westtx28 0 Posted January 13, 2011 I have a Vivotek IP7161 2-Megapixel IP Camera. It came with a 4.5-10mm lens and I need to change that out with a lens with a greater focal length (around 40-50mm). I want to get an IR-corrected lens and there are many out there but I am confused on the resolution capabilities. Do I need a HD lens for this camera? The Vivotek suggested replacement is a Tokina 6-60mm TVR0616DC-IR but I don't see it listed as a HD lens. I thought the resolution was more of a factor of the sensor than the optics but I could be totally wrong. Any insight? Share this post Link to post Share on other sites
cglaeser 0 Posted January 13, 2011 I thought the resolution was more of a factor of the sensor than the optics but I could be totally wrong. Any insight? Low-cost CCTV lenses do not have the resolving power of high quality HD lenses. There is a very noticeable difference between CCTV lenses and HD lenses when attached to an HD camera. Best, Christopher Share this post Link to post Share on other sites
Soundy 1 Posted January 13, 2011 Expand your search to "megapixel" or "MP" lenses, as well as "HD". Share this post Link to post Share on other sites
westtx28 0 Posted January 13, 2011 Expand your search to "megapixel" or "MP" lenses, as well as "HD" I am having a hard time finding a megapixel lens that is ir-corrected and has a max focal length of 30-50mm. The application is capturing license plates coming into a facility day and night. The camera is day/night with removable IR-Cut filter. I need the greater focal length to get a tight enough shot from the building the camera is mounted. If I had to make a choice between megapixel and ir-corrected what should it be? Share this post Link to post Share on other sites
Bean00 0 Posted January 13, 2011 Well, they aren't IR corrected but Tamron and Fujinon both have the focal length you need. http://www.tamron.com/en/cctv_ip/megapixel_varifocal_normal/ Look at the M13VG550 http://www.fujinon.com/ProductDocs/YV3.3x15SA-SA2.pdf Share this post Link to post Share on other sites
shropna 0 Posted January 13, 2011 Expand your search to "megapixel" or "MP" lenses, as well as "HD" I am having a hard time finding a megapixel lens that is ir-corrected and has a max focal length of 30-50mm. The application is capturing license plates coming into a facility day and night. The camera is day/night with removable IR-Cut filter. I need the greater focal length to get a tight enough shot from the building the camera is mounted. If I had to make a choice between megapixel and ir-corrected what should it be? IR corrected lens, only if You use IR light. If camera just removes IR cut filter at dark scenes, not necessary to have IR corrected lenses. Also, megapixel lens should be "corrected" also from chromatic aberrations, so, less sensitive to light wavelength changes... And, some cameras, like Sanyo HD series, has built in automatic refocusing function, when IR cut filter is removed, for best adaptation to IR wavelength. Share this post Link to post Share on other sites
Soundy 1 Posted January 13, 2011 IR corrected lens, only if You use IR light. If camera just removes IR cut filter at dark scenes, not necessary to have IR corrected lenses. Not correct. The IR cut filter exists in the first place because normal ambient IR affects the exposure and color balance of a color image. The reason for removing it at night when the camera switches to B&W is to allow the extra IR light in, when the color won't be affected. Without the filter in place, a non-corrected lens will cause the image to go soft at night, as the IR light focuses "shorter" than visible light (ie. the point of focus is in front of the sensor, instead of on it). In short: yes, you DO need IR-corrected lenses for proper operation of a true-day/night camera. And, some cameras, like Sanyo HD series, has built in automatic refocusing function, when IR cut filter is removed, for best adaptation to IR wavelength. I don't know about Sanyo's implementation, but I've played with day/night auto-ABF on a Pelco Sarix and found it iffy at best. Give the above IR issue, auto-ABF alone is not a perfect solution, as without the proper lens, IR and visible light are still focusing differently. Share this post Link to post Share on other sites
shropna 0 Posted January 13, 2011 Soundy, this correct, if you have wide spectrum (tungsten) lights outside. But, when lights outside is Natrium (Sodium) or Mercury based (lots of them), this light source doesnt have IR spectrum Yes, Sarix also has IR "refocusing" feature. About lenses. This is extremely difficult to build IR corrected MEGAPIXEL lens on small imager (1/3', 1/2') image format, due small imager pixel pitch. Ask about this issue Baylab, he is lens guru. Share this post Link to post Share on other sites
shropna 0 Posted January 13, 2011 Some charts, for understanding: Share this post Link to post Share on other sites
