| Photo Information |
Copyright: Alain Thibodeau (Athila)
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| Genre: Places |
| Medium: Color |
| Date Taken: 2014-02-16 |
| Categories: Experimental, Macro |
| Camera: Nikon D300 |
| Details: Tripod: Yes |
| Photo Version: Original Version |
| Date Submitted: 2014-02-16 14:00 |
| Viewed: 1401 |
| Points: 8 |
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| [Note Guidelines] Photographer's Note |
Hi all,
For this post I am not trying to show the most beautiful picture of a ball point pen, but to illustrate that we can do Hyper Macro pictures of very small subject (insect head for example) without even owning a macro lens or a microscope. Note that red BG image are straight JPG image w/o any PP to show real resolution. Left images are full, no cropping. Right images are enlarge twice to verify difference of resolution between f/16 and f/32.
Most of you have heard before about supplementary close-up lens. What is a close-up lens? Simply said, a close-up lens is a lens that screw in front of another lens and that permit to focus closer. In theory it is a bit more complicated than that to explain, but it does give a good idea of what it is.
We are used to call converging close-up lens by their power (+1, +2, +4, +10, etc), but in fact it is just another way to define the close-up lens focal length. By definition these diopter values (+1, +2,…) are calculated as : Diopter = 1000mm ÷ focal length.
As an example, a
+1 diopter = 1000mm ÷ 1000mm (Focal length)
+2 diopter = 1000mm ÷ 500mm (FL)
What is the diopter of a 50mm lens?
Diopter(50) = 1000mm ÷ 50mm = 20 diopter.
So all lenses have a diopter values when calculated as above.
Where I want to go with this discussion is that we can use almost any camera lens as a close-up lens having more or less power. However, there is some restriction that I will explain.
Looking through a thin close-up lens having quite a large diameter normally works well.
Some are simple lens with some defaults called aberration. Some are better because made of two lenses (doublet) and are better corrected for chromatic aberration and field flatness.
Looking through a thick lens as a 50mm that are often well corrected for field flatness and chromatic aberration, will enlarge the image the same as a thin close-up lens, but if the rear lens mounted on your camera has a field of view too wide (short focal length), you may see the inside barrel of the front lens, and the image will suffer of light fall off in the corner of the image.
Lens mounted in the front and have large aperture are less likely to show light fall off. In this example here I am using a 135mm as the rear lens, and a 50mm f/1.4 as the front lens. This setup works well with no light fall off.
Most people buying their first camera with a lens kit often get an 18-55mm zoom and a 55-200mm zoom. With this kit, they can try this technic, but be aware you may not be able to use on the rear lens (55-200mm) the range lower than 100mm, and you front zoom lens will have to be set at its widest aperture and at 55mm. But you still can make some great shot. Often both lenses have the same diameter for filter size, and it is easy to find a reverse ring for them.
Down in my picture, you can see some lenses suggestion. Enlarging lens can be a great choice. Because I worked as an engineer for LEICA (Leitz Canada) years ago, I have a partial 50mm f/2 Sumicron lens that would work great too, it doesn’t have a bayonet at the back, but it is not necessary. I mostly used the Nikkor 50mm f/1.4 because of its wide aperture and because it is easy to fit with a 52mm male to 52mm male ring (see picture) that permit to attach both lens face to face.
Magnification is calculated as Rear lens focal length ÷ Front lens focal length. In my case it would be 135mm ÷ 50mm = about 2.7X magnification.
At these high magnifications, DOF is very shallow; you need to close down the aperture quite a lot. I compared one image made at f/16 and one made at f/32. In theory at f/32 you lose more definition, however I prefer the gain of DOF to the loss of resolution.
For my next post I did some focus stacking hoping to have the best of both worlds, better resolution since I shoot images at f/11 and larger DOF since it is photo stacking. This technic is more difficult to use with live subjects.
It is kind of hard to tell every detail in such a short space, if you have any question, don’t hesitate to contact me.
Alain |
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