# Thread: Focal plane of camera (Lumia 520)

1. ## Focal plane of camera (Lumia 520)

Hi,
I am working with Lumia 520 on a camera application. For the project, I will need to calculate the shift in the pixels given the physical shift of the camera. Clearly, I will need to know the dimensions of the focal plane to do so. For finding the focal plane, having the lens to sensor distance and focal length should be enough. From the data given on the website, I found that focal length of the camera is 28mm. Further, it is also given that the focus range is 10cm to infinity.

I am a little confused with this data. The distance between the lens and the sensor will be very small, which will be less than 28mm. This seems a little odd to me, since any object at finite distance should be formed between f and 2f. Perhaps I am missing something important here? Further, if that thing gets cleared, how do I estimate the distance between the lens and the sensor or the lens and the focal plane. I can adjust the manual focus distance, but it is a number between 0 and 1000, which gives me no clue about the physical distance.

2. ## Re: Focal plane of camera (Lumia 520)

Hi You could find good explanation here :
http://en.wikipedia.org/wiki/Focal_l...In_photography
http://www.cambridgeincolour.com/tut...era-lenses.htm

You want compute distance only with focus information?

3. ## Re: Focal plane of camera (Lumia 520)

Hi yan_,
I have focal length information, information about manual focus, normalized between 0 and 1000 and I know that the least focus distance is 10cm(Data from Nokia website) I wish to calculate the focal plane dimensions using the above information.

Thank you.

4. ## Re: Focal plane of camera (Lumia 520)

focal plan dimensions?

5. ## Re: Focal plane of camera (Lumia 520)

I'm not sure you can rely on the manual focus being normalized. I'm also not entirely certain that the lens even moves if you reduce from 1000 to 999. You also can't rely on the manual focus having the range 0 - 1000. It currently does for Nokia devices and on the Emulator but e.g. HTC devices report min/max values of 0/22.

As for focal plane dimensions. I believe he wants to calculate the height/width of the rectangle that is currently in focus in the real world. E.g. I focus full format on a book on my desk. Given the focus value returned and knowing the properties of my device's Camera I could then calculate the height and width of the book itself.

6. ## Re: Focal plane of camera (Lumia 520)

Hi SB Dev,
The second paragraph in your reply exactly describes what I would need. Can you give me a little lead in this aspect?

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