Changing lens on a Lorex Bullet camera

[mikegerard 0]

I have 4 Lorex Bullet cameras with 4mm lenses. I want to change one to 8mm and one to 6mm. I'm not sure what the Lorex model number is but they are identical to the Hikvision DS-2CD2012-I

http://www.hikvision.com/UploadFile/image/2014032411124257029.pdf

 

Does anyone have experience changing out these lenses?

 

My quick search says that I'm going to unscrew the camera from the back and pull out the board with the lens. The old lens will be glued on and I should be able to remove the glue with tweezers and maybe a little solvent.

The new lens I can buy online at M12 lenses. Since I have a 1/3" CMOS I want lenses for 1/3"

So here is a 6mm

http://www.m12lenses.com/6-0mm-F1-4-Mega-Pixel-CCTV-Board-Lens-p/pt-0614bmp.htm

and here is an 8mm

http://www.m12lenses.com/8-0mm-F1-4-Mega-Pixel-CCTV-Board-Lens-p/pt-0814bmp.htm

 

Is there anything I'm missing here or any advice that you can provide to help me?

 

Thanks

Mike

[MaxIcon 0]

That's about right. Someone recently removed the glue with a heat gun using a directed nozzle, but I used brake cleaner applied with a fine paintbrush for mine, then pried at the glue with a tiny screwdriver until it popped off.

 

I've had good luck with the lenses from M12lenses.com. There are 2 main risks with a replacement lens:

 

- Needs to screw in too far to focus, and the back of the lens hits the IR filter assembly.

- Doesn't need to screw in as far to focus, leaving the lens protruding enough to hit the glass when the sensor board is remounted.

- Lens body above the threaded portion is too big to fit into the IR board hole.

 

I've had both of these problems with various lenses and cams, but all my M12lenses gear has fit so far (I haven't ordered any of the big body styles). Still, you never know with a particular lens until you try.

 

The other problem I had with an M12lenses 16mm lens was that it screwed in just the right amount, leaving the lens body nearly flush with the IR LEDs. This meant I couldn't get a good grip on the lens to focus it without blocking it. In hindsight, I should have removed the IR board for focusing, as it only takes a few moments extra.

[buellwinkle 0]

With the 16mm lens, was that on the 2032 mini bullet? Do you think their 25mm lens has a chance? Yes, 3 tiny screws and the LED ring comes off. I'm trying to get the longest focal length as possible and still fit and work as a science experiment to see if it can be used for LPR. Also, for what it's worth, the factory 4mm lens is 18mm long and the head is 13.5mm wide.

 

 

That's about right. Someone recently removed the glue with a heat gun using a directed nozzle, but I used brake cleaner applied with a fine paintbrush for mine, then pried at the glue with a tiny screwdriver until it popped off.

 

I've had good luck with the lenses from M12lenses.com. There are 2 main risks with a replacement lens:

 

- Needs to screw in too far to focus, and the back of the lens hits the IR filter assembly.

- Doesn't need to screw in as far to focus, leaving the lens protruding enough to hit the glass when the sensor board is remounted.

- Lens body above the threaded portion is too big to fit into the IR board hole.

 

I've had both of these problems with various lenses and cams, but all my M12lenses gear has fit so far (I haven't ordered any of the big body styles). Still, you never know with a particular lens until you try.

 

The other problem I had with an M12lenses 16mm lens was that it screwed in just the right amount, leaving the lens body nearly flush with the IR LEDs. This meant I couldn't get a good grip on the lens to focus it without blocking it. In hindsight, I should have removed the IR board for focusing, as it only takes a few moments extra.

[MaxIcon 0]

Yes, the 16mm was on the 2032. I'm also looking at 25mm, as I'm also testing for budget plate capture on the street with the Hiks, and 16mm isn't quite enough, even in the daytime. It's a tough nut to crack, as you know.

 

This is the 16mm I got, because it looked like a standard size for these cams:

http://www.m12lenses.com/16-0mm-F1-8-Mega-Pixel-CCTV-Board-Lens-p/pt-1618mp.htm

 

The only 25mm they have looks like it's going to be too big for the IR board hole, so I haven't figured out what to order yet.

 

The other issue I've had is that the image quality isn't too good so far on these longer lenses that fit on the Hik. I'm guessing they have to do some design trade-offs to get that much zoom into a compact package.

 

The 16mm above has a lot of chromatic aberration and a fairly short depth of field, making the focus even trickier. M12Lenses was reported to be working on stocking 3MP rated lenses, which may help the IQ, but I haven't seen any yet.

[buellwinkle 0]

As a photographer I use telephoto lenses when I purposely want a shallow DOF, the reason people use like 85mm lenses for portraits, to get what they call the bokeh, which is a pretty blurred background behind the subject. So it is what it is and I'm using 50mm on an Axis camera for LPR, but there's a certain point where the car passes the camera that I'm trying to capture, so it's focused for that and it works out well. At 25mm you should get a very clean plate at 30-40, I figure maybe a 10'-12' wide path.

 

I have a 25mm lens ordered from where else, China, that may fit. It's slightly longer than the factory lens at 20mm long (factory is 18mm) and the head is 14mm, slightly wider than the factory lens, but still should fit in the foam hoodie on the glass and the hole in the IR ring is 15-16mm. Back-focus is about 8mm. it's made for a larger sensor and MP.

 

I measured it out and the lens can stick about 4-5mm past the current lens and still fit and not hit the glass. Even them, maybe with a few washers, I can move the cast metal bracket away from the glass to make more room and there's space between the front and back half of the cameras so I can probably pickup 1-2mm if needed. I don't want to tell people where I got it because until it's proven, don't want to see people waste their money because nobody knows more than you that M12 lenses are a crap shoot.

[MaxIcon 0]

Sounds good. I'm looking forward to hearing how that works out. I've got a 25mm ordered as well; same thing - may fit, may not, but it looks like it's close. Mine's a few weeks out, probably. It claims to be for a 5MP sensor, but it wasn't too expensive, so I'll believe that when I see it.

 

Here's what the lens and camera vendors need to spec to get rid of the guessing:

 

- The lens length and back focus length, which tells how far the top of the lens will be from the sensor when it's focused.

- The distance between the sensor and the glass on the camera, which will tell if the lens will hit the glass when focused.

- The width of the hole in the IR board and the width of the top part of the lens, which will tell if the lens will fit into the IR board hole if the wide part is below the IR board level.

 

At least some vendors are starting to spec those things.

[buellwinkle 0]

Here you go, 25mm in a ds-2cd2032, plate at 40-45' at VGA resolution. There's some CA, maybe slightly more than the factory lens, but should not affect LPR use at all. Lens fits barely, needs longer screws to hold the lens bracket to front lens assembly. Will research that.

 

 

This is with the 12mm lens

 

[MaxIcon 0]

That looks pretty good. Where'd your lens come from?

 

I got my 25mm lens yesterday, and it's a 1/2" lens, which is good in this case, as it adds more equivalent zoom and gives better edge resolution. The specs are very good for an inexpensive lens, but I won't be able to mount it until the weekend to see if they're pulling my leg.

 

This is the link to the lens I got. The MT9P031 listed in the description is a 5MP sensor, implying this is a 5MP rated lens, but it's only $10 shipped, so that seems unlikely...

http://www.ebay.com/itm/25mm-1-2-inch-Cmos-MegaPixel-Board-CCTV-PC-camera-Lens-M12x0-5-for-MT9P031-/121375945476?pt=US_Surveillance_Accessories&hash=item1c4291f304#ht_1184wt_916

[buellwinkle 0]

Actually does pretty well at night with the built in IR LEDs at 45' reflecting off the plate. Exposure time is 1/200th/sec, gain set to 75, VGA resolution. I think any LPR software should be OK with this as the characters are 17 pixels tall. You can probably go as far as 50', beyond that, characters get less than 15 pixels tall, you may not get recognition. If anyone wants the lens, PM me.

 

 

For software, if there's any C developers out there that want to volunteer their time, I don't think it will be that hard to get this written using openalpr software as a standalone program.

[catseyenu 0]

This is seriously cool. " title="Applause" />

I'd like to find a 2.8mm lens for one of my 2032's.

Question, will ROI enhance/help this (or facial recognition)?

[buellwinkle 0]

This is seriously cool. " title="Applause" />

I'd like to find a 2.8mm lens for one of my 2032's.

Question, will ROI enhance/help this (or facial recognition)?

 

I believe someone tried the 2.8mm on the bullet and it didn't work out well, part of the image was cropped. I would imagine the wider angle the lens, the more barrel distortion, especially close up, and less likely for facial recognition. But availability, sure, you can just about any lens size for that camera, but it's trial and error. The ds-2cd3332-i eyeball comes in 2.8mm.

[catseyenu 0]

I was thinking ROI on the LPR and facial recognition, not with my "wish I had" 2.8mm lens. Sorry for any confusion.

[MaxIcon 0]

I got my 25mm 1/2" lens and mounted it. It was quite a pain, and in general, I wouldn't recommend the Hik 2032 for lens conversions. I'll post some screen shots and such later, but here's the overview:

 

This lens should give a longer zoom than a 25mm 1/3" lens. I made the FOV measurements but haven't crunched the numbers yet.

 

- The lens is a little too long at the focus point, and I had to replace the sensor board screws with slightly longer ones to re-mount it. These are M1.0 screws, and I keep a bag full of tiny screws scavenged from old hard drives and such for just this reason (or repairing Macs).

 

- Depth of field is not great, as mentioned before. The longest distance I can focus from the bench is about 50', so that's what I used, but the distance to my plate capture area is about 100'. Since the Hik can only be focused when completely disassembled, this is a hard thing to do, and may have affected my results.

 

- The Hik captures images fine at this distance if the lighting is good, like direct sun on the plate. In the day, if the plate is in shadow, it starts to blur, even at high shutter speeds. At night, if everything is perfect, you can get a readable plate image, but if anything's not right, it's a blur. Whether this would be helped with a 100' focus instead of a 50' focus remains to be seen.

 

I've got a Dahua 4300S that's easier to deal with lens adjustments on, and I'll probably switch over to it for further testing.

 

In the meantime, I turned on ROI for the plate area, and will see if that helps.