A7ii, IBIS and Macro Extenders

Discussion in 'Adapted Lenses' started by Tipton, Mar 27, 2017.

  1. Tipton

    Tipton TalkEmount Regular

    149
    Jan 30, 2016
    Rae Leggett
    I use a Vivitar S1 90mm Macro with extender for my occasional amateurish handheld macro shots of flowers. IBIS will definately help there. With IBIS in my new A7ii, I can set the focal length of the lens I'm using. Should I set it to 90mm when I use the extender, or to the overall focal length?
     
  2. AlwaysOnAuto

    AlwaysOnAuto TalkEmount All-Pro

    Feb 17, 2015
    Why not try it both ways and see which works best for you?
    You're not going to break anything, you'll just find it harder to focus one way vs the other I believe.
    I've never used my extension tube on my A7ii so I don't know which will work best.
     
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  3. Hawkman

    Hawkman TalkEmount All-Pro

    Sep 10, 2013
    Virginia, USA
    Steve
    Hmmm, this is an interesting question, and one that one of the true experts in lens focusing here on the forum might be better able to answer. That said, I'll take a stab at it with my limited understanding....
    As I understand it, macro extenders do not change the focal length of the lens, but rather move the back of the lens farther from the imaging plane (the sensor) and thus change the focal point thereby enabling the lens to focus at closer distances to the subject (and consequently reducing the ability to focus at longer distances to the subject, i.e., no more infinity focus). Based on this, I would expect that for purposes of IBIS, as the focal length of the lens is the operative factor to be controlled since it affects the field of view and hence the relative movement of the subjects in view, then the presence of an extender should not affect the function of the IBIS as it does not change the focal length of the lens. Of course, as I don't have a body with IBS (much to my chagrin) I can't test my theory.
     
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  4. JMM

    JMM TalkEmount Regular

    154
    Jul 29, 2016
    John
    First thing is that focal lenght changes with focusing, hence 5 axes ibis works only with 8 pin lenses (via la-ea4) or 3 axes with other lenses. Other thing is that since you working with huge magnification, IBIS efficiency gonna be heavily stretched and you should try some huge numbers, as it's gonna be similar to supertelephoto.
     
  5. chalkdust

    chalkdust TalkEmount Veteran

    360
    Sep 25, 2015
    Bert Cheney
    Great question, Tipton. I am silently nodding my head in agreement with AlwaysOnAuto, Steve, and John. I do not have any extension tubes,so i suppose it is merely academic to me. But I am curious...
     
  6. Tipton

    Tipton TalkEmount Regular

    149
    Jan 30, 2016
    Rae Leggett
    Well, I did some experiments. These are all of the same crocus at the side of my house. Jpegs straight out of the camera.

    The first is Sony A7ii + Vivitar S1 90mm Macro, handheld, with the extender attached, f/2.5. For those not in know, the extender for the "bokina" is not just a tube, it has glass in it, and adds a lot of weight. IBIS is OFF. 20170327-DSC00173.

    For the next photo, same conditions, except IBIS is on, and set to 90mm. (different angle, too)

    20170327-DSC00187.

    Now I mentioned the glass and weight of the extender for a reason. Those previous two pics are taken of a tiny flower at maybe 9 inches distance, but the whole thing is heavy. Camera plus lens is easily four pounds. It's easy to find focus but hard to keep it. This last pic, I took off the extender, left IBIS on, set to 90mm.

    20170327-DSC00202.

    Now here you can see the difference in DOF. And this is from maybe 3 inches away. The thing is, it's a lot easer to use because the lens weighs half as much!
     
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  7. chalkdust

    chalkdust TalkEmount Veteran

    360
    Sep 25, 2015
    Bert Cheney
    Tipton, with respect to your original question, I think you are saying that the proper setting for macro is simply the focal length of the lens. Further, you are saying that for this lens handheld, you prefer using it without the extender due to the weight.

    Did I get that right?
     
  8. Tipton

    Tipton TalkEmount Regular

    149
    Jan 30, 2016
    Rae Leggett
    Basically, yes. The extender adds too much weight to use handheld. On a tripod, I would use the extender and turn off IBIS.
     
  9. JMM

    JMM TalkEmount Regular

    154
    Jul 29, 2016
    John
    Uh, im not sure where that conclusion is coming from as 1 and 2 image is equally sharp, despite different focus, and 3rd one is blurred.