The ZS20/TZ40 as a "microscope"

Started Feb 28, 2013 | Discussions thread
Ianperegian
OP Ianperegian Veteran Member • Posts: 3,597
Re: The ZS20/TZ40 as a "microscope"

Cyril Catt wrote:

I have tried as you suggested, with a 2x Kodak teleconverter for a DC290, the only teleconverter I can find at the moment. It gives a more enlarged image - though fisheye-lens-distorted - than the one I previously posted, but I cannot focus it well enough to resolve the sloping lines within each coloured cell.

The image I posted was made with the front of the lens surround in actual contact with the computer screen, made possible by the TX1's extreme close focussing ability, which may make it difficult to focus at something on the other side of a reversed telephoto converter.

Cyril,

There are several different ways you can increase the magnification using your TX1.

You can simply use the camera with a high dioptre closeup lens attached to the front of the camera lens.  If you used the high power Raynox DCR-250, for example, it has a power of 8 dioptres (the FL is 125mm).  That would provide a greater magnification than your supermacro mode, and the distance of the lens to the subject would be greater as well.

However, if you use a reversed lens from a 35mm flim camera, you can get an even greater magnifying power.  If you use a reversed 50mm lens as I did, then it has a power of 20 dioptres.

The distance from the closeup lens (in this case the reversed 50mm lens) to the subject (the LCD screen) will be about 50mm (the FL of the lens).  That is a much greater distance than your TX1 in its supermacro mode, and so you can get a lot more light in.

The use of teleconverters is not essential in the above setup.  I used stacked TCs to increase the FL of the ZS20 lens.  The TCs were not reversed, and they were not used as closeup lenses.  TCs are quite different kinds of lenses to normal lenses.  TCs are "afocal", whereas closeup lenses are converging (positive) lenses (like a magnifying glass).  I hope that explains it.

If I had left off the TCs completely, and just used the ZS20 with the reversed 50mm lens, that would still have given quite a high magnification.  However, that would have given less magnification than I achieved by adding the TCs (directly, not reversed) to the front of the ZS20 before I added the reversed 50mm lens.

The difference in magnification with the TCs, compared to without the TCs, is just the factor of the power of the TCs that were used.  For the TCs that I used (E15ED stacked with Oly C180), that is 1.5 x 1.7 = 2.55.  So by adding the stacked TCs I increased the effective FL of the ZS20 by a factor of 2.55 (approximately).

Therefore, adding the stacked TCs also increased the effective magnification of the setup by the same factor of 2.55 times.  In other words, without the TCs it would be 480/50 =  9.6 times.  With the TCs added I achieved (480x 2.33)/50 = 22 times.  I hope that helps to explain it.

Ian

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