3Mp narrower than 2Mp

[aurmol 0]

Did you notice the 3mp ip cams are narrower than the 2Mps (1080p) in the field of view even if the lens are 3.6mm? Why would anyone want to get narrower field of view? It's as if the 4:3 image was taken from the same sensor as 16:9 such as the sides are blackened?

 

for example.. compare

 

http://www.dahuasecurity.com/products/ipc-hfw4200e-509.html

 

to

 

http://www.dahuasecurity.com/products/ipc-hfw4300e-510.html

 

the 1080p model has 88 degree horizontal field of view while the 3mp model has 72 field of view. All rest same including 3.6mm lens.

 

Do both use the same sensor with the 3pm cutting the sides? If not, what sensors do they use?

Is this true with all brands like Hikvision, Geovision, Axis, etc for lens of the same focal length (comparing 1080p vs 3mp)?

 

btw.. the 1080p version uses the sony Exmor, while the 3mp uses the aptina sensor.. which can resolve more shadows and details at the grass for example (anyone has tested these)?

[Digiscan 0]

Hikvisions do the same thing. it narrows it, but it also makes it higher

[Securame 0]

2MP model has 1/2.8" sensor. 3MP model has 1/3" sensor.

 

With the same lens, bigger sensor = wider FOV.

[aurmol 0]

2MP model has 1/2.8" sensor. 3MP model has 1/3" sensor.

 

With the same lens, bigger sensor = wider FOV.

 

but 1/2.8" vs 1/3" with mere difference of 1/0.2" is almost insignificant. I think dahua sensors are all 16:9. In their 1.3Mp and 3Mp models 4:3 sensors. It's like dahua just cut the sides. This occurs to both 1.3Mp and 3.0Mp in all models at 3.6mm at mere 72 degrees field of view. Only the 1080p 2Mp dahua ip cams are wider at 88 degrees... the 16 degrees of difference can't be caused by the mere difference between 1/2.8" vs 1/3" sensor.. would it?

[Boogieman 1]

1/3=.33333 so its more than a .2 difference..

With dahua if you get the 3mp camera the horizontal field of view will remain the same whether you set it to 2mp or 3mp...however the 2mp camera itself is different.

With hikvision if you set the 3mp camera to 2mp you will get a wider view...

Wider view is not always preferable because you lose some detail as the pixels are spread over a wider area...also depending on the area a wider view will result in capturing a wall or other area that you dont want..

3mp will give you more vertical fov and may be something you want in a particular location.

[buellwinkle 0]

Sensor size and just variances in the M12 lenses is why you get different field of views. I can show you a 4.1mm lens on a camera that is wider than most cameras with 2.8mm.

 

For example, this is 4.1mm from Bosch camera I recently reviewed, 5MP but 16:9 format like the 1080P cameras. It has a bigger sensor than most cameras at 1/1.8" and uses CS lenses vs. M12 lenses on less expensive cameras.

 

 

This is from a Hikvision ds-2cd2132-i mini dome with a 2.8mm lens. Not as wide as the Bosch

 

 

This is from a Dahua ipc-hdbw2200e that is 1080P and 3.6mm, about the same width as the Hikvision 2.8mm, a little less wider, yet both are mini-domes

[aurmol 0]

1/3=.33333 so its more than a .2 difference..

With dahua if you get the 3mp camera the horizontal field of view will remain the same whether you set it to 2mp or 3mp...however the 2mp camera itself is different.

With hikvision if you set the 3mp camera to 2mp you will get a wider view...

Wider view is not always preferable because you lose some detail as the pixels are spread over a wider area...also depending on the area a wider view will result in capturing a wall or other area that you dont want..

3mp will give you more vertical fov and may be something you want in a particular location.

 

note 1/2.8" = 0.357"

and 1/3" = 0.333"

 

now 0.357" - 0.333" = 0.0236"! So it's much less than 0.2" difference.. its 0.0236 inches and pretty small and insignificance... are you still saying the 16 degree field of view difference between the 1080p and 3mp is due to the 0.0236 inch (0.6mm) sensor size difference? or dahua all use 16:9 sensors and jus cut the sides in the 1.3mp, 3mp models.

[buellwinkle 0]

Trying to do math is totally worthless for this because the focal length and sensor size are not the only things that determine the field of view with M12 lenses are there's no standard for things like backfocus. I can buy a few 3.6mm lens, stick them in the Dahua camera and each one will have a different field of view.

 

In addition, some camera companies put in higher resolution sensors to provide different field of views depending on if you choose a 16:9 or a 4:3 format. For example, Bosch uses a 6.1MP sensor in their 5MP camera to provide 5MP at 16:9 or 4:3 so you could get a wider FOV in 16:9 vs. 4:3, same lens, same camera. Hikvision does to with their sensors that are closer to 3.3MP to provide a wider view in 16:9 (1080P) than with 4:3 (3MP). Dahua I believe just crops their 3MP sensor to make 1080P, even in their 1080P only cameras.

[aurmol 0]

Trying to do math is totally worthless for this because the focal length and sensor size are not the only things that determine the field of view with M12 lenses are there's no standard for things like backfocus. I can buy a few 3.6mm lens, stick them in the Dahua camera and each one will have a different field of view.

 

In addition, some camera companies put in higher resolution sensors to provide different field of views depending on if you choose a 16:9 or a 4:3 format. For example, Bosch uses a 6.1MP sensor in their 5MP camera to provide 5MP at 16:9 or 4:3 so you could get a wider FOV in 16:9 vs. 4:3, same lens, same camera. Hikvision does to with their sensors that are closer to 3.3MP to provide a wider view in 16:9 (1080P) than with 4:3 (3MP). Dahua I believe just crops their 3MP sensor to make 1080P, even in their 1080P only cameras.

 

2 months ago I was deciding between their 1080p or 3Mp. But I got the 1080p because they are all 88 degree field of view versus the 3Mp 72 degrees. Now if you will notice, the older 1080p, the one you reviewed, the Dahua ipc-hdbw2200e was already discontinued. It was the only one using 3Mp sensor to give 1080p at 72 degrees by probably cropping the vertical to make it 16:9. The latest 1080p now all use the same new 1/2.8" raw 1080p sony exmor sensor with 88 degree angle while all 3Mp that uses the 1/3" aptina now are 72 degree. Dahua doesn't have any 1080p now using 3Mp aptina sensor. If you have any review of the latest sony exmor used in 1080p, please. share it to compare it to the older model sony exmor used for example in 3300S.. unless you are saying the 3300S (older) and 4200S (below) uses the same sony exmor sensor?? but the new one is 1/2.8" while the old one you reviewed is 1/3".. the one where you mentioned has poorer details than the 3Mp aptinas. I wonder how the new 1/2.8" sony exmor used in 1080p compared to the 3Mp aptinas now. I'm deciding whether to get another sony exmor or the 3Mp aptina with narrower field of view but taking advantage of possible deeper dynamic range.

 

http://www.dahuasecurity.com/products/ipc-hfw4200e-509.html

 

http://www.dahuasecurity.com/products/ipc-hfw4300e-510.html

[buellwinkle 0]

Dahua goes in/out of production on different models, hard to say what is discontinued or not, but the 'lite" series 2MP (1080P) using 3MP sensors are still on their website and they are still making them. They did discontinue it for a few months with no explanation, then they brought it back a few months ago.

 

The ones you speak off are more expensive and actually use older technology, because I reviewed Dahua with Sony Exmor sensors 3 years ago. What you think is new is just the square form factor they introduced a year ago. What I don't like about that sensor is the narrow dynamic range that gives too a high contrast. Makes for a better looking picture, but loses detail in the shadows.

 

Who at the Dahua factory are you in contact with?

[aurmol 0]

Dahua goes in/out of production on different models, hard to say what is discontinued or not, but the 'lite" series 2MP (1080P) using 3MP sensors are still on their website and they are still making them. They did discontinue it for a few months with no explanation, then they brought it back a few months ago.

 

The ones you speak off are more expensive and actually use older technology, because I reviewed Dahua with Sony Exmor sensors 3 years ago. What you think is new is just the square form factor they introduced a year ago. What I don't like about that sensor is the narrow dynamic range that gives too a high contrast. Makes for a better looking picture, but loses detail in the shadows.

 

Who at the Dahua factory are you in contact with?

 

No one. Just their website. 2 months ago I was deciding whether to get the 1080p or 3Mp. But the former is just much wider so 3 of them. Now I need another one and thinking whether to try the 3Mp. I thought Sony Exmor is always better than Aptina. Do you have other reference why the Aptina has wider dynamic range? Yes. Sony Exmor gives very nice picture. If I got the following model. Would it have high dynamic range too (but it says S/N: 50 db)? I can't return it once ordered. But the much lower 72 degree angle keeps me thinking otherwise.

 

http://www.dahuasecurity.com/products/ipc-hfw4300e-510.html

 

The one you reviewed was 4300s.. the above is 4300e.. any idea what is "s" versus "e"? If it has wider dynamic range.. then I'd get it and sacrifice the wider view. And why can't dahua produce an 88 degree version of its aptina 3Mp?

[aurmol 0]

I think a more interesting comparison would be knowing if the Hd-cvi or the sony exmor ip cam are better in the contrast.. we know the aptina sensors would be better than the hd-cvi... Buellwinkle.. why haven't you tested/reviewed any of the hd-cvi?

 

and how come the field of view for all dahua hd-cvi are totally unknown or not written in the spec such as:

 

http://www.dahuasecurity.com/products/hac-hfw2200e-608.html

 

Any idea of the field of view angle?

[Securame 0]

2MP model has 1/2.8" sensor. 3MP model has 1/3" sensor.

 

With the same lens, bigger sensor = wider FOV.

 

but 1/2.8" vs 1/3" with mere difference of 1/0.2" is almost insignificant. I think dahua sensors are all 16:9. In their 1.3Mp and 3Mp models 4:3 sensors. It's like dahua just cut the sides. This occurs to both 1.3Mp and 3.0Mp in all models at 3.6mm at mere 72 degrees field of view. Only the 1080p 2Mp dahua ip cams are wider at 88 degrees... the 16 degrees of difference can't be caused by the mere difference between 1/2.8" vs 1/3" sensor.. would it?

 

A 1/2.8" sensor is 18% bigger than a 1/3" sensor. So 72º * 1.18 = 85%. I am not saying that is the explanation, but it would make sense.

 

I think a more interesting comparison would be knowing if the Hd-cvi or the sony exmor ip cam are better in the contrast.. we know the aptina sensors would be better than the hd-cvi... Buellwinkle.. why haven't you tested/reviewed any of the hd-cvi?

 

Well... The domain http://www.NetworkCameraCritic.com should give you an idea on what he reviews, network cameras. I will guess that's why he hasn't reviewed any HDCVI cameras, because they are not network cameras. Just my guess.

[aurmol 0]

2MP model has 1/2.8" sensor. 3MP model has 1/3" sensor.

 

With the same lens, bigger sensor = wider FOV.

 

but 1/2.8" vs 1/3" with mere difference of 1/0.2" is almost insignificant. I think dahua sensors are all 16:9. In their 1.3Mp and 3Mp models 4:3 sensors. It's like dahua just cut the sides. This occurs to both 1.3Mp and 3.0Mp in all models at 3.6mm at mere 72 degrees field of view. Only the 1080p 2Mp dahua ip cams are wider at 88 degrees... the 16 degrees of difference can't be caused by the mere difference between 1/2.8" vs 1/3" sensor.. would it?

 

A 1/2.8" sensor is 18% bigger than a 1/3" sensor. So 72º * 1.18 = 85%. I am not saying that is the explanation, but it would make sense.

 

I think a more interesting comparison would be knowing if the Hd-cvi or the sony exmor ip cam are better in the contrast.. we know the aptina sensors would be better than the hd-cvi... Buellwinkle.. why haven't you tested/reviewed any of the hd-cvi?

 

Well... The domain http://www.NetworkCameraCritic.com should give you an idea on what he reviews, network cameras. I will guess that's why he hasn't reviewed any HDCVI cameras, because they are not network cameras. Just my guess.

 

Why did you get the 18% figure? Let's compute

 

1/3"=0.3333333333333^2=0.11111

1/2.8"=0.357^2=0.12755

 

0.12755 is just (0.12755-0.11111)/0.11111 or 0.147 larger than 0.11111.. may I know how you compute the 18%? Thanks!

[MaxIcon 0]

OK, I'm a math guy, but you guys are chasing the wrong ghost here, and it's taking you down the rabbit hole.

 

The issue isn't so much sensor size as it is M12 lens image circle size. As BW stated earlier, you can install 3 different 4mm (or whatever) lenses on the same cam and get 3 different FOVs.

 

The old FOV calculators don't really work with IP cams and M12 lenses. It's almost impossible to tell what your final FOV will be without putting the lens on and measuring it. Vendors need to spec this stuff in more detail; some do now.

 

Even the vendor numbers aren't always accurate, and they often don't spec the different aspect ratios, like 4:3 vs 16:9, but will only spec one.

 

Also, the image sensor size isn't the real size, but what they call a "class" or "optical format" size, left over from when image sensors were mounted in glass vacuum tubes, and the size referred to the tube ID.

 

The diagonal for a 1/3" image sensor is closer to 1/4" in the real world. You can get these numbers from the spec sheet for the sensor, but you can approximate them by multiplying the sensor size by 2/3.

 

Finally, most modern sensors aren't square, so the relationship between the real diagonal size and the real x and y size will depend on the actual sensor die and number of pixels (not always the same as the resolution; there are usually more pixels than the resolution spec).

 

So, before you can compare sensor X to sensor Y, you need the spec sheet on each to get the real numbers.

 

Here's an example. The Aptina AR0330 sensor, used in the Hik 2032 camera, is a 1/3" sensor. Per the data sheet:

 

Optical format:

1/3-inch (6.0 mm)

Entire Array: 6.09mm (this is about 0.24")

Still Image: 5.63mm (4:3)

HD Image: 5.82mm (16:9)

(you can use the aspect ratio and trig to calculate the x and y dimensions)

 

Active pixels:

2304(H) x 1536(V): (entire array):

5.07mm(H) x 3.38mm(V)

2048(H) x 1536(V) (4:3, still mode)

2304(H) x 1296(V) (16:9, sHD mode)

[Q2U 0]

I got everything up to the point where you said you were a math guy!

[aurmol 0]

OK, I'm a math guy, but you guys are chasing the wrong ghost here, and it's taking you down the rabbit hole.

 

The issue isn't so much sensor size as it is M12 lens image circle size. As BW stated earlier, you can install 3 different 4mm (or whatever) lenses on the same cam and get 3 different FOVs.

 

The old FOV calculators don't really work with IP cams and M12 lenses. It's almost impossible to tell what your final FOV will be without putting the lens on and measuring it. Vendors need to spec this stuff in more detail; some do now.

 

Even the vendor numbers aren't always accurate, and they often don't spec the different aspect ratios, like 4:3 vs 16:9, but will only spec one.

 

Also, the image sensor size isn't the real size, but what they call a "class" or "optical format" size, left over from when image sensors were mounted in glass vacuum tubes, and the size referred to the tube ID.

 

The diagonal for a 1/3" image sensor is closer to 1/4" in the real world. You can get these numbers from the spec sheet for the sensor, but you can approximate them by multiplying the sensor size by 2/3.

 

Finally, most modern sensors aren't square, so the relationship between the real diagonal size and the real x and y size will depend on the actual sensor die and number of pixels (not always the same as the resolution; there are usually more pixels than the resolution spec).

 

So, before you can compare sensor X to sensor Y, you need the spec sheet on each to get the real numbers.

 

Here's an example. The Aptina AR0330 sensor, used in the Hik 2032 camera, is a 1/3" sensor. Per the data sheet:

 

Optical format:

1/3-inch (6.0 mm)

Entire Array: 6.09mm (this is about 0.24")

Still Image: 5.63mm (4:3)

HD Image: 5.82mm (16:9)

(you can use the aspect ratio and trig to calculate the x and y dimensions)

 

Active pixels:

2304(H) x 1536(V): (entire array):

5.07mm(H) x 3.38mm(V)

2048(H) x 1536(V) (4:3, still mode)

2304(H) x 1296(V) (16:9, sHD mode)

 

Thanks for your information. Before I avoided the 4MM because of narrow angles.. but checking out dahua only 5mm bullet cam at 4MM. I realized it has 82 degrees angle of view.. even wider than the 3.6mm 1080 at only 72mm.. but I don't know how it would behave when 16:9 versus 4:3. It seems Hkvision can make you use all resolution below it with no loss of area while the dahua may seem just cut the view left and right. This is what happened to their 2.8mm 1.3M aptina. When switching to 720p, the vertical get cut. When switching to D1. The horizontal get cut so you only have 60% of the area of 1.3Mp. I wonder what would happen to the 5mp dahua if you want only 1080p temporarity. If anyone has idea. Please let me know. Thanks.

[MaxIcon 0]

When you switch between wide screen (16:9) and old school (4:3), you'll always have a different FOV in one axis or another, unless they compress or stretch one of the views.

 

For example, on the Dahua 2100:

720p is 1280×720 (on all cams, since 720p is a standard)

1.3MP is 1280×960 (not a standard, so some 1.3MP cams have different resolutions)

 

Both images show the same 1280 pixels for the width, but the 1.3MP has an extra 120 pixels each on the top and the bottom, and you see more FOV. They could use the same FOV for both, but the 1.3MP would be stretched vertically to fit the same view into more pixels, throwing away the real extra pixels.

 

Most cams these days use the same FOV for all 4:3 settings (1.3MP, 3MP) and the same FOV for all 16:9 settings (720p and 1080p). How the 5MP will display will depend on the resolution.

 

Divide the horizontal resolution by the vertical resolution to figure it the aspect ratio for your cam's 5MP setting:

1280/720 = 1.78 (same as 16/9)

1280/960 = 1.33 (same as 4/3)

[aurmol 0]

When you switch between wide screen (16:9) and old school (4:3), you'll always have a different FOV in one axis or another, unless they compress or stretch one of the views.

 

For example, on the Dahua 2100:

720p is 1280×720 (on all cams, since 720p is a standard)

1.3MP is 1280×960 (not a standard, so some 1.3MP cams have different resolutions)

 

Both images show the same 1280 pixels for the width, but the 1.3MP has an extra 120 pixels each on the top and the bottom, and you see more FOV. They could use the same FOV for both, but the 1.3MP would be stretched vertically to fit the same view into more pixels, throwing away the real extra pixels.

 

Most cams these days use the same FOV for all 4:3 settings (1.3MP, 3MP) and the same FOV for all 16:9 settings (720p and 1080p). How the 5MP will display will depend on the resolution.

 

Divide the horizontal resolution by the vertical resolution to figure it the aspect ratio for your cam's 5MP setting:

1280/720 = 1.78 (same as 16/9)

1280/960 = 1.33 (same as 4/3)

 

No. The FOV of the 1.3MP dahuas are 89 degrees while all their 3MP are just 72 degrees. These use aptina sensor. While the 2Mp or 1080p uses sony exmor and are 88 degrees FOV. And because I need about 90 degrees FOV. Im hesitant to get the narrow 3Mp. The 5MP are 82 degrees fov. So are the 4K (8mp).

[MaxIcon 0]

When I said most use the same FOVs for similar aspect ratios, I meant within one camera model/lens/sensor combo, not across models. Different models with different sensors and different lenses are going to have different FOVs, even if the resolution and focal length specs are the same.

 

Sounds like the Dahua 5MP does a mix of direct sampling and pixel scaling for their different resolutions, which doesn't make any sense to me, but I quit buying Dahua after my last 4300S 3MP.

 

Here are the FOVs I measured on the 4300S.

 

You can see that the 16:9 resolutions all have the same FOV, as do the 4:3 resolutions. The measured resolution is also slightly different from what they spec. At the time, their spec was only for 3MP/4:3; they didn't include a spec for the 16:9 settings. That may have changed.

 

Dahua HFW4300S Resolutions:

3MP = 2048 x 1536

1080P = 1920 x 1080

SXGA = 1280 x 1024

1.3MP = 1280 x 960

720P = 1280 x 720

D1 = 704 x 480

 

OEM 3.6mm lens - Dahua's original lens

3MP, 1.3MP, D1 = 70 degrees H, 51 degrees V

1080P, 720P = 65 degrees H, 36 degrees V

SXGA = 65 degrees H, 51 degrees V

 

One option is to change the lens for a wider view, but that's also unpredictable, due to the issues we've been talking about.

[aurmol 0]

..

[aurmol 0]

buellwinkle, max.. or anyone who owns the dahua 4300s with great dynamic range. Is the dynamic range a function of the sensor or circuitry after it? Because there is this dahua model 3Mp WDR Ultra Smart Ip cam http://www.dahuasecurity.com/products/ipc-hfw8301e-626.html

 

It says Ultra (Wide Dynamic Range) up to 120dB. It also uses the 3mp aptina sensor.

 

Now is the 4300S dynamic range also 120dB (just not written but emphasized in the ultra smart model? Or did they further improve the dynamic range of the already good 4300S to make it even greater? What is your opinion? Anyone own the 8301e? How does it compare to the 4300S in the dynamic range. Just the same?

[MaxIcon 0]

It's a combination of sensor and software, I believe, but I don't know much about the low-level implementation of WDR beyond the theory.

 

Generally, inexpensive cams have mediocre WDR. I don't care much for Dahua's WDR on either my HFW3300c or HFW4300s; it tends to make the image washed out before it improves things much. I may not have the latest firmware, though.

 

Typically, to get better WDR performance, you have to pay more money.

 

Korgoth does some nice WDR comparisons in this thread:

viewtopic.php?f=19&t=35128&start=30

 

The cheapest cam he shows with great WDR is the Vivotek IP8355H, which is a $700, 1.3MP cam. Next comes the Sony EB632R, which is 1080p and runs $1300.

[aurmol 0]

It's a combination of sensor and software, I believe, but I don't know much about the low-level implementation of WDR beyond the theory.

 

Generally, inexpensive cams have mediocre WDR. I don't care much for Dahua's WDR on either my HFW3300c or HFW4300s; it tends to make the image washed out before it improves things much. I may not have the latest firmware, though.

 

Typically, to get better WDR performance, you have to pay more money.

 

Korgoth does some nice WDR comparisons in this thread:

viewtopic.php?f=19&t=35128&start=30

 

The cheapest cam he shows with great WDR is the Vivotek IP8355H, which is a $700, 1.3MP cam. Next comes the Sony EB632R, which is 1080p and runs $1300.

 

Are you talking of natural dynamic range of one implemented in software? I thought "WDR" is a software implementation. Maybe it is possible for a camera to have excellent natural dynamic range but mediocare WDR?

[MaxIcon 0]

Inexpensive cams use simple software WDR, which generally applies different levels of processing to the extreme ends of the histogram.

 

Better WDR can come from a variety of techniques, like logarithmic sensors (not so common), image processing hardware, or multi-exposure image processing.

 

The Vivotek listed above uses multi-exposure processing, which works fine in bright light, but becomes harder to use at long exposures for low light because there's not enough time to get multiple exposures of the same image:

http://www.vivotek.com/wdr/

http://en.wikipedia.org/wiki/High_dynamic_range_imaging

 

It's definitely possible to have a poor dynamic range image from a sensor with good dynamic range, but generally, these inexpensive sensors don't have great dynamic ranges. Better sensors cost more, and you need more powerful CPUs and more memory to process multiple images into one in realtime, all of which adds to the cost.

 

You have to figure a complete camera that costs $85 from China doesn't have a high priced sensor or lens. It's quite amazing that they work as well as they do.