So sorta I fixed my 16-45. I will send my worst copy off to CRIS and have them tighten and align it since I think it has problems beyond just a wobbly barrel and looks sort of decentered. My fix was simple. Realizing that when the barrel was aligned and not drooping I was getting fairly sharp pictures edge to edge a lightbulb went off. I can just simply add more dimension to the barrel of the lens so it is tighter inside the tube. I started off cutting a piece of inkjet film as a shim. It certainly reduced the wobble. I then cut a piece to the dimensions of the barrel. After noticing an improvement in reducing the amount of wobble when slid in between the outer and inner barrels I added a piece of paper to the mix and found it gave just enough tightness. Zooming is slightly stiffer, but it doesn't seem so tight it will wear out the zoom cams. I now went from nearly 1/4" of wobble to maybe 1mm or so. I'm very sharp till the extreme edges of the frame. And that's at f5. This lens really performs when it is aligned correctly. I'm going to keep using it this way until something breaks or it goes bad and will have a decent copy as a backup hopefully. So if anyone has problems with their 16-45 because the barrel gets loose, my advice is to just simply shim it and save yourself the $200 CRIS will ask for. It feels much more robust now. I don't know why pentax just didn't make the tolerances tighter to begin with. Even with tight gears there still is a lot of clearance between the inner and outer barrels and I firmly believe that is what loosens whatever internally is supposed to be holding it tight. I looked at some pictures of a deconstructed 16-45, and couldn't see any way to tighten them internally short of replacing parts where tolerances had become loose. I think its a horrible design if you ask me. I kind of like the reverse zoom and it seems to work well with the optical formula though. It would be really cool for Pentax to update this lens, and since they discontinued it, I'm hoping some sort of mid-grade replacement is coming. Hopefully with WR.
On Thu, Jul 25, 2013 at 11:21 PM, Mark C <pdml-m...@charter.net> wrote: > On 7/25/2013 7:45 PM, Mark Roberts wrote: >> >> More to the point, light fall-off in the corners (not vignetting, which is >> darkening caused by an obstruction) is rarely a problem. In Lightroom I >> *add* this effect frequently and only *very* rarely feel the need to correct >> for it. > > > I once read a darkroom book where ther author said that it is the rare photo > that does not benefit from having the corners burned in a bit. Sorta the > same idea... > > Mark > > > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and > follow the directions. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
