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Re: [Minolta] Re: Celtic lenses (was Minolta enlarger lenses)

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  • David Kilpatrick
    ... The element/group configurations involved were so common at that time you could have found a dozen different labelled lenses with apparently similar specs
    Message 1 of 15 , Oct 10, 2006
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      sybersitizen wrote:

      >Okay David, it's time to report back on this. I must say that the
      >response from the masters of Minolta manual focus lore has been
      >underwhelming. Normally that community enjoys talking about the
      >Celtics, but this time around they were strangely silent. In fact, I
      >only got one useful (very useful!) response, from the owner of this
      >impressive site:
      >
      >http://minolta.eazypix.de/
      >
      >In particular, have a look at the table on this page:
      >
      >http://minolta.eazypix.de/lenses
      >
      >Assuming that his data is accurate, he points out that there are two
      >Celtics on that list - the MC 135mm f/2.8 and the MC 200mm f/4 - that
      >show a unique arrangement of elements and groups when compared to the
      >corresponding Rokkors. This is two more than I thought there were, so
      >that partially supports your contention. But the information on the
      >other Celtics does not indicate that they differed from the Rokkors,
      >so there's no additional evidence suggesting that the entire Celtic
      >line was different. It is true that even if the numbers of elements
      >and groups matched, the Celtics may have used different lens
      >components and/or formulas; but that can't be determined from this
      >data.
      >
      >Regarding the Celtics being outsourced to another manufacturer,
      >nobody has offered any additional information. It could well be true
      >that some or all of those lenses were assembled elsewhere, though I'm
      >sure that I've never seen that stated anywhere before. I hope that
      >you are documenting your experiences with Minolta's ancient history
      >somewhere other than in these group messages, because information
      >like that will be harder and harder to come by as time passes.
      >
      >
      >
      >
      >
      The element/group configurations involved were so common at that time
      you could have found a dozen different labelled lenses with apparently
      similar specs - same filter thread, same E/G numbers, same aperture,
      even close to the same weight. At the time the Celtic lenses were being
      produced, I am not aware of Minolta having a lens plant which could have
      produced them; several new independent lens plants were opening, there
      was a small revolution taking place in Japanese lens production, and I'm
      pretty sure my contacts at Japanese Cameras Ltd were right in suggesting
      that the Celtic brand in general was not the main Minolta production
      line, and I'm pretty sure it was an outside contractor.

      One way to check is to study the engraving of the Celtic lenses under
      high power magnifier. The Minolta plant had remarkably high quality
      engraving and painting. Even products like lens hoods stand up to high
      magnification inspection for quality. I handled Celtic lenses at
      photokina shows, and came across one or to used ones. I thought the
      baffling/sealing round the rear and the aperture actuator was inferior,
      and the feel of the aperture mechanism was not as good.

      When Minolta introduced the XD-7 (XD-9) some comments were made about
      not guaranteeing the operation of the 'failsafe' aperture mechanism with
      MC lenses. All MD lenses had an improved aperture mechanism, which was
      more linear in action and more predictable in result. This was necessary
      to enable shutter shutter priority action, and also the 'virtual
      program' mode (the XD-7/9 was almost incapable of wrong exposure).
      However, I converted old MC lenses like the 100mm f2 which had the same
      aperture control geometry, to be MD lenses - adding a lug - and used
      them successfully on the XD models.

      It could be that MD Celtic lenses were not outsourced, or if they were,
      the aperture mechanism would have been supplied or tightly specified by
      Minolta. Many independent MD lenses, made without the degree of
      attention Minolta paid to the aperture function, are not as accurate as
      Minolta optics on the MD and the later programmed X-700 etc series.

      David
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