Timeline for I'm hoping to prove this distance to camera equation:
Current License: CC BY-SA 3.0
9 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| May 17, 2017 at 4:02 | vote | accept | Taro | ||
| May 17, 2017 at 4:01 | comment | added | Taro | Thank you so much, Alan. You have been an immense help :) | |
| May 16, 2017 at 3:59 | comment | added | Alan Marcus | Infinity – As far as the eye can see: This is a variable based on lots of stuff. As a rule of thumb you can consider infinity to be about 300 focal lengths distant. Thus a 55mm lens is in use, infinity is about 300 X 55 = 16,500mm = 16.5 meters = 54 feet. At infinity, rays of light from a distant object arrive at the camera as parallel rays. | |
| May 16, 2017 at 2:52 | comment | added | Taro | Thank you, Alan. Just to be clear, the object is considered at infinity if it is beyond the hyperfocal distance, correct? | |
| May 16, 2017 at 0:46 | comment | added | Alan Marcus | You must know focal length of the lens. An object 37 meters distant can be assumed to be at infinity. If we know image height is 18mm than ratio is 18/55=0.3273. Height is 37 X 0.3273 =12.1091meters. Suppose you know the height is 4 meters & distance = 37 meters, object ratio is 4/37=0.1081. Then image size is 55 X 0.1081 = 5.9459mm. | |
| May 15, 2017 at 23:19 | comment | added | Taro | Thanks again, Alan. This is for an object estimated to be 37-metres from a 55mm lens. So, how would I go about determining the object-to-camera distance where this factor becomes negligible? | |
| May 15, 2017 at 18:21 | comment | added | Alan Marcus | The focal length is the distance between lens and focused image when the lens is targeting a far away object. As you ocus on nearby objects, the lens to focused image increases. At "unity" (magnification 1), lens to focused image is 2 X the focal length. Technically the measurements you need is distance from rear nodal to focused image and distance to front nodal and the object. I think for your calculations, the differences between object and front of lens and rear of lens to focused image will do just find. OK to use focal length for distance lens to focused image. | |
| May 15, 2017 at 16:23 | comment | added | Taro | Thanks, Alan. I guess maybe I don't understand focal length as well as I thought I did. You appear to be using the distance between lens and film surface as focal length. It was my understanding that the focal length is the distance between lens and focal point. Wouldn't the image projected onto film surface need to be some distance BEYOND the focal point? Thanks, again. | |
| May 15, 2017 at 15:44 | history | answered | Alan Marcus | CC BY-SA 3.0 |