SUNBA - cheap PTZ with 20x zoom?

[cam235]

For my long-distance LPR application I need a long zoom lens, like 100 mm. I have a Dahua 4MP box camera with a 60mm lens and I found it isn't quite good enough. All of the CS-mount lenses of ~100mm focal length I have found seem to be intended for old-school standard-def analog cameras, not megapixel class IP cameras.

However I see the PTZ models often have long optical zoom like 20x. One such is the SUNBA601-D20X which is 1080p and features 4.7 - 94 mm lens, that should be long enough. This is a cheaper PTZ than the Dahua models so I'm sure the motor reliability suffers, but I don't actually want PTZ features at all, I would leave it parked at the same angle 100% of the time. Can anyone advise if this camera would be a reasonable choice?

 

[nayr]

you are aware that lenses dont have megapixel ratings; a lens is a lens is a lens.. now quality may varry; but there is no such fucking thing as a 2MP Lens or a 10MP lens or a 100MP lens, just the size of the aperture.. mine said VGA and it works fine w/a 4MP camera, could I get a sharper image with a lens 10x more expencive, fuck yeah I could, but it does the job as it is so why bother.

will a 4MP camera notice optical flaws that a 720p camera wouldn't? yeah, lower detail cameras wont benifit from a high quality lens.. but high quality optics can rape your bank account fast; dont let perfection be the enemy of the good

sunba's are junk toys; leave em be..

 

[cam235]

I do appreciate your viewpoint and I agree you can't specify a lens is good for "X megapixels". That said, in the past several years I've got a reasonable number, more than 20 different lenses (including M12 and C/CS mount) which I've put on various IP cameras and I have found the ones I like all do make some such claim (MP, 5 MP, etc), and the cheaper ones that I regretted buying do not. I think I got particularly unlucky with the latest buy, a cheap noname CS-mount 6-60mm which may have misaligned elements: it kind of works but has a fuzzy oblong double-image on details at the long end, making license plates mostly unreadable at the distance I want (250 - 300 ft).

 

[nayr]

thats the deep optics; your focal point narrows the further away you get due to the limited aperature.. your problem is the focal point you want is farther away than the lens can accomplish..

300ft away on my lens is blurry, I have my focus stretched out and its just barely enough to reach 180ft...

its tricky to get infinite focusor even hyperfocus when your using such large lenses, if you have a 100mm lens it should focus out to 300ft, regardless of quality.. but a 60mm trying to see that far probably dont have the range nessicary to achieve it because the apertures are so small.. I tried and could not achieve infinite focus with my setup, so I focused it at the point on the road where the action is.. might just be a compromize of LPR; in that you need really sharp focus to complement the high shutter speeds.

Play with this: Hyperfocal & Depth of Field Calculators - Focus Pocus - Outsight Photography

 

[cam235]

Yes, that's a good point about the depth of field. I played with the focus for a while, but couldn't quite get a usable image at distance. At this point I'm thinking about trying a good quality 5-100mm lens like
Kowa LMVZ510A 1/3" Varifocal Auto-Iris Lens LMVZ510A B&H

 

[nayr]

you dont need $200+ optics for a License Plate setup, its job is to do one thing.. and all night long it cant see anything at distance anyhow.

Look how shitty this image is, the guy and dog are a lil fuzzy.. that car/tree out in the distance is entirely out of focus.. I used the cheap optics and it shows


but it has no problems giving me legible plates:


would a nicer lens make those images better? yeah very likely.. is a nicer lens worth the money? I cant see how.. if I knew it'd let me achieve infinite focus I'd still not be willing to spend more than I did for the camera just on the optics.

 

[cam235]

As you say, your example image looks perfectly good for LPR, and even the model name is clear. I may just be asking too much of the lens to reach 300' because I'm not getting quite as solid an image as you show. Maybe OK by eye but ALPR struggles with it.


At night, still enough light around 250' away, and image readable by eye but difficult for ALPR, maybe there's some more software tuning I could do.

 

[nayr]

yeah that car is only 180ft w/my 60mm.. i do think your trying to reach to far w/60mm; considering the size of your timestamp to the vehicle..

more zoom will give OpenALPR more pixels for the plate and less noise; thats going to help recognition alot..

If I crop out just my plate:


its 230x146 pixels, how many are you getting?