Horzontal viewing angle? Im so lost!

[zikronix 0]

Ive been looking at some acti cameras and Im having some trouble trying to figure out what camera is going to give me the most viewing angle and the best low light performance, based purely off of lens and sensor. The part im having trouble with is why the vairfocal which has a better lens seems to have a smaller viewing angle.

 

Here are the contenders

 

Fixed (Why is the horizontal angle more)

E72 Fixed 2.93mm / F2.0 Horzontal 83.3

E82 Fixed 2.93mm / F2.0 Horzontal 85.7

 

Vairfocal

E82 f2.8-12mm / F1.4 Horizontal 70.5-28.2

E86 f2.8-12mm / F1.4 Horizontal 70.5-28.8

 

 

The fstop on the varifocial should give me better low light perfomance, but the viewing angle is less than the fixed. I also want to know how these would compare to the viewing angle of the Swann/Lorex Domes and bullets I currently have.

[buellwinkle 0]

My guess is different engineers testing each model came up with different calculations, all correct yet all wrong, mostly wrong.

 

I can tell you their new domes are physically identical except where some have fixed and some have fixed or varifocal lenses.

 

The E82 as an example has a 1/3.2" sensor and 2.8mm lens in the spec sheet. The E86 has a 1/3" sensor. They are probably the same sensor, so lets say 1/3". You should have a 81.2mm horizontal viewing angle if the information is correct.

 

The E72 should have the same 1/3" sensor, 2.93mm lens, but F2 so lower light capability than F1.4 on the E82/E86. This should give you a 78.6 degree horizontal viewing angle.

 

In contrast, the Lorex domes have a fixed 4mm lens, 1/3" sensor, claims 83 degree viewing angle BUT, if their lens/sensor specs are correct, you should have a 61.9 degree viewing angle. But what's odd is with the same lens, Hikvision shows it as 75.8 degree viewing angle. Again, goes against the realities of math. From personal experience, this camera lens can't be 4mm as I feel it viewing angle is wider than a 4mm would suggest. Just compare on my blog, the images of my driveway from reviews of the Swan vs. ACTi E32, two bullets, same sensor size, the ACTi seems like a true 4mm lens, the Swann seems to be too wide to be a 4mm lens, I would guess it to be more like a 3.2mm lens and same with the Hikvision DS-2CD2132-I dome.

[zikronix 0]

So that leads to the next question. Do you think the varifocal with its 1.4 FSTOP and the supposed tighter viewing angle is better than the fixed 2.0 with its wider viewing angle, im looking at basic WDR for both model types.

[buellwinkle 0]

Don't know at the moment because I'm testing their 2MP models and they are both varifocal.

 

I did play with the E72 which is fixed and was not happy with low light sensitivity as I was with the E32 which is fixed but has an F1.8 lens and that's back with ACTi for further testing. BUT, I do have an ACTi D82 which is the same 3MP but with the F1.4 varifocal lens on my desk and hope to have it up and running later today and I can tell you if the lens makes a difference.

[zikronix 0]

Don't know at the moment because I'm testing their 2MP models and they are both varifocal.

 

I did play with the E72 which is fixed and was not happy with low light sensitivity as I was with the E32 which is fixed but has an F1.8 lens and that's back with ACTi for further testing. BUT, I do have an ACTi D82 which is the same 3MP but with the F1.4 varifocal lens on my desk and hope to have it up and running later today and I can tell you if the lens makes a difference.

 

Good to know.

 

The D82 doesnt have WDR according to acti, so it would be interesting to see how it performs, one could assume that the E82 might peform better

[MaxIcon 0]

Are these using M12 lenses? If so, the answer is in the lack of standards for M12 lenses and sensor coverage. Technical lecture coming up...

 

Back in the old days (when was that, Grandpa?), everything used CS or C mount lenses, which had a standardized distance from the mount flange to the sensor (back flange length), and most sensors were standard sizes (and 4:3 aspect ratios). It was easy to calculate and predict field of view for any given combination of sensors and lens.

 

M12 lenses are different - they don't have a back flange. What they use is the distance between the rear of the lens body (or sometimes the rear of the last lens element) to the sensor. This may be called back flange length (erroneously) sometimes, or back focal/focus length, but regardless, there are no standards.

 

This length is different for different lenses, even those available for the same camera, or lenses with the same MM and sensor sizes. The different lengths make for a different image circle, which is the size of the spot the lens makes at the back focal length.

 

Different lenses will give a different spot size when they're focused. Add to that the fact that sensor sizes are much more varied these days, and you end up with the situation where one 4mm lens will cover a certain sensor a certain amount and a different sensor a different amount, and 2 different 4mm lenses will cover the same sensor differently.

 

This has some unintended consequenses that some of us have noticed, like lenses that screw in until they hit the IR filter body and still aren't focused, or lenses that screw all the way out of the threads and still aren't focused. M12 lenses are a jungle, both in quality and design.

 

So, in order to know what your field of view will be for a given lens combination, you need to know 2 things - the sensor's actual dimensions, and the spot size of the lens, both of which aren't called out very often. Some lenses will include a back focal length spec, but that's pretty rare too, and only helps if you know the back focal length for both the original lens and the replacement lens.

 

This is why vendors are calling out these numbers for specific combinations, and why different model cameras with seemingly similar lens and sensor sizes will give different fields of view.

 

Replacing an M12 lens that doesn't come from the original camera's designer is a roll of the dice. You'll often get unexpected results, and unless you have all the info, it's really hard to tell what you'll get.

 

This will not improve anytime soon, probably not ever.

[buellwinkle 0]

Most new cameras have M12 lenses, rare that I see a CS lens anymore. I think it's size, people want smaller more discrete cameras. I have a Hikvision 3MP mini bullet on it's way with a 12mm lens, lets see how that compares to the Q-See 720p bullet with a 6mm lens. I'm hoping it's half the viewing angle.

 

As for the D vs. E, yes, WDR should be the only difference so it should provide a better picture as WDR tends to add noise and reduces contrast on many cameras, so a trade off.

[zikronix 0]

so the D camera might actually be better picture quality due to its lack of wdr, but the one with wdr may or may not improve low light /high and low contrast situations at the cost of picture quality.

[buellwinkle 0]

Mostly WDR helps during the day with high contrast situation. For example, say someone has a ball cap on and created a shadow half way down his face. The top part of the face may not be easily identifiable. So WDR enhances/brightens shadows and darkens part of the image that is overly bright to even out the image.

 

The way I feel about WDR is that it's nice but when I dissect a video to get snapshots to law enforcement, I use Photoshop CS6 to enhance the image and it does a way better job at it than most if not all cameras I've toyed with including high end DSLR cameras.

 

In a perfect world, sensors would be noise free and worked in very low light and had a wide dynamic range. But since they don't, at least not in this price level, manufactures compensate with this image processing. It's not magic, the sensor on a camera with WDR is not better than one without it, it's in the processing of the video.

[buellwinkle 0]

OK, be lost no more. Do not go by the lens focal length or aperture. I can tell you that side by side, the E32 with F1.8 4.2mm lens has better low light capability, and about the same horizontal viewing angle at the D82 F1.4 varifocal lens set at it's widest setting, 2.8mm. I didn't believe it at first so I re-adjusted the lens on the D82 and that's as wide as it gets.

 

Theoretically, same 3MP sensor. I have them side by side, so looking at the same view you can judge the viewing angle. Weird huh?

 

[zikronix 0]

How would you say the d82 compared to the e72 dome in lowlights sensitivity, how would you say it compares with the lorex domes

[buellwinkle 0]

I would say the D82/E72 at night are the same other than the option of WDR on the E72 and varifocal on the D82. The Hikvision dome is not ready. It has LED light bleed issues, but their engineering is actively working on it.

[MaxIcon 0]

Most new cameras have M12 lenses, rare that I see a CS lens anymore. I think it's size, people want smaller more discrete cameras.

 

The other big driver is price, of course. A good quality 3MP IR CS mount lens can easily cost as much as a whole inexpensive IP cam like the 2100. M12 lenses are a lot cheaper to build, even using high quality components. If only they were as easy to spec.

[zikronix 0]

Man that e32 really performs at night after looking at the picture on the phone. I gotta find a dome that has that kinda quality at night for about the same price. I want to move from bullets to domes. The e82 looks soft. Is that ir bouncing off the dome, softness in general, lens, wdr....why is it so much softer.

[buellwinkle 0]

Man that e32 really performs at night after looking at the picture on the phone. I gotta find a dome that has that kinda quality at night for about the same price. I want to move from bullets to domes. The e82 looks soft. Is that ir bouncing off the dome, softness in general, lens, wdr....why is it so much softer.

 

The softness is noise reduction working overtime. But before you pass total judgment, I installed the latest firmware upgrade which is new on all the cameras and we'll see tonight if it makes a difference.

[zikronix 0]

Man that e32 really performs at night after looking at the picture on the phone. I gotta find a dome that has that kinda quality at night for about the same price. I want to move from bullets to domes. The e82 looks soft. Is that ir bouncing off the dome, softness in general, lens, wdr....why is it so much softer.

 

The softness is noise reduction working overtime. But before you pass total judgment, I installed the latest firmware upgrade which is new on all the cameras and we'll see tonight if it makes a difference.

 

 

How did that turn out?