... That being said, it has long been a known? fact that at 1/500 second, at f/16, you are going to get virtually the same exposure with a leaf shutter as you would get at 1/250. The way it was explained to me, it has to do with the ineritia at the very beginning of the shutter movement combined with the small areas which the shutter uncovers at the smallest f/stops.
... And you believed the guy that gave you the "known fact" (note 1) explanation?
There ARE tolerances placed upon shutter speeds, usually by the manufacturers themselves, but they tend to be "buried" in a mountain of other design parameters - look at it this way... why would ANYONE consider a tolerance approaching 100% (1/500th actually exposing the film for ~1/250th second) EVER be considered "good"?
There are volumes of maintenance problems that could/ would slow a shutter down at any speed. MAINTENANCE problems - not DESIGN.
Note 1) Whenever I encounter the words, "known fact", a red flag goes up: probably ... most likely... NOT TRUE.
He is actually right about leaf shutters overexposing at high speeds and small apertures. It is because the timing starts when the blades reach the fully open position, but when you shoot with a small aperture, the small hole is fully uncovered long before the blades reach the full open position, and as the blades close it takes a short time for the blades to close enough to cover up the small opening you have at a small aperture.
Some remarks on the CLA part:
Today's synthetic oils are a lot better than the old oils, they age much slower.
I do all the CLA on my leaf shutters for my 4x5 inch shutters my self, Compur and Copal and have reached times between CLA's
of several years with an occasional shuttertest inbetween just to be shure.
Nobody will complain about an oil change and lube job for their car at least once a year, so why do we complain about some CLA
for our treasured lenses aech couple of years then ?
All the best for 2009,
Peter
Well, it is a C lens, a T*, came in its original packaging with virtually NO sign of use since purchased. The only giveaway is the paint scraped away at the filter mount. I have no idea what the lens cost, as it was a gift from someone who really cares about me.
Could the culprit be too little use? From what I understand, the original (only) owner hadn't used it for the last 15 years or so, and sparingly prior to that.
Thanks so far for your wonderful advice!
- Thomas
Well, it is a C lens, a T*, came in its original packaging with virtually NO sign of use since purchased. The only giveaway is the paint scraped away at the filter mount. I have no idea what the lens cost, as it was a gift from someone who really cares about me.
Could the culprit be too little use? From what I understand, the original (only) owner hadn't used it for the last 15 years or so, and sparingly prior to that.
Thanks so far for your wonderful advice!
- Thomas
Not so much tested, but from experience, about 1/2 stop, maximum.I wonder if anyone has every tested to find the actual amount?
When I send in my H-lenses, I ask the technician to calibrate the exposing time of the 1/500 point not for the fastest speed possible, but for about 1/350.
Changing oil in the car costs about $20 to do it yourself and $30 if you pay a mechanic. CLA on a shutter costs $150 and is not a do it yourself job for most people. That's why people complain.
He is actually right ...
I suggest that you re-read this carefully.
It is because the timing starts when the blades reach the fully open position, but when you shoot with a small aperture, the small hole is fully uncovered long before the blades reach the full open position, and as the blades close it takes a short time for the blades to close enough to cover up the small opening you have at a small aperture.
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