hacking a zoom camera

Michael_K

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I'm working on hacking up a zoom camera. This would complement my regular car DVR, and a 2-camera system would give me an interior camera (with IR).

I need some guidance here.

First, I read here that car DVRs use M12 mounts, and that the Mpixel rating of the lens should be at least what the sensor has.

What are recommendations for focal length? I've seen 6 mm up to 25 mm.

Should I be concerned about sensor size? One of the stores mentioned that. (ebay? aliexpress?)

And, it should be "IR cut" -- correct?
 

jokiin

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yes you need an IR filter, there's a bunch of info in the Mobius section from @Harsh and @Dashmellow with various lenses they've tested including results and where to buy, that would be a good place to start your research
 

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You may gain some insight through these threads: Original Mobius with Night Recording and Mobius Telephoto Dashcam

There has also been work done using the F-1 and other cams with telephoto and enhanced night vids. Regular dashcams come with an "IR cut" filter installed, as do some aftermarket lenses. If you want to use IR illumination for total darkness recording you don't want that filter as it blocks (cuts) IR. The downside is that daytime and low-light recording without the filter adversely affects true color rendering and exposure values. Both IR and Telephoto work are fairly deep subjects and quite interesting, and the work regarding them is ongoing with dashcams which you'll find much sharing of here on DCT.

Phil
 
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Michael_K

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AE stores recommended are Fulekan and Treeye.
You were anticipating me asking that, weren't you?
I checked out aliexpress and ebay; there are thousands of lenses from a couple hundred manufacturers. My next question was how to narrow it down.
 

Harsh

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You were anticipating me asking that, weren't you?
I checked out aliexpress and ebay; there are thousands of lenses from a couple hundred manufacturers. My next question was how to narrow it down.
The information is all there but yes, just to make it easier...
 

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I'm working on hacking up a zoom camera. This would complement my regular car DVR, and a 2-camera system would give me an interior camera (with IR).

I need some guidance here.

First, I read here that car DVRs use M12 mounts, and that the Mpixel rating of the lens should be at least what the sensor has.

What are recommendations for focal length? I've seen 6 mm up to 25 mm.

Should I be concerned about sensor size? One of the stores mentioned that. (ebay? aliexpress?)

And, it should be "IR cut" -- correct?
A few days ago you asked the same questions in your thread "looking for a zoom camera" and in several posts I provided the very same links as @Harsh and @SawMaster (and more) to lengthy threads on DIY zoom and telephoto lens modifications that are full of comprehensive information, discussion, videos, screen shots and how-to photos, along with resources and vendor recommendations.

Given the nature of your query I was a bit surprised that you didn't even bother to reply to the responses you received. Now you've started a whole new thread in a different sub-forum about the same thing and others are directing you to those same threads. Everything you want to know about this subject (and more) will be found in those threads, so I'd suggest investing the time to explore them.
 
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Michael_K

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A few days ago you asked the same questions in your thread "looking for a zoom camera" and in several posts I provided the very same links as @Harsh and @SawMaster (and more) to lengthy threads on DIY zoom and telephoto lens modifications that are full of comprehensive information, discussion, videos, screen shots and how-to photos, along with resources and vendor recommendations.

Given the nature of your query I was a bit surprised that you didn't even bother to reply to the responses you received. Now you've started a whole new thread in a different sub-forum about the same thing and others are directing you to those same threads. Everything you want to know about this subject (and more) will be found in those threads, so I'd suggest investing the time to explore them.
Yes, I was wondering what you'd (in the plural sense) think about that. After I started that first discussion, I got to know the forum a bit better. It occurred to me that, maybe, I put it in the wrong section (General discussion). Frankly, I was just going to let that thread end, and continue it here. Perhaps I should have posted something like "Should we move this to DIY?"
Maybe I'm delving into this project to fast. I'm still trying to find a unit to use here.
 

kamkar1

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8 - 12 mm i feel give you the same readable detail as you get with your own eyes, so with Danish / EU plate design this mean i can read a plate on a distance of 5 - 6 car lengths, where a normal lens you get like 1-2 car lengths.
And already here you are down to a field of view of 30 - 40 degrees or there about, and i would not go much more narrow than that personally.

You can get a feel for my 12 mm lens as i pull up behind this painters little VW van, and factoring in i drive a small snub-nosed car where the front plate are 3 - 4 feet or so in front of the bottom part of my windscreen.
So as you can see it is pretty much in your face, just like it is when i am stopped right behind a van. / the focus on this day was a tad too near, i now have it focused out where plates first become readable.


Compared to a regular dashcam you can really see the visual increased reach you get, what are a few pixels out in the distance on a regular dascam, you can tell what it is with the 12 mm lens.

This are the middle 50% of the 2 camera feeds, nothing cut off the side, so as you can see off the video image before you start to play it, the 12 mm lens pretty much just have the middle 1/4 of the regular wide angle camera.
But out at that distance you still have 3 lanes with in the footage so still usable at a fairly short distance if you want a closer look

 
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Michael_K

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8 - 12 mm i feel give you the same readable detail as you get with your own eyes, so with Danish / EU plate design this mean i can read a plate on a distance of 5 - 6 car lengths, where a normal lens you get like 1-2 car lengths.
And already here you are down to a field of view of 30 - 40 degrees or there about, and i would not go much more narrow than that personally.

Compared to a regular dashcam you can really see the visual increased reach you get, what are a few pixels out in the distance on a regular dascam, you can tell what it is with the 12 mm lens.

This are the middle 50% of the 2 camera feeds, nothing cut off the side, so as you can see off the video image before you start to play it, the 12 mm lens pretty much just have the middle 1/4 of the regular wide angle camera.
But out at that distance you still have 3 lanes with in the footage so still usable at a fairly short distance if you want a closer look
For some of the videos done with zoom lenses, they have 25 mm focal length lens. I think that's too much, especially if the road is curved.
I figure I'll get at least a few (e.g. 8 mm, 12 mm, 16 mm), and see which I like best.
 

kamkar1

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Yeah with a long lens making a turn, then the world just rush by sideways while you are turning.
A great many weekend warriors IE people that play with airsoft and paintball weapons have larger lenses on their gear, or snipers at least to they can share their kills with a "scope" like view. ( cross hairs added in post )
I have also played with filming thru the scope of my air rifle, and when i hunt rats at night with IR for light i like to be able to record that too, but at the moment those experiments are on hold.
 

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For some of the videos done with zoom lenses, they have 25 mm focal length lens. I think that's too much, especially if the road is curved.
I figure I'll get at least a few (e.g. 8 mm, 12 mm, 16 mm), and see which I like best.
There is more to determining which focal length lens to purchase than simply picking some random focal lengths to try. Each M12 lens is formatted to match a camera sensor of particular size. While you can use a lens designed for a larger sensor than you may have in your camera the result will be a FOV that appears as if you have installed a longer focal length lens than you actually have. Many dash cams and actions cameras use a 1/3" sensor while a great many aftermarket M12 lenses on the market are optimized for CCTV cameras that have 1/2.5" or 1/2.7" sensors. The inverse also applies. If the lens throws an image circle too small for the sensor you mount it on you will get vignetting.

There are other important considerations in choosing an aftermarket lens for a DIY project like this. Not all M12 lenses are the same. The lens you choose must be able to fit and function with your particular camera's lens barrel, so it requires the proper thread depth and the optical characteristics to match. This means that the lens you purchase must have a compatible BFL (Back Focal Length) and allow for the MBF (Minimum Back Focus) distance from the sensor. So, in some cases you could end up with a lens than can't be screwed in far enough to focus or you could have a lens that you end up screwing in so far attempting to focus it that you could jam it up against the sensor, thus damaging it. For related reasons, depending upon the lens you might also need to know other specs like the FFD (Flange Focal Distance), for instance. (varifocals have a flange) Of course, you'll also want to determine which aperture you want in your new lens.

Again,...... if you take the time to read and explore the threads you were referred to, you will learn all about this.

I think you are going about this backwards. To quote from your earlier post in this thread, "Maybe I'm delving into this project to fast. I'm still trying to find a unit to use here." I would tend to agree. I believe you will be better off first deciding on which camera you wish to modify and only then begin to explore which lens or lenses would work best for your goals and be most appropriate for the camera you've purchased for the project.
 
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There is more to determining which focal length lens to purchase than simply picking some random focal lengths to try. Each M12 lens is formatted to match a camera sensor of particular size. While you can use a lens designed for a larger sensor than you may have in your camera the result will be a FOV that appears as if you have installed a longer focal length lens than you actually have. Many dash cams and actions cameras use a 1/3" sensor while a great many aftermarket M12 lenses on the market are optimized for CCTV cameras that have 1/2.5" or 1/2.7" sensors. The inverse also applies. If the lens throws an image circle too small for the sensor you mount it on you will get vignetting.

There are other important considerations in choosing an aftermarket lens for a DIY project like this. Not all M12 lenses are the same. The lens you choose must be able to fit and function with your particular camera's lens barrel, so it requires the proper thread depth and the optical characteristics to match. This means that the lens you purchase must have a compatible BFL (Back Focal Length) and allow for the MBF (Minimum Back Focus) distance from the sensor. So, in some cases you could end up with a lens than can't be screwed in far enough to focus or you could have a lens that you end up screwing in so far attempting to focus it that you could jam it up against the sensor, thus damaging it. For related reasons, depending upon the lens you might also need to know other specs like the FFD (Flange Focal Distance), for instance. (varifocals have a flange) Of course, you'll also want to determine which aperture you want in your new lens.

Again,...... if you take the time to read and explore the threads you were referred to, you will learn all about this.

I think you are going about this backwards. To quote from your earlier post in this thread, "Maybe I'm delving into this project to fast. I'm still trying to find a unit to use here." I would tend to agree. I believe you will be better off first deciding on which camera you wish to modify and only then begin to explore which lens or lenses would work best for your goals and be most appropriate for the camera you've purchased for the project.
You just have to get the right focal length and sensor distance, and make sure the sensor size listed for the lens is bigger than your camera sensor. Every dashcam seems to use a 1/3" sensor so you probably aren't even going to find a lens that won't cover it

Sellers don't seem to have sensor distance information and considering the time you'd spend trying to find that information I think it's worth just experimenting. I have bought 6 tele lenses and so far I have not found a lens that doesn't work with my Mobius or CCTV cameras. Worst case I had to modify the cases to get the lens to screw in more
 
D

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Here are my product suggestions

Varifocal lens with a shallow thread that may require modification of your camera: https://www.amazon.com/gp/B01HH4MZCM
Set of 6mm 8mm 12mm https://www.amazon.com/gp/B01MDTOU9C
I use the 6mm in a Mobius and the 8mm in a CCTV camera


Edit: OOPS I forgot to mention those don't have IR filters so you need to buy IR filters and glue them to the lens. Tiny spots of superglue or silicone would work. These were the filters I got. Despite the pic only 2 come in an order https://www.amazon.com/gp/B015R07LPO
 
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Michael_K

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Here are my product suggestions

Varifocal lens with a shallow thread that may require modification of your camera: https://www.amazon.com/gp/B01HH4MZCM
Set of 6mm 8mm 12mm https://www.amazon.com/gp/B01MDTOU9C
I use the 6mm in a Mobius and the 8mm in a CCTV camera


Edit: OOPS I forgot to mention those don't have IR filters so you need to buy IR filters and glue them to the lens. Tiny spots of superglue or silicone would work. These were the filters I got. Despite the pic only 2 come in an order https://www.amazon.com/gp/B015R07LPO
Ok, thank you for the suggestions.
Having read several threads here regarding lenses, I'm sure that I'll go with either Treeye, Fulekan, Peau Productions, or M12 lenses.
They've shown that they have good quality, and will accommodate this community.
 

kamkar1

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My 12 mm come from peau, but i think i might have spent more money for that than i needed to.
Those other sites are bookmarked now.
 

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You just have to get the right focal length and sensor distance, and make sure the sensor size listed for the lens is bigger than your camera sensor. Every dashcam seems to use a 1/3" sensor so you probably aren't even going to find a lens that won't cover it

Sellers don't seem to have sensor distance information and considering the time you'd spend trying to find that information I think it's worth just experimenting. I have bought 6 tele lenses and so far I have not found a lens that doesn't work with my Mobius or CCTV cameras. Worst case I had to modify the cases to get the lens to screw in more
For some reason you seem to be parroting much of what I said in my post you are quoting, except that you are over-simplifying how it all works and some of what you say is not quite correct. I'll just leave it at that.

Sellers DO provide the required specs on lenses if you buy from a quality vendor. Most of the vendors that @Michael_K mentions in his post provide those specs and more for example. So when you say that, "Sellers don't seem to have sensor distance information" you are wrong. All the recommended vendors provide the required specs such as BFL and MBF which are in fact the relevant specifications for "sensor distance information".

And it is not a good rule of thumb to "make sure the sensor size listed for the lens is bigger than your camera sensor." You may well want to purchase a lens that matches your sensor size if you want a lens that performs according to its listed focal length. These are indeed available if you look for them.
 
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Dashmellow

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Here are my product suggestions

Varifocal lens with a shallow thread that may require modification of your camera: https://www.amazon.com/gp/B01HH4MZCM
Set of 6mm 8mm 12mm https://www.amazon.com/gp/B01MDTOU9C
I use the 6mm in a Mobius and the 8mm in a CCTV camera


Edit: OOPS I forgot to mention those don't have IR filters so you need to buy IR filters and glue them to the lens. Tiny spots of superglue or silicone would work. These were the filters I got. Despite the pic only 2 come in an order https://www.amazon.com/gp/B015R07LPO

I mostly disagree with your recommendations. The varifocal lens you recommend is quite good actually, except that it is widely available everywhere else for half the price and a good vendor will install an IR cut filter for free. Also, quite a few of us here on DCT have purchased that varifocal lens and no one but you claims that it has shallow threads. Depends on your camera and lens module I guess.

Buying cheap M12 lenses on Amazon where you have no idea what the vendor is shipping you is never a wise plan. Often you'll receive sub standard quality that can't match lenses from a specialist.

OMG!! Do not EVER use Super Glue to attach dichroic filters to a lens. You stand a very good chance of fogging both the filter and the lens!! Don't use silicone either. That can cause similar problems because common silicone out-gases acetic acid fumes. Use UV curing cement which is what lens manufacturers and quality vendors use. There is plenty of good discussion on this subject here on DCT.
 
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Dashmellow

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Ok, thank you for the suggestions.
Having read several threads here regarding lenses, I'm sure that I'll go with either Treeye, Fulekan, Peau Productions, or M12 lenses.
They've shown that they have good quality, and will accommodate this community.
Sounds like you've made some headway in exploring more about this subject before jumping in. That's great! It will make a big difference as you proceed with your project. All those vendors are excellent except maybe M12 lenses. One fellow posted some examples of a lens he purchased from them that appeared to be seriously defective or of very poor quality and this turned me off to that vendor. They also don't provide as much info as to what they are selling as the other vendors do. Their stuff seems to be more on the low end of things regardless of price. I'd stick with Treeye, Fulekan or Peau. There are a couple of other good vendors on AliExpress but for now that's a great start and you can't go wrong. Avoid those Amazon links.
 
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Michael_K

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Sounds like you've made some headway in exploring more about this subject before jumping in. That's great! It will make a big difference as you precede with your project. All those vendors are excellent except maybe M12 lenses. One fellow posted some examples of a lens he purchased from them that appeared to be seriously defective or of very poor quality and this turned me off to that vendor. They also don't provide as much info as to what they are selling as the other vendors do. There stuff seem to be more on the low end of things regardless of price. I'd stick with Treeye, Fulekan or Peau. There are a couple of other good vendors on AliExpress but for now that's a great start and you can't go wrong. Avoid those Amazon links.
Cool! I was going to ask which you didn't like (and, I figured it would be M12).
I love researching a subject (I'm really analytical and technical).
 
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