free web tracker

Playing around with a stock 18-55 and a Sigma 70-300 ...
Now, with an SMC Takumar 105 and a CZJ Flektogon 35 too ...

Saturday, October 1, 2011

SMC Pentax-A 100 f/2.8 Macro: Some samples ...

A few months ago i borrowed this lens from a friend of mine, to take some sample pictures to sell it (he doesn't have a Pentax body for testing).

As soon as i mounted the lens on the camera, i was disappointed, as i discovered that the camera was unable to control the diaphragm of the lens. After a simple inspection, i discovered that the electrical contact for the auto operations on the mount was missing ...
But, since i don't use this contact to take pictures, i decided to try it anyway, using it in stop down mode through the green button on the camera ...

The lens has revealed to be really easy to focus, thanks to its excellent contrast and to the long throw of the barrel (it goes down to 31cm, to achieve the 1:1 reproduction ratio). Although quite heavy (half the weight of my K10D), it balanced quite well on the camera. The exposure has been a bit tricky since, being seen as an M42 lens by the camera, i have been forced to use the spot metering in conditions where another kind of metering would have been more useful. Anyway, shooting raw has allowed an easy correction of the overexposure ...

Here are some sample shots. mostly taken wide open:

SMC Pentax-A 100 f2.8 Macro - _IGP4008

SMC Pentax-A 100 2.8 Macro - _IGP3950

Porst Color Reflex MC Auto 55 f1.2 - _IGP4263

This last picture has been taken probably at f/5.6 or f/8.

Definitively, this lens renders a bit better than my Kiron 105 macro and it has a better native contrast too (thus, focusing more easy) ...

My impressions:
  • Although this lens is not really compact as my other 100mm, it balances quite well on my K10D and is easy to handle (medium-sized hands).
  • The excellent contrast and the long throw, coupled with the reduced DOF of a 100mm lens, make focusing quite easy. But for sure, it is not suited for action shots ...
  • The lens is fully usable starting wide open. Sharp enough across the whole (APS-C) frame and with a nice bokeh.
If you want to see more sample pictures at full resolution, the set is available on my Flickr photostream clicking here ...

For the technical fans, here are the technical data of the lens:

Lens name: smc PENTAX-A MACRO 1:2.8 100mm
Production: 1985 to 1989 (approx.)
Optical formula: 7 elements in 7 groups
Aperture blades: 8
Minimum focusing distance: 0.31 m
Maximum reproduction ratio: 1:1
Filters thread: 58 mm
Weight: 470 g

Labels: ,