Lens Combo’s for Macro – First Test Results
As promised, the first round of results from testing various combinations of stacked lenses, a teleconverter and extension tubes with the Tamron AF90mm f2.8 DI macro lens. My initial goal here was to determine which combinations would best provide higher magnifications (1x life-size plus) while still offering enough lens-to-subject distance (hereafter simply’ l>s’) for supplemental lighting.
Some things to keep in mind:
- In my case, the ‘l>s’ distance refers to the outer edge of the lens barrel rather than the glass itself, and the distance measured his approximate.
- Stacked lenses refers to the reverse mounting of a short lens in front of a longer lens – macro couplers can be built or purchased. I bought mine from B&H. In all cases this lens is set to maximum aperture (largest opening) and the distance to infinity.
- To determine magnification you need to know the width of your sensor (23.7mm for the D 70) and the percentage of coverage of your viewfinder (but I did not account for this variance in my calculations). Magnification = width of sensor/width of view through the finder.
Now, the setup I used for testing:
A - a Nikon SB-900 flash with a LumiQuest diffuser.
B - Nikon D70, with a Nikon DR-6 right-angle viewfinder
C – a circular lens support, part of a macro-bench (under development) to support long lens combinations.
D – a metric section of paper measuring tape, mounted in a 35mm glass Gepe slide mount in a perspex slide holder
E – halogen focusing lights
The units to be tested are the Tamron 90mm macro, the Kenko Pro 1.4x teleconverter and the set of three Kenko extension tubes – here most often used as a single 68mm unit. In addition I have a 50mm f1.8 Zuiko and a 28mm f3.5 Zuiko for use as reversed stacking lenses. Now mathematics is not my strong point, but I believe that 5 units gives a possible 120 combinations – keeping in mind that the Tamron can only be used on the end…and not including the stacked lenses, which can only be used on the 90mm…(mind boggles at this point). I was not prepared to test every combination – I quickly eliminated any combos (and their potential offspring) that proved not to be feasible. Keep in mind that most of my macro photography is done in the field, so that in most cases I will not be using combo’s that exceed 4x magnification. Unless you have tried it, you will never quite believe how much effort goes into taking macro photos at higher magnifications: keeping your subject in frame, in focus, in the correct plane, and then still considering composition and lighting….a single successful photo at 4x magnification can sometimes be exhausting!
Here is an example of a lens combination that is simply impracticable: the D70 + 1.4x + 68mm ext. + 90mm + rev. 50mm – it provided almost 5x magnification with the 90mm racked out to its closest focus, but the l>s distance was a mere 5mm! Placing the 1.4x before the extension tubes and stacked lenses ruined the lens-to-subject distance.
However, removing the rev. 50 mm with this same combination gave 3x mag. with a respectable 50 mm l>s.
Rather than list all the results, I will post only the best of the combinations – those that provided the best l>s with the least total combination length:
1 to 1.5 x mag., the 1.4x tele-extender with the 90mm (focusing to infinity!) with a l>s of 14 cm.
2 x mag., the 1.4x + 36mm ext. + 90mm @ min. focus, with a l>s of 7cm
3x mag., the 1.4x + 68mm ext. + 90mm @ min. focus, with a l>s of 5cm
4x mag., 68mm ext. + 1.4x + 90mm @ max. focus + rev. 50mm, with a l>s of 3cm
5x mag., the 1.4x + 90mm @ min focus + rev. 28mm, with a l>s of 4cm
8x mag., 68 mm ext. + 1.4x + 90mm @ max. focus + rev. 28mm, with a l>s of 3.5cm (results in 3mm viewfinder width, as in above image)
Note that there is less than a 2mm difference in the horizontal field of view between 5x mag. (4.7mm) and 8x mag. (2.96mm) so in the age of 10 MP+ cameras, cropping is a very real solution to obtain the effect of magnification. Beyond 8x life size you are probably better off moving to a microscope.
Keep in mind that, unless you have the same brands and models of equipment, you will need to do your own testing to determine good macro combinations.
Next: testing the lens combinations for quality.
Born in Canada, but of Dutch descent, my early life was influenced by travels with a constantly moving family. We moved through Canada and South Africa until I reached the age of 17, when we settled down in Edmonton, Alberta. Over the years I have developed a multitude of interests which I now share by means of photography and blogging.
Hello Adrian, without the ‘hands on’ the numbers slip off the mind like water off a ducks back. Since I am self taught it is informative to see what others do to get a good macro shot. I often wonder too if anyone else uses achromats.
I agree. I will write up a small reference card to take in the field.
I recently purchased a Canon 500D achromat for my zoom lenses, but have yet to put it through its paces.
Happy experimenting with all this gear. I’ve used similar setups.
A macro lens and a teleconverter (with and without extension) gives you a great combination of closeness and working distance (lens to subject distance). And you are not constrained by focusing distance – you can pull back and go to the minimum distance freely.
With a reversed lens or a diopter like the 500D, you have a limited range of distance from the subject for sharp focus. You can get close, but you may not get the composition or subject size you want.
The Canon MP-E lens is also limited in focus range and working distance, but it’s more manageable because you can vary the amount of magnification. That gives the compositional freedom missing with a reversed lens.
With any of these high magnification setups, having a long lens plate or rail on a tripod/ballhead is a huge convenience. Some people do shoot handheld at 2x to 5x, but I can’t get a sharp image that way.
Back in film days, shooting at 4x hand-held with flash might give 2 or 3 usable images from a roll of 36. Now, how I love digital!
I have begun using a 2-way rail for some macro shots – very convenient with an immobile subject, and excellent for fine-tuning composition.
[...] part I must make do with what I have. This means researching and testing my current lenses (and macro combinations) so that I get the most out of [...]