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photo:macrophotography

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macrophotography

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summary

  • digital cameras have made macro work so much easier and more fun.
  • there are lots of cheap ways of achieving pretty good macro photos.
  • for flash photography:
    • external, off the camera flash photography is often needed and for this TTL flash makes life so much easier, special lens mounted “ring flashes” can also be used but tend to give flat lighting.
    • to avoid blown highlights, consider applying diffusers to your flashes to soften the light.
    • the main difficulty is ensuring your subject stays in focus - even small camera movement when hand held may put the subject out of focus. It is very hard to achieve hand held at magnifications greater than 1:1, thus use a tripod if possible.
    • consider bounce flash to avoid excessive reflections from shiny subjects.
    • both Olympus Four Thirds & Canon provide either Twin Flash or Ring Flash but either system requires cords and perhaps do not integrate as well with other flashes as does Nikon's wireless i-TTL system although Nikon do not provide a ring flash.
      • Canon's unit does allow it to wireless control other flashes via E-TTL.
  • for available light, you will need:
    • a sturdy tripod, preferably with an adjustable stage to help adjust the camera to subject distance
    • a camera that allows mirror lockup to minimise vibrations (or a camera with no mirror at all)
    • if hand-held, an image stabiliser or low noise at high ISO, or both.
  • good, accurate manual focus is critical.
  • choose camera position, etc to ensure background is not distracting
  • for photomicroscopy, best results with greatest ease of use are with a mirrorless camera which can be remotely controlled, no need for mirror lockup, swivel out LCD screen and HDMI live video out:

the macro lenses

  • unless you need AF, consider using Olympus OM, Canon EF or Nikon F mount lenses as these can be used on most cameras (except Nikon dSLRs)
  • for nature macro work, a long working distance becomes important and usually with some background compression to make the subject “pop” - so many recommend a 200mm equiv. lens as a modern internally focusing 100mm actually becomes 80mm focal length at macro distances.
  • if you are wanting to use a legacy macro bellows system such as that made for Olympus OM:
    • be aware, you will most likely need a 7mm extension tube as well to allow adequate clearance when mounting the bellows, otherwise the bellows may hit against the camera's flash eg. Olympus dSLRs, Canon EOS dSLRs
    • using the OM bellows on Canon EOS:

Introduction:

  • macrophotography is photography using magnifications of around 1:1 (ie. subject area is same as film or sensor area)
    • the term is usually applied to a range of magnifications from half-life size (1:2) to about 5x magnification (5:1) which on a 35mm film camera means a subject area down to about 5x7mm for the 5x magnification, although some regard magnifications up to 20x are the realm of macrophotography. Higher magnifications are the domain of microphotography and the use of microscope objectives.
    • most “macro” zoom lenses are really just close up lenses and only allow magnifications to 1:4 or 1:3 (ie. 1/3rd life size)
    • traditionally with 35mm film photography which has a film size of 36x24mm, this means that the lens system can allow focus at least to a field of view of that same size (ie. 36x24mm) and perhaps even smaller.
    • for simplicity, when talking of magnifications, it is probably least confusing to use this as the standard rather than use the size of the digital sensor, although the latter is perhaps more correct technically.
      • the Olympus ZD 50mm f/2.0 macro is regarded as a 1:2 macro lens as at closest focus, the subject area is 36x24mm (in 3:2 aspect ratio) and this is twice as large as the sensor hence 1:2 BUT this subject area is the SAME as a 1:1 macro on a full frame dSLR, and thus it really performs the SAME function as a “1:1 macro lens” would on a full frame camera
  • effective aperture decreases by 1 stop for 1:2 magnifications and by 2 stops for 1:1 macro.
  • the main aspects to look at in a macro system are:
    • magnification - does it suit your needs of magnification
      • this is dependent on both the closest focus point and the lens focal length
    • depth of field:
      • macro work usually results in very narrow DOF which mandates using the smallest apertures such as f/16 to show your subject fully sharp. Smaller apertures risk image degradation due to diffraction effects.
      • lens focal length is irrevelevant to macro depth of field if one is aiming to shoot a certain subject size to fill the sensor.
      • the smaller the sensor, the less magnification factor of the lens is needed for a given subject size, and thus at the same f/ratio, you get MORE depth of field - just what we need, this is why a 2x crop sensor can be very handy indeed!
      • an option may be to tilt the focus plane to suit the subject orientation by using a tilt-shift lens.
      • software-based depth of field adjustment:
        • Helicon Focus - automatically stacks images taken with different focus points to generate an image with much greater DOF.
        • for example, see this 7.5x macro created from 229 shots with 0.03mm steps in focus - to achieve this extreme macro he uses this equipment.
    • working distance - how close do you need to get to the subject to achieve that magnification
      • this is dependent on the effective focal length.
      • the greater the working distance:
        • the less chance of scaring a live subject
        • the less chance you will have of getting pollen, etc on your lens
        • the less chance you will have of being bitten by your subject
        • the more flexible the possibilities for lighting the subject.
        • but unfortunately, the flatter the lighting will be with on lens twin light flashes, thus you may need to resort to more cumbersome flash setups, thus the Canon MR24 twin flashes will not be as effective mounted on an EF 180mm macro lens as they would be on a 65mm or 100mm lens.
    • image quality
      • has the lens been optimised for close focus
      • has the lens been designed for a flat field - in other words, does the point of focus make a flat plane parallel with the film or sensor rather than being a curved plane which would put the edges of a flat object out of focus.
    • ease of use:
      • for live subjects, ease of use becomes very important.
      • manual focus and manual lens stop down takes much longer and you may miss your shot if subject flies away, here AF may have an advantage, although in general, AF is more of a hindrance in macrophotography.
      • using a reversal mount requires adjusting subject distance for focus and requires you to press the lens DOF button to achieve stopped down apertures during the exposure.
      • using extension tubes for manual lenses may require you to press the lens DOF button to achieve stopped down apertures during the exposure.
      • the BEST combination for live subjects without flash would be either:
        • a mirrorless camera systems or digital SLR cameras with live preview (for accurate manual focus), preferably a tiltable LCD screen for easy viewing, reasonably low noise at ISO 400-800 (allowing faster shutter speeds) + a 100-200mm effective macro lens.
    • optionally, a tilt lens for adjusting plane of focus:
      • these are manually focussed and manually adjusted lenses but not easy to use
    • how about a macro probe lens?:

There are several ways to achieve macro photos:

use close up filter or macro adapter

  • add a close-up filter or macro adapter onto the front of your existing lens
  • generally this will give you the worst quality but it may be your only option with cameras with fixed lenses or those on a limited budget.
  • with the main lens focussed at infinity, adding a close up lens will allow closer focus depending on its diopter value:
    • 1 diopter ⇒ 1m
    • 2 diopter ⇒ 0.5m
    • 4 diopter ⇒ 0.25m
  • When the main lens is focused at its closest normal focus point these distances are somewhat reduced. Maximum magnification depends upon the focal length of the lens in use.
  • these simple lenses introduce some astigmatism and distortion that is directly proportional to their power, it's best to stop the lens aperture down by 2-3 stops (say from f/2.8 to f/8) when shooting with close-up lenses, especially those with higher diopter numbers.
  • Rules for stacking close-up lenses: Place the highest-power lens closest to the camera lens, then the next highest, etc. and avoid stacking more than two close-up lenses if possible.
  • A minor downside is that your camera won't focus to infinity with a close-up lens in place.
  • LMScope high quality macro/micro adapter fits onto almost any lens of focal length 20-90mm via a step down adapter to its 37mm thread:
    • LM DSLR 80mm macro:
      • 12.5 dioptres thus allows macro down to 3.12x
    • LM DSLR 40mm macro:
      • 25 dioptres thus allows macro down to 6.25x; more expensive and bigger;
  • see some examples by Danny Young of what can be achieved by adding a Raynox DCR-250 onto a Panasonic Lumix 45-200mm kit zoom on a Micro Four Thirds system - not bad at all!

use extension tube or bellows

  • add an extension tube or bellows between the camera body and your lens.
  • this will give better quality, but you need to increase your exposure a little as your effective f/ratio increases, for example adding a 25mm extension tube is approximately equivalent to 1 aperture stop down in exposure, and putting a OM 50mm macro lens at closest focus (equiv. to 25mm extension tube in itself) which adds 1 stop in addition to the 1 stop of a 25mm extension tube.
    • In the old days you had to manually calculate this effect (and still need to today if using a flash that doesn’t have TTL control) but with TTL metering the camera automatically allows for this.
    • poor quality control may mean your flat macro lens plane may no longer be parallel to your sensor
    • poor design with lack of flocking may add flare
    • the longer the extension tube, the more vignetting you are likely to get, especially at wider apertures
    • many lenses perform poorly at closer than designed focus distances so image quality is somewhat a trial and error process for a given lens.
  • a minor downside is that your camera won't focus to infinity with an extension tube in place.
  • you can calculate your new focus range using this calculator
  • with a 1:1 macro lens of 150mm focal length or less you can get to 2:1 magnification or higher using a full set of extension tubes (68mm)
  • for Canon EOS SLR’s the only bellows that works is a third party bellows made by Novoflex and very expensive!
  • an extension tube usually also means that autofocus capability is no longer possible and with some lenses focus is not possible (such as fisheye lenses)

use a macro lens

  • use a lens optimised for close up work (ie. a macro lens not a macro adapter)
  • this will usually give the best quality if it is a good macro lens.
  • can be used with a teleconverter or an extension tube for higher magnifications.

add a teleconverter:

  • although this does not allow you to focus closer, it will increase your magnification at a cost of effective aperture and optical quality.
  • a 1.4x teleconverter will cost 1 F stop in exposure as with a 25mm extension tube on a 50mm lens, and have the benefit of maintaining a good working distance while the extension tube provides in effect a 2x magnification but requires closer working distance.
  • if you are using a Canon EOS 100mm macro lens then normally you cannot put Canon’s 2x or 1.4x convertors behind it because the Canon convertors only work with longer focal length “L” lense. To solve this, put a small extension tube between the lens and the convertor
  • the Olympus Four Thirds teleconverters can be used on any Four Thirds lens, unlike the Canon ones.
    • the Olympus EC-20 2x teleconverter works very well with the 50mm f/2.0 macro lens and allows double your magnification to give a 18x12mm subject area (true 1:1), or it can be used to double your working distance and still maintain a 36x24mm subject area.

reverse your lens:

  • this can be done in one of 2 ways:
    • purchase a special reversal mount for your SLR mount which will have a male filter thread on it of a given size which will allow screwing a lens onto it back to front
      • a 50mm standard lens for 35mm cameras when used on the 2x crop Olympus E-digitals in this way will give a subject image of about 22x28mm at a working distance of about 10cm.
      • shorter focal length lenses will give greater magnification but shorter working distances
      • the 21mm Olympus OM Zuiko gives a subject area of only 5×6.5mm on the Olympus E-digitals
      • you must manually press the lens DOF preview button to stop down the aperture during the exposure - luckily, the Olympus OM lenses have a DOF preview button
      • focus is not changed much using the lens focus ring and thus you must alter camera to subject distance to achieve focus.
      • special problem with Canon EOS lenses on Canon EOS bodies:
        • this can only really be done through the Novoflex reverse adapter which maintains the electrical connections between the lens and body, but is a relatively expensive solution.
    • purchase a special male-male filter ring adapter which screws onto your normally mounted lens and allows a second lens to be screwed onto it back to front.
      • this is similar to using a close up lens on your main lens.
      • Magnification ratio is calculated by dividing the focal length of the normally mounted lens by the focal length of the reversed lens (i.e., when a 50 mm lens is reverse mounted on a 200 mm lens a 4:1 magnification ratio is achieved).
      • The use of automatic focus is not recommended due to the extra weight of the reverse-mounted lens.
      • The diaphragm of the reversed lens is kept fully open in this mode so it doesn’t matter what sort of lens it is
      • A big advantage of all supplementary lenses is that they do not affect the effective aperture of the main lens.
      • the main problems here are that:
        • it leaves the rear lens exposed and vulnerable to damage
        • you cannot use AF

extreme macro - photomicroscopy with a bellows instead of a microscope

  • at > 1:1 you may need to start opening up the aperture more to avoid diffraction softening, thus consider F5.6 at 5:1.
  • to get greater than 5x on full frame, you need a bellows and one of these lenses - see here, ie:
  • then you need an extreme macro set up such as this equipment, or this kit using an OM bellows
  • note, you need to ensure there are NO camera vibrations during the exposure otherwise even when using flash, the vibrations will alter camera position relative to the subject at very high magnification (eg. 40x or higher) making stacking of images problematic
    • thus use mirror lockup and live view mode with remote control
  • take test shot to determine optimum aperture and the single shot DOF
  • you then need to take 100-200 shots with focus adjusted in tiny increments - slightly less than the single-frame depth of field (eg.0.03mm)
  • then you need to use software to stack these images to give an apparent increased depth of field:
    • Zerene Stacker (seems to be favored over Helicon Focus or CombineZP) - automatically stacks images taken with different focus points to generate an image with much greater DOF.
    • for example, see this 7.5x macro created from 229 shots with 0.03mm steps in focus
photo/macrophotography.txt · Last modified: 2020/06/05 15:08 by gary1
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