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I don't have experience in photography, yet I've been curious about this question for a while and thought I'd ask about it here.

I have a few SLR lens for different cameras.. Nikon, Canon and more. Some are macro lens, and some zoom.

Now what I was wondering about is what does it require to install them on incompatible devices and cameras, for example attaching them to my Fujifilm FinePix S4500 which does not allow removing it's lens, or attaching them directly to phones and webcams..

Is this a matter that can be solved in a simple way such as placing the lens as close as possible to the camera as possible? or maybe exposing the sensors and placing -them- as close as possible to the lens?

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2 Answers 2

up vote 5 down vote accepted

Probably the crucial concept you need to know about here is that of flange focal distance - for any given lens system, commonly called a "mount" (examples would be the Nikon F mount and the Canon EF mount), the lens must be positioned a precise distance from the sensor (46.50 mm for the Nikon F mount and 44.00 mm for the Canon EF mount). The tolerance on this distance is really very small - typically of the order of hundredths of a millimeter (or tens of microns if you think in those terms); if your lens is out by more than that, you won't get sharp images.

In practical terms, what this means is that you can't fit an arbitrary lens to an arbitrary camera unless you happen to have access to much higher precision engineering kit than most people have, even if you could get the current lens off your Finepix camera / phone / webcam / whatever.

On the other hand, fitting a lens designed for one interchangeable lens mount (e.g. Nikon F) to a camera with a different interchangeable lens mount (e.g. Canon EF) is possible. In the cases where you want to fit a lens with a longer flange focal distance (e.g. Nikon F at 46.50 mm) to a camera with a shorter flange focal distance (e.g. Canon EF at 44.00 mm), various companies will make you a precisely machined adapter which just mounts the lens the precise distance further away from the sensor (2.50 mm in the case above) than it would for a "native" lens.

The more difficult case is mounting a lens with a shorter flange focal distance to a camera with a longer flange focal distance as you can't get an adapter to mount the lens inside the camera body! This kind of adapter needs to have extra glass in it in order to cause the lens to focus at the right point, which generally makes them much more expensive than the simple adapters referred to in the previous paragraph.

Also, in both cases, you will tend to lose any electronic control over the lens when you're using an adapter, unless it's an official adapter designed for converting one lens mount from one company to another lens mount from that company (e.g. Nikon produce an adapter for mounting a Nikon F lens onto a Nikon 1 mount camera).

One other thing you'll need to consider is that of imaging circle: simplified very slightly, a lens is designed to work with a specific size of sensor. Using a lens designed for a smaller sensor on a camera with a larger sensor will result in the image circle not covering the edges of the larger sensor.

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Thank you for the detailed answer! –  Don Oct 8 '13 at 11:32

The chances you can mount an SLR lens onto non-slrs mostly point and shoot and take good pictures are slim to none.

While it is possible to take a valid picture by keeping two lenses as close as possible, the process is going to be so tedious ..it is not practical.

Things might be easy if you own a 3D printer and a scanner :)

If you are talking about having a nikon SLR lens for a canon,sony(SLR bodies) etc or vice versa.. there are lens mounts like these. ..again, choice of lenses are going to be restricted.

The main problem in trying to take a picture by keeping two lenses as close as possible is (while the optics may not come in the way) - keeping the light from entering the lenses into the wrong end.

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This is incorrect. A lens is designed to cast an in focus image on a plane a certain distance from the lens. If you simply get them as close as possible, this often will not result in an in-focus image. You have to mount it at the proper flange focal distance and then have to worry about crop factors when using radically different size sensors. (Since the image circle on something like a Canon L series lens is 35mm sensors rather than a very small cellphone sensor.) –  AJ Henderson Oct 7 '13 at 4:00
I should have clarified further when stating its possible instead of just saying the process is going to be tedious. Thanks for your technical terms to explain things. –  vikata kavi Oct 12 '13 at 1:11

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