macro photography and extension tubes

Discussion in 'Australia Photography' started by s, Feb 23, 2004.

  1. s

    s Guest

    Budding photographer here.. a lot of the stuff i photograph is close-ups of
    wildlife in the yard ( bugs, critters and flowers ). I currently use a
    28-90 for most of it, i stand a little back and zoom right in. Results are
    OK. BIggest problem i currently face is getting close to small objects.
    Tried to photograph a baby gecko last night and end up 1.5m away from the
    damn thing zoomed in with a 90-300 lens!

    After having done some reading, i'm now curious about macro lenses (e.g.
    canon EF100 f/2.8 macro USM) and what effect they have. Alternatively, how
    much effect do the extension tubes have ?

    As i'm not quite sure exactly what a dedicated macro lens do for me, which
    seem to cost at least $700, while the extension tubes cost less than $500.
    That seems like a good way to get started, but the cost difference makes me
    wonder if there's a quality difference.

    E.g. what would the canon EF25 tube do to my 28-90 ? Would it reduce the
    minimum focus distance ? If i stood the same distance from the object,
    would i get the object filling more of the view ?

    I currently have a canon 300v, 50mm/f1.8, 28-90USM and 90-300USM.
     
    s, Feb 23, 2004
    #1
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  2. I have only limited experience here - use an extension tube on my manual
    Nikon F3 & 105 2.8 macro ("micro" in Nikon terminology) to photograph
    flowers.

    One thing I have found is that you have to be close - real close - with an
    extension tube in order to focus with this lens - I presume the same
    principal would apply to the Cannon lens - so this would be a waste of time with
    insects, etc, as you would probably spook them.

    Just wondering myself - what is the solution to this?
     
    John Phillips, Feb 23, 2004
    #2
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  3. s

    Howard Tam Guest

    I did some macro in the wild as well, but I am a Nikon user, hope the answer
    still helpful to you.
    Pls see below.
    Howard


    I think a 28-90mm for nature macro on insect, gecko is too short, I am using
    a 300mm F4 with 52.5mm extension tube for dragonfly, butterfly, etc.
    With Canon gear or third party lenses, think about the 180mm as a start, or
    even longer.
    Extension tube contains no lens elements, it only gives you closer focusing
    distance.
    But you also loss some light, so you generally want to use it with prime
    lenses, not
    zoom lenses, except the expensive constant large aperture zooms.

    Quite a number of dedicated macor lenses, or macro zooms will let you go
    down to
    1:2 or more with close up lens, or extension tubes.
    I am not a Canon user, but I hope this is correct. The EF25 should reduce
    your
    minimum focusing distance of the 28-90 but the image also becomes darker,
    due
    to the extension. If your subject distance is the same, I think you may get
    the same
    magnification, but I am not sure, I have to try it with my setup to verify
    or recall
    this. But I think if you use a close up lens, then you can have the same
    subject
    distance and get higher magnification.
    Is the 90-300USM a macro zoom?
     
    Howard Tam, Feb 23, 2004
    #3
  4. s

    Scott Coutts Guest

    Yeah, a macro lens or extension tubes will be much better! You wont be
    able to fill the frame properly when shooting small objects with either
    of those lenses
    Well, you can use either of those, or for the cheapest option, buy some
    close-up lenses for the front of your smaller lens. You screw them on
    the front like filters. The extension tubes will give you at least the
    same magnification as the macro lenses will, and often more.
    The macro lens will also double as a normal 100mm lens. You can use it
    to shoot whatever you want. As soon as you put on an extension tube, you
    loose the ability to focus to infinity (until you take it off of
    course). In fact, you lose the ability to focus on anything further than
    maybe 30cm away from the lens with a short tube, and with a long (set
    of) tube(s) you wont be able to focus further than maybe 3cm.

    The macro lenses will sometimes give you better quality, but tubes are
    usually as good and much cheaper. They often have the problem of making
    the minimum focussing distance too small, though.

    When you look at lenses, they all have a 'magnification' figure listed
    usually as a ratio. So 1:1 (or 1, or 1x) means that an object that is
    1cm high will appear 1cm high on the negative, if you measured it's
    image. A 1:2 (or 0.5, or 0.5x) would mean that if you measured it's
    image on the neg, it would be 0.5cm high etc. Most lenses have a ratio
    much lower. The highest you'll get from a lens that you can put on your
    camera is 5x (5:1) and that comes from the MP-E65 lens. But you usually
    dont need that kind of magnification.

    Also, with a macro lens, you can change the level of magnification
    you're getting. With tubes, you have fixed increments (i.e. you can only
    change it by adding or removing more tubes one on top of the other).
    Firstly, dont buy the Canon tubes. They're a complete waste of money.
    Buy Kenko ones as they're much cheaper and do essentially the same
    thing. Besides, you get three tubes with the Kenko (and other brands).
    There's no glass in any of them, so cheaper ones wont have lesser image
    quality

    Anyhow, it will just allow the objects to fill more of the frame. All
    the tubes do is move the lens further away from the film/sensor plane.
    Yes, greatly! In fact, so much so that often this is a problem with tubes.
    Usually you will have to get within cm of your subject when using tubes.
    That can be an advantage of getting a lens - the 100mm macro will allow
    you to stand further away than the tubes will, but still fill the frame.
    The 180mm macro will allow you to stand even further away and still fill
    the frame. With tubes, the more you put on, the more magnification you
    get, but the closer you have to be to the subject.
    The 50mm is the best lens for this, because it has quite a flat focal
    plane and it's also very sharp.

    Do a google-groups search on this group using 'macro' as the search term
    and you'll find lots of threads about this very subject. There was one
    not long ago with lots of info.


    Scott.
     
    Scott Coutts, Feb 23, 2004
    #4
  5. s

    s Guest

    So the extension tube + my 90-300 is possibly a reasonable combination in
    lieu of purchasing a dedicated macro lens ?
    No, it's plain zoom, minimum focus distance is around 1.5m.
     
    s, Feb 23, 2004
    #5
  6. s

    s Guest

    ok, that's what i wanted to know, it's becoming clearer now ( no pun
    intended ).
    What do the close-up lenses do ? They just seem to look like filters.
    ok, so the lens is the flexible option in terms of use for other items,
    while the tube is the cheaper option, but is limited in that it will limit
    you to close-up ONLY.
    I'd often wondered about the 1:1. I was suprised that it would in theory
    limit you to objects around 35mm in size, but i guess this is all about
    taking images of very small objects.
    ... hence the advantage of a dedicate macro lens.
    Currently it has a minimum focus distance of around 45cm. At that distance a
    my hand or a standard-sized rabbit-photo print fills the view.

    I can see i need to do some tinkering. It's all well and good to describe
    this, i need to see it in action. A friend has an older canon 50mm macro
    lens. I tried it once but didn't really understand what i was doing back
    then. I might borrow it again.
     
    s, Feb 23, 2004
    #6
  7. s

    Scott Coutts Guest

    They just allow you to get closer. So they have the effect of making
    your lense into a macro lens. But they have the same disadvantage as
    tubes in that they will reduce your min focussing distance dramatically.
    They also have the disadvantage that, because they are a 'screw-on
    lens', they will often decrease the quality of your image. The usual
    effect is softness and chromatic abberation (coloured fringes on the
    edges of objects in your image). If you're going to get these, then
    unlike the tubes, I would recommend the Canon ones (since there's glass
    involved).
    Perfectly correct :) The lense will also give you the highest quality
    image, and of them, the 180mm will be best. But the tubes are fine, i
    reckon.
    No, not at all. A 1:1, or 1x, would be 'life size'. For example, if you
    have 'greater-than-life-size', i.e. 2:1, then you can photograph
    something that is half the size of the frame, and it will fill the
    frame. That 5:1, or 5x, will allow you to photograph something 1/5 the
    size of the frame and it will fill the frame.

    Oh, also, bear in mind that as you increase your magnification, you're
    also decreasing your depth of field. So by the time you get to 5x, your
    depth of field is very, very thin. If you stop down to get a bigger
    depth of field (which will still be very small, in the mm range), then
    you encounter problems with lighting your object. Welcome to the world
    of macro ;) Nah, it's great fun once you get a system worked out, and as
    long as you understand the limitations/restrictions.
    I mean't that the 50mm is the best combo with the tubes. Your focus
    distance will be reduced a lot from there.
    Also remember that auto-focus isnt much good at high macro. Best to use
    MF and move the camera or subject, if possible.

    If you look for the other thread, you'll have the sizes and focussing
    distances of the three tubes that you get when you by a set.
     
    Scott Coutts, Feb 23, 2004
    #7
  8. s

    Phred Guest

    Going back 30 or so years, ISTR that you can use a normal lense as a
    "macro" up to a point, by screwing it on to an extension tube back the
    front. This may give a better macro image because the distances
    involved are closer to the "design" optics except that subject and
    image are reversed (i.e. the film plane becomes the "subject").


    Cheers, Phred.
     
    Phred, Feb 23, 2004
    #8
  9. s

    Howard Tam Guest

    Pls see below.
    Howard
    It depends on what image quality you are after, zoom plus extension tube is
    usually
    not a good combination, as the aperture of most zooms is small, then you
    have extra
    light loss from the extension tube, it's ok for static subject, but then you
    are interested
    in insect, etc.

    The longer the focal length, the longer the extension tube is required to
    produce the
    desired magnification; for a 300mm lens, I use the Nikon 52.5mm tube which
    is ok.
    For shorter lens, like the Nikon 105mm micro, you may like to use something
    shorter
    to give you the desired magnification, and less light loss.
     
    Howard Tam, Feb 24, 2004
    #9
  10. Macro photography is the art of photographing small objects, such as insects and
    small flowers. The photographer can either use a camera with a general-purpose
    lens, and use accessories which enable him to focus closer than normally, or a
    lens specially designed for macro photography. For example I have a Canon EOS
    1000F with a 35 to 80mm normal lens, and an 80 to 200 mm tele-lens, and a Nikon
    Coolpix 4500.

    With the Canon, the normal lens will focus on an object at a distance of about
    300 mm, regardless of the focal length, and at this setting the size of the
    smallest object which will just fill the field of view varies from about 135mm
    to 310mm, depending on the focal length. Similarly, with the tele-lens, the
    shortest object instance is about 1500mm, and the smallest object size varies
    from 270 to 675mm.

    On the other hand the Nikon is specifically designed for macro photography, and
    it will focus down about 20mm, giving a minimum object size of about 18mm,
    without requiring any accessories.

    Notice that lens makers usually specify the magnification achievable with a
    particular lens. This is the size of the image, divided by the size of the
    object. However if you are comparing cameras with different image sizes (for
    example a 35mm camera with either a digital or a large format camera), this
    value is not particularly helpful. It is more useful to talk about the size of
    the object which will just fill the image, because most of the time you will be
    looking at the same size of print, regardless of the camera format.

    At first glance you might think that the Nikon was so superior that I would
    never use the Canon again, but there are several gotchas. The first is that the
    autofocus is not particularly satisfactory, and it is difficult to tell from the
    low resolution LCD viewing screen whether the object is in focus, particularly
    outdoors. The second is that at minimum working distance the lens is almost
    touching the object. This makes it somewhat difficult to illuminate the object,
    especially if you are trying to use natural light, and if you try to photograph
    an insect or a small animal you are very likely to frighten it away.

    So, while this camera is good for dentists photographing teeth, or doctors
    photographing skin cancers, it is less useful than you would expect for nature
    photography. On the other hand the unaided Canon is quite unsuitable for macro
    photography. There are three ways to overcome this.

    The first is to use a lens specifically designed for macro work. Unfortunately
    these are very expensive, are either rather limited in their capabilities, or
    are totally unsuitable for general use, are heavy and generally have a
    relatively short working distance so that they are also likely to upset the
    subject. For example Canon offer several macro lenses suitable for my camera,
    including a 50mm F/2.5 compact macro, RRP $730, and a 100mm F/2.8 macro at an
    RRP of $1250

    They also offer a special macro lens for extreme close-up work which enables you
    to work at magnification is between 1.0 and 5.0 (corresponding to minimum object
    sizes ranging from 7 to 36mm). This is a manual focus lens, and costs $2200.
    If you had to work in this range it would probably be a very elegant solution.

    The second is to use extension tubes, which go between the camera body and the
    lens, and increase the effective extension of the lens. These have two
    disadvantages:

    a. If the camera is at all sophisticated, the extension tubes must be
    specifically designed for the camera, as they must provide connections for the
    auto focus and the like, and there is limited demand for them, so they tend to
    be expensive, and

    b. As the lens is moved away from the camera, the effective F number of the
    lens is increased, reducing the exposure, and the photographer may have to allow
    for this.

    Canon offer two extension tubes -- a 12mm and a 25mm at $150 and $250
    respectively. It is not clear from the specifications on the Web whether these
    provide full functionality, and what effect they will have on the normal lenses.
    The construction of the lenses makes it impossible to calculate this, but I
    would guess that the two tubes together would enable you to work up to
    magnification of about 0.5 on the normal lens, and rather less on the tele.

    The third is to use close up lenses. These are very simple relatively
    inexpensive meniscus lenses with a relatively long focal length. In principle
    these should reduce the quality of the main lens, but in practice you are always
    battling for depth of focus in macro photography, so you are always working at
    the smallest possible aperture, and under these conditions the degradation
    introduced by the close up lense appears to be negligible.

    I have a set of close up lenses for the Canon, which originally consisted of
    three lenses, with focal lengths of 250, 500, and 1000mm, but have lost the
    500mm lens. These can be used with both main lenses. If I focus the camera at
    infinity, and fit the 1000mm closeup lens, the camera will focus on an object
    about 1000mm from the front of the lens with either normal lens. With the main
    lens fully extended, the distance to the object will be about 600mm.

    With the 250mm closeup lens, the corresponding distances are approximately 220
    to 270mm. From this we can work out the following table:

    FL of main lens Close up lens Smallest object Magnification range
    (at closest focus and infinity)

    35 250 225-275 0.12-0.16
    80 100-120 0.30-0.36
    200 40-48 0.75-0.90
    35 1000 620-1300 0.028-0.058
    80 270-450 0.080-0.133
    200 108-180 0.20-0.333

    It can be seen that the close up lenses enable the photographer to get quite
    reasonable magnifications without getting too close to the work, and without
    requiring any adjustments to the exposure. They are lightweight, compact,
    relatively easy to use and relatively inexpensive. In practice I have never
    noticed any degradation caused by aberrations in the lens. The telephoto lens
    gives the largest magnification, but, as always, it is also more sensitive to
    camera movement.

    CONCLUSION. If you have to do a lot of macro photography, of immobile objects,
    it may be worth investing in a macro lens, especially if you can bring the work
    back to the studio. But if you are a general-purpose photographer, and want to
    be able to photograph the odd flower or insect which takes your fancy, or even
    do an occasional job involving close-up photography, and don't want any more
    heavy junk in your camera bag to weigh you down, buy a set of close up lenses.
    I would not recommend extension tubes under any circumstances.


    Roger Riordan AM
     
    Roger Riordan, Feb 29, 2004
    #10
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