Mark, this is exactly the response I was hoping for. Thank you *very* much. I never would have thought the lens would be the part causing the problem, nor that wider angle lenses would produce greater magnification (though that kinda makes sense now that I think about it). I will try it with my FA 50 (my only other small prime with an aperture ring) right now.
Thanks, John On Sat, Jul 7, 2012 at 6:57 PM, <[email protected]> wrote: > That is basically the same setup that I use for my snow crystal shots, > except I use a 50mm lens reverse mounted. In fact, it is so simlar I > just now pulled it out of the closet, set it up and put my D-FA 100mm > macro on it. I have 300mm of extension (tubes and bellows) with the lens > reverse mounted at the end. > > Your focusing problem lies in how how the D-FA 100 close focuses. I had > no problem getting a shot in focus when the lens was set to infinity, > and actually had ample working room. As I adjusted the lens's focusing > mechanism I quickly was unable to get anything into focus. Obviously, > something about the internal focusing on the D-FA causes a problem with > it reverse mounted. > > Focusing on a ruler, with the D-FA 100 at infinity, and using a full > frame 35mm film camera (also pulled from the closet), I saw 8 to 9 mm in > the view finder. SO I reckon it to be about 4x life sized. With the 50mm > I routinely use on this setup, the finder on the full frame camera shows > about 4 mm, so about 8x. > > If you really want to get extreme get a short and fast lens and use it > on all that extension. A 24mm on 300mm of extension would result in 16x > or so magnification. Set the lens to infinity or use one that does not > use internal focusing. > > Regarding protecting the delicate rear element of the lens - put a short > extension tube on the rear lens mount. It will serve as a hood and also > offer some protection to the rear element. To help with focusing - set > up your rig in a dark place. Put a bright flashlight on the finder > (where your eye would go). It will project a little rectangle of light > that you can use to align your subject and get a sense of focusing > distance with (when the rectangle is sharp, you are in focus.) > > Have fun - > > Mark -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
