100mm Lens vs. 100mm Macro Lens

Discussion in 'Digital Photography' started by sanPietro98, Nov 21, 2011.

  1. sanPietro98 macrumors 6502a

    sanPietro98

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    #1
    I enjoy taking close-up shots of objects, but I want to "get closer."

    But is there any difference in magnification between a 100mm Macro lens and a 100mm prime other than minimum focusing distance?

    I'm asking because I see shots that people have taken with a 100mm Macro lens, but my 100mm non-macro lens doesn't even come close to that level of magnification. Is it because of the minimum focusing distance that allows them to physically get closer, or do these folks use extension tubes?

    I realize I can use my 70-300 lens to get closer, but I'm wondering if there's an inherent magnification difference between 100mm and 100mm macro. Just trying to better understand the optics involved.

    Thanks in advance for your feedback.
     
  2. snberk103 macrumors 603

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    #2
    As I understand it, the macro lense allows you to get closer. You can use extension tubes on a non-macro lense, but it may not be worth it. However, another benefit of a macro lense is that it should also be "flat field". When you get a lense close to the subject, the image it projects back towards the sensor tends to have its plane of focus curved like a bowl - the corners of the sensor may not see afocussed image, if the centre area is sharp. However a good macro lense projects a flatter image towards the sensor, keeping more of the image in focus. Hope that helps.
     
  3. sanPietro98 thread starter macrumors 6502a

    sanPietro98

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    #3
    That does help -- thanks.
     
  4. compuwar macrumors 601

    compuwar

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    #4
    It is almost all because of the minimum focusing distance. There may be some focal length variation with focusing distance on most lenses, but mot of the effect is simply due to being closer. Hold your hand 1 foot away from your face, then move it to 6"- same effect.

    Paul
     
  5. fcortese macrumors demi-god

    fcortese

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    #5
    Having just gotten a 100mm Macro, it allows you to focus much closer either manually or dialing in a range 0.3m-0.5m (1-1.6 feet) or 0.5m to infinity. You can then use your autofocus to zero in on your subject. The lens can also be used as a 100mm prime lens. These can be expensive (I found mine at a hugely reduced price at an estate sale). A less expensive option is to use the Canon 500D close-up filter on your 70-300, like it is done here.
     
  6. -hh macrumors 68020

    -hh

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    #6

    Agreed. FWIW, a set of Extension Tubes usually aren't that expensive and can usually be used on "all" lenses in one's collection ... not a bad thing to experiment around with (particularly for macro work): don't forget that they can often be stacked, too.

    For cost, B&H has a 3 piece set (13 mm, 21 mm, 31 mm) from Vivitar for Canon EF for under US$100. Since extension tubes don't have any glass in them, it isn't a big deal to select an off-brand IMO.


    Its been awhile since I've mucked with my extension tubes, but I recall that they can be a bit frustrating at times to work with, as it is easy at first to forget that it has introduced a "maximum focus distance" (no "infinity" setting anymore), plus it can take some time/work to sort out focusing...and where that focusing is. My recommendation is to NOT start with small animals (eg, chipmunks): with a tripod and a static subject (eg, flowers), it shouldn't be too much of a problem.


    -hh
     
  7. flosseR macrumors 6502a

    flosseR

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    the cold dark north
    #7
    well i have been down the extension tube road and while it works.. its a big pain in the butt to be honest. focusing is NOT easy with them.
    Has to be said also: Macro lenses are incredibly sharp, even when used as a portrait lens. This might not be what you want as they bring out every skin flaw very well :)
    They work brilliantly however and the 100mm L IS macro from Canon has superb IS built in as well.

    Bear in mind that IS or for Nikonians VR, will not give you much when you get down to 1:1 magnification but anything "normal" and the IS or VR will be a godsend.
    For the record i have a 105mm VR and i wouldn't trade it for anything.. i also use it for portraits because the bokeh is very appealing to me.


    //F
     
  8. sanPietro98 thread starter macrumors 6502a

    sanPietro98

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    #8
    Great link. I'll look into the close-up filter. I didn't know that even existed.
     
  9. compuwar macrumors 601

    compuwar

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    #9
    It depends on how large you want to get-- both extension tubes and diopters don't provide a lot of magnification, so if you want to go to 1:1, you really need a macro lens. Diopters on a longer focal length lens will get closer, but flaws will be more obvious as well, and they reduce your working distance (mostly an issue with live subjects.) The best combination is extension tubes combined with a Macro lens that will do 1:1 (not all macro lenses are 1:1, many are 2:1- check the specs if you need 1:1.)

    Paul
     
  10. harcosparky macrumors 68020

    Joined:
    Jan 14, 2008
    #10
    The 100mm Macro lens should give you 1:1 reproduction of the subject on the sensor.

    A 'normal' 100mm lens will not do this.

    That's why it is called " macro ", it allows you to get really close to small objects to get much much better detail. Sometimes more detail than you might want.

    I use a Canon 100mm L Macro for coins, and jewelry and there are times when I catch flaws on an item that were not seen with an eye loupe.

    1:1 Macro and a 24" monitor will do that.

    You can also get a 180mm Macro which will still give you 1:1, but from a bit farther back.

    If you are taking macro shots of insects and other small living critters, you might want the 180mm macro.

    I also have a TAMRON 180mm Macro that cost less than the Canon 100mm L Macro and just as sharp.

    .
     

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