Coating on lens

[wittaj]

So I messed up big time and hopefully someone can help .

I upgraded a camera and moved the camera that was at it's place (the Dahua dual cam AKA booby cam dome LOL) to another location that isn't critical and was going to be used as overview cams for an area already covered.

While I was repositioning the two cams for the new location (which with a dome means the dome cover is off), a burst of wind with dirt dust decided to blow by and stuck to the lens. Given it was the lens itself, I didn't want to touch it and blowing on it didn't get it off.

So I decided to use a can of compressed air and had it perfectly level and started the air off of the camera and cleaned the one lens off and then the next lens as I turned to it the frozen white gas spray came out and within a few seconds it appeared the coating was damaged. Looking at the camera on the GUI was a big mess right in the center of the frame.

So I decided to wipe it and clearly the coating is now gone when looking at the two lens you can see a difference between the two.

Now the entire image is blurry. Does the coating actually result in messing up the focus or is there now a smear residue that I need to remove? If so, what should I use?

Again, it isn't a critical location and is an overview camera, but I would like it to not be blurry LOL. Lesson learned...and another reason to avoid domes LOL.

 

[pozzello]

hm. i have the same boobie cam and had not noticed such a coating, but also haven't needed to clean them although i did swap out one of the lenses...
while dialing in focus for the swapped lens, i noticed the dome itself actually affected focus, so it was bit of a pain to dial in... (had to adjust, place dome, remove dome to adjust some more, iterate) point is, perhaps your out-of-focus is due to the dome removed, not from the cleaning? ie, see if it's better with the dome back on... ?

 

[wittaj]

hm. i have the same boobie cam and had not noticed such a coating, but also haven't needed to clean them although i did swap out one of the lenses...
while dialing in focus for the swapped lene, i noticed the dome itself actually affected focus, so it was bit of a pain to dial in... perhaps your out-of-focus due to the dome remved, not from the cleaning? ie, see if it's better with the dome back on... ?

Yep, blurry either way. When looking at the lens, the side that is not affected kinda has almost a green-like tint to it and the other side that got damaged is more clear-like without the green tint. They both exhibited the greenlike coating prior the compressed air.

They were both in focus until I sprayed the compressed air. It was blurry right in the center and in focus on the side, but when I wiped it, the whole thing became blurry, so it makes me believe the coating changes the light and thus the focus just enough or maybe there is still residue that is now blurry. I wiped several times with no improvement. Or is the focus that sensitive that just wiping it changed focus? I thought they were screwed and glued in?

How did you go about changing the focus - I guess I could try that. I am not concerned about it being super sharp, but would like it a little less blurry than it is now.

 

[pozzello]

I wiped several times with no improvement. Or is the focus that sensitive that just wiping it changed focus? I thought they were screwed and glued in?

yes, unless you pick the glue off, the lens should not move to change focus. it does sound like some sort of optical coating got nuked, or the lens (plastic?) got damaged by the super-cold spray...

good news is that such lenses are cheap to replace... normal M12 in that unit, i believe, plenty to choose from for 1/2.8" sensors... i think i had a 12mm in one side of mine at one point.

to adjust focus (and remove lens), find the glue at the lens thread/mount junction and pick it off with an exacto blade, then screw/unscrew lens to adjust focus, or unscrew entirely to remove/replace. you can also just grab the lens with padded pliers and forcefully unscrew to break glue hold...

 

[wittaj]

I recall you mentioning that now. I will have to dig up that old thread. I certainly was thinking of wishing it had a little more mm, so this is the perfect time to try it now LOL.

I guess I will try with some alcohol or something stronger first in case there is some gunk film that isn't seen. By all looks it appears fine and not damaged, but who only knows sometimes. Lesson learned.

 

[wittaj]

So doing some more research, I found some similar instances with regular cameras and people said their camera went blurry and cleared up in a day or so as the super cooled air must have put a microscopic thin layer of condensation freeze on the other side of the lens. After a couple of days, most of the blurriness went away, but still had some.

I just now took some alcohol to the lens and cleared it up the rest of the way.

Camera destroyed averted for the moment LOL. But next time no compressed air LOL.

 

[pozzello]

ah, that makes some sense. condensation inside the lens assembly itself. should work itself out eventually, assuming the cam's moisture-sucking silca pods still have some life in 'em... these can also be 'refreshed' by baking in a very low oven (170F or less) for an hour or two to drive off any accumulated moisture.