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  1. #31

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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Ed Sukach @ May 5 2003, 04:10 PM)</td></tr><tr><td id='QUOTE'>Is the plane of focus different when the grain focuser is used one-paper-thickness further away?&nbsp; Of course. </td></tr></table><span class='postcolor'>
    Ed, if the thickness of a paper sheet would make a significant change to your focus than your enlarger must be adjusted to a fraction of an arc second to be able to provide this plane evenly (otherwise it would depend on where you place your grain focuser). Not to mention an uneven easel or the field curvature of the lens.

  2. #32

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    I knew you were going to bring up the el optimization of thr rodagon G, it preformed well enough on a 2x factor. I also have a Schneider Componon S 90 mm for MF enlargements, at f11, and 2.5x factor, I still can see a significant difference between focusing with paper underneath and not.

    I assure you this is not one of those urban legends, like " hypo is heavier than water"....

  3. #33
    Ed Sukach's Avatar
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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (tschmid @ May 5 2003, 06:32 AM)</td></tr><tr><td id='QUOTE'></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Ed Sukach @ May 5 2003, 04:10 PM)</td></tr><tr><td id='QUOTE'>Is the plane of focus different when the grain focuser is used one-paper-thickness further away?&nbsp; Of course. </td></tr></table><span class='postcolor'>
    Ed, if the thickness of a paper sheet would make a significant change to your focus than your enlarger must be adjusted to a fraction of an arc second to be able to provide this plane evenly (otherwise it would depend on where you place your grain focuser). Not to mention an uneven easel or the field curvature of the lens.</td></tr></table><span class='postcolor'>
    I&#39; don&#39;t quite understand ....

    Have you ever done "The Brick trick"?

    P.S. A "fraction of an arc second?" One second would be .000 1 (one ten thousandth) in every 20.0. (take your pick, inches or meters).
    I think my Omega is pretty good - but not THAT good.

    E.S.
    Carpe erratum!!

    Ed Sukach, FFP.

  4. #34

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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (tschmid @ May 4 2003, 11:09 PM)</td></tr><tr><td id='QUOTE'>
    BTW: A Rodagon-G is optimized for el-factors above 15x. I dont&#39;t think it performs well at 2x. Mine (105 and 150) do not at these scales. </td></tr></table><span class='postcolor'>
    Well, now you&#39;ve confused me, are you saying that the 105 and 150 Rodagons work well at 2.5 or not well. My 150mm is a Schneider Componon-S, it is optimised for 20x, all my other lenses are Rodagon the 105 Rodagon G makes a sweet 30x-35x but is very grainy at 20x or 10x. The 300mm has its sweetest area around a 10x, and the Apo-Ronars from 360mm, 480mm, 485mm, and 760mm, well I don&#39;t know their sweet spots. My copy board is on a calibrated track so I am limited in enlargment due to the track length, but they always perform well for the range they are offered.

    I didn&#39;t understand till recently when I started acquiring lenses, what a difference the right enlarging lens can make&#33;&#33;&#33; Lense are my friends.
    Embrace **it! **it. . .just another name for fertilizer. . . Grow baby Grow!

  5. #35

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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Darkroom ChromaCrafts @ May 7 2003, 12:34 AM)</td></tr><tr><td id='QUOTE'>Well, now you&#39;ve confused me, are you saying that the 105 and 150 Rodagons work well at 2.5 or not well. </td></tr></table><span class='postcolor'>

    Jill, the normal Rodagon 105 and 150 do perform well at 2x (although there are better lenses for low magnifications). The Rodagon-G is a special version optimized for mag-ratios >15x (differs depending on focal length). Strictly spoken, each lens has an optimum mag-ratio and is more or less a compromise above and below this point. A normal Rodagon is as bad at 25x as a Rodagon-G is at 2x.

    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Darkroom ChromaCrafts @ May 7 2003, 12:34 AM)</td></tr><tr><td id='QUOTE'>My 150mm is a Schneider Componon-S, it is optimised for 20x, all my other lenses are Rodagon the 105 Rodagon G makes a sweet 30x-35x but is very grainy at 20x or 10x.</td></tr></table><span class='postcolor'>

    The 150mm Componon-S is not really optimized for 20x, but it may be fine there. Never tried 20x with my Componon-S 150mm. The Schneider counterpart to the Rodagon-G is the G~Componon, which is very rare. I have never seen one. The Componon-S 5.6/150 should be best around 5x-8x.

    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Darkroom ChromaCrafts @ May 7 2003, 12:34 AM)</td></tr><tr><td id='QUOTE'>The 300mm has its sweetest area around a 10x, and the Apo-Ronars from 360mm, 480mm, 485mm, and 760mm, well I don&#39;t know their sweet spots. My copy board is on a calibrated track so I am limited in enlargment due to the track length, but they always perform well for the range they are offered.</td></tr></table><span class='postcolor'>

    I cannot comment on these lenses, but I don&#39;t think that the 300mm is best at 10x either. Longer focal lengths are usually optimized to lower mag-ratios. On the other hand they do not fall off that much at higher ratios than shorter focals do.

  6. #36
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  7. #37
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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Aggie @ May 7 2003, 09:36 AM)</td></tr><tr><td id='QUOTE'>whoa,&nbsp; you mean I have learn about different enlarger lenses now?&nbsp; Damn I just figured out LF lenses.&nbsp; So what are the differences for the normal idiot like me who does the home darkroom thing in the future?&nbsp; I know about 50mm for 35, 75-80 for 645, 100 for 6x7, and 135 for 4x5.&nbsp; that is the extent of my enlarger knowledge.</td></tr></table><span class='postcolor'>
    "Don&#39;t be intimidated by the mountains of technical knowledge"
    - Stillman Clarke

    Yes, each enlarger lens if designed for optimal performance at some specific enlargement ratio. That does *NOT* mean that they are useless at another - only that the designer had that particular charactersitic as a "target", along with many others.

    A lens designed for use with 35mm probably would be designed to give the best perfomance at a ratio that would produce an 8" x 10" print. It would be perfectly acceptable at 5" x 7" or 11" x 14" - that "latitude" would ALSO be a design criteria.

    There are specialized lenses for the extremes... i.e. enlargements of 6cm x 7cm formats to 30" x 40" inches... and they would be appropriate, and cost justifiable, if one was to often make large prints like that. Otherwise ... the "standard&#39; Rodenstock, Schnieder or Nikon ... or ...? - will be just fine.

    aal
    Carpe erratum!!

    Ed Sukach, FFP.

  8. #38

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    Like he said.

    A few more things. Some of the 80&#39;s will handle 6x7. The 105 are needed for 6x9. 150mm is good for 4x5 to. If you&#39;re buying used just get the top of the line lens from any of the big companies. If everything else in your setup is perfect then maybe consider springing for APO lenses.

    Avoid the lower priced consumer lenses sold by all the companies. They work but used they aren&#39;t much less then the top lenses from the same company.

    Some people will tell you to go up a size in lenses. Claiming if you use an 80mm lens for 35mm film it&#39;s better. This claim seems to be based on the belief the companies are selling lenses that aren&#39;t up to covering the format they are designed for. Going with a longer lens costs you some in terms of enlargement size. A longer lens will need a taller enlarger to get the same max size enlarger.

  9. #39
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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Robert @ May 7 2003, 03:16 PM)</td></tr><tr><td id='QUOTE'> Some people will tell you to go up a size in lenses. Claiming if you use an 80mm lens for 35mm film it&#39;s better. This claim seems to be based on the belief the companies are selling lenses that aren&#39;t up to covering the format they are designed for. Going with a longer lens costs you some in terms of enlargement size. A longer lens will need a taller enlarger to get the same max size enlarger. </td></tr></table><span class='postcolor'>
    I think that is directed more at the condensor or diffuser end of the enlarger. Quite often you will get more even light coverage with the longer focal length lens, which is usually only noticeable when printing expanses of even tones like sky.
    The better enlargers mostly can do well enough to not worry about coverage.
    Gary Beasley

  10. #40

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    Aggie,
    knowing your enlarger lenses is not less important than knowing your camera lenses. Besides the technical aspects, each lens has its individual characteristics. If I like to have it real sharp and detailed, I mount a 7-element Zeiss on my enlarger. If there is too much sharpness, I&#39;ll put on an old uncoated Componon, which still yields better results than a modern lens with a corresponding filter (and sometimes is even cheaper to buy than a good filter). A Zeiss S-Tessar from the 60&#39;s (a "low-end" el-lens from Zeiss that still outperforms some modern ones), e.g., passes UV light seamless and can still be focused sufficiently exact with visible light. Or buy a real-low-grade-all-plastic Trinar for 5 bucks (e.g. on Ebay) and try things like coating with wax.

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