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Infrared Security Camera Lenses


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#1 Joven76

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Posted 21 January 2009 - 12:39 AM

Ok, I'm about to get a DVR Security system shortly and have been researching the types of infrared security cameras to get... I know that the higher the TV lines, the better the picture, and how to make sure that each camera needs to record at least 30 frames per second, however I'm a little fuzzy on the lens size... I've seen some with a lens that 3mm and others that are 12mm...

My questions are this... What's the difference between the lens size, what does it all mean, and which size is better than the other???

Any help anyone can offer would be greatly appreciated...

Thanks...

Christopher
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#2 Retro

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Posted 21 January 2009 - 11:46 PM

Ok, I'm about to get a DVR Security system shortly and have been researching the types of infrared security cameras to get... I know that the higher the TV lines, the better the picture, and how to make sure that each camera needs to record at least 30 frames per second, however I'm a little fuzzy on the lens size... I've seen some with a lens that 3mm and others that are 12mm...

My questions are this... What's the difference between the lens size, what does it all mean, and which size is better than the other???

Any help anyone can offer would be greatly appreciated...

Thanks...

Christopher



There is no simple answer to that, unfortunately. The "size" (12mm, etc..) is just the focal length of the lens. But it is not very helpful on it's own. You also need to know the size of the imager (1/3, 1/4, 1/2 inch, etc...)

There are tools here to use to get a better understanding:

http://www.supercirc...esources/tools/

They also have some very good prices on video equipment.

The semi-simple answer is with a 1/3 inch imager (most common) anything below 6mm is wide angle and anything above it is telephoto. If you get a decent camera, you can get a variety of lenses for it. But the most useful will always be a wide angle lens. But, you do not want to go so wide that you get a fish-eye effect (although sometimes, you have no choice if you want to cover the room.

Oh, one last thing... the speed of the lens is important too. A pinhole or board camera is going to be much less sensitive to light and have a softer focus than a C-Mount lens camera. When you see a board camera that claims .5 lux, they are usually telling you the sensitivity of the imager, but the lenses are often F16 or higher, so you get much much less sensitivity than that.

Also, stay away from CMOS imagers unless they are all you can afford. They are getting better, but they are still not quite there yet. A good sony SuperHAD CCD imager will go a long way.

#3 Retro

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Posted 21 January 2009 - 11:52 PM

I also wanted to add that the bigger the imager, the better. 1/3 is the smallest and most common. 1/2 is perfect, and 1 inch would be near broadcast quality. :)

Even 1/2 inch CCD cameras are starting to get a little pricey though, so consider a mixture. Have at least one very good quality camera for that high-prize area you want to cover in your investigation. Then a bunch of lesser quality ones just for extra coverage.

#4 jennifer8055

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Posted 22 January 2009 - 01:36 AM

Hi,
If you're looking for a home security system comparison you should check out http://usalarmcompanies.info . They give you a free complete comparison of the various home alarm system providers in the US and you can choose one based on the size of your home, your requirements, budget etc.

#5 Retro

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Posted 22 January 2009 - 07:33 AM

Christopher. My apologies. From some info I was reading at the site I linked, they say that 3mm is comparable to what we see with the human eye. Anything higher is considered telephoto, according to them. In practice though, 6mm is generally considered the medium range. But of course, again, this depends on the size of the imager. You choose the lens for the amount of area that you need to cover, which is why having a few different ones to choose from is a smart idea for an investigator since you will be installing them in new and different locations all the time.

If you want any more help or need some questions answered, I will try to help. I used to install video camera systems (both hidden and regular) for businesses. I do not sell anything and no longer do installs, so all advice is free. :D

Some more advice: Place IR illuminator away some distance from your lense to reduce the amount of "orbs" you will capture. Also, consider if you will be doing your investigations entirely indoors or if you might need a weatherproof camera. Finally, consider that if you will be putting it in extremely cold places, you might need a defogger (heater) in the camera body. That last one is pretty unlikely to be needed for your purposes, but it is something to consider.

Edited by Retro, 22 January 2009 - 07:36 AM.


#6 Joven76

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Posted 22 January 2009 - 07:39 AM

The cameras I'm looking at are Super HAD CCD 1/3" cameras with 6mm lenses... I can get other lens sizes as well... But I'm under the impression this is fine for a standard 14 x 14 room... Or should I get some smaller lenses???
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#7 Retro

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Posted 22 January 2009 - 07:53 AM

The cameras I'm looking at are Super HAD CCD 1/3" cameras with 6mm lenses... I can get other lens sizes as well... But I'm under the impression this is fine for a standard 14 x 14 room... Or should I get some smaller lenses???



To start out, the 6mm is probably fine. I would suggest picking up some spare lenses in other sizes after you put your initial kit together. Don't discount getting at least one telephoto lens, too. When you go in to do an investigation, you will find that you usually can't just mount them exactly where you would like to.

6mm is just fine for starting out, though.

Edited by Retro, 22 January 2009 - 07:55 AM.


#8 Joven76

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Posted 22 January 2009 - 09:21 AM

Sounds good... I'm just waiting for a quote for extra lenses from the company I'm buying them from before I order them... Thanks for the explination Retro!!!

Christopher
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#9 CaveRat2

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Posted 22 January 2009 - 10:15 AM

When buying a camera system with multiple cameras, I agree with getting several lenses. Make sure though if you buy each at different times to get ones that are interchangable. Often different makes / models don't match up with each other, especially if you go with some of the discounted ones that come with package deals.

You also mention IR capabilities. while anything 1/3 " or over will give satisfactory results under visible light, things change when dealing with IR. Due to the longer wavelengths involved clarity is not quite as good if a smaller lens / CCD element is used. This is the main reason for the grainy appearance often seen in IR illuminated images. I would recommend stepping up to 1/2 " CCD element or larger if you are going with IR illumination. The cost will be higher, but that is the price to get optimum performance in the IR spectrum.

#10 Retro

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Posted 22 January 2009 - 08:56 PM

The best way to ensure that your lenses will work is to get all c-mount cameras, but they are usually too big and too expensive to buy several in one shot. The board camera lenses have standardized quite a bit, but with different sized imagers (1/3, 1/2, etc...) they often have different barrel lengths. This is what Caverat is referring to, I think. They will not screw all the way down to allow you the full focus range without breaking your imager.

I agree, at least 1/2" if you can afford them. But if you have to cut back for budget reasons, then get at least one 1/2". I think you will be alright with smaller imagers for simply monitoring areas where you don't expect much activity. But, you will kick yourself if you put a low quality camera in a high activity area.

The idea behind the super HAD is that it uses round pixels instead of square pixels, which is generally easier for the eyes to recognize more detail. They are also much more sensitive to low light.

And Caverat, is definitely right. Focusing for IR is very different than focusing for normal light. Really, an imager would have to be specially designed for IR to yield the very best results. I have never researched that much, but I am sure that they exist. The Sony Nightshot camcorders seem to do the best in consumer levels, and those use the Super HAD imagers. So, perhaps those were designed for this.

Oh, and also be aware that some lenses actually incorporate IR filters on them to eliminate IR. You want to avoid these if possible. And some imagers have the filters installed on them, as well. In normal light, IR cause a soft focus effect as well as reacting to certain light and certain colors in odd ways (in fact, some fabrics make people look like ghosts :whee: .) So, most cameras designed for normal light conditions put filters on them to get rid of the IR. Watch out for this.

Edited by Retro, 22 January 2009 - 09:00 PM.


#11 Retro

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Posted 22 January 2009 - 09:04 PM

Here's something to read about Super HAD technology. I knew that I was remembering ex-view from somewhere. It appears the ex-view CCDs are better designed for IR. This article also mentions some panasonic imagers that compare, and sharp also makes a similar imager.


http://www.mintron.c.....CD camera.htm

Edited by Retro, 22 January 2009 - 09:07 PM.


#12 Retro

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Posted 22 January 2009 - 09:23 PM

Just so you have an idea of what is out there:

http://cgi.ebay.com/...1742.m153.l1262

This is a pretty nice camera. It has a varifocal lens with 3.5-8mm and is C/CS mount, meaning other standard lenses could be fitted. It is only a 1/3" imager, but has the ex-view CCD imager. The details in this listing might also help to understand more about the technology.

This style and technology is what we are talking about when we mention high quality cameras. I just wanted to show you this to "put a face to the name." I have purchased from this seller before, but they are not the only ones to sell this, of course.

#13 Joven76

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Posted 22 January 2009 - 11:56 PM

Here is the camera I was looking at... From what I've read, it's pretty good... Not the ex-view CCD, but doesn't seem bad from the look of it...

Camera

On a side note, the seller did say that he has larger lenses available... I'm just waiting for a price...

This auction is done, but he said he has more and will relist them... Let me know what you think...

Christopher

Edited by Joven76, 22 January 2009 - 11:58 PM.

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#14 Retro

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Posted 23 January 2009 - 03:02 AM

Looks like a decent enough camera from the specs in the listing. Looks suspiciously like what every ghost hunter uses on TV. :clap:

My only real concern with this camera is the location of the IR LEDs. If you get in a very dusty area, keep in mind that your image could going to be overcome with reflections off the dust. If it is bad enough, it could completely obscure the image. If it is bright enough, the autoiris/autoexposure feature will darken the image to prevent blooming and anything beyond the birght dust will completely disappear in blackness.

A separate IR illuminator is always the better option, but there are many times you just can't get that gear in there. Just keep this mind.

Oh, and don't use the autobacklight feature unless you absolutely have to.

#15 Joven76

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Posted 25 January 2009 - 07:50 PM

Ok,I think I understand about the different lens sizes now and their functions, but I've now run into another question... I've seen TAPS put their cameras on what look light stands like photographers use... However, what I can't figure out is how they attach them to the top of the stand... So, I've been looking into really tall tripods, but have only found some that extend up to 5 feet... I've also thought about utilizing the small tripods and setting the camera on a dresser or something, but I don't want that to be my only method...

Do any of you utilze tripods or light stands??? How do you connect them to the light stands??? What are some other suggestions??

Thanks...
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