Godders -thanks for the reminders. Re sensor crop vs DoF - D'OH!!! Of course. Hey my excuse is my back is bad and I'm in pain - addling my brain.
Thanks so much for that. I will do some further testing and might even make my own set of distance markings... now where is my Dremel bwahahahahah. On 3/10/13, Godfrey DiGiorgi, discombobulated, unleashed: >One factor: > >Many of the less expensive mount adapters allow the lens to focus "past >infinity", an inexpensive way to ensure that all lenses CAN focus to >infinity by making the adapter+camera registration just a little shorter >than nominal. The idea seems to be that since most users are likely to >be looking TTL anyway with adapted lenses, they can set the focus >accurately, and who cares what the focusing distance scale actually reads? > >This is annoying and confusing for those (like me) who like to use the >DoF markings on the distance scales. The ONLY third-party mount adapters >that are rigorously maintaining the proper mount register, in my >experience with about eight different vendors' products, are Novoflex, >Voigtländer, and Rayqual. > >Another factor: > >Remember that the DoF markings on the lens barrel for most "legacy" or >"manual" lenses was designed to be used with 35mm film camera format, >24x36 mm. Your Fuji, like my Ricoh, is 16x24mm format, which is cropping >the original field of view and implicitly adding more magnification. >More magnification == less DoF, so the markings are off. The >magnification or crop factor for your Fuji is 1.5x, so a first order >approximation to adjust the DoF markings is to use the set of markings >for a one stop larger opening than what you set on the lens. That is, if >you set the lens for 10' focus distance, and set f/8, the actual DoF >range to include infinity will set the infinity mark at the far f/5.6 >setting. Presuming, of course, that the distance scale index is accurate >(meaning that the mount register is correct). > >A combination of these two factors is likely the cause of your >observations. To solve the problem: > >- calibrate the distance scale index so you know where the true >registration mark on the focusing ring should be. > >- for zone focus, use one-stop larger markings than the actual aperture >you set. -- Cheers, Cotty ___/\__ Broadcast, Corporate, || (O) | Web Video Production ---------- <www.seeingeye.tv> _____________________________ -- 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.
