testshoot

That's not possible. The rear lens element is located, you guessed it, at the rear. Cutting would just render the lens unuseable. Actually, on the lenses I tested the rear lens was not all the way at the back of the threads. One each of the lenses I am guessing there was about 2.5mm space from the last element to the end of the threads. I am guessing on the lenses where I wasn't able to screw the lens in far enough that I could have either cut down the lens mount or cut some threads off of the back of the lens, depending on where the obstruction was. One supplier did suggest buying a shorter lens mount which would be the same as cutting some threads off of the lens mount if you were talented enough to do that without messing things up. I haven't been able to get a BFL spec from Dahua and some of the lens suppliers won't give or don't have a BFL spec for their lenses so it is a bit of a crap shoot.

Image quality is primarily the optic, the sensor, and the software that takes the raw data and makes it into an image. About all we can change on a camera is the lens. I have to assume a lens that cost $15 is better than if you pay $14 for six of them. Also, as a general rule, lenses sold with a metal mount are better than ones sold with a plastic mount. I am working with two vendors to find a good quality compatible 12mm lens. Rage's price of $89 is outrageous no matter how good it is and I am not desperate enough to pay as much for a lens as the whole camera, or nearly so.

Hello, I think the 16mm would be too narrow and I think he had chromatic aberration on the 12mm or it wasn't IR compatible. I checked the DX page and it doesn't mention IR for the lenses. His sample show was in a cloudy condition and he mentioned fringing when the sun came out. He also said the 6mm in the kit was lower quality than the 6mm that came with the camera indicating that the whole set of lenses is of lower quality that the Mega Pixel brand. I am in email communication with the person from m12lenses. They are trying to help me find an appropriate 12mm lens. Since the Mega Pixel 12mm lens couldn't screw in far enough, they are suggesting that changing the mount might be the solution. Don't know what that will take. They asked for the length from the PCB to the top of the mount to see if they have a shorter mount that will let the 12mm lens screw in the 2-3mm more that it needs.

M12lenses.com sells what appear to be two grades. One line is simply called "board lenses" with no brand name. The 12mm lens is f2.0 and sells for$5.27. They also sell a "Mega Pixel" brand that is labeled MEGA, the same labeling as the Dahua provided lens. The MEGA 12mm lens is F1.8 and marked IR and sells for $14.70. The cheaper lens also appears to have a plastic body vs. metal. Bikerider was able to buy a set of 4 or 5 lenses for the same price as I paid for one MEGA lens. He was able to get the 12mm and 16mm to work, as apparently their BFL was appropriate for the Dahua camera. I am unable to find the BFL spec for the MEGA brand of lenses, or any other brand for that matter so I can know without buying whether they will even focus, never the less the quality of the lenses. I am in contact with another company, Peau, that only sells plastic body lenses and is asking what the BFL should be, and I can't even tell them. I just didn't think this would be so tough given we are working with a standard M12 lens. I did check the Atrix brand but it seems the don't offer a 12mm lens. Mobotix says they glue their lenses in place and want 200 Euro to swap the lens. They don't appear to sell the lenses themselves individually for those who want to attempt the replacement. I checked the specs on the Mobotix site and they give no information on the BFL for their M12 line. It would seem there is a potential market for people like myself who would like to buy a quality lens and swap them. I can't believe everyone is happy with the Q-See 6mm only option, especially given that Dahua at least offers the 3.6 and 8mm options. I contacted Cherry who has been mentioned as a good source for Dahua and she didn't know if there was a 12mm option that worked or that she could sell. If nothing else materializes, I might buy the Mega 8mm option and settle for the wider than desired width. Thanks

The guy wanted $89.00 for the lens...he is crazy. I saw his prices for the GoPro lenses and already thought his pricing was high. They guy is making a huge profit on these lenses. The MEGA lens which is of good quality (glass lens, metal body) goes for $14 and BikeRider got a set of 4 or 5 lenses for $15...although I am guessing they were plastic. Thanks anyway, but I am not desperate enough to pay that much for a lens, even if it was platinum plated.

Just noticed your lens is marked 3.6mm EGA. I am guessing EGA is a brand vs. the Mega brand on the 6mm lens in the Q-See version. Since you apparently didn't change the lens (yet), I am guessing you ordered it as a 3.6mm? 3.6mm is one of the two lenses I bought for my cameras and it focused, unliked the 12mm which couldn't screw in enough. The Mega brand 3.6 screws in almost exactly the same distance as the 6mm. I am assuming the 8mm is almost the same distance as it is the other of the three offered by Dahua.

If you will notice, there is a lock ring that screws down to the base to lock it into position after you screw it in and out to find the focus. It is a knurled ring right above the base, below the exposed threads. I did hear back from the Ragecams guy saying he might have some lenses but didn't elaborate other than to say 12mm was a narrow view. I am surprised he commented on that as you would think I would have known that and wanted that?

Thanks for the suggestion. I wrote Ragecam. It seems his stuff is incredibly expensive. I saw the same Mega lens I bought for $15 he was selling for $70. Will wait to see what his response is before I jump to a conclusion. Appreciate your reply!

To add my 2 cents worth, I purchased the 3.6mm and 12mm lenses from M12lenses.com. They have a couple different quality levels. It was suggested to get the Mega brand as that is what Dahua supplies in the cameras so that is what I bought. The 3.6mm lens went in fine and works great, as expected. The 12mm lens is too long, and can't screw in far enough to focus. It was only have trying it in a couple of cameras that the contact at M12lenses told me the distance needed. With the Dahua 1.2mp camera, you need a lens that is shorter than about 20.5mm, i.e. the distance from the tip of the lens to the sensor. The 12mm lens, when screwed in all the way, still stuck out over 22mm so it would never focus. The 12 and 16mm lenses that bikerider tested apparently were short enough to screw in far enough to focus. I was disappointed that the Mega 12mm was too long to work as I assumed all the 12mm would be made equally. Bikerider reported some quality issues with the lenses he bought, in particular in strong light, which is what we have a lot of here in New Mexico. Is there another brand that is of a higher quality like the Mega brand but is short enough to work in the Dahua camera? From Dahua, they only offer the 3.6, 6, and 8mm. If I have to, I can get the 8mm, but would really like a quality lens in the 12mm format. Thanks

Thanks for the tip. The downside of that method is one more lens to create aberrations and more light loss. I am a photographer and we use teleconverters to do the same thing you are suggesting. It is always preferred to buy the right lens vs. using a teleconverter however for a photographer, the teleconverter can typically be used on a variety of lenses giving us more flexibility in our kit. I have gotten a reply from bikerider regarding his testing and the link to his test results. He mentions his test camera was a Dahua bullet, but not what model, so his results might be different than mine. I only tested the 3.6mm which worked fine but the 12mm wouldn't focus. He was able to get his 12mm to work and a 16mm as well. viewtopic.php?f=19&t=33089&start=15 Thanks

I have little experience other than trying to get a Foscam wireless camera to work. Even though it was only one room and two walls away from the router it would not keep a connection and was not a reliable method plus wireless is always a security issue on top of the dropout problems. I don't intend to ever try wireless again for an application where I want to be insured of a constant connection. I suppose there are other cameras that would work wirelessly better than the Foscam, but then you still have the security issue.

Hello, The purpose of this particular cam is to show the Sandia mountain range, or a portion of it on my weather website. I was purposely picking a narrow lens to reduce the width to 29 degrees which at the same time would reduce the vertical FOV as well. Since this cam is to be displayed on the web for my weather site visitors, I don't want to show anything but the mountain and in particular I don't want to show the back of my two neighbors houses. Blocking out that area would look bad in that application. Seems the blocking purpose is more aimed at eliminating areas that would have motion that you wouldn't want to trigger a motion alert. Or not to show something on a cam that would be for public consumption, but I think having a blocked out area wouldn't look good. I guess it wouldn't be as bad if it was a narrow strip along the bottom, something I might need to do even with a narrow FOV. As it is, I am already thinking my neighbor might get upset thinking I am using it to spy on them. I just ordered a roof mount antenna tripod on which to mount the camera, up on the roof to give me a higher angle and reduce the backyard problem. Still hoping to find a way to get the camera to show less FOV both horizontally as well as vertically. Thanks for the suggestion.

Could be you got a bad lens. The QC for these inexpensive lenses is not the best (part of how they keep the cost down), and often the customer provides the basic QC when they install it. You can roughly check the back focal length by pointing the lens at something bright a little ways off, watching the light coming out the back, and moving a piece of paper back and forth until the image focuses on it. A light fixture works well, or the sun shining through trees can work better for distance. Since it focuses up close and won't focus at a distance, you could also try holding the lens slightly away from the threads to see if you get better focus. This takes a steady hand and a dark area, with something lit that you can point at. If you can focus further out by holding the lens a little further away from the camera, it means your focal length is too long, and once you start screwing it in, your distance images are focusing behind the sensor. Ideally, you want the focal point in front of the sensor when the threads first engage, so that by turning it further in, you move the focal point back onto the sensor. Thanks for the test tip. I bought the more expensive Mega brand hoping to get a higher quality lens vs. the $4 ones. I wrote bikerider in hopes to hear back on his testing. What I found said the 16mm was soft. Haven't heard of anyone trying with the 12mm. I could use the 8mm which should work, but would rather have the 12mm as I don't want the height of the wider lenses, i.e. I don't want to freak out my neighbors by having their houses in view nor do I want to aim it way up and get a lot of sky.

I am dealing with someone named James Stewart who said I should ask Dahua after I proved him wrong.

I had already read that message string, and read it again from where your link started. Saw where bikerider mentioned testing the lenses, but never saw the results of his testing. I did see lowpro mentioned swapping for the 3.6mm lens from M12, the same lens and the same vendor I dealt with. As you know, the 3.6mm lens swapped easily and works fine. Tried the 12mm on a second camera and the same result. Would focus on things close, but not at a distance...meaning not even something 8' away. Thanks