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. enjoy Godfrey - [email protected] On Oct 3, 2013, at 9:50 AM, Steve Cottrell <[email protected]> wrote: > Okay folks here's a question I'll throw to the floor. > > I've finally been able to mount a fully manual wide angle lens onto my > Fuji X-E1 and I was testing with it this afternoon. > > For the curious, this is what the combo looks like: > > <http://pdml.posthaven.com/fuji-and-wide> > > BUT if I try and 'zone' focus with it, the background is out of focus. > > Facts: lens is M39 mount and mates to camera via a M39-to-Fuji X (FX) > adaptor. Camera set to Auto so you offer it some light through the lens > and it will correctly calculate the exposure. This is flawless. Lens set > at (say) f/16, and infinity mark on focus barrel is moved to the f/16 > mark so that everything between the two f/16 marks should be in focus > according to depth of field. > > Result: foreground is sharp, everything from about 20 feet away to > infinity is soft. > > However: if I leave the infinity mark at maximum focus (eg lens set to > infinity focus), and stop down to (say) f/16, then everything from about > 2 feet away to infinity is in sharp focus! > > Supplementary question: > > To mount an M39 lens onto an FX body, apparently there are two routes: > just by using a M39-FX adaptor. OR by using an M39-Leica M (LM) adaptor > AND a LM-FX adaptor as well. Wouldn't the two methods produce differing > lens flange - to - sensor plane measurements? I appreciate this question > really needs to be addressed to something like the Fuji forum, but > thought I would put it past the ,might PDML collective first. > > Would an incorrect lens flange-to-sensor measurement create the zone- > focus issue above? > > Many thanks > > -- > > > Cheers, > Cotty > > > ___/\__ Broadcast, Corporate, > || (O) | Web Video Production > ---------- <www.seeingeye.tv> > _____________________________ > > > > -- > 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. -- 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.
