 nm. (1,000 nm is one micron.) Longer wavelength IR is used in systems to see heat levels as in thermal imaging cameras like the Flir are between 1 - 10 microns or 1,000 to 10,000 nm. For our purposes we are concerned with "near infra-red" of approximately 700 nm to 1000 nm or thereabouts. (That's essentially what we want to block with the standard IR cut filters that come on dash cam lenses.)

Certain aspects of the near infra-red spectrum are of interest to photography hobbyists and for scientific purposes and for those purposes various glass or dichroic filters are available that can pass or block specific parts of the near infra-red spectrum to achieve specific effects. That is probably why he is asking the question. Then again, he might also have asked "how far you want to go?" because perhaps you might want a lens capable of being used on a thermal imaging camera which works well beyond the near infra-red part of the spectrum.

For photography purposes you can read all about this kind of thing at LifePixel.com and see some examples of what various IR filters can do. Some of these IR filter effects can also be mimicked in Photoshop as explained on that site. With a camera that allows you to access and manipulate the entire RGB 0-255, 8 bit color pallete such as the Mobius you can make various color corrections directly in-camera as I did with the varifocal IR lens I installed in one of my cams and that I demonstrate in my thread about that project.

Edmund Scientific (along with Edmund Optics) is a scientific supply house and it sounds like the technician is a geek who is trying to offer you the expertise he usually offers to students, professors, scientists, experimenters and industry who usually turn to a place like that for their needs. He probably doesn't "get" that you are asking for a normal IR corrected lens for normal video capture.

I guess to answer his question you just need to say that you want to shoot normal video with the entire near infra-red spectrum blocked.

On the other hand, Edmund might not be the best place to find what you are looking for.
 
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The sensors in our dash cams are sensitive to the near Infra-Red spectrum as well as the visible spectrum. IR starts at 700 nm (nanometers or nanometre) and for photography extends to about 1,000 nm. (1,000 nm is one micron.) Longer wavelength IR used in systems to see heat levels as in thermal imaging cameras like the Flir are between 1 - 10 microns or 1,000 to 10,000 nm. For our purposes we are concerned with "near infra-red" of approximately 700 nm to 1000 nm or thereabouts. (That's essentially what we want to block with the standard IR cut filters that come on dash cam lenses.)

Certain aspects of the near infra-red spectrum are of interest to photography hobbyists and for scientific purposes and for those purposes various glass or dichroic filters are available that can pass or block specific parts of the near infra-red spectrum to achieve specific effects. That is probably why he is asking the question. Then again, he might also have asked "how far you want to go?" because perhaps you might want a lens capable of being used on a thermal imaging camera which works well beyond the near infra-red part of the spectrum.

For photography purposes you can read all about this kind of thing at LifePixel.com and see some examples of what various IR filters can do. Some of these IR filter effects can also be mimicked in Photoshop as explained on that site. With a camera that allows you to access and manipulate the entire RGB 0-255, 8 bit color pallete such as the Mobius you can make various color corrections directly in-camera as I did with the varifocal IR lens I installed in one of my cams and that I demonstrate in my thread about that project.

Edmund Scientific (along with Edmund Optics) is a scientific supply house and it sounds like the technician is a geek who is trying to offer you the expertise he usually offers to students, professors, scientists, experimenters and industry who usually turn to a place like that for their needs. He probably doesn't "get" that you are asking for a normal IR corrected lens for normal video capture.

I guess to answer his question you just need to say that you want to shoot normal video with the entire near infra-red spectrum blocked.

On the other hand, Edmund might not be the best place to find what you are looking for.


I has become frustrating to deal with them. No matter what I say I want they come back with different proposals kinda, I could understand if it was meant to make me what I need instead of what I want, but that doesn't seem to be the case, I asked for a M12 type lens, 12mm with IR filter, f1.4, but they came back today giving me the option of getting up to a 8mm lens with a f1.8, that's a lot different from my perspective, but photography/lenses is something I've tried to learn in a couple weeks and that's impossible!

Another question if you have the time is on apertures, I asked for a 1.4 because I thought that would give a bright picture. However no one seems to have them in that size for a M12 type lens practically all start at 1.8 and go up (numerically). I've sent emails to companies to explain why to no avail or answer most of the time.
For dash cams I thought what I was doing would be great but since they (1.4's) aren't available (only a couple from China at $100.00 delivered to US) I thought it was time to ask/bother you to find out if I'm doing the wrong thing in my specification requests?

Where is the best place to search for a lens.
 
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I has become frustrating to deal with them. No matter what I say I want they come back with different proposals kinda, I could understand if it was meant to make me what I need instead of what I want, but that doesn't seem to be the case, I asked for a M12 type lens, 12mm with IR filter, f1.4, but they came back today giving me the option of getting up to a 8mm lens with a f1.8, that's a lot different from my perspective, but photography/lenses is something I've tried to learn in a couple weeks and that's impossible!

Another question if you have the time is on apertures, I asked for a 1.4 because I thought that would give a bright picture. However no one seems to have them in that size for a M12 type lens practically all start at 1.8 and go up (numerically). I'e sent emails to companies to explain why to no avail or answer most of the time.
For dash cams I thought what I was doing would be great but since they (1.4's) aren't available (only a couple from China at $100.00 delivered to US) I thought it was time to ask/bother you to find out if I'm doing the wrong thing in my specification requests?

Where is the best place to search for a lens.

I'm not sure why they would offer you a different focal length lens. As for the question of "IR filter", based on my previous post it may be helpful to say IR-CUT filter instead of "IR" filter.

As I mentioned, Edmunds may not be the best place to buy a M12 lens for a dash cam.

It's not especially easy to find large apertures on some of the longer focal length M12 lenses. Peau Productions sells a 2MP ƒ/1.6 12mm with an IR-cut filter. (this might be the same one @kamakar1 bought)

AliExpress might be the best bet to find what you want. I've actually been poking around over there myself looking at faster, longer focal length lenses similar to the Starlight one @dirkzelf has been testing but I haven't had the time to really explore thoroughly. You'll find some faster lenses there in the 6mm and possibly 8mm range that are intended for a 1/2.5" sensor so they should provide a greater telephoto effect when used on a smaller sensor camera like the Mobius.
 
I'm not sure why they would offer you a different focal length lens. As for the question of "IR filter", based on my previous post it may be helpful to say IR-CUT filter instead of "IR" filter.

As I mentioned, Edmunds may not be the best place to buy a M12 lens for a dash cam.

It's not especially easy to find large apertures on some of the longer focal length M12 lenses. Peau Productions sells a 2MP ƒ/1.6 12mm with an IR-cut filter. (this might be the same one @kamakar1 bought)

AliExpress might be the best bet to find what you want. I've actually been poking around over there myself looking at faster, longer focal length lenses similar to the Starlight one @dirkzelf has been testing but I haven't had the time to really explore thoroughly. You'll find some faster lenses there in the 6mm and possibly 8mm range that are intended for a 1/2.5" sensor so they should provide a greater telephoto effect when used on a smaller sensor camera like the Mobius.

Thanks for the reply and links. I've used AliExpress and Alibaba on quite a few occasions, they basically put you in touch with intermediary's that speak english and act as salesman for various companies in China, after writing to many of these companies you will find they are offering the same lenses or sure seem to be.
When you ask for a particular lens giving the specifications you want you will receive lots of replies usually quite different from what you requested, make sure you get it across that you are not interested in anything but what you have specified are you will get replies that are all over the place. Miss Wu is the main intermediary I have dealt with but a few others, be very careful. My last reply was from Miss WU was about a lens $60.00 + $30. shipping.
This seems to be one of the better manufactures: https://www.aico-lens.com/products/cs-mount-lens/ Their are many many others, but like I said before somehow they all seem to carry the same lenses or not much difference if any. You will run into Miss Wu a lot. When you can finally get a price they will be all over the place for the same lens from different places.

I took your advice on the lens you ordered from Banggood and ordered it also.
Also the lens that kamkar 1 bought at Peau Productions was from China, you will run into that one a few times, by that I mean it has the same specs, but who knows if it is the same lens, however that is all we have to go on.
I don't remember seeing a Starlight Lens, I'll check it out.

Thanks for all your help, it is appreciated very much.
 
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