"I thought that maybe this was just a defective cover, but it happened on all the cameras with the 8mm lens. Camera works great with 2.8 to 4mm lens and the cover on. Anyone else ever have this issue? I'm assuming Arecont covers are not compatible with the full selection of their lens???"
Sounds like a reasonable hypothesis. Different lens lengths may react differently with the dome cover.
Did you ask Arecont tech support? Even if someone here has experience, I'd definitely want a definitive answer from the manufacturer.
A number of dome camera manufacturers provide a piece that fits over the lens to simulate the bubble for focusing. We use these regularly.
Then again, some don't. In that case, we have often resorted to either cutting a piece of an old bubble out or holding the actual bubble in front of the lens while focusing. If all else fails, we found we have to use a lot of back and forth - moving focus a notch, then installing the bubble... Rinse, repeat.
It is a bit odd for that to happen with an 8mm lens, though. It typically affects longer focal length lenses - 12mm moderately, but 50mm much more.
I believe Arecont included a focus device in their domes, at least the ones we used.
Right, same experience here. The focus device is a piece of glass in a fixture that snaps onto the varifocal lens assembly. It has the same refractive index and curvature as the dome. We could actually send you one if you wish -- one came with each camera, and we only need one. Maybe John could support passing your mailing address in a non-public way?
Bosch Security Systems Inc.
*DISCLAIMER I AM AN ARECONT VISION MANUFACTURER REP*
The resolution is to follow our installation manual for the product. We state that there will be a focus shift with the bubble in place and provide instructions how to focus the MicroDome camera when using a higher millimeter lens like the 8mm, 12mm or 16mm. We even provide a chart to tell the installer how far to turn the lens (clockwise or counterclockwise) to compensate for the bubble. They can check the focus by holding the bubble in front of the lens and fine tune as necessary.
Thanks gentlemen for your input. I will check the install manual for this info. Who would have thought to read the manual? :). BTW, I've installed over 300 Arecont cams in the past two years and been very pleased. However, this is the first install where I tried the the longer lens beyond 4mm in a micro dome. The image even after "mostly" in focus is just poor in comparison to the 4 mm image. It's like u just can't get the dome cover clean enough in my limited experience. I'm guessing the longer focal length just magnifies every tiny flaw in the cover? I will think more carefully about a different model camera for those applications that require the longer lens' in the future. Maybe even remote focus! LOL
john, I appreciate IPVM and this forum.