What size lens to get?

C

chadman

Young grasshopper
Jun 10, 2016
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It seems 2.8 is kind of standard, but see some have other options such as 3.6, 6, and up to 100. I plan to have one camera at my front and back door of my house, so it would not be very far from the target. The other 2 or more will be on on the base of the roof looking overlooking my yard. I guess the target would be more like 20-50'. Any sizes you would recommend or does 2.8 do a good job for both scenarios?
 
2.8mm is rarely adequate outdoors, you have a 15' range at night before you loose ID capabilities.. most people are better off with 4mm-8mm in most residential outdoor situations.

use the ipvm calculator, dont settle for less than 100ppf at night
 
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nayr said:
2.8mm is rarely adequate outdoors, you have a 15' range at night before you loose ID capabilities.. most people are better off with 4mm-8mm in most residential outdoor situations.
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I've been preaching this for so long. Glad someone more knowledgeable than me is also saying the same!
 
The rationale was 2.8 / 3 is most common for manufacturers is that many / most users want a sufficiently wide FoV. As you all know, that's the tradeoff, 4mm gives longer range than 2.8mm but at the cost of narrow FoV. At that point, you are faced with seeing nothing in certain areas (especially up close) or adding more cameras.
@nayr if you are doing 4mm or 8mm typical in residential, are you then mounting multiple cameras near each other to deal with the narrower FoV?
 
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The problem I find @john-ipvm is that 2.8mm for 2MP and 4MP 16:9 cameras is roughly 105 degrees and most DIY installers (and quite shockingly quite a few professional installers) are installing them in corners and end up with 15 degrees of wall videoing. Some are oblivious to the IR reflection because wide-angle gives such a pretty image (although maybe not enough detail for recognition or evidence) but others come on here and moan about how terrible their night-vision is.

When 2.8mm was 90 degrees (e.g. 3MP) it was less of an issue but still an issue.

Also, a lot of people don't seem to understand the obvious that it's a trade-off. How many times people have posted here asking for 90 degree+ FoV and 30m+ distance.

Just my thoughts. For me people spend too long picking camera model and not enough time picking the correct lens length and correct install location which are equally or in some cases more important.
 
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For me, I pick a job for the camera. Driveway cam with car prowlers around? Pick where the car is parked and show the car and a bit beside both doors for ID purposes. Even with my cars parked within 10-15' of the house, sometimes 5', that means a 6mm camera. Two driveways = two cameras, plus a wider angle cam on the front door for a total of three out front for me. All three are varifocal and one's a PTZ so the lens length is variable at times but are generally really close to what a fixed 6mm gives me. The PTZ is usually closer to 7.5mm equivalent and is easy to say because it spits out 1.5x on the OSD and I know the base lens is 5.1mm. Both driveway cams will give me a good general description of anybody entering my 50' driveways at night and a really good chance of a clear face shot 15-20' away if they come up to the car doors.

For me, a 2.8 lens is more of a "what's going on" lens instead of an "ID who did it" lens unless they come just about right up to the camera at night. 15' can be a looong way at night for a 2.8.
 
haha, glad I asked. I was thinking 2.8 for all of my cameras. I guess the ones by my front and back door would be good for the 2.8 since it's really close to where the target will be. I planned to use the Hikvision turrets and see they come in 2.8 or 4. Now I wonder if 4 will work ok for the yard cameras. My yard is not very big. One will be above the garage looking down the drive way and another catching the side of my house.
 
john-ipvm said:
@nayr if you are doing 4mm or 8mm typical in residential, are you then mounting multiple cameras near each other to deal with the narrower FoV?
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everyone thinks they want a nice wide angle FOV, until someone comes and steals some shit at night and they realize how few pixels a wide angle actually captures of useful information.

you dont need more cameras to fill in the blind spots, you just need to install them smarter using a bit of psychology.. no need to record all the grass in your yard if you have a choke point that everyone has to pass through to get into your yard.. whats the point of recording every single movement of a trespasser if your only hope at ID is if they stumble close to a camera.. focus on the identification part, once you got that.. if you want a nice wide view of the entire yard and not a narrow slice at choke points then put a wide angle up high to augment the zoomed cameras, but cover your bases first and get your cameras capable of identification deployed first.

for example, driveway cams should not be watching mostly hoods, roofs and windshields.. unless the crook is crawling on your vehicles the pixels are wasted.. zoom in, put it in cooridor mode and focus all your surveillance on the narrow path between your two cars where a prowler is going to hide and see if you left your doors unlocked.. then you'll get some great ID shots of them, yeah you wont see the other side's of your cars, but if you watch your cameras long enough you'll learn all the prowlers go down the middle and use 2 cars parked next to eachother as cover.
 
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its possible, but easy is a relative thing.. you'd have to disassemble the camera, replace the lens, power it up disassembled, set the focus correctly, then turn it back off and put it all back together.

in theory that is, there could be fitment issues with the new lens.. depending on the camera and how much room they left you with to play with.
 
nayr said:
everyone thinks they want a nice wide angle FOV, until someone comes and steals some shit at night and they realize how few pixels a wide angle actually captures of useful information.

you dont need more cameras to fill in the blind spots, you just need to install them smarter using a bit of psychology.. no need to record all the grass in your yard if you have a choke point that everyone has to pass through to get into your yard.. whats the point of recording every single movement of a trespasser if your only hope at ID is if they stumble close to a camera.. focus on the identification part, once you got that.. if you want a nice wide view of the entire yard and not a narrow slice at choke points then put a wide angle up high to augment the zoomed cameras, but cover your bases first and get your cameras capable of identification deployed first.

for example, driveway cams should not be watching mostly hoods, roofs and windshields.. unless the crook is crawling on your vehicles the pixels are wasted.. zoom in, put it in cooridor mode and focus all your surveillance on the narrow path between your two cars where a prowler is going to hide and see if you left your doors unlocked.. then you'll get some great ID shots of them, yeah you wont see the other side's of your cars, but if you watch your cameras long enough you'll learn all the prowlers go down the middle and use 2 cars parked next to eachother as cover.
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100% this, the amount of people trying to cover every inch of their garden but compromise the security of the entry points to their property or house is crazy!

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chadman said:
Is it easy to change the lenses on a Hikvision turret camera if you change your mind?
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Possible yes, easy no. Easy to damage yes.
 
Probably want a 2.8mm if situ above or on the side of the door but then on the sides 4mm (or 6mm+) to cover the approach.

That's what i was planning for a driveway about 2 car lengths long.

I'm not sure what visitors may think if they see a mini dome 2.8 above front door and also a video doorbell (dahua villa) on the side of the door (might be too much?)
 
Thanks! I ordered 1 2.8 and 4 4.0mm cams. Got some wires ran from the basement to the garage. Hopefully this weekend I can run them up the attic the correct location. Provided it cools down some. Temps have been in the 90's and I dread working in the attic.
 
chadman said:
Thanks! I ordered 1 2.8 and 4 4.0mm cams. Got some wires ran from the basement to the garage. Hopefully this weekend I can run them up the attic the correct location. Provided it cools down some. Temps have been in the 90's and I dread working in the attic.
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Get up in the attic at 4 or 5 am (fam will love you...) or wait for a rain storm.
 
How can you verify the lense size? Reading some reviews users ordered 4mm, but got 2.8. Looks like the model number is the same for both. Looking at the Hikvision DS-2CD2342WD-I.
 
I agree with a lot of what is said above. I have 3 cars in the drive way and 3 cameras to cover them for face recognition. I have two 4mm and one with 6mm as it sits a little further back. As a bonus they cover across the street but that part is not for face recognition. Just generally to see what is going on. I have 6 cameras to cover the back yard and the sides of the house. One being 12mm to cover the main rear sliding door and get good face recognition. I live on the corner of a 4 way intersection and have 3 Huisun PTZ cameras for license plates. One more Huisun PTZ to cover an area where there has been graffiti and trash left.

Also I can't forget the 4MM Hikvision bullet camera that covers the front door. This one has been really interesting. I had no idea that I had a wildlife corridor going by the front entrance of my house until I installed this camera. Skunks, possums and a couple of rodents passing by so far. By the way the camera that covers the trash has proved interesting. My wife spotted some trash left one morning and says I have a job for you to do and see who left the trash. It was the usual stuff you see discarded from fast food bags.

So going back over the recording I see this car pull up with two people. Girl driving with a boy friend in the passenger seat. They sit there for about a 1/2 hour and then the passenger side door opens and he gets in the back seat. I can also see her crawling to the backseat between the bucket seats. Unfortunately they had tinted windows and I could not see all that well into the car. However they were there for two hours doing what they were doing in the backseat. The he gets out of the back and goes and sits in the front seat and she crawls back into the drivers seat. They are there for about an additional 10 minutes and then after they left I could see the trash they left by the curb. I was able to copy down the license plate number just in case. Hehehehe
 
Which lens did you get? Install it and measure the angles. You'll probably find they match neither of the closest lens sizes exactly because, well, China. Published sensor sizes are wrong, as well as the portion of the sensor that's actually used. You could disassemble the cam and see if it is labelled.
 
Kawboy12R said:
Which lens did you get? Install it and measure the angles. You'll probably find they match neither of the closest lens sizes exactly because, well, China. Published sensor sizes are wrong, as well as the portion of the sensor that's actually used. You could disassemble the cam and see if it is labelled.
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i got both 2.8 and 4mm. Some users reported they ordered a 4mm, but got a 2.8. Was hopping there was an easy way to check.
 
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