The SA Pentaxians were at it again last night when MACRO was the order of business.
As always a great night's entertainment with the usual display of new and/or unusual aquisitions.

Thanks to Wedgetail for the use of his premises.

These were shot with the K100 F4 MACRO...

A couple of the Crown of Thorns...





Some rock crystals (i'm obviously not a geologist!!)





and one taken with Digitalis' Sigma 180mm macro




A couple of innovative approaches...

First..The Ikea Diffuser (there were two of thses custom built jobs in action) This is the MoiVous version shot with k100 F4.




And of course the bog standard setup of Sigma 180 and Pentax ring flash with 114mm of extension...



The last one taken with the DA*60-250 @60mm.

[Adam]

I love the rock shots! Those four 4-petaled flowers weren't made to be photographed, though, IMO

[Digitalis]

and some images from the resulting 114mm of extension used on the Sigma 180mm f/3.5 APO EX DG

The tripod head i'm using is the fantastic manfrotto 405 - which is designed for precision and proved ideal for this particular exercise in ridiculously high macro magnifications. The AF160FC's modelling lights illuminated the subject well enough for me to obtain critical focus, because I lost a approximately 6~8 stops of light from the use of stacked extension tubes, the K-7's viewfinder was completely dark necessitating the use of modelling lights.

Exposure was at f/16 ISO 400 - needless to say focus and exposure were very difficult to calculate. The ring flash even at 1/4th power was easily able to expose the subject properly (I do the flash metering in my head). I did a second exposure at 1:1 power at ISO 100 and there really isn't much difference apart from the noise. Needless to say mirror lock up was CRUCIAL at these magnifications.

can anyone calculate the actual magnification of this set up? I'll hazard a guess; it is somewhere within the vicinity of 11X. though one must take into account the Optical characteristics of the Sigma 180mm f/3.5 APO IF. It is a known fact that IF lenses get a wider FOV at closer focusing distances, I have never measured the focal length shift with the sigma 180. Cinematographers refer to this focal length shift as "breathing"

Top image: sigma 180mm f/3.5 at 1:1 magnification with no extension tubes, on the bottom 1:1.5 magnification with 114mm of stacked extension tubes. Pentax AF160FC ring flash used with both images.