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  1. #61

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    Quote Originally Posted by hpulley View Post
    The floating element ring is annoying on the KL lenses. It does make it sharper but makes focusing a two step process.
    Well, about half of the C-series lenses have the floating elements as well. And nobody is forcing you to use it! (just ignore it if you don't need laboratory-perfect flat-field imaging at closer-than-infinity distances) - it's your choice. More than half of the time, I ignore mine - only using it when I am taking serious close-ups.

  2. #62
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    Quote Originally Posted by philosomatographer View Post
    Well, about half of the C-series lenses have the floating elements as well. And nobody is forcing you to use it! (just ignore it if you don't need laboratory-perfect flat-field imaging at closer-than-infinity distances) - it's your choice. More than half of the time, I ignore mine - only using it when I am taking serious close-ups.
    I usually either:

    a) first set the ring to either infinity or the closest distance (as seems appropriate) and then focus using the bellows; or
    b) if there is time, guestimate and set the distance on the ring first, and then focus using the bellows.

    I've wondered if the floating element has more effect on flat field performance/field curvature than it does on centre sharpness.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  3. #63
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    OK, I just know on the original 65mm and the 'C' 90mm there is no ring. I bought a 90mm KL because they're cheap as paperweights these days and while it is sharper the KL version now has the ring. I think the 'C' 65mm may have the ring too but my original Sekor (non-C) does not.

    I've forgotten to use it at all on my 90mm for a whole roll and the shots still looked OK to me for shots which are not that close. For close-ups it does seem to make a difference.
    Harry Pulley - Visit the BLIND PRINT EXCHANGE FORUM

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  4. #64
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    Quote Originally Posted by hpulley View Post
    OK, I just know on the original 65mm and the 'C' 90mm there is no ring. I bought a 90mm KL because they're cheap as paperweights these days and while it is sharper the KL version now has the ring. I think the 'C' 65mm may have the ring too but my original Sekor (non-C) does not.

    I've forgotten to use it at all on my 90mm for a whole roll and the shots still looked OK to me for shots which are not that close. For close-ups it does seem to make a difference.
    I don't know if you've seen Mamiya's instructions for use of these floating element lenses. Here is a link to a useful if slightly older manual, courtesy of Mike Butkus' site:

    http://www.cameramanuals.org/mamiya_...nge_lenses.pdf

    The applicable info is on page 7 of the manual which is the 9th page of the pdf.

    Essentially it recommends for "spur-of-the-moment snapshots" that the infinity mark be used for everything from 7 feet to infinity, and the 3.3 foot mark be set for everything closer than 7 feet.

    It also confirms that the purpose of the floating element is to "obtain sharp resolution down to (sic) the picture circumference".

    And finally, it confirms that when turning the floating ring "no variations can be observed on the ground glass focusing screen".
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  5. #65
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    My RB67 with metered CDS prism weighs 7 pounds. While I like my RB, I use my 645 much more. The images I get with my 645 lenses are richer in color and contrast than what I get from my RB.

  6. #66
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    Quote Originally Posted by snegron View Post
    My RB67 with metered CDS prism weighs 7 pounds. While I like my RB, I use my 645 much more. The images I get with my 645 lenses are richer in color and contrast than what I get from my RB.
    Why do you think that would be?

  7. #67

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    I cant believe I'm going to ask this but...what is a "metered CDS prism"????

  8. #68
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    Quote Originally Posted by Wayne View Post
    I cant believe I'm going to ask this but...what is a "metered CDS prism"????
    A prism with a built in meter, using a CdS (Cadmium Sulfide) light sensitive cell. CdS cells were a next generation after selenium cells, much more sensitive but requiring a battery. Silicon cells came after CdS cells and are better - for one thing, Cds cells tend to have considerably slower response and can take a second or two to completely respond to changing light. Cds cells still pretty much work fine for meters though.

    http://en.wikipedia.org/wiki/Photoresistor

  9. #69

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    So this a built in or add on internal metering system?

  10. #70
    Roger Cole's Avatar
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    It's a metering system built in to the prism. So in this case the prism and metering system come together as a unit. Many medium format cameras have these available. You can get metering prisms or non-metering prisms.



 

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