On Jun 5, 2012, at 9:20 PM, Boris Liberman wrote: > Larry, as far as I recall, the Katz Eye focusing screens (according to > Rachael Katz herself) on K-7 (*) typically required 0.2 or 0.25 mm shims > instead of the stock one. I think that mine was calibrated by 0.2 mm shim.
Interesting. Since the active surface is next to the shims, it shouldn't matter what focusing screen you use. Unfortunately, this was a $15 ebay special, not a katzeye. I'm having other (metering) issues, and when money is available want to upgrade to either a katzeye, or to try one of those modified Canon (ees?) screens. > > I should point out that the service I received from Rachael was truly amazing > as she helped me all the way through. I have this e-mail exchange archived > and it is more than 25 e-mails worth. Rachel is amazing. I sent her a note about a problem and she called my cell phone 20 minutes later. It turns out that my problem was caused by two shims being stuck together in my K20 when it was assembled. By the way, the K-5 has a separate latch to hold the shim in place, which makes replacing the focusing screen worlds easier. Stock shim. Measured with my dial caliper at .0125" or about .3mm http://www.flickr.com/photos/ellarsee/7158255285/ First attempt, part#xxx0040 .0082" or about .21mm listed as 0.2. without the number after the second . printed http://www.flickr.com/photos/ellarsee/7162042991/ Second attempt, part number xxx00030 .0065" or about .17mm Listed as 0.2 http://www.flickr.com/photos/ellarsee/7347253162/ The Pentax shims were not marked, except on the outside of the package. I now have nearly a full set in case anyone is stuck. The stock shim 0.4? 0010 0.1 0020 0.15 0040 0.2(5?) 0050 0.3 0070 0.45 0080 0.5 I don't know why my mic is off, but what mattered was some level of consistency, rather than absolute accuracy. > > Having said that, I do remember clearly that just a single attempt was enough. > > On 6/6/2012 04:19, Larry Colen wrote: >> I'd love to be able to plug 12" distance, 3/64" front focus, and >> whatever the shim thickness is into a formula, and get the correct >> shim thickness on the first try. I suspect that what I'll have to do >> is measure the shim, change the shim to the next thinner, try the >> same setup, and then interpolate between the two to get the proper >> thickness. > > I doubt such a formula would exist. You see, the problem as far as I > understand is that manufacturing process is inherently imprecise and these > imprecisions are quantifiable only in statistical terms... > > Oh, and by the way, the shims I got from Katz Eye Optics were marked by their > respective thickness - no need to measure. Nor do I have an equipment that > can provide accuracy of 0.1 mm anyway... > > So I humbly suggest you do it by trial and error. I reckon you might be able > to look up the thickness of the stock and Katz Eye screens on the web and > measure the thickness of your specific screen (should it be not Katz Eye). > Then you would be able to figure out the shim thickness based on the > assumption that 0.2 or 0.25 mm is a reasonable starting point. > > HTH. > > Boris > > (*) I can only hope that the situation with K-5 is the same as that with K-7, > as I hope that this kind of production tooling wasn't changed between the two > cameras. > > -- > 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. -- Larry Colen [email protected] sent from i4est -- 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.
