Tom12345 0 Posted October 18, 2011 why the hell do i have great focus during day then at night it goes soft....doesn't it have something to do with the cut filter or something???? Share this post Link to post Share on other sites
ljarrald 0 Posted October 18, 2011 why the hell do i have great focus during day then at night it goes soft....doesn't it have something to do with the cut filter or something???? the ir cut filter is a little piece of glass that slides into the line of sight during the day. at night it moves away but if there is nothing there, the camera WILL go out of focus. iknow this because i was trying to fix an auto iris lens that had an ir cut filter (iris was messed up) an i ended up accidently breaking the ir filter. it has the ir blocking glass that goes infront in the day, and had normal glass that slid across at night. this is to keep it in focus. i knocked the glass out by accident which caused it to go blurry at night. i bought a new lens. Share this post Link to post Share on other sites
Old Car Guy 0 Posted October 18, 2011 It’s called focus shift. Focusing your cameras at near dark will help to keep the camera in focus both day and night. I would search the forum for more info. Some CCTV sales sites also offer info. Share this post Link to post Share on other sites
Tom12345 0 Posted October 18, 2011 It’s called focus shift. Focusing your cameras at near dark will help to keep the camera in focus both day and night. I would search the forum for more info. Some CCTV sales sites also offer info. ok i gotta try that....i think when the lens opens up to f 1.2 it gets soft anyhow..... Share this post Link to post Share on other sites
Soundy 1 Posted October 18, 2011 it has the ir blocking glass that goes infront in the day, and had normal glass that slid across at night. this is to keep it in focus. IR light focuses differently from visible light, which means when the cut filter moves away, the visible-light portion of the image may still be in focus, but the IR wavelengths' focus will be soft. Normally you'd use IR-corrected lenses, which have optics specifically designed to address this problem. In your case, the extra glass may be designed to compensate for it, although in the TDN cameras I've used, the glass does nothing special - without IR corrected lenses, they also go fuzzy when they switch to night mode. The other issue is that as the aperture opens up, the depth of field decreases (see http://en.wikipedia.org/wiki/Depth_of_field for more info). With auto-iris lenses, the aperture tends to be decreased during the day (when cameras are most often set up), which provides greater DOF, and so you have a wider range of adjustment where things are still in focus... but once it gets dark and the iris opens, the DOF gets thinner, and if your point of focus is too close or far, then everything gets fuzzy. This problem is not specific to TDN cameras, BTW. Share this post Link to post Share on other sites
Tom12345 0 Posted October 18, 2011 it has the ir blocking glass that goes infront in the day, and had normal glass that slid across at night. this is to keep it in focus. IR light focuses differently from visible light, which means when the cut filter moves away, the visible-light portion of the image may still be in focus, but the IR wavelengths' focus will be soft. Normally you'd use IR-corrected lenses, which have optics specifically designed to address this problem. In your case, the extra glass may be designed to compensate for it, although in the TDN cameras I've used, the glass does nothing special - without IR corrected lenses, they also go fuzzy when they switch to night mode. The other issue is that as the aperture opens up, the depth of field decreases (see http://en.wikipedia.org/wiki/Depth_of_field for more info). With auto-iris lenses, the aperture tends to be decreased during the day (when cameras are most often set up), which provides greater DOF, and so you have a wider range of adjustment where things are still in focus... but once it gets dark and the iris opens, the DOF gets thinner, and if your point of focus is too close or far, then everything gets fuzzy. This problem is not specific to TDN cameras, BTW. yes that makes perfect sense....i think it is a combo of aperture and the ir.. any ip cameras out there that have good focus in day and night.... Share this post Link to post Share on other sites
Soundy 1 Posted October 18, 2011 It's not a function of the camera (at least not directly), it's all in the lens. Make sure you're using a lens that is specifically designated for day/night cameras, or that have "IR" or "IR corrected" labeling on them. The other option is a camera with auto-backfocus feature, that will re-adjust the backfocus after any day/night switch. Share this post Link to post Share on other sites
Tom12345 0 Posted October 18, 2011 It's not a function of the camera (at least not directly), it's all in the lens. Make sure you're using a lens that is specifically designated for day/night cameras, or that have "IR" or "IR corrected" labeling on them. The other option is a camera with auto-backfocus feature, that will re-adjust the backfocus after any day/night switch. mabye this dome just ain't gonna work so good at night then...mabye then lens for ip megapixel domes just arn't there yet...i can focus it awesome for night,,but when day comes it looks like crap...and vice versa Share this post Link to post Share on other sites
Soundy 1 Posted October 18, 2011 It's not a function of the camera (at least not directly), it's all in the lens. Make sure you're using a lens that is specifically designated for day/night cameras, or that have "IR" or "IR corrected" labeling on them. The other option is a camera with auto-backfocus feature, that will re-adjust the backfocus after any day/night switch. mabye this dome just ain't gonna work so good at night then...mabye then lens for ip megapixel domes just arn't there yet...i can focus it awesome for night,,but when day comes it looks like crap...and vice versa Does the lens say IR on it anywhere? Or day/night? If not, then it's nothing to do with whether it's a dome, or IP, or a megapixel camera, or a megapixel lens. From your description, it sounds like you're using a non-IR-corrected lens on a TDN camera... and that's purely user error. Share this post Link to post Share on other sites
Tom12345 0 Posted October 18, 2011 It's not a function of the camera (at least not directly), it's all in the lens. Make sure you're using a lens that is specifically designated for day/night cameras, or that have "IR" or "IR corrected" labeling on them. The other option is a camera with auto-backfocus feature, that will re-adjust the backfocus after any day/night switch. mabye this dome just ain't gonna work so good at night then...mabye then lens for ip megapixel domes just arn't there yet...i can focus it awesome for night,,but when day comes it looks like crap...and vice versa Does the lens say IR on it anywhere? Or day/night? If not, then it's nothing to do with whether it's a dome, or IP, or a megapixel camera, or a megapixel lens. From your description, it sounds like you're using a non-IR-corrected lens on a TDN camera... and that's purely user error. here are the specs...they are the same lens as the dome with ir http://www.samsung-security.com/SAMSUNG/upload/Product_Specifications/SNV-7080-Specifications.pdf i threw a couple mir 1000 illuminators into the mix some night vid http://youtu.be/AEGnENReZRA?hd=1 Share this post Link to post Share on other sites
mike_va 0 Posted October 18, 2011 At that distance and MP cams I'd add more IR than a CNB... The sign on the toilet or whatever shows up good because it reflects better than the face. Here is a random person at 150ft with a Raytec RM100-10 and Axis P1344 with 1/30s shutter, this is a screenshot of 1/4 of the picture. No streetlights at all where those cars are. 50+ feet further out there are some house lights though. Share this post Link to post Share on other sites
Tom12345 0 Posted October 19, 2011 At that distance and MP cams I'd add more IR than a CNB... The sign on the toilet or whatever shows up good because it reflects better than the face. Here is a random person at 150ft with a Raytec RM100-10 and Axis P1344 with 1/30s shutter, this is a screenshot of 1/4 of the picture. No streetlights at all where those cars are. 50+ feet further out there are some house lights though. yeah i'll have to massage a Raytec sometime into an install. i have two of those cnb's mir pointed in the same direction mabye i can relocate on closer to the dark areas...thanks for responses everyone Share this post Link to post Share on other sites
rory 0 Posted October 19, 2011 focus it in low light, then fine tune it under IR. Best to do this in a controlled environment, or at least have something in the center and at both edges to focus on. Share this post Link to post Share on other sites
