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comparing 2.8mm lens and 16mm lens

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cam235

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In case of interest. Here are two images taken at the same time using two different Hikvision domes. (A) is mounted just under the roof, and (B) is at waist level and about 15 feet farther back.

(A) Hikvision DS-2CD2132F (3MP dome) with the stock 2.8 mm lens
(B) Hikvision DS-2CD2542FWD (4MP mini-dome) with an aftermarket 16 mm lens from http://www.ebay.com/itm/321917625469

The 16mm lens was pretty cheap: $13 shipped for two of them. Still the image looks OK. It does extend a few mm farther out from the camera, so the original dome does not fit back on. I'll have arrange something else to keep the spiders out of it.
2p8mm.jpg 16mm.jpg
 
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cam235

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Given the low cost of it, I was pleasantly surprised by this lens. I believe it will mount on and work with any 1/3" sensor camera with a M12 lens mount, including the 2CD2T55. The question is whether there is too much additional length over the stock lens to fit inside the housing, and I don't know that answer. With some "box-type" camera housings there is enough extra room inside in back, that you can shift the entire camera assembly backwards to accommodate a longer lens in front, possibly needing longer screws or a different internal mounting scheme.

* actually there may also be some cameras with a super-short M12 thread barrel designed for short wide-angle or fisheye lenses, that would not be not long enough to hold this lens at the right distance from the sensor.

16mm-lens.jpg

The photo shows the lens with a M12 lock ring to help hold the right focus point. That ring wasn't included, I got it from http://www.m12lenses.com/M12x0-5-Lock-Ring-Plastic-p/pt-lr001p.htm Note I would be careful about actual lenses from m12lenses.com, I have several but frankly even their so-called "MP lenses" seem designed for 1MP or less, not the newer HD cameras.
 
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cam235

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I 3D-printed a replacement dome the same size as the original, but opaque and with a hole for the new longer lens (green is what I happened to have). Kind of a chameleon eye look.

Hik2a-crop.jpg Hik-crop1.jpg
You can see the lens extends a bit outside the dome surface. This does not expose the light sensor or IR LEDs, which I don't need- but turns out my 0.8mm printed shell allows enough daylight through for the sensor to work anyway.

It was nice of Hikvision to assemble the clear dome part using a bracket and screws so I could easily replace it. I had assumed it would be just glued or co-molded. I put the hole right at the top of the dome (centered) thinking to mount the camera vertical and have it pointed at the horizon, forgetting that in this model the dome sits at an angle of about 20 degrees to the flat base, but I can either mount the camera at that angle, or just reprint the dome with the hole in the right place.
 
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cam235

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Glad you like it! If anyone else is thinking of doing this, be aware with a somewhat long lens like this one (f/2.0, f=16 mm) you have to make a choice about where the focus is, and it might be a compromise. If you set the best focus on far-distant objects, something that is 30 feet away will already be somewhat blurry. This is where a box camera with an auto-iris lens could do better, at least during the day when the iris would be stopped down giving better depth of field. Unfortunately I've found the good quality C/CS mount DC-iris lenses cost about as much as the camera itself.
 
nayr

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mind sharing the source for your 3d printed dome? There are printing services for people without access to one.. this could be a good camera for LPR usage if you make it easier for anyone to use whatever mega zoom lens they need.. the 12mm celling on most cameras is rarely enough.
 
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cam235

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Sure I can put up the 3D files somewhere, but I'd think it would be easier to just use a bullet style cam, if they are similar in price? You might still have to modify the case to fit a 16mm lens, but it might be easier to do.

BTW I have looked for an even longer M12 lens, but those I've found are not high quality. I have a 25mm but I think it was intended for an old-school low-res camera. For fun I tried a high quality 70mm Sigma Macro lens for Canon DSLR plus several adaptors to get to M12. Image quality was actually pretty good, but I can't dedicate that lens to the project.
 
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the bullets have the same issue w/out having enough room.. sometimes the sensor can float behind the glass out of its original mounting, but it seems the newer models have even more shit packed in there and it makes it even harder to accomplish.
 
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cam235

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IMG_20151004_131519.jpgIMG_20151004_1312373_rewind.jpg Here are the hikvision Bullet cams with 25mm lens installed in a test location, I beleive I could make out the plates from 100 and 150 ft away.
 
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