Bullet Cam, replacing the lens

[admin]

With bullet cams, there is some confusion because we deal with two things called a lens. The first is a protective glass or plastic disc. The second is the internal optics.

First, the front lens is a simple round bit of lexan or glass. It is easily replaced and we stock replacements at a very low cost. The lens is held on by a screw on housing.


If you look at the side of the bullet camera, you will see a separation line abour 1/2" back from the front. Grasp the end and unscrew it (by hand) from the main housing. Inside are the replaceable lens and a small o-ring that provides a water seal.

If you are replacing the outer lens, take out the broken one and any bits of glass or plastic. Insert the new lens into the inside of the front end and then insert the o-ring (if it separated from the main housing) into the front end also.

Screw the front end carefully onto the main housing so that the o-ring is gently compressed. You don't have to screw it really tight.

[admin]

Every so often, it is rare, we get a front end that does not want to come off.

Protect the surface with some rubber if you can find some... and using some gripping pliers, CAREFULLY unscrew the front end. If you end up damaging the front end, we have replacements.

[admin]

The internal lens has to small holes that are diametrically opposed. In other words, they are opposite sides. If you look into the business end of the camera with the front end unscrewed, you will see a small flat surface around the glass lens. This flat surface has two holes in it.


Carefully place the tips of a set of needle-tipped tweezers into the holes. It is easier at this point to hold the tweezers steady with constant pressure, and turn the camera.

You can then unscrew the internal lens from the camera body. Do not screw it in further by accident as you can possibly damage the optical sensor ship.

You will find under the lens a spring. This spring may come out or not. The purpose of the spring is to provide a force to the lens so it will not accidently rotate in use. Occasionally, the spring will become a bit relaxed and the lens will rotate a little and become unfocused. Simply pull the spring out a bit to make it a little longer. You can also apply a very small amount of blue loctite to the lens threads.

Once the old lens is out, carefully by hand screw the new lens into the housing (make sure the spring is installed first!). Try to not touch the glass element (or it will have to be cleaned).

Careful to not cross thread. Once the lens is in as far as you can install it with your fingers, now it is time to use the tweezers again and focus the camera.

Hook up a monitor to the camera. If you are using a PDR100 with the camera, you can insert the camera connector into the PDR and use the AV out cable to a monitor. Alternately, we can supply a camera adapter and you can provide 12V DC to the camera and hook the RCA jack into a suitable monitor.

Again, it is easier to turn the camera while holding the tweezers under pressure. Note the image on the monitor. As you screw in the lens, you are adjusting the focus and the image should get sharper. Continue until the image is very sharp. Now turn a little more until you can just tell the image has degraded. Now back off 1/4-1/2 turn. That should be about the best setting.

Replace the front end housing, o-ring, and outer lens per above.

Note, you may wish to use an anti-fog wipe on the outer lens to prevent fogging from temperature changes and condensation. We have replacement anti-fog wipes.

[admin]

Lastly... if all that seems a bit much, it really isn't. But we are also happy to provide the service for you to replace the lenses. We also stock cameras with 70, 90, and 120 degree lenses.

[admin]

We have determined that a recent batch of cameras from us include some with a faulty lens. It took us a bit to determine the issue but in the end, it was pretty simple.

If you have a newer bullet camera from us, and it rattles at all when you tap it... this indicates the problem. A camera like this, under use, can become worse and become blurry.

The fix is simple and we can do it for you. Just for your information, it means we can either replace the lens per this thread, or we can also fix the lens (unless it has catastrophically failed). Fixing the lens means we remove it, and then unscrew the front end of the lens (the metal part with the two tweezer holes). Apply new loctite to the threads and screw the front end back on, until it is quite tight. The factory problem was just not making this tight enough, allowing the internal lens bits to move under shock.

[desperado]

I'd like to get a little more detail on doing the camera focus after changing lenses. We aren't getting good results.

When doing this at your factory, do you point it at some kind of a grid or image? If so, can you post the image (or a link to it) for download and printing?
What kind of lighting is best?
What is the best or minimum distance to have the target at when doing the focus?
Finally, what is a reasonable minimum monitor size for getting good results. I've tried using the 5" monitor we purchased from you, but am not getting good results. :(

[RandallNoll]

desperado,

We use an LCD computer monitor to do our focusing here. It's probably 17-19" diagonal. I would say you probably want at least an 8-10" monitor. The lighting isn't a huge issue, more is better, but we do ours indoors with some natural light coming in. The cameras have a very wide focal range. We usually shoot for getting something in focus that is 15'-20' or so away. This usually leaves you with good focus all the way down to 1' or so.

Tip: if you are in focus at 1" (can see your fingerprints) then the lens needs to be threaded IN toward the camera body to move the focus further away.

Thanks!