SJCAM SJ8 for NIGHT VISION? Please help

[Dashmellow]

I would suggest buying only one F1 at first in order to see how well it works for you. You may find that a different camera will make a good compliment to the F1. The Gitup1 for example is available at a very attractive price these days (with Pro packaging) and it's a camera that has big pixels that offer fairly decent low light performance. It's a really versatile, well made camera that happens to be pretty easy to open up and work on for customizing. Of course, you can always go for the second F1 if you really like it.

 

[elchivatto]

Very good camera, but sometimes I'll need 60fps at daytime, so I'll need another option.
Oh, one more thing, I asked to guys from "threeye" what lens is needed for the mod the F1 and they said something that I can't understand

"So you mean you want a camera which you could use it at night time, if so, that need a lens with 850nm ir filter, and per your requirement, i recommend you this lens, but you need to leave a message in your order so our collegue would see and replace the ir filter by 850nm ir filter, ok? thank you.

https://www.aliexpress.com/store/pr...l?spm=2114.12010612.8148356.25.28045efeCKGTXs

I thought that I need a lens without any filter, but he said 850nm filter for IR... I had search about it but there a lot of kinds of filters recommended for different situations. So again, which one I need? I want to my camera could see the most colours possible, not only black and white, specially the skin and faces if there's some light, because black and white sometimes looks creepy or weird warm colours are more natural, like pink or orange

 

[Dashmellow]

Very good camera, but sometimes I'll need 60fps at daytime, so I'll need another option.
Oh, one more thing, I asked to guys from "threeye" what lens is needed for the mod the F1 and they said something that I can't understand

"So you mean you want a camera which you could use it at night time, if so, that need a lens with 850nm ir filter, and per your requirement, i recommend you this lens, but you need to leave a message in your order so our collegue would see and replace the ir filter by 850nm ir filter, ok? thank you.

https://www.aliexpress.com/store/pr...l?spm=2114.12010612.8148356.25.28045efeCKGTXs

I thought that I need a lens without any filter, but he said 850nm filter for IR... I had search about it but there a lot of kinds of filters recommended for different situations. So again, which one I need? I want to my camera could see the most colours possible, not only black and white, specially the skin and faces if there's some light, because black and white sometimes looks creepy or weird warm colours are more natural, like pink or orange

60fps, Oh, ok I forgot about that part.

Anyway, sometimes there is a bit of a language barrier with vendors on AliExpress except that my experience with Treeye has been pretty good, especially with Sophie who seems to have very good English language skills. The folks at Treeye are happy to converse with you and they go out of their way to be helpful so I would try again to explain what you need. Then again it is good to already know what you need before you order.

One of the main things you'll need to know when buying a lens is the sensor it is designed for. Each lens throws a "circle of coverage" big enough to cover the size of the particular sensor. If the lens makes an image circle that is too small for the sensor you will get vignetting. You can use a lens that throws a bigger circle of coverage than required for the sensor in your camera and this can provide excellent results because most lenses are sharper towards the middle of their coverage but you will end up with some degree of telephoto effect using such a lens. This can be fine and if you choose an appropriate focal length to accommodate for the smaller sensor it opens up the range of available lenses to choose from. Obviously, in your case you will want a high quality lens with the biggest possible aperture. That thread I referred you to where I put a CCTV IR zoom lens on a Mobius action cam was an example of what I am talking about. The zoom lens is designed for a 1/2.5" sensor (bigger) but is installed on the Mobius camera with a 1/3" sensor (smaller).



This is a graphic I created to demonstrate what I was referring to above about what to expect when you use a lens with a larger circle of coverage on a smaller sensor.
The red and white rectangles represent two different sized sensors.

 

[elchivatto]

Your explanations are very clear, you're a definitely a good teacher.
What do you think about the filter? Should I buy a lens without filter (full spectrum), or with the 850nm they said?

 

[Dashmellow]

Your explanations are very clear, you're a definitely a good teacher.
What do you think about the filter? Should I buy a lens without filter (full spectrum), or with the 850nm they said?

Well, if you want to use the lens with your IR torch you don't want any sort of IR-cut filter on it. It's not really too hard to add a filter on the back of the lens yourself later on if you want to. There is some discussion here on DCT that will explain more about how to do that. Basically, you just buy an IR-cut filter of the correct size and carefully attach it using inexpensive UV cured cement. If you read through that whole thread about the IR zoom lens on the Mobius, I started out with an IR lens without a filter and added an IR-cut filter several months later which turned it into a normal lens.

 

[elchivatto]

Thank you!!

 

[elchivatto]

Hi again guys. I'm still having some doubts, I hope I'm not bothering too much.
1. About the IR flashlight, there are different options 940nm and 850nm. Wich one should I buy?
2. For short distance, is better a zoomable flashlight attached to the camera, or better buy the tiny LEDs and put them around the lens?
3. Looks like the Threeye guys don't understand so well, I asked them 3 times and they recommend different lens. The last one was a 2.8mm 4K starlight lens, with aperture F 1.2 do you think this is the best choice?

 

[kamkar]

940 Nm you cant see wit the eye ( looking at the source itself,,,, and be careful with that IR light can damage eyes though you cant really see it )
850 Nm lights you can see as a faint red glow

So in a dark place people will see you 850 nm light if you point it at then, that will not happen with a 940 nm one
Personally i use 850 nm for when i shoot rats at night and on my home made night vision goggle.

you can see it for yourself if you walk around at night looking at CCTV cameras.

 

[Nigel]

940 Nm you cant see wit the eye ( looking at the source itself,,,, and be careful with that IR light can damage eyes though you cant really see it )
850 Nm lights you can see as a faint red glow

So in a dark place people will see you 850 nm light if you point it at then, that will not happen with a 940 nm one
Personally i use 850 nm for when i shoot rats at night and on my home made night vision goggle.

you can see it for yourself if you walk around at night looking at CCTV cameras.

Also the sensors are normally a lot more sensitive to the 850 light so that is normally the one to use.

 

[kamkar]

Yes that seem to be the case, but my one 940 Nm light are much smaller than any 850 nm i have.
I would go for 850 nm for sure.

 

[elchivatto]

Please, what can you say about the questions 2 and 3?

 

[kamkar]

#2 a "zoomie" as it is called among flashlight addicts i think will be fine, they most often go from extreme flood ( spread ) to extreme beam, but zoomed in you can get a square hot spot, but a round or square dot of light dont matter to me.
you can see what i mean in this video of a zoomie.

On my NVG ( Night Vision Goggle ) i do only use a cluster of regular 5 mm LEDs, but it also only work good for the area just in front of me, but besides the wider the FOV on the lens the more it make things to apper farther away then they really are, on my NVG i use a 4 mm lens ( i think ) but this mean distance as i see it in the goggle are natural but my FOV are lesser then.

#3 a F 1.2 means it let thru more light to the sensor, the smaller F number the more light is passed thru the lens, and F 1.2 is about as good as it get in this regard.