Nickfed said:
.Surely this is baloney. Relying on the slope of the sensor to solve the "problem" will only guarantee it's not going to be solved and can only lead to more trouble. If there was a problem, it would be easier to get it right in the first place than to try a fix as dumb as this. You only have to open the back of a Zorki-6 and look, to see that there is nothing to suggest that the curved foot does anything more than serve to reduce wear more cheaply than a wheel, and probably more reliably. Again, if you care to do the geometry, I'm sure you will find that the broader surface presented is immaterial to the rangefinder operation. I submit that the "adjustment" in the follower, which is hardly available to the user, is only there to fix some gross mis-adjustment at the other end of the arm. It's the last component in the assembly, thus the obvious place for a final check
I guess that's my 2c!!
OK, more baloney:
Barnack & company designed a coupled rangefinder and we find this in Leica and clones like the Canon. Mr Barnack however did not design the ones found inside a Zorki or FED. The Soviets modified it to suit their production needs. More on this later.
And before you further dismiss as baloney what I've said about Soviet Rangefinders, may I suggest that you read first a Soviet repair manual which discusses rangefinder adjustment. The fact that you find absurd the notion of adjustable sensor tips would make it seem that you are not really familiar with the mechanics of the Soviet LTM RF coupling.
Soviet Leica clones need to be adjusted for infinity using the RF adjusting screw and adjusted for minimum focus using the RF sensor tip.
Read Izaak Maizenberg, or any Soviet publication on Camera repair and you'll see what I mean. I believe that you aren't quite familiar with how their system works.
The roller sensors found in Leica or Canon required high precision during manufacture. The system to which they're attached to also require precision during manufacture and assembly. Their accuracy would allow them to couple, measure and align (and all those things which RFs do) at all distances with just one adjustment.
Requiring high precision during the parts' milling, manufacture, and assembly mean more time and effort- bottom line would mean less cameras made within a given production period.
The Soviet production system placed quotas above anything else. Quantity over quality. Haven't we been hearing about iffy soviet quality control as the first concern about anything soviet-made? They wanted more cameras in less time, so
they had to adopt output-increasing measures. One avenue had been to make the RF less effort and time consuming to do.
By putting less stress on precision (make the parts loose first), more could be made, more could be accepted for assembly, and less thrown out. The RFs were assembled with intent to be adjusted individually later for focusing and lens coupling. That's why many of the early FED and Zorki left with passports which described not only what their measurements were, but sometimes what their optical working distances were.
The sensor tip wasn't even sloped when the Soviets started making them. The roller sensor wasn't used, perhaps because it required more effort and cost to do.
They adopted an adjustable pivoted sensor which allowed subsequent adjustment so that it can jive with the rest of the rangefinder for correct distance measurement. The first sensors were oval/rectangular in shape. Then they became tiny and tear-shaped. The sloped tip came later- first seen in Zorki-1 and then later on all the subsequent FED and Zorki. The changes in the shape of the sensor tip were a design evolution - the wider sloped sensor allowed more adjustment compared to the rectangular or tiny wedges formerly used.
They were not there simply as an answer to wear.
It would be impossible to see on film any effect on focus which a distorted sensor
tip can cause - Zorki-1 and FED-1 cameras don't have opening backs.
I stand by my adjustment methods. First they work, the cameras I shoot with have proven that fact. And second, more importantly, it conforms to the methods long established by the Soviet factories, technicians, and designers who built, designed, and repaired these cameras.
Attached are jpgs of the sensors used in FED and Zorki cameras.