Macro working distance (Oly 12-50 content)

exakta

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I am no way experienced at macro shooting. A few years ago I got the Oly 12-50 and use it's not-quite-macro mode mainly for insects and flowers.

I'm starting to think about working distance after a recent shoot where my body was casting shadows on the subject.I've been reading threads here and at DPR about folks wanting a longer macro option than the 60/2.8, such as a 100mm, as well as threads about using Raynox diopter attachments with longer zooms, like the 40-150R or the 14-150 II, for greater working distances.

I measured my 12-50 today. The spec for minimum focus distance from the sensor plane is 20cm/8" (for 0.36x), I measured it with a ruler as just slightly better at 7.25". The clearance from the lens hood to the subject is only 2.25", 3" without the hood.

The 12-50 is locked at 43mm in macro mode. I expect the working distance is proportional to focal length, i.e. for 60mm to be about 10" for 0.36x, for 150mm about 25" for 0.36x (obviously even less at greater magnification). I recently read a book on close-up shooting which discussed how diopter attachments and internal focusing (like the 60mm) actually reduce effective focal length, meaning working distance is reduced proportionally. In that case how much of the theoretical working distance improvement of 2" using the 60 instead of the 12-50 is lost at 0.36x?

For you veteran macro shooters what do you consider to be reasonable working distances both in terms of ambient lighting of the subject and not spooking small creatures?
 

archaeopteryx

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I expect the working distance is proportional to focal length
Not in a strictly linear sense. Since focus distance is proportional to focal length working distance tracks with that but varies with the extent focus breathing reduces the focal length, differences in physical lengths of lenses (which is also a function of how they focus), filters, hood, diffuser, lights, or whatever else is involved in the rig.

For conventional macro lenses calculating focus distance and then subtracting off the mount's flange focal distance and length of the lens plus whatever usually gives a good estimate of working distance. (This is not the case for coupled lenses but those are currently out of scope to this thread.)

In that case how much of the theoretical working distance improvement of 2" using the 60 instead of the 12-50 is lost at 0.36x?
You'll get a more accurate answer faster by measuring it directly but you can also model the focus breathing of the lenses of interest and calculate focus distance from the usual thin lens approximations if you want. For zoom lenses you'd also need a model of the lens length since choice of lens can have greater influence on working distance than choice of focal length, both due to trombone zooming and due to differences in focus breathing.

For example, I don't have an Olympus 60 macro but just measured working distances of 18 and 20 cm with the Panasonic-Leica 45 at 0.36x, with and without hood, respectively. For the Panasonic 12-60 f/3.5-5.6 at 0.36x it's 12 cm at 45 mm and 14 cm at 60 mm, without hood.

what do you consider to be reasonable working distances both in terms of ambient lighting of the subject and not spooking small creatures?
Availability of ambient lighting depends on how much you're relying on beam versus diffuse radiation and what compositional angles you're using with respect to the available light sources. As a loose rule of thumb I'd suggest having a working distance the same or larger than the diameter of the lens or hood is usually sufficient to not encounter too many restrictions on ambient light availability. For low magnifications like 0.36x this is rarely an issue but will be problematic with the 30 mm μ43 macros as they approach 1x. The 45 mm is fine at 1x with its hood. The Olympus 60 mm is fine too, though I'm not familiar with its hood details.

For critters it depends quite a bit on the critter and, for pokilothermic critters, the ambient temperature. But, in general, figure flight distances between one and two orders of magnitude larger than body size and responsible photography operates farther out to stay beyond alert distance. For this reason a lot of insect photography is done with low magnification coupled lenses (low diopter close up lenses on long telephotos) for greater working distance than macro lenses provide (also 300 mm zooms are quite a bit cheaper and decidedly less lens to lug than 150–200 mm macros in mounts which have those available).
 

John King

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Extension tubes used with a long FL lens will give you high magnification and much longer working distances.

e.g. using an EX-25 with my FTs 50-200 gave me this shot. The correa flower is about 1-1.5 cm long.

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archaeopteryx

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Extension tubes used with a long FL lens will give you high magnification and much longer working distances.
I get a maximum around 0.34x from either Olympus 50-200 with a 25 mm tube, consistent with the size of the flower and μ43 sensor size. While I think this thread follows marketing use of macro at 0.5x or below, the definition of macro is formally 1x or more, and it's perhaps debatable if ~0.33x qualifies as a close up magnification.

As context,
  • Most people who do a substantial macro probably consider 2–5x to be high magnification as this is the upper bound of extension based macro lenses. Lately there's been a push to extend traditional infinity to 1x macro designs to 2x as well as some proliferation of alternatives to the 1–5x Canon MP-65.
  • Most people who do photomacrography probably consider high magnification to be 40 or 50x, perhaps 100x. ~4x, 5x, 10x, and 20x are routine magnifications. This also applies to some forms of photomicrography. I use mostly 1.5–6x and not so much 10+x.
  • Compound microscopes for visible light usually have an upper end of 1000–4000x and it's common to do photomicrography of those aerial images. Diffraction does mean much of the additional magnification over 400x or so is empty (doesn't add detail) but I frequently find 2000x of some use anyways.
If options aren't restricted to visible light high magnification can be a few orders of magnitude higher. ;)

Usually what I suggest is understanding the desired subject size and composition, calculating the magnification needed, and then working out the lenses required. Rigging for more magnification (or working distance) than needed has a way of making life harder than necessary.
 

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