I've read that screw mounts are virtually immune to wear, since the register distance is established by the seating of the lens to the body, unlike bayonet mounts, in which the sliding friction on the lugs could, over time (a LONG time) cause "slop."
First time I read that Pentacon produced a lens in Nikon/Canon/Olympus/Pentax versions .
]BX20S] fits in my hands comfortably, has loads of available lenses from Prakticar (usually CZJ made), CZJ and Sigma as well as Tamron Adaptall lenses.
It's not the glass that is problematic. It's time needed to change the lens and clunkiness of aperture stop-down mechanism. There's a reason why screw mount was replaced with bayo just like there's a reason why SLR surpassed rangefinders, except for certain brands which are defining social status much like Rolex in wrist watches.What we found "disturbing" was that the Nikon/Canon/Olympus/Pentax versions of the same lens was between 20% to 50% MORE than the screw mount version! I shot hundreds of B&W rolls for publication and my 50mm Pentacon was beautifully tack sharp with nice contrast.
It's not the glass that is problematic. It's time needed to change the lens and clunkiness of aperture stop-down mechanism.
I mean automatic diaphragms which although have a small pin on the lens, still require a fairly large push-plate in camera body. Or at least that's what I've seen in Zenits and Spotmatics. Not sure how it is with Practika.I agree on the changing time. But what clunkiness?
Such would only apply on the non true-automatic diaphragm lenses. For instance the all-manual preset early Helios lenses, the springloaded preset Meyer lenses or, more applicable, the Isco release-button connected diaphragm.
To avoid misunderstanding, "Practicar" was no manufacturer, but just a brand which Pentacon made up to designate all lenses they offered with the Pentacon-B mount, whether they were made by Meyer, Zeiss, IOR or a japanese manufacturer. At least one of the lenses actually made by Zeiss was just branded Practicar, the others Practicar Zeiss Jena.
It doesn't feel terribly precise and requires more force to be applied on the pin, since it's distributed along the plate. gives me the impression of of lots of things going on inside the camera with all that slap.The push plates typically are that large, or better, wide. Only smaller one I know is at the Pentacon F. The wider the plate, the more tolerance on deviation of the mount threads from the standard start position, resp. deviation of the pin location to that position.
But all these plates are inside the mirrorbox anyway, why bother?
Not sure what you mean. Te set up is pretty much the same on all makes of screw mount lenses, none feel imprecise to me, nor is there any slack in operation or reliability. Forces? If there is nothing wrong with body or lens, these elements move with miniscule force.It doesn't feel terribly precise and requires more force to be applied on the pin, since it's distributed along the plate. gives me the impression of of lots of things going on inside the camera with all that slap.
You should probably try Zenit camera then, to feel the differenceNot sure what you mean. Te set up is pretty much the same on all makes of screw mount lenses, none feel imprecise to me, nor is there any slack in operation or reliability. Forces? If there is nothing wrong with body or lens, these elements move with miniscule force.
When I got my Praktica LTL I discovered that the meter key wouldn't stop the lens all the way down. I adhered a little card stock, colored black, to the stop down plate. Problem solved. While full aperture metering is nicer than stop down, the LTL has certainly the most convenient of all. Right index finger to meter and shoot, just a tiny movement from the meter key to the shutter. Excellent ergonomics, much better that the Pentax Spotmatics, with the exception of the Spotmatic L.Not sure what you mean. Te set up is pretty much the same on all makes of screw mount lenses, none feel imprecise to me, nor is there any slack in operation or reliability. Forces? If there is nothing wrong with body or lens, these elements move with miniscule force.
Not sure what you mean. Te set up is pretty much the same on all makes of screw mount lenses, none feel imprecise to me, nor is there any slack in operation or reliability.
Perhaps, I've only shot pre-select Helios on Zenit.You should probably try Zenit camera then, to feel the differenceanyway, it all feels different than bayonets to me.
There isn't any discoloration on the top plate.
OK, that makes sense. Thanks for the information.All L-models have chromed plastic top covers. They will not discolour. Maybe you refer to possible corrosion, were the copper underlayer will produce coppersalts, visable as dots of green salts.
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