extension tubes with macros for critters?

Discussion in '35mm Cameras' started by etosha, Feb 24, 2006.

  1. etosha

    etosha Guest

    Hi,

    I'm going to Gabon for a month in the rainforest and I was wondering if
    you could help me decide whether or not to buy a Kenko extension tube
    set for my macro lenses. The gear to be used for close-up work is:

    Minolta Dynax 9
    Sigma EX 105/2.8
    Sigma EX 180/3.5
    Minolta 5400HS flash

    others: Sigma EX 2x teleconverter, tripod, off-camera flash bracket

    The 105/2.8 lens focuses to about 31cm but for some smaller critters
    such as ants this is not enough, and to get in-yer-face pics of
    caterpillar heads, for example, that simply is inadequate. So the
    question is:

    is the use of extension tubes to get closer to the subjects a viable
    option?
    is there a significant loss of optical performance?

    help appreciated,
    cheers,

    Marko
     
    etosha, Feb 24, 2006
    #1
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  2. etosha

    Annika1980 Guest

    is the use of extension tubes to get closer to the subjects a viable
    No, only Depth of Field. Extension tubes are hollow so there is no
    glass there to degrade the pic.
     
    Annika1980, Feb 24, 2006
    #2
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  3. etosha

    Matt Clara Guest

    While that's true, most lenses aren't designed for close focus, and some
    will perform better than others in that capacity.
     
    Matt Clara, Feb 24, 2006
    #3
  4. etosha

    JimKramer Guest

    And some will preform much worse. If the lenses you have are very
    sharp then you can use extension tubes with some success. Otherwise a
    big soft image isn't much better than a small soft image.

    Bear in mind shallower depth of field, more susceptibility to camera
    shake, inherently unreliable flash metering, if you are really
    "chasing" critters they will be moving too.

    Extension tubes are great for a number of things, but a better, I.E.
    closer focusing distance, macro lens may be a better investment.

    Be prepared to take multiple exposures as your keeper rate will go down
    too.

    If you get the extension tubes make sure you take some time to
    experiment with them before you go and play in the field.

    Jim
     
    JimKramer, Feb 24, 2006
    #4
  5. Yes. Tubes are more rigid than a bellows, both mechanically and
    functionally; you might want to consider owning both.
    That depends on the lense. Many macro lenses earn that title
    only by being able to focus close. The best macro lenses are
    also optimized for use at close focus distances (as opposed to
    being optimized when focused at infinity).

    Note that some lenses that are optimized for close focus use a
    floating element in the optics which moves in relation to other
    elements as the focus is changed. For those lenses the added
    extension from a tube or bellows is *not* compensated for; in
    addition, unlike other lenses it will make a difference where
    the lense's own focusing mechanism is positioned.

    Consider, in addition to tubes/bellows, obtaining a "reversing
    ring", which allows the lense to be mounted backwards. For most
    lenses that will provide a sharper image because it is closer to
    the image ratios the lense was designed for.
     
    Floyd Davidson, Feb 24, 2006
    #5
  6. etosha

    etosha Guest

    thanks, everybody, for the answers. I googled a bit, but could not find
    a Minolta AF 58mm reverse ring (the Sigma EX 105/2.8 is a 58mm lens,
    magnification ratio 1:1). Do any of you know if they exist? How about
    using a coupler reverse ring 58 to 77 between the Sigma 180/3.5 (77mm)
    and the 105/2.8 (58mm) lenses?

    cheers, Marko
     
    etosha, Feb 25, 2006
    #6
  7. You'll need to use whatever reverse adapter you can find (49mm??) and
    adapter rings to reduce the 58mm to match the reverse adapter. It
    looks like 58-55mm or 58-52mm, and then either 55 or 52mm to 49mm would
    work. The step down adapters are $5 each. See eBay item 7593103793
    and take a look at their eBay store (Fotodiox).

    I've bought several adapters and such from them and have been happy
    with what they've sent.
    See eBay #7592735627.
     
    Floyd L. Davidson, Feb 25, 2006
    #7
  8. etosha

    Alan Browne Guest

    Is the 180mm f/3.5 above the "macro" version?

    A friend of mine uses one with the Maxxum (Dynax) 9 with excellent,
    sharp, contrasty macro results.

    I use the 100mm f/2.8 macro (Minolta) to equally fine results. I would
    be tempted to aquire the Sigma 180 f/3.5 macro as well, but other lenses
    are higher up on my list.

    For _really_ close macro, the 1-3X Minolta f/1.7-2.8 (50mm I believe)
    macro lens is the one to get although it might be difficult to find in
    the new or used market and it is very expensive (US$1,500, grey market,
    B&H).

    It requires a very disciplined approach to the work that might try the
    critters patience before you get the shot. The zoom is motorized for
    very fine control. Also difficult to light the shot with flash as
    you're very close to the subject.

    Regrettably, Minolta macro (ring) flash is extremely expensive. I'm
    hoping to find a Minolta ring flash kit on the used market or perhpas
    get the vivitar version.
    Of course.
    As others have pointed out you need a fortuitous match of lens and tube
    length to get great results. The tubes are relatively cheap (Kenko) so
    it's a good risk to take and can always be sold used for a small loss if
    they don't work out for you.

    If your 180 and 105, above, are the macro versions (the 105 must be with
    35mm close focus) I'm not sure at all that it can be used with ext. tubes.

    Cheers,
    Alan.
     
    Alan Browne, Feb 25, 2006
    #8
  9. etosha

    etosha Guest

    Hi Alan,

    The Sigmas I have are macro lenses and pretty good as such. I found a
    site exploring the use of extension tubes with the Sigma EX 105/2.8
    macro. It's hard to tell from the scan whether the sharpness of the
    combo is acceptable or not. Might give it a try, though.
    The test is here:
    http://mypage.direct.ca/s/selliot/macro.html

    cheers, Macromarko
     
    etosha, Feb 25, 2006
    #9
  10. etosha

    Alan Browne Guest

    All of the ones with the TC's are a bit soft. It would better to post
    full size crops of the images to really discern sharpness with the
    extenders.

    IMO it is is not useful to use the tubes (no sharpness loss if well
    matched to the lens) with TC's which always have a sharpness price
    regardless of quality.

    [ In replies on newsgroups it is best to include the "Alan wrote:" and
    relevant portion of the post you're replying to such that context and
    attribution are maintained. ]

    Cheers,
    Alan
     
    Alan Browne, Feb 25, 2006
    #10
  11. etosha

    Mark² Guest

    -And light loss.
     
    Mark², Feb 25, 2006
    #11
  12. etosha

    Alan Browne Guest

    Light isn't lost, just spread out more on the film so a longer exposure
    is required.

    ;-)
     
    Alan Browne, Feb 25, 2006
    #12
  13. etosha

    Mark² Guest

    Right.
    I call that light loss.
    :)
     
    Mark², Feb 25, 2006
    #13
  14. etosha

    Alan Browne Guest

    Only on a unit measured area. Otherwise nothing is "lost".

    ;-)

    Let's fight!
     
    Alan Browne, Feb 25, 2006
    #14
  15. etosha

    Mark² Guest

    "Wasted" might be a better term...or perhaps "not captured."
    :)
    Put up yoru dukes, pal!
     
    Mark², Feb 25, 2006
    #15
  16. etosha

    Alan Browne Guest

    I see your dukes and I raise you three Earls, a viscount and a rather
    bankrupt baron!
     
    Alan Browne, Feb 25, 2006
    #16
  17. Lots of little things in here. The 31cm distance is to the film
    plane, and in reality, this will not change with extension. The front of
    the lens will be able to get a few centimeters closer, but the kicker is
    that the lens is moved much further from the body, so the image spreads
    out more, like moving a slide projector further from the screen.

    However, with all three Kenko tubes on either of those lenses, the
    increase in magnification is probably not what you're hoping for. The
    formula is to divide the extension into the focal length, and this
    provides the increase in magnification.

    So, take the 105mm at closest focus, 1:1 ratio (lifesize). Three
    tubes - 12, 20, and 36mm - gives 68mm, divided into the 105. That gives
    you 1.54:1, or one-and-a-half lifesize. And much less for the 180mm.

    At the same time, you have to factor in the light loss (yes Alan,
    it's a loss, regardless of nonsense semantics), reduced DOF usually
    requiring a small aperture, and the lens being closer to your subject.

    What you're likely to find is that, even with a tripod and macro
    slider, on live subjects in situ, as it were, you are highly unlikely to
    nail sharp focus, or produce a decent pic without motion blur because
    you'll need a really long shutter speed. And that's if the subjects let
    you get that close.

    You can combine options for greater effect, and there's no good
    formula for this. I've used macro lenses with a teleconverter *and*
    extension tubes, and gotten some decent shots from it. Also worked with a
    TC but no tubes, which produces a better magnification than all three
    tubes, above. You can also use diopters with any of the above, but be
    warned - you're severely testing the limits of degradation with such.

    Your highest magnifications, however, are going to come with lens
    reversing (mounting a lens directly on the camera body backwards) and
    lens stacking (mounting a lens reversed on the front of a longer lens).
    These produce some wickedly high magnifications, and at the cost of
    producing DOF that can be measured in fractions of a millimeter. When
    doing reversal work, you'll want a wider angle lens - 28 to 50mm, I
    usually prefer 35mm. The reason is, you need to cover the film plane with
    the image, so you need an angle of view (when used normally) that will
    exceed the width of the film when reversed. Any kind of telephoto will
    vignette badly - they're normally capturing a very narrow field.

    Stacking works better with a smaller focal length reversed onto a
    longer one - 50mm onto a 200mm, or more. Rear focal length divided by
    front gives increase in magnfification, in this case 4:1 from a lens that
    would normally be 1:1. Such a method requires very sharp and limited
    distortion lenses, though, and you're likely to still crop the resulting
    image to remove aberrations from the edges.

    For both techniques, both camera and subject will have to be
    totally motionless, you're probably going to want a cable/remote release
    and mirror lockup, and lighting becomes a royal pain in the ass. This is
    primarily "studio" work rather than field work. The "studio" might be a
    camp table in the woods somewhere, but basically, you're going to need to
    rigidly control the conditions, and forget about snagging the subject as
    it goes about its business. The benefit of this is, your studio
    background can be a twig or a leaf - absolutely nothing else is going to
    be even slightly in focus (though avoid specular highlights).

    To that end, you may want to consider taking along collecting
    bottles (film cans, whatever) full of alcohol to pickle the best
    subjects, and posing them as needed. Not exactly a non-intervention
    practice, but then again, your presence there defeats that, and you're
    probably crushing hundreds when you walk and sit down ;-)

    Additionally, if you're looking to identify them afterwards,
    producing the specimen is quite likely your only hope - identifying
    species, even by trained entomologists, often requires seeing things your
    photos simply do not show. And you'll have the chance to redo the shots
    in better conditions if needed.

    Hope this helps. Good luck, and enjoy your trip!


    - Al.
     
    Al Denelsbeck, Feb 26, 2006
    #17
  18. etosha

    Alan Browne Guest

    Humor impariment tuneup due, Al.
     
    Alan Browne, Feb 26, 2006
    #18
  19. etosha

    Annika1980 Guest

    To that end, you may want to consider taking along collecting
    Dude, that's just WRONG!

    The whole fun of shooting macro is the challenge of it. It is damn
    hard to get those little critters in focus while they go about their
    business. Your technique would be like shooting wildlife by taking
    pictures of deer heads on someone's wall.
     
    Annika1980, Feb 26, 2006
    #19
  20. etosha

    Mark² Guest

    Are you serious?
    Surely you must realize that a huge degree of authenticity and reward is
    lost when you kill the subject, and then artifically pose it while dead.

    Do you find equal enjoyment in viewing pictures of dead insects/animals
    compared with live specimens in their natural habitat?
    I don't, and certainly find no joy in the process of photographing stuffed
    animals/pickled bugs.
    :)
     
    Mark², Feb 26, 2006
    #20
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