Could one change the lens in A119 Mini2 ?

[d986p]

Hi,

The sensor in this device seems to be enclosed in an M12/cs mount. Now ... is it possible to remove the IR filter or if needed, change the M12 holder and an IR pass lens to use this camera in NIR ?

Thanks and regards

 

[Nigel]

Yes, should work quite well as an IR camera, the sensors are designed for NIR use, although you may find the IR image rather out of focus since the lens is not designed for IR use, so it may be better to install a lens actually designed for IR. The lens just unscrews from the M12 mount, so replacement is quite easy,.

 

[d986p]

Thank you Nigel !

What I worry about is where the IR block filter is ... With the lens or with the lens holder ..

If with the holder, then I will also have to either change the holder with one that does not or break the plate.

 

[Nigel]

Thank you Nigel !

What I worry about is where the IR block filter is ... With the lens or with the lens holder ..

If with the holder, then I will also have to either change the holder with one that does not or break the plate.

I've not seen inside a Mini 2, but all Viofo cameras that I have seen inside have the IR cut filter glued to the bottom of the lens, so when you unscrew the lens the filter comes out too, then you can try to unglue it, or much easier break it and remove the pieces, or probably more sensible, replace the lens by one without an IR cut filter. I think the sensor is quite big for an M12 mount, so be careful if buying a new lens, or the edges of the image will not be good.

 

[Dashmellow]

you unscrew the lens the filter comes out too, then you can try to unglue it, or much easier break it and remove the pieces, or probably more sensible, replace the lens by one without an IR cut filter.

Breaking an IR-cut filter into little pieces in order to remove it from a lens is never a good idea, although one can find many examples of this method being demonstrated on YouTube.

The proper method for removing an IR filter from the back of an M12 lens is to apply a modest amount of heat using a hair dryer or heat gun which will soften the UV setting optical cement that was used to install it at the factory. It should easily come right off.

In all likelihood there is no reason to replace the lens unless you wish to alter the focal length, aperture or other optical qualities of your existing lens.

Always handle the lens and filter while wearing white cotton or nitrile gloves and you can then save the IR filter for a future project or perhaps to restore your camera to it's original state if so desired.

 

[d986p]

Awesome ! Huge thanks to the both of you !

@Dashmellow
I want to use it in total darkness with ir led or lasers and telephoto lens ... I was aiming to buy an imx462 module for raspberry pi for this. But this sensor is starvis 2 and within my budget.
Will buy another lens without ir block filter. So get to use both as a dashcam and as a night vision in NIR ...

 

[gse]

Will buy another lens without ir block filter. So get to use both as a dashcam and as a night vision in NIR ...

This is the original Mini 2.
You don't need to break anything.
I think you can warm it up, pick it up with a needle and remove it.
If you remove the IR filter, then the video will be like a barbie, everything is in pink.

 

[Dashmellow]

Awesome ! Huge thanks to the both of you !

@Dashmellow
I want to use it in total darkness with ir led or lasers and telephoto lens ... I was aiming to buy an imx462 module for raspberry pi for this. But this sensor is starvis 2 and within my budget.
Will buy another lens without ir block filter. So get to use both as a dashcam and as a night vision in NIR ...

Not so sure about lasers but IR emiiting LEDs should work fine. Keep in mind that if you want to use a telephoto lens with IR LEDs you will need a fairly powerful IR light source depending on the distance of your subject. What do you want this modifed camera for anyway?

You may find this six year old post of mine interesting and instructive. I used the LED emitters from an old CCTV camera to illuminate an outdoor scene capturing foxes at night on a Mobius camera fitted with an IR telephoto lens. The LED light source has 42 emitters. Using the same set-up with a modern Starvis 2 sensor would likely be far more effective than with the older sensor on the original Mobius camera.

Mobius Varifocal Zoom IR​

As @gse mentioned when you remove the IR-Cut filter your images will look pinkish or magenta during daylight hours like in the image below but at night in the dark you will just see black & white images under IR illumination.

 

[Nigel]

Awesome ! Huge thanks to the both of you !

@Dashmellow
I want to use it in total darkness with ir led or lasers and telephoto lens ... I was aiming to buy an imx462 module for raspberry pi for this. But this sensor is starvis 2 and within my budget.
Will buy another lens without ir block filter. So get to use both as a dashcam and as a night vision in NIR ...

Don't use lasers, you are likely to damage the sensor. I don't see how you would get a decent image anyway?

Do bare in mind that if you want a lens, and especially a telephoto lens, to focus in both visible and IR light then you really need one that is designed to do so, a normal lens designed only for visible light is likely to have very poor focus in IR even if carefully focused. Also, the sensor has a limited frequency range, so choose your IR LED frequency to match.

As said above, you will end up with magenta images whenever there is IR light in the image.

 

[Dashmellow]

Do bare in mind that if you want a lens, and especially a telephoto lens, to focus in both visible and IR light then you really need one that is designed to do so, a normal lens designed only for visible light is likely to have very poor focus in IR even if carefully focused. Also, the sensor has a limited frequency range, so choose your IR LED frequency to match.

I do understand the principle you are talking about regarding IR focus issues and it is certainly valid but after many years of experimenting with and modifying lenses in both dash cams and CCTV cameras I find that it is not as big a problem as one might think. There is quite a bit of wiggle room between theory and practice when it comes to these things and I have had good success finding a good point of focus that works well in both daylight and under IR light.

In fact, most CCTV cameras on the market use solenoid operated IR-cut filters that are removed from the light path at night using a photo-diode and then reinserted into the light path of the lens in the morning for normal color imagery. These cameras use pretty standard lenses and indeed most standard M12 lenses on the market seem up to the task. Many say "IR" right on the bezel. Even lenses that do not have that designation seem to work fine. Only once did I encounter a lens that I could not get to focus in both environments.

Nevertheless, anyone who wants to experiment with IR lenses should understand the principle at work. IR light focuses at a different plane on the sensor than visible light and this can result in either the night or daylight image being slightly out of focus depending on the initial point of focus. Some sensors seem more accommodating of this than others due to how they collect light.

 

[d986p]

Felling like running around like a lilliput near the legs of a couple of very knowledgeable godly giants trying to listen and understand the topic of their discussion. Ecstatic right now

With the little I understand about optics, it seems the further away a lens focus (in VIS light) is , the extended the focus points for various wavelength gets due to further fanning out. it is like cutting the rainbow at even shallower angles.

Only going for say 850 nm to 950 nm. I think 850 led is what I want. Checked the frequency response curve for IMX462. most responsive in that range. hope this will be somewhat similar.

@Dashmellow
I thought IR written on the lens meant it had anti reflective coatings that worked in IR range too. So it was usable in IR.
Or may be it means it has IR block to improve VIS light photography .. which is true ? I googled this now and failed to ascertain this.

Me wanting VCSEL 850 nm laser is cause , these waste less power as heat and gives off stronger light that will travel further afield. and VCSEL s have more symmetrica beam right off he device without lens etc to form and collimate the beam. Wont e focusing and certainly not pointing towards lens sensor though.
@Nigel
I want to use it at night. So no issues with its performance at daytime. I like to trek and go to forlorn areas and jungles. It has always been my habit to be in the dark when alone outside and not light torch unless really need to. simply to enhance personal safety. feel safer in the dark. Cause usually people will think I am sleeping.

This will be my eyes in the dark. Might also Buy LWIR devices like topdon or Infiray. Working for this first cause I can illuminate here.

Thank you for all your kind responces , guys !!!

 

[Nigel]

I think 850 led is what I want.

I guess you know that most people can see a red glow from an 850nm source if they look directly at the source, but the sensor is more sensitive to 850 and it generally gets better focus because it is closer to visible light.

Checked the frequency response curve for IMX462. most responsive in that range. hope this will be somewhat similar.

Yes, Sony keep trying to improve their IR sensitivity, but the Starvis sensors are all very similar on frequency response, Starvis is designed for security cameras, including IR.

With the little I understand about optics, it seems the further away a lens focus (in VIS light) is , the extended the focus points for various wavelength gets due to further fanning out. it is like cutting the rainbow at even shallower angles.

It depends a lot on the lens, the issue is chromatic aberration if you actually want to research it, some lenses have better correction for it than others, some just don't bother correcting the IR. I don't think the sensor has anything to do with focus, at least for normal flat sensors.

I thought IR written on the lens

Given that most of these lenses are of cheap Chinese manufacture, the IR marking could mean anything or nothing! If you go for a proper Japanese lens then it may mean something, but still be different between manufacturers! Some of the cheap Chinese lenses are very good, you just don't know what you are getting until you test it!

 

[Dashmellow]

The really cheap IR Chinese M12 lenses are probably nothing more than clear glass with IR printed on the bezel. Better quality IR lenses are designed to optimize, collect, focus and collimate light in the NIR (near infra-red) and SWIR (short wave infra red) spectrum by using specific substrates or anti-reflection coatings to maximize performance for applications operating above 650nm. Some use germanium in the glass formulation and other related elements to achieve this.

Because glass has different refractive indices for the light of different wavelengths, the position of the focal point will be different. That is why there can be focus issues between IR and daytime photographic capture. However, there is some leeway as some of these IR lenses can gather light in the 430-900nm range or greater. Neverthess, however these M12 IR lenses are optimized they do transmit the full spectrum of wavelengths and when fitted with an IR-cut filter they perform as normal lenses as evidenced by dash cams and action cameras.

For someone who simply wants to remove the IR filter from a standard lens there will be no issue as long as you focus it properly for your intended purpose. When you use the same lens for IR photography and natural light photography things become more challenging but it can work. As I've mentioned, this is how virtually all IR enabled CCTV cameras function as they use solenoid operated IR filters that are removed from the light-path at night when a photo-diode detects that the illumination has dropped to below 5 Lux and returned to the light-path in the morning when the level exceeds about 5 Lux. Most CCTV cameras offer excellent focus and performance both day and night without requiring refocusing on the fly.