Macro Woe

Discussion in 'Photography Beginners' Forum' started by RxForB3, Feb 14, 2012.

  1. RxForB3

    RxForB3 No longer a newbie, moving up!

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    I'm very interested in macro photography, so I bought a set of Kenko extension tubes. I haven't played around with them a whole lot, but I'm really not having much luck. My problem is judging how far away to have the lens so that the subject can be focused upon. Sometimes it seems like I have to hold the lens practically touching the object, but other times it focuses from a foot away or so. I tried to photograph a slug I found on my door the other day, but even if I had him in focus momentarily (which required getting the lens much closer than I liked...just imagining cleaning slime off the lens), by the time I took the shot he'd already moved out of focus! I didn't realize slugs could move that fast :)

    Part of the problem, I'm sure, is that I've been practicing with several combinations of the tubes and lenses. Is there any way to determine ahead of time exactly how far away I should be based on the choice of tubes and the lens? Would a dedicated macro lens make things much easier? I'm heavily considering buying one of the canon 100mm macros and actually leaning towards the L version.

    Here are a couple of the only "successes" I've had so far. And I use the term success very loosely. Any help?

    1.

    [​IMG]
    Meh by RxForB3, on Flickr

    2.

    [​IMG]
    Underexposed by RxForB3, on Flickr

    3.

    [​IMG]
    Meh 2 by RxForB3, on Flickr

    Number 2 is obviously underexposed. Numbers 1 and 3, I think the flash looks unnatural (though admittedly I'm just using the flash on the camera itself...no speedlite). I believe these were taken using some combination of tubes along with the 55-250mm lens, though I don't recall exactly. I didn't have a tripod, which made things very difficult, but out of many shots, these were the only possibilities.


     
  2. TheFantasticG

    TheFantasticG No longer a newbie, moving up!

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    What MM were you shooting at?

    Oh, and practice to learn those distances better.
     
  3. LightSpeed

    LightSpeed TPF Noob!

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    It's principle of magnification.
    The bigger things are in the frame, under heavy magnification, the less they have to move to be out of the frame.
    Light becomes an issue under heavy magnification, if you haven't noticed yet. I'm betting you have noticed.
    I base this on the heavy flash on your vette
     
  4. RxForB3

    RxForB3 No longer a newbie, moving up!

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    Yes, I noticed :) I have a feeling I'll have to break down and buy a speedlite if I want to do any indoor macros with the extension tubes. Would light be less of an issue with a dedicated macro lens, or should I be budgeting for both the flash and the lens? I'm really liking the thought of having the L quality lens, but I suppose in the end I could get a good flash AND the regular 100mm for the cost of the L.

    TheFantasticG, I assume you're meaning millimeter? In which case, I unfortunately can't remember. The exif on at least two of them say 116mm, but I believe that's just of the lens itself, and not taking into account the extension tubes.
     
  5. LightSpeed

    LightSpeed TPF Noob!

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    In macro, it's a given in certain situations that image quality will be degraded.
    The problem rears its ugly head in the form of diffraction.
    The closer you get , the more depth of field you need.
    The depth of field window closes and becomes extremely shallow.
    To counter this we tend to use small apertures. The smaller the aperture beyond say f8-f11 or so, the more diffraction.

    Here's a shot at F32
    If I could have gotten the depth of field I needed at F16, the image quality would have been better.
    [​IMG]
     
  6. KenC

    KenC Been spending a lot of time on here!

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    The most useful way to approach this is to see how big your subject is compared to a standard film/sensor size (1x1 1/2 "). For example, if your subject fits nicely within that size (not much smaller) then you need a 1:1 magnification, which you get when the extension tube length is equal to the lens focal length, both in millimeters, e.g. about 50 mm of tube(s) with a 50 mm lens. You can search for formulas to calculate this for other magnifications and also formulas that will tell you the subject-film/sensor distance, but the distance is something you are just stuck with for a particular lens. If you use a longer focal length lens you get to be further away, but you need more extension to get the same magnification.
     
  7. RxForB3

    RxForB3 No longer a newbie, moving up!

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    Lightspeed, thanks for your instruction. I'll have to look up diffraction and find out how to recognize it. Using a higher aperture setting (if I'm saying that right...I'm still getting my head around a lower number being "wide open") and longer depth of field isn't something I probably would have thought of at first.

    KenC, thank you thank you thank you! Your explanation really clarified a misconception I had that was probably a big part of my problem with judging distance. I was just assuming that the longer the extension + focal length of the lens = more magnification! Basically I thought the longer the tube, the bigger the subject. Now I'm excited to find time to give it another go!

    To the subject of lenses, would buying a macro lens be helpful or should I focus on learning how to use extension tubes, first? I'm really really tempted to get a macro lens, but being a musician, I know that learning the basics first is very important.
     
  8. Helen B

    Helen B TPF Noob!

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    One important thing that is often forgotten is the intended final size of the viewed image. If you want to do this stuff well it's probably an advantage to understand how important that is, and how you can work backwards from it to the best capture method. How big do you want your images to be and how will you be displaying them?

    Proper macro lenses are usually a much better option than extension tubes. Bellows are an in-between solution, but one that can give you tilt - which might be very important for your application. Of course you have to use the right lens, the correct way round, with bellows. There are cheap options. Macro lenses should be designed for close work both optically and physically - ie the lens optics should be optimised for close-up (when focused close - they may have floating elements to achieve that) and the focus throw should be long enough to allow you to focus close without tubes or bellows.

    I do something like the kind of macro you are doing. Now I use macro lenses with tilt (and shift, but shift is rarely necessary in macro). Before those were available for Nikon, which is not so long ago, I used bellows with tilt and dedicated macro lenses, reversed cine lenses or enlarger lenses - the latter are very cheap these days. I also use very high quality auxiliary lenses (the ones that screw into the front of the main lens) - but they can be quite expensive. Rather than simply go the route everyone else goes, it might be worth looking around and deciding what suits you best. The equipment that is ideal for taking pictures of bugs may not be ideal for still life, and vice versa.
     
    Last edited: Feb 15, 2012
  9. pgriz

    pgriz Been spending a lot of time on here!

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    Macro, as you’ve already discovered, brings its own set of challenges. The first, and most important, is understanding that you have a very thin depth-of-field, measuring in many cases in fractions of a millimeter. This has a number of consequences. The first, as Lightspeed alluded to, is that you need to increase (as in higher f/numbers) your aperture to get more DOF, but that drops the amount of light you get, AND brings in detail-killing diffraction. The very thin depth of field also means that getting focus on your chosen subject is quite difficult, and any camera motion is amplified. As the DOF is so thin and the light is so feeble, getting a focus on your chosen spot is almost always a manual exercise, and then again, you need enough light to see.

    The common solution for light is a combination of flash (lots of light close up and usually the extremely short duration of the flash pulse freezes any motion) and some sort of focusing light (either sunlight, or a high intensity flashlight). But that introduces the issue of getting the exposure right, using the appropriate methods of triggering flash off-camera, and using diffusers to make the light less harsh. As well, all of the lighting issues of any subject (main light, fill light, etc.) are still there, but now on a very small stage.

    Another component of the solution is to use a tripod and a focusing rail. This works for stationary subjects but not so much for moving ones. Also, since the DOF is so thin, it’s really hard to get the exact right point of focus (which you now get by moving the camera back and forth on the focusing rail instead of using your len’s focusing ring), so it’s common to tether the camera to a laptop and see the image blown up on the laptop or even large screen. As Helen has noted, the solution you come up with depends on whether your subject is stationary or moving, and whether it's in the studio or in the field.

    Extension tubes work well to bring the lens further out from the camera (and in turn, allow a closer focusing distance), but the light path through a lens in macro is different from what it would be if it was focused at a distance, and various optical effects start showing up. The benefit of macro lenses, is that they are designed to focus up close, and their optical characteristics at close range are exemplary. Even if you put extension tubes on these, you will still probably get better image quality than with non-macro lenses. For lower levels of magnification, add-on magnifier lenses can work, but they usually diminish the optical quality unless you spend lots of money on the best quality.

    If you google “macro setup” you will see very elaborate concoctions, all designed to allow control over a very narrow DOF. You don’t need to go to that extent to start out, but macro is one place where equipment rules.

    If you are starting out, you can get decent shots as long as you have lots of light, as in direct sunlight. Of course, that may mean that it’s hard to see the LCD screen to get the focus right.

    Macro photography is a really rewarding area of photography, but you need to plan ahead and assemble the right tools to allow you to accomplish your goals.
     
  10. RxForB3

    RxForB3 No longer a newbie, moving up!

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    Heh, well I guess you just solved my quandry over whether to buy a the Canon 100mm macro or the L version :) My justificaton is that even if I may not be able to use it to the full extent it's designed at first, I plan on having it for years to come and hope to get much better over those years.

    The pictures I displayed are not really an indication of the sort of macro I intend to do. I mostly plan to do nature photos. In which case, I imagine the macro lens would be the best way to go to start with. I've seen some photos that were a combination of the macro lens and extension tubes, which I really liked. Now I just need to figure out where to buy it and what length warranty I want. I have a curious 4 year old, so accident protection is probably a must!
     
  11. gsgary

    gsgary Been spending a lot of time on here!

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    Do some reserch on focus stacking Focus stacking - Wikipedia, the free encyclopedia
     
  12. Derrel

    Derrel Mr. Rain Cloud

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    You want help with the Kenko tube set? First off...use the SHORTEST tube much of the time. The middle tube is useful at some times. The longest tube is almost useless for most people.

    Use the longer focal length lenses or zoom focal lengths; with either the middle-length or the longest of the three tubes added to a typical 28-70 or 24-70mm, at the shorter focal lengths, the focusing point can be literally INSIDE the lens barrel.

    Really short focal lengths, like 18-24mm on 1.5x bodies...are almost useless.

    Spend about one half of an hour and begin with the shortest tube and one lens: figure out the Minimum Focusing Distance and the Farthest Focusing Distance. Get a "feel for" the focusing range that the lens has with the shortest tube on it, at the minimum focusing distance and at Infinity focus on the main lens. Then, proceed to the middle-length tube. Make yourself a simple chart with lens model, focal length used, and MFD and FFD figures. Within a week, you'll be nailing it.
     
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