Wrong lens types / using an unsupported lens mount (SOLVED)

[AdnascentiaV]

I'm wondering what happens to a body and lens if you are to use an unsupported mount like a efm on a sl2 or trying to use a nikon lens on a Canon body (without adapter) . How sure should I be before trying to attach a lens to a camera body? Would they simply not fit or would something get shorted and both be ruined? Just being cautious.

Edit: The reason behind this was I have the oportunity to tryout a varity of lenses including several canon, and nikon and was wondering about the level of cautiousness I should use while trying them out. E.X. (seems stupid now but) should I just see if they work or should I be researching each individual lens and body combination. that's what seems to be the case.

[Waddizzle]

You will break the camera.  The lenses do not fit properly, and there are other differences, both mechanically and electronically.

[shadowsports]

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@AdnascentiaV wrote:
I'm wonder what happens to a body and lens if you are to use an unsupported mount like a efm on a sl2 or trying to use a nikon lens on a Canon body (without adapter) . How sure should I be before trying to attach a lens to a camera body? Would they simply not fit or would something get shorted and both be ruined? Just being cautious.

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Ask yourself this question...  would you try to use the wrong calibre ammunition in a firearm? 

[RobertTheFat]

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@AdnascentiaV wrote:
I'm wonder what happens to a body and lens if you are to use an unsupported mount like a efm on a sl2 or trying to use a nikon lens on a Canon body (without adapter) . How sure should I be before trying to attach a lens to a camera body? Would they simply not fit or would something get shorted and both be ruined? Just being cautious.

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The lens opening in a Canon mount is larger than most, which is why so many 3rd-party lenses can be used with adapters. So you probably won't break anything, but the lens would rattle around and probably fall out. Bottom line: The idea is a total non-starter.

[ebiggs1]

"Would they simply not fit ..."

Yes!  

[TCampbell · Accepted solution]

There are many physical and electronic problems with the idea.  

Many have pointed out that physically the lens isn't going to attach to the camera's mounting flange correctly ... and then there's the electronic interface that allows the camera to control the lens.  If that interface isn't compatible then there's no way to control the lens.

But another issue is that lenses are designed to be able to bring an image to focus when the lens is positioned at a specific distance from the sensor.   Canon's mirrorless lenses are designed for an 18mm flange-to-focal-plane distance.  Canon's DSLRs are designed for a 44mm flange-to-focal-plane distance.  

Even if you could get around the physical mounting problems, the lens would be much too far from the sensor.  When you push the lens much farther from the sensor it is "as if" you inserted extension tubes on the lens.  This causes the entire focus range to shift much closer.  Meaning the lens can focus on close objects, but is actually incapable of focusing on distant objects and it wont be able to focus to infiinity (use of extension tubes to position a lens farther from the sensor than designed is a way to do close-up photography).

So basically even if there were some type of adapter to let it mount, you wouldn't have a workable lens for any type of photography other than close-up photography.

BTW, the reverse situation actually does work.  If you own a Canon "mirrorless" body, you actually can attach lenses meant for Canon DSLRs.  This is because those lenses are designed for a 44mm distance to the sensor, the body provides an 18mm distance, so Canon makes an adapter which takes care of the physical mounting problem AND positions the lens an extra 26mm away from the body so that the lens is held at the precise 44mm mounting distance as intended.