Killertechno
Posts: 194
Joined: Wed Jan 02, 2013 8:28 am

Camera lens: 1:1.9 versus 1:1.8

Sun Mar 26, 2017 10:14 am

Hi guys, I'm totally newbie about optics.
I was taking a look to lens for Pi camera to try to select wich one could be suitable to watch all room, then I've seen there are following lens used with Pi camera insteas magnifing glass (to check PCB boards):
- 35mm 1:1.9
- 35mm 1:1.8
May someone tell me differences?
Other question: if I use 35mm 1:18 lens mounted on specific support, I suppose I can focus an object (x example) placed 20mm far from lens.
CCD is placed (x example) 40mm from lens.
If I change adapter, so CCD is placed (x example) 41mm or more from lens, should I change lens type?
Thanks.

User avatar
jbeale
Posts: 3578
Joined: Tue Nov 22, 2011 11:51 pm
Contact: Website

Re: Camera lens: 1:1.9 versus 1:1.8

Tue Mar 28, 2017 5:43 pm

If you are talking about the official Raspberry Pi camera board, it already comes with a fixed stock lens which is not "supposed" to be changed.
That doesn't mean you can't remove the lens and substitute something else but this is a "hack" and at your own risk. You can also add any of various external wide-angle, telephoto, or close-up adaptor lenses which are sold for use with mobile phones, without needing to modify the camera board itself.
See also: http://elinux.org/Rpi_Camera_Module

If you did replace the moderately wide-angle 3.04mm (V2) or 3.6mm (V1) RPi stock lens with an external 35mm lens, that would be a super-telephoto on the RPi camera, with the very narrow field of view that a 350mm lens would have on a full-frame SLR camera. That's because the RPi camera sensor is about 10x smaller than the image frame in a full-frame SLR camera.

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