Lens rec for the Pan

[C.O.P. 0]

Unless you guys throw another wrench (point out a flaw) in my plans, I think I have settled on either 2 Panasonic WV-CP504 box cameras

 

ftp://ftp.panasonic.com/pub/Panasonic/business/security/spec_sheets/WV-CP500series_specifications.pdf

 

or 1 WV-CP504 and 1 WV-CW504 to get me started.

 

ftp://ftp.panasonic.com/pub/Panasonic/business/security/spec_sheets/WV-CW504Series_specifications.pdf

 

I'll be using seperate IR illumination... either 2 long range or 1 short and one long depending on what setup i go with above.

Unless you want to make suggestions in advance, I am not at specifics for the IR yet.

 

What I am interested in are suggestions for lenses for the box cameras. Because it will be focused about 50 feet away (give or take after final adjustments), using IR light at night (mostly) I think I would want a 50mm, varifocal, AI lens. I was considering the Tamron 13VG550-SQ

 

The Tamron 13VG550-SQ is a 5-50mm vari-focal auto iris lens that offers the highest quality images for all mid and longer range applications. This flexible lens has an extended adjustment range (10X) while maintaining a compact and lightweight chassi design. Sharper image quality is made possible through Tamron's use of two aspherical lens elements that enhance performance by eliminating distortion and providing superb corner to corner sharpness. The 13VG550-SQ offers excellent low light performance through the f/1.4 coated optics and increased dynamic range by incorporating a 3 blade iris with a neutral density filter. Ships with a pre-wired 4 pin connector. For all 1/3" CCD cameras that has a standard CS lens mount. This "best in class" lens is only a few dollars more than our lowest cost 5-50mm lens. The Tamron 13VG550-SQ is worth every penny. !

 

Angle of view: 5.3 degrees (at 50mm) to 53.4 degrees (at 5mm).

 

but it does not specify "IR correction"... unless "The 13VG550-SQ offers excellent low light performance through the f/1.4 coated optics and increased dynamic range by incorporating a 3 blade iris with a neutral density filter." = IR correction.

 

I looked at the panasonic lenses but besides being almost double the price, I don't think the specs looked as good (of course I am not very sur what is important either).

 

This thread has pics and descriptions of the area I want to cover and the task I want to accomplish.

viewtopic.php?f=34&t=19883

 

Any thoughts? Am I getting there?

[bike_rider 0]

I don't know about those lenses, but the Pany is a good camera. My 484 is easily my best camera.

 

If the description does not say "IR Corrected", then it isn't.

 

Focal length is all about how much area you want to cover. Check out the many calculators on the web, http://www.webcamsoft.com/en/faq/lens_calc.html

 

Let's say you want to cover a lane (one lane), call it 10 feet wide, at a distance of 50 feet. On a 1/3" sensor camera, that's 24mm. It is always nice to get a vari-focal lens so you can fine tune.

[C.O.P. 0]

Hi Bike,

 

See, no senior moment. Here's one of your responses.

 

Thanks for the link. I took a look and all I have to say is OMG... I'm an accountant, not a darn rocket scientist!

Seriously... I suspect something like that would be useful to get the best photos in a rare/unique photo opportunity but you guys don't actually calculate it for each project, do you? I was hoping to use the very scientific approach of "trial and error"!

 

My mentality (which I suspect is the same for many amatures) is big distance = big lens. A 5-50mm lens can be adjusted to equal anything from a 5mm lens to a 50mm lens, right? My exposure to this forum has forced me to realize many of my assumptions (about cameras and photography... I still think women are aliens!) are not true!

 

Grr... now I have to look up those formulas to see what each variable means or I'll lose sleep!

[bike_rider 0]

Yes a 5-50 will cover the range from 5mm to 50mm. Since 24 is nicely in the middle, then 5-50 is a good range to get so you are flexible. The calculators are good for a rough estimate. You don't want to get a 5-50 when you really wanted 65. Lots of bullets max out at between 9 and 12 mm and that can be be a real problem if you want to see faces clearly because you have to put the camera really close to the subject.

 

So, you don't have to know exactly what mm you need, but you should have some idea.

[cglaeser 0]

A 5-50mm lens can be adjusted to equal anything from a 5mm lens to a 50mm lens, right?

 

Equal in performance? No, for several reasons.

 

First, it's important to consider the aperture. A 5-50mm may be f1.8 wide open, but typically has a much smaller aperture at the long end unless it is a very expensive lens. A smaller aperture (larger f number) means less light is focused on the sensor, and if low light performance is a consideration, then you want all the light you can get. If you know the focal length needed, then it will be less costly to get a wide aperture in a fixed long lens compared to a zoom lens at the long end.

 

Second, it is easier to design for good detail, contrast, IR correction, etc, etc, in a fixed lens or even a 3x zoom lens that it is in a 10x zoom lens. So, the more the zoom range, you will likely sacrifice other features of the lens, unless, of course, you are will to pay a premium, and even then, dollar for dollar, a fixed lens will always win.

 

So, if you know the focal length you need, there may be reasons to go fixed. That said, this is security, not photography, and relatively inexpensive varifocal/zoom lenses are common and do just fine. But it is important to understand the trade-offs.

 

Best,

Christopher

[C.O.P. 0]

Thanks Chris.

 

The lens I mentioned above claims to have a "f1.4 coated lens" etc. The site I found it on has it priced about $99.00. I'm not sure if thatis considered high or not. Compared to the prices I was getting on the Panasonic 40mm ($180+) ftp://ftp.panasonic.com/pub/Panasonic/cctv/SpecSheets/WV-LZA61-2S.pdf

 

it certainly seems cheaper and better f1.4 vs f1.9. The Panasonic mentions nothing about aspherical lenses or better dynamics... am I supposed to be able to glean this information from the specs provided?

 

Besides the idea Panasonic lenses probably play nicer with Panasonic cameras than 3rd party lenses do, is there a reason the panasonic lens would be better?

 

In short, much like the 1/120,000 shutter speed pitch from Samsung, I am not sure what is marketing "fluff" and what is functional. The site sellina the 3rd party lens gave some information about "focal length", "lens aperture", "IR correction", and "aspherical lenses". Obviously I can't link it but I could do a copy and past if anyone is interested in what they have to say.

[cglaeser 0]

The lens I mentioned above claims to have a "f1.4 coated lens" etc.

 

If it's a $99 10x varifocal lens, odds are good the f1.4 is at the wide end only. So, if you set the camera to 5mm, then you will get f1.4. If the lens is set longer, the aperture will decrease (f number will increase). The longer the reach, the smaller the aperture (except in more expensive lenses with constant aperture). A smaller aperture means less light, which means lower performance in low light. A one stop reduction in the lens means the lux performance is halved (e.g. a 0.3 lux camera now requires 0.6 lux due to 1 stop loss in the lens).

 

Security camera manufacturers are notorious for this type of misleading information. Lux values are reported at the slowest shutter speed possible, which may be 2 seconds or more, with no information on IRE, gain, etc. Lens apertures are similarly misleading, and spec sheets typically only list the widest aperture of a varifocal/zoom lens. The better manufacturers generally have more complete and meaningful data sheets (e.g. f1.8 @ 5mm; f3.5 @ 50mm; or something like that).

 

There's a reason why lenses with apparently similar specs may have big differences in price (precision glass, coatings, etc, etc). In general, you get what you pay for. However, keep in mind that, dollar for dollar, a fixed lens will typically outperform a varifocal lens, so if you know in advance the focal length you need, then the money spent on a fixed lens will likely produce better results than the same amount spent on a 10x varifocal.

 

Best,

Christopher

[hardwired 0]

If you stick with a reputable manufacturer (Tamron, Computar, Fujinon come to mind), you probably will not go too wrong, even without specific Day/Night correction, because the Panasonic you chose will refocus itself during the day / night changeover.

 

having said that, there's no specific downside to choosing a D/N corrected lens, other than the price.

 

Do try to stick to the smallest varifocal range you can choose, though. A simpler lens calculator can be found here.. http://www.pelco.com/sites/global/en/sales-and-support/downloads-and-tools/tools/lens-calc.page

 

Remember to set the calculator to 1/3" to match the Panasonic's imager size.

[C.O.P. 0]

Thank you so much for the info. Now I am getting somewhere.

 

cglaeser,

 

I did notice the Panasonic lens says f1.6 wide and f1.9 tele.

The Tamron says f1.4-360... does that mean f1.4 wide and f3.6 tele? If so, I start to see why the Panasonic lens is so much more expensive.

 

I found the Tamron 40mm IR lens that also has the f1.4-360 spec.

 

So the next question is: for night time use, am I better of using a lens with a low f value or a lens with a higher f value but has IR correction?

[C.O.P. 0]

What does the spec mean for a lens when it says "f1.4-360" or "f1.4-300", etc.

I have a clue about the "f1.4" but what does the number after the dash mean?

 

Also, I discovered this statement on the Bosch lens site:

 

"The high design standards of the 1/2-inch lenses

make them a perfect match for both 1/3-inch and 1/2-inch

type cameras. When used with 1/3-inch type cameras, the

1/2-inch lenses provide a more "telephoto" effect."

 

http://resource.boschsecurity.us/documents/IR-CorrectedZoo_DataSheet_enUS_T2388579979.pdf

 

It's my understanding the smaller the mm is on a varifocal lens, the better picture you will get at night (lower f). My thought then is why not go with a 1/2 lens that is a smaller mm with a natural "telephoto effect" to reduce the "f" than a larger mm 1/3 lens?

[cglaeser 0]

It's my understanding the smaller the mm is on a varifocal lens, the better picture you will get at night (lower f).

 

Be careful not to confuse focal length and aperture. Although practical design considerations do link the two, one does not necessarily imply the other. For example, it's possible to have any combination of short vs long focal length and large vs small aperture. For example, if you are willing to spend the money, you can purchase a long focal length and large aperture. And, some pin-hole spy cameras have a short focal length and small aperture. So, while in practice cost often dictates that longer focal lengths have smaller apertures than shorter focal lengths, this is not always the case.

 

My thought then is why not go with a 1/2 lens that is a smaller mm with a natural "telephoto effect" to reduce the "f" than a larger mm 1/3 lens?

 

1/2" lenses are bigger and typically cost more than 1/3" lenses. However, depending on the specs, the cost difference may not be that great, and it may be cheaper to build/distribute/stock 1/2" to cover both applications.

 

Best,

Christopher

[C.O.P. 0]

To clarify my question (though I understand what you're saying)...

 

on average, it would be better to use a 40mm 1/2" lens if you can to do the same job as a 50mm 1/3" lens because, in general, the aperture opening on a 1/2 zoomed to it's 40mm max will be larger than the aperture opening on a 1/3" zoomed to it's 50mm max?

 

The idea being the "tele" effect of using the 1/2" lens on a 1/3" camera will allow you to use a shorter focal length lens to shoot the same distance as, say, a 1/3" 50mm lens but the sensitivity will be better at night due to (in general) the larger aperture opening on the 1/2" lens.

 

Here is my understanding of how the aperture opening is effected by zoom:

If you roll up a piece of paper then pull the inside out to make a "telescope/cone" shape, the more you extend the cone, the smaller the opening will be at the far end. The smaller the opening, the less light you get coming into the cone. Therefore, if you start with a larger sheet of paper (making the original roll larger), you can extend the cone as far as the original roll but the small end will be larger at the same length. Is that a good comparison?

[cglaeser 0]

on average, it would be better to use a 40mm 1/2" lens if you can to do the same job as a 50mm 1/3" lens because, in general, the aperture opening on a 1/2 zoomed to it's 40mm max will be larger than the aperture opening on a 1/3" zoomed to it's 50mm max?

 

No, you're going to tie yourself in knots trying to select this way. A 1/2" lens requires more precision glass than a 1/3" lens, and there are so many trade-offs in lens design, this type of general statement is not helpful in selecting a lens.

 

If you are comparing a 1/2" and 1/3" lens and you want the one that has be largest aperture, then look at the specs and pick the one with the largest aperture. Varifocals can be tedious to compare because you don't usually know the aperture at each focal length. However, one nice feature of aperture is that it remains constant regardless of the sensor size (ignoring third order issues like vignette, etc). So, a 1/2" f1.8 is f1.8 on a 1/2", 1/3", and 1/4" sensor.

 

Best,

Christopher

[C.O.P. 0]

Got ya.

 

Now what about that "f" spec question. What does the number after the dash mean?

 

Originally, I assumed a spec of "f1.4-360" on a varifocal meant it was f1.4 in wide and f3.6 tele.

[cglaeser 0]

Now what about that "f" spec question. What does the number after the dash mean?

 

I don't know. I've never seen this in photography, which is the source of most of my lens knowledge.

 

Originally, I assumed a spec of "f1.4-360" on a varifocal meant it was f1.4 in wide and f3.6 tele.

 

Unlikely because many CCTV lenses have this specification and I doubt all of them are f3.6 at the long end. Could have something to do with circle coverage (not all lenses cover a circle), but again, that's just a wild guess.

 

Best,

Christopher