Anyone tried adjusting focus on Dahua fixed-lens turrets?

[mech]

I'm wondering if focus can be improved on my cam, this seems sub-standard. I see the same effect at night on reflective license plates, definite "ghosting." It's a Dahua fixed-lens turret/eyeball. I would consider disassembling it if I could get a better result.

 

[silencery]

It can be done and it's not hard, but very time consuming.

You have to take down the camera, open up the case, and adjust the lens by a 1/4 turn. Remount, test, rinse, repeat.

 

[mech]

Thanks silencery I think I will make that a Saturday project then The neighbors will probably think I've gone off the deep end. Well, if the shoe fits... yeah.

 

[alastairstevenson]

I'm wondering if focus can be improved on my cam, this seems sub-standard.

That focus looks perfectly good to me, judging from the scale you've zoomed the image up to.
What's the model of camera / what resolution do you have it set to?

 

[mech]

It's a IPC-T5442TM-AS-LED at native resolution, so 4MP 2688 x 1520.

 

[aristobrat]

If you haven't already, you might try increasing the shutter speed before trying to adjust the focus in case it's some motion blur that you're seeing there.

 

[mech]

If you haven't already, you might try increasing the shutter speed before trying to adjust the focus in case it's some motion blur that you're seeing there.

Good point. I was also getting that effect on stationary objects (a reflective license plate) and thought of a couple possible reasons. One would be if the lens were not at its best focus, but another would be if the light is simply bouncing between the camera's face window and its lens, the way you can get ghosting if a camera looks through a double-pane window at an angle. In this case, the camera angles down, so that could be the reason too. I sure wish it were a varifocal turret so I could experiment with the focus. Maybe I'll just leave it alone for now, I was just hoping to get a little more detail at the fringes of its useful identification range.

 

[silencery]

Yeah, I was replying quickly earlier, so I failed to mention you probably want to try other adjustments first.

I'm all for squeezing out maximum performance from all my equipment, but refocusing is really arduous, and better results aren't guaranteed.

Depending on your circumstances, you may be better served with a varifocal for this location

 

[user8963]

i have the same problem on a new 1831-pir ... the focus is on 3-5ft .

does someone know if dahua glue the lens, or can i just adjust it without removing a bunch of glue ?

 

[tigerwillow1]

I tried refocusing a dahua bullet and found the following:
1. Lens barrel is secured with an adhesive that has to be first picked off
2. 1/4 turn at a time adjustment is way to much
3. This is the big one. Before starting look carefully at the entire frame. Is the focus consistent everywhere, or are some spots in focus while other are blurred? In my case, one side of the image was blurred. All I was able to accomplish was focusing the blurred side, and blurring the clear side. I'm chalking this up to imperfect angular alignment between the lens and image sensor. I'm assuming the cameras are machine focused at the factory and it could be hard to beat that manually.