what does 720p resolution mean?

[Terry_yang 0]

one of my customer asked me if my lens can support to 720p resolution. so waht does that mean?

[Soundy 1]

"720p" is a term semi-specific to HDTV - it means 720 lines of vertical resolution, progressive-scan. Standard-definition NTSC TV picture is 480i, or 480 interlaced lines. Basic progressive-scan DVD players can output 480p, if the television supports the progressive signal.

 

HDTV specifies four video/resolution formats: 720i, 720p, 1080i, and 1080p. A typical device with 1080-line resolution will have a total resolution of approximately 1920x1080 pixels. In CCTV terms, that equates to about a 2MP camera.

 

I say the term is "semi-specific" to HDTV, because although it actually exists AS a specification for consumer HDTV transmission, the terms "720p" and "1080p", and "high definition" itself for that matter, are being used more and more frequently by CCTV manufacturers... and rather improperly so, IMHO.

 

As for your customer's question, lenses don't "have resolution" as such. ANY lens will "support" 720p.

[cglaeser 0]

Everything soundy said above, but I would add that high quality lenses can resolve more detail than cheaper low quality lenses.

 

Best,

Christopher

[Terry_yang 0]

I see. normally the high resolution camera will perform better with a HR lens. so a 720p camera is high in resolution, right?

[cglaeser 0]

I see. normally the high resolution camera will perform better with a HR lens. so a 720p camera is high in resolution, right?

 

Yes, although I think it's more common to refer to them as megapixel cameras when referring to security cameras. The old adage applies, you get what you pay for. More expensive lenses are usually more expensive for a reason, which could include better at resolving detail, less dispersion, larger aperture, wider zoom range, support for larger sensor, etc, etc, etc.

 

Best,

Christopher

[Soundy 1]

To clarify: the lens doesn't "have resolution" as such. Cheaper lenses will be manufactured to lower standards and not usually be as "clear" or "sharp" as possible. On normal analog cameras, these deficiencies aren't usually noticeable because of the low image resolution, but as the resolution of the camera increases, poor-quality optics becomes more noticeable...

 

So, you get so-called "megapixel lenses"... which as far as basic lens theory and design goes, are no different than cheap lenses... but they ARE designed and built to a higher quality standard, so they produce clearer images with higher-resolution cameras.

 

If you're familiar with the photographic world (and digital SLRs in particular) comparing a "standard" lens to a "megapixel" lens would be analogous to comparing a basic $150 "kit" zoom lens to a $1500 professional-grade zoom: the basics of both are the same, but one is built better, using higher-quality glass and closer manufacturing tolerances, and will therefore produce a better picture.

 

Or to use another analogy: a Honda Civic engine works great in a Honda Civic. In basic concept, it's no different from the engine in a big Ford F-350. You could even put the Civic engine into the Ford (okay, not easily, but you get the idea), and it will work... but not as well as it could, because the truck is larger and heavier and needs more power to work effectively. The deficiencies of the smaller engine - particularly the lack of torque - become more noticeable with the greater load.

[Terry_yang 0]

To clarify: the lens doesn't "have resolution" as such. Cheaper lenses will be manufactured to lower standards and not usually be as "clear" or "sharp" as possible. On normal analog cameras, these deficiencies aren't usually noticeable because of the low image resolution, but as the resolution of the camera increases, poor-quality optics becomes more noticeable...

 

So, you get so-called "megapixel lenses"... which as far as basic lens theory and design goes, are no different than cheap lenses... but they ARE designed and built to a higher quality standard, so they produce clearer images with higher-resolution cameras.

 

If you're familiar with the photographic world (and digital SLRs in particular) comparing a "standard" lens to a "megapixel" lens would be analogous to comparing a basic $150 "kit" zoom lens to a $1500 professional-grade zoom: the basics of both are the same, but one is built better, using higher-quality glass and closer manufacturing tolerances, and will therefore produce a better picture.

 

Or to use another analogy: a Honda Civic engine works great in a Honda Civic. In basic concept, it's no different from the engine in a big Ford F-350. You could even put the Civic engine into the Ford (okay, not easily, but you get the idea), and it will work... but not as well as it could, because the truck is larger and heavier and needs more power to work effectively. The deficiencies of the smaller engine - particularly the lack of torque - become more noticeable with the greater load.

Nice comment. With the development of the camera, the Mega Pixel lens will be more popular.

[cglaeser 0]

To clarify: the lens doesn't "have resolution" as such.

 

Well, lenses do resolve. Lens resolution is typically defined as the ability of a lens to resolve detail. See Wiki for a more detailed description of lens, sensor, and optical resolution.

 

http://en.wikipedia.org/wiki/Optical_resolution#Lens_resolution

 

Best,

Christopher

[Soundy 1]

To clarify: the lens doesn't "have resolution" as such.

 

Well, lenses do resolve. Lens resolution is typically defined as the ability of a lens to resolve detail. See Wiki for a more detailed description of lens, sensor, and optical resolution.

 

http://en.wikipedia.org/wiki/Optical_resolution#Lens_resolution

 

Best,

Christopher

 

Yes, but people in this case tend to think of "resolution" as "X by Y pixels". "Resolution" and "resolving power" are nowhere close to the same thing.

[cglaeser 0]

Yes, but people in this case tend to think of "resolution" as "X by Y pixels".

 

What people, who said pixels?

 

"Resolution" and "resolving power" are nowhere close to the same thing.

 

Resolving power? Who said "resolving power"? We were talking about lens resolution, which is about the ability to resolve detail. In case the Wiki link did not work, here is the definition from Wiki (the emphasis is mine).

 

"Lens Resolution: The ability of a lens to resolve detail is usually determined by the quality of the lens but is ultimately limited by diffraction."

 

I think you may be confusing detail with focal length, which is something entirely different. Lens X with a short focal length could have exceptional resolution (meaning exceptional detail), while lens Y with a long focal length could have poor resolution, meaning poor detail.

 

Best,

Christopher

[Soundy 1]

Yes, but people in this case tend to think of "resolution" as "X by Y pixels".

 

What people, who said pixels?

 

Nobody "said" pixels. The way MANY (even MOST) people ask about "lens resolution" indicates that they equate it with image resolution. The way manufacturers market lenses doesn't help matters.

 

"Resolution" and "resolving power" are nowhere close to the same thing.

 

Resolving power? Who said "resolving power"? We were talking about lens resolution, which is about the ability to resolve detail.

 

"Lens Resolution: The ability of a lens to resolve detail is usually determined by the quality of the lens but is ultimately limited by diffraction."

 

I realize that. Sorry, in photographic jargon, this measurement is often called "resolving power".

 

I think you may be confusing detail with focal length,

 

Not at all. As I've mentioned before, I come from an extensive background in photography; I understand these concepts quite well.

[hardwired 0]

Brings up one of my rants.. Only a very few lens manufacturers include objective (MTF or LP/MM) information, which makes it almost impossible to tell whether a lens will really be suitable for a given "Megapixel" rating without testing it...

 

I got lenses on a early Arecont dome that looked like crap when I put them on a standard res cam, let alone a Megapixel cam.

 

Arecont replaced them with another "no name" selection that was better, but images from them still are not anywhere as good as I get with a box style Arecont, and a good brand name lens.

 

I really wish more Megapixel cam manufacturers would go with a bigger imager, and DSLR lenses, like Avigilon has. Lens manufacturers on the DSLR side of things have a long head start on CCTV manufacturers about dealing with Megapixel optics.