Swann vari-focus bullet question.

[thmaxxer 0]

I am curious if anyone is experiencing something similar or if I maybe got a lemon cam. When the heat of the day sets in, it almost looks like the cam is getting so hot that the focus is slightly moving and the image begins to blur. Nothing bad like you can't make anything out, but it looks blurred compared to early morning and late evening razor sharp images. I did some temp readings and when the cam is at it's worst the housing was 127 degrees, the bricks were 135. (It's at the top of a peak against a dark red brick covered wall and I live in Houston.) I'm wondering because the focus is SO SO SO sensitive if the internals of the cam are getting hot enough to move things around a tiny bit and that's causing my not so sharp picture. My initial set-up of the cam was about noon, not the hottest part of the day, but not far from it. Just wondering if anyone else has had similar issues in higher heat areas.

 

Thanks.

[MaxIcon 0]

There was a post a while back where someone had this problem with their Dahua bullet, and since then, I've seen it a few times on my Dahua HFW3300C full-size bullet. It definitely seems to be heat related, and if I refocus it while it's hot, it gets blurry again when it cools down.

 

No idea why yet (no time spent chasing it), but you might be right - these are so sensitive to the lens focus that a pretty small mechanical shift could cause it.

[JoeyJoey 0]

I had an awful time trying to focus the dome version of this camera.

 

I didn't want to read this post, as I ordered the bullet version that will placed in direct sunlight.

[rayt 0]

i have 2 of these installed, but both in a shaded area, i'm not sure but if these white housings have a external temp that high, can you imagine the internal temp?

 

I think the hottest day i had them in was ~90 degrees day with some sun, but nothing as bad as focus shifting.

 

Wished i could find the auto focus version at a good price, it would solve your problems!

[thmaxxer 0]

I too had quite a time focusing the dome, it seriously took close to an hour. Thankfully the dome is inside and is at a constant 74 degrees with no issues of focus change. Joey, you may want to somehow (if at all possible) protect the cam from direct sunlight, mine isn't really in direct sunlight except for first thing at sunrise, but during that time the temps are around 76-80. Mine gets the heat from being at the peak and the bricks radiate their heat so well, it gets hot and stays hot. Also I don't know where you are located but if it's not terribly hot, you may be fine.

[thmaxxer 0]

 

Wished i could find the auto focus version at a good price, it would solve your problems!

 

Starting to think this may be why they have auto-focus versions.

[zikronix 0]

 

Wished i could find the auto focus version at a good price, it would solve your problems!

 

Starting to think this may be why they have auto-focus versions.

 

In theory if you tighten down the adjustments, tight(er) with a flat screw driver they shouldn't move. I live in AZ, and I picked up a ton of fixed domes from a vendor in a "Panic" sale last night...LOL. I still have my one varifocal dome, and ill tell you right now if it moves in the heat. That will NOT work

[Swann Tech 0]

Hi guys,

 

While 127°F is within the ranges given by our QA, the internal case temp will be significantly hotter than that. That would probably take the camera out of the operational temperature profile.

 

It is quite likely that you are distorting the lens body at such high temperatures. That would result in the loss of focus reported.

 

Try some additional cover for the camera. If your environment is that harsh then you will need to accommodate for that with a little extra effort.

[MaxIcon 0]

Most of my cams run at around 100-115 degrees case temp when the ambient temp is in the 70-80 degree range. Some internal components will definitely be hotter, as Swann Tech points out, and small cams build up more internal heat than larger cams.

 

Since a focus shift would be caused by the lens moving relative to the sensor, and the actual lens mount above the sensor is plastic, this is what would be likely to shift. The Hik lens doesn't have a setscrew (setscrews are worst case for stability) or lock ring, but is held in place by a drop of glue, so the lens relative to the lens mount doesn't seem a likely candidate for shifting.

[zikronix 0]

Most of my cams run at around 100-115 degrees case temp when the ambient temp is in the 70-80 degree range. Some internal components will definitely be hotter, as Swann Tech points out, and small cams build up more internal heat than larger cams.

 

Since a focus shift would be caused by the lens moving relative to the sensor, and the actual lens mount above the sensor is plastic, this is what would be likely to shift. The Hik lens doesn't have a setscrew (setscrews are worst case for stability) or lock ring, but is held in place by a drop of glue, so the lens relative to the lens mount doesn't seem a likely candidate for shifting.

 

So if im understanding correctly your saying the plastic housing of the lens if most likely shifting do the heat? Thus causing the loss of focus?

 

So would it be safe to assume the domes could have the same problem? Which in Arizona isn't going to work, not when its 120 out side!

[MaxIcon 0]

Theoretically, yes, the lens mount assembly shifting seems most likely, since focus is all about lens to sensor spacing, and even a small amount of shift will cause focus change. There's really not much else, unless the sensor itself is shifting position, which seems unlikely, but these cams keep surprising me.

 

I haven't found the problem to be repeatable enough to test, but it's a hot weekend, so I'll try setting up my Dahua in the sun to see what it does. I haven't seen this problem on my Hiks, which only get the morning sun.

[thmaxxer 0]

Most of my cams run at around 100-115 degrees case temp when the ambient temp is in the 70-80 degree range. Some internal components will definitely be hotter, as Swann Tech points out, and small cams build up more internal heat than larger cams.

 

Since a focus shift would be caused by the lens moving relative to the sensor, and the actual lens mount above the sensor is plastic, this is what would be likely to shift. The Hik lens doesn't have a setscrew (setscrews are worst case for stability) or lock ring, but is held in place by a drop of glue, so the lens relative to the lens mount doesn't seem a likely candidate for shifting.

 

So if im understanding correctly your saying the plastic housing of the lens if most likely shifting do the heat? Thus causing the loss of focus?

 

So would it be safe to assume the domes could have the same problem? Which in Arizona isn't going to work, not when its 120 out side!

 

 

zikronix, its not terrible. I will see if I can get 2 different shots put together and post them.