| Author | Comment | Last activity | Moderation | ||
|---|---|---|---|---|---|
| funkycbj | "Light is transmitted but it is diffusely scattered past a certain depth, which seems to be ~7mm. The minimum thickness increases with the size of ..." | Read more » | about 11 years ago | |||
| nedhorning | "Thanks for the suggestion. Maybe a teflon sheet is the way to go although I don't have any experience with these. Some of the thin sheets seem tran..." | Read more » | about 11 years ago | |||
| funkycbj | "Krylon extra flat black spray paint is diffuse and spectrally flat across the vis-nir. A small sheet of teflon isn't too expensive and works great ..." | Read more » | about 11 years ago | |||
| nedhorning | "I have been making some progress toward standardized calibration targets. Does anyone viewing this know of a source for inexpensive paints/coatings..." | Read more » | about 11 years ago | |||
| cfastie | "The Canon A2200 (refurbished) is on sale today (November 21) for $48.99 (free shipping) with a one year warranty: http://shop.usa.canon.com/shop/e..." | Read more » | about 11 years ago | |||
| nedhorning | "Hi Thorsten, Glad to hear you're making progress. When you run the plugin are you specifying that the channel from the visible image to use for th..." | Read more » | about 11 years ago | |||
| Thorsten | "Ned, I followed your advice and now have processed my first dual camera images (RGB and 850nm IR) using your PhotoMonitoring plugin, which works li..." | Read more » | about 11 years ago | |||
| mathew | "cool test! this is definitely the most pixels in a research note, as far as I've seen. " | Read more » | about 11 years ago | |||
| mathew | "I think doing calculations based on red and green might be two ways to get to the same result that Chris was seeking in his Oaktober note-- the cha..." | Read more » | about 11 years ago | |||
| warren | "It's weird because we think of green being reflective, but compared to IR, it's very absorbent. " | Read more » | about 11 years ago | |||
| cfastie | "Mathew, That does seem to be a consistent pattern. I think you are right that a green filter might offer the purest visible light channel in a sing..." | Read more » | about 11 years ago | |||
| mathew | "looking at the sensor sensitivity graph for the Nikon D200, its interesting that green is the least sensitive channel in the infrared band, implyin..." | Read more » | about 11 years ago | |||
| cfastie | "Hi Pat, The Wratten 25A is an old standard photographic filter that is still widely available in glass and gel. I think Ned bought a genuine Kodak ..." | Read more » | about 11 years ago | |||
| patcoyle | "Thanks Chris and Ned, this is an encouraging line of inquiry. Remind me on the source for the Wratten 25 filter material, or is it in the prior not..." | Read more » | about 11 years ago | |||
| cfastie | "The aperture mechanism definitely varies among Powershots. By peering into the front of the lens I learned that the high end ones have an actual ir..." | Read more » | about 11 years ago | |||
| timmm063 | "Have you considered watching other sites for cameras that are refurbished? One I would recommend is canonpricewatch.com. It also shows prices for o..." | Read more » | about 11 years ago | |||
| danbeavers | "The filter should have nothing to do with the difference in quality between the center and edge of the image since it is uniform in density. Lense..." | Read more » | about 11 years ago | |||
| cfastie | "I was assuming that the best way to preserve image quality when removing a glass filter would be to replace it with another glass filter. Plastic, ..." | Read more » | about 11 years ago | |||
| warren | "Very interesting line of inquiry. I've always been a bit confused about the role of the filter material itself in focus -- my assumption has been t..." | Read more » | about 11 years ago | |||
| nedhorning | "Is this your conclusion or do we have to test lots of other materials that commonly show up in the NDVI images we take? I have looked at a lot of..." | Read more » | about 11 years ago | |||
| nedhorning | "Chris, So many questions... I think more testing is necessary but I'll take a shot at answering each question. I'd like to hear what other folks th..." | Read more » | about 11 years ago | |||
| cfastie | "Ned, The NDVI image made from the Rosco 2008 photo by stretching the histograms is surprisingly similar to your calibrated NDVI image from the red ..." | Read more » | about 11 years ago | |||
| cfastie | "Ned, this is good evidence that some materials, like grass clippings and pine boards, will be more easily distinguished from live green plants in N..." | Read more » | about 11 years ago | |||
| nedhorning | "If you use a dual-camera setup I suggest using an unmodified camera and a NIR-pass (visible cutoff) filter for the other camera. Some people use un..." | Read more » | about 11 years ago |