Canon EF-S to EF converter?

Discussion in 'Photography Beginners' Forum' started by Hock, Aug 16, 2009.

  1. Hock

    Hock TPF Noob!

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    So... I was browsing the canon product line late at night.. and i came across the extension tubes. It seems to me that it will accept an EF-S or EF lens, but will only fit an EF camera (not that it matters, since all EF cameras take EF-S). So by doing this... have you converted an EF-S lens to EF mount?
    Also... since you would lose the focus at infinity b/c now the lens is too far away from the body... but is that still the case with the EF-S lens, since it would come into the extension tube more than the EF lens?
     
  2. Stosh

    Stosh TPF Noob!

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    If I understand EF and EF-S correctly, the only difference is that the rear element is allowed to stick out further (closer to the image plane) in the EF-S. The reason this is allowed is because since the sensor is smaller, the mirror that flips up is also smaller. I'm pretty sure the distance from lens mount to focal plane is the same. If it weren't, then you couldn't use EF lenses on a EF-S body and enjoy parfocal benefits. So when they say EF and EF-S "mount" it's confusing because the mount distances are identical.

    So when you put on an extension tube, you now eliminate the rear element protruding too far, thus you've turned your EF-S into an EF lens. Unfortunately it probably won't cover a full frame sensor like it should unless it's a big extension tube.

    For your second question, yes you would still lose infinity focus because actual mount spacings are identical, so if you lose it for one, you lose it for both.
     
  3. gryphonslair99

    gryphonslair99 Been spending a lot of time on here!

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    Except that you have you mounts confused. EF mounts fit full frame and crop sensor body cameras. EF-S only fits crop crop sensor bodies in the XXD and Rebel series. EF bodies do not take EF-S lenses.
     
  4. KmH

    KmH Helping photographers learn to fish Supporting Member

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    But, they can. The extension that causes the mechanical interference with the mirror is removable if the lens owner is willing. There are tutorials out there I have seen. Unfortunately, I can't provide a link.
     
  5. Derrel

    Derrel Mr. Rain Cloud

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    A few months back, I read of a setup a guy was using with a Kenko AF extension tube using a Canon EF-S zoom lens, the 17-85 f/4~5.6 IS, on a Canon 1D Mark III camera.
    So yes, an extension tube CAN allow a person to mount an EF-S lens onto a body not designed for EF-S lenses, which do protrude farther into the camera than EF mount lenses do.

    The only PROBLEM though is that one loses infinity focus, but I guess if one's hard-up to mount an EF-S lens onto an EF body, it can be done by using an extension tube. I do not own any EF-S lenses; does anybody know if there is a Canon or 3rd party 1.4x telephoto converter that will accept EF-S lenses?

    In answer to your question, have you converted an EF-S lens to an EF lens by using an extension tube on it--I would say the answer is definitely a "no". But using an extension tube *will* allow a lens to be mounted. No guarantees about a full image circle or anything like that though.

    What I do not understand is why Canon deliberately made the EF-S mount so incompatible; Nikon;s entire line of DX lenses will fit onto ANY Nikon-mount body,and will usually cover the entire FX field except t the very-widest angle settings, and they will automatically switch from wider-field sensor capture to the smaller-field sensor capture area on Nikon bodies that capture at different sensor sizes (like 1.5x and 2.0x). I just can;t understand why Canon made this decision to protrude even farther into the body when it's obviously not a *required* engineering decision.
     
  6. Josh66

    Josh66 Been spending a lot of time on here!

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    The image circle is also smaller. It doesn't need to be as big to cover the smaller sensor. This allows the lens to be made with less glass, saving weight.
     
  7. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    Marketing probably - anyone upgrading from EFS to an EF camera would have to also replace their glass - which is also most expensive (most times). That is the most likley answer, but it could also be to avoid confusion with EFS lenses being used on Fullframe cameras and getting a host of complaints about massive vignetting occuring. I guess that Nikon might use more glass (more weight and more cost) in their crop sensor lenses to lessen this problem?
     
  8. Stosh

    Stosh TPF Noob!

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    I should have been more clear that the only PHYSICAL difference was the protrusion. Thanks Josh for clearing that up because the image circle is certainly smaller on EF-S lenses.

    I don't really see how this is possible. The mechanical interference you refer to is more than just a piece of metal or something easily removable. It's the optics too. You couldn't remove glass and expect to have any results at all. I'm not saying there's isn't a rare case lens that exists where you can remove something small and have it work on an EF body, but most have optics in the way too.

    Agreed that it's not required, but it certainly makes it easier on the lens designers and manufacturing. It would make almost no difference at all on lenses above 35mm focal length. The problem is with wide angle lenses. The closer your glass can be to the focal plane the easier it is to design and manufacture. That's why super wides are so expensive.

    I've never owned any of Canon's EF-S glass, but I did own the Tokina 11-17 "zoom" lens and it fit just fine on my 5D II with no modifications when used at 17mm. I bought it for use with my XTi, but when I upgraded to the 5D II it wasn't good enough despite the reviews on the web saying it was fine at 17mm. When compared to a consumer grade lens, it was marginal, but compared to an "L" lens it was not acceptable. Of course it's 1/3 the price of an equivalent "L" zoom.
     
  9. Hock

    Hock TPF Noob!

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    Sorry i got that messedup.. it was late i ment to say EF lenses will fit all EF bodies (EF and EF-S)
     
  10. Josh66

    Josh66 Been spending a lot of time on here!

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    Do I sense a little hostility there...?

    I didn't mean to offend you, and even if you knew, there are others reading this that probably didn't know...

    After re-reading your post, it is clear to me that you already knew this. Beginners may not have known from your post alone though...
     
  11. KmH

    KmH Helping photographers learn to fish Supporting Member

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    EF-S 18-55/3.5-5.6 conversion for EOS 10D Here's one.
     
  12. Josh66

    Josh66 Been spending a lot of time on here!

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    You can remove material to make the lens physically fit, but you cannot solve the problems caused by the smaller image circle...
     

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