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  1. #11
    df cardwell's Avatar
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    Well, we're at the point where contradiction is the only thread this can run.

    Try a Proxar, try a Tube.

    Lots of fine pros, and technical photographers, have made fine images with Proxars.

    Some folks don' t like 'em.

    Become your own expert, and let us know.

  2. #12
    Ed Sukach's Avatar
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    Quote Originally Posted by Q.G. View Post
    Well... no.

    The use of supplementary lenses changes more than just the focal length.
    It also changes the correction of the lens.
    Changes "correction"? Properly, affects the characterstics of the optical system...

    Proxars are very simple, single element lenses. Not even achromats. So much for "proper designing".
    ??? In any lens, no single element is 'even an achromat'. Where does it say that 'being at least an achromat' is an absolute necessity?

    It's hard, impossible even, to design them properly anyway.
    First, because unless you want to have matched proxars, i.e. different ones, each dedicated to be used with only one lens, having others for use on another lens, yet others for use on the same lenses, but in combination with a second proxar, etc., they must be of a simple 'general purpose' design that can never be "proper".
    "Hard"? "Can ever be..." ?? For Zeiss, manufacturer of the Hasselblad Proxars? Compared to their involvement in sophisticated optical systems, the engineers assigned to something like this would be complaining of "nothing to do."
    Note that the Proxars ARE designed for a "matched" purpose ... the Hasselblad lens system. "Impossible ..." ? Uh ... no, not impossible. Not even close.

    Second, because the lenses they are used on already are properly designed bits of optics, that do not respond well to having another lens stuck in front of them.
    [Sarcasm key on] Of course ... Hasselbad sanctifies Zeiss Proxars by allowing their name on them ... Hasselbad LIKES products that screw up their optics .... [Sarcasm key off]

    Proxars are easy to use. But bad for image quality (and they really are, despite some people not noticing they are).
    Ah ... a little mind game. How does one tell if an image is of "bad quality" if one cannot perceive that the image is of "bad quality"? - And, specifically, why should I care?

    So tubes are used for image quality, Proxars for being lazy.
    There is nothing wrong with the use of either extension tubes or bellows ... but they both require additional work to determine proper exposure. There is nothing wrong, in my opinion with using dedicated supplementary lenses, Proxars", either.

    "Lazy" ....? OK. What is wrong with avoiding extra effort, and related potential for error?


    Add to signture: Optical Quality Assurance Specialist - in a "previous life".
    Carpe erratum!!

    Ed Sukach, FFP.

  3. #13
    df cardwell's Avatar
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    We balance contradictory qualities in photography. That's how to use technology.

    Transitioning from photomicroscopy to commercial photography meant dealing with MANY compromises !

    While it is generally true you can get a higher MTF from an extension, compared to a Proxar,
    the test has to be structured carefully to present the difference.
    Depending on the actual picture taking,
    the conditions might not exist to reproduce the experimental results.

    For portraiture, and the odd still life,
    high contrast lighting isn't used( for example, Kohler illumination).
    This hard lighting necessary to reveal the differences between a 150 Sonnar w/Proxar,
    or ext. tube, or an S-Planar, is opposite what one wants for imaging a human face.
    Further, the structure of a human face is so coarse (eyelashes, for instance)
    that imaging them is not a big problem. The working range of an extension tube
    is narrower than a Proxar, and changing from one tube to another might break the rhythm of a sitting,
    increases the likelihood of dust getting into the camera, and magnifies the possibility of damaging the lens.
    Taken all-in-all, many folks found the Proxar being a better solution for this kind of work.

    My own experience ?
    Throughout the 1980s, I did exactly this kind of work.
    For my first project, I rented a 150, tubes, and a set of Proxars,
    and shot a sample, under a broad light source on Kodachrome 64.
    The Proxars were plenty good enough, and the convenience of shooting a living,
    breathing, and moving human being outweighed minor advantages of using extension tubes.
    The test also demonstrated that using a 'chimney magnifier', instead of a prism,
    contributed more to good image quality than whether I was using tubes or Proxars.
    But focus screens are much improved from those DARK days.

    The client was happy,
    and I performed several contracts. After the second job,
    I could buy a Hazylight and a 135 Macro Planar with the new macro focus tube,
    which beat Tubes and Proxars to bits.

    Now, shooting a flat object, or in the 1:3 - 3:1 macro range,
    a tube WOULD be better (although changing tubes in the field would still be a problem).


    A hot lens for a Proxar is the 250 Sonnar !

    .
    Last edited by df cardwell; 05-11-2008 at 12:41 PM. Click to view previous post history. Reason: typos

  4. #14

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    Quote Originally Posted by Ed Sukach View Post
    [Sarcasm key on] Of course ... Hasselbad sanctifies Zeiss Proxars by allowing their name on them ... Hasselbad LIKES products that screw up their optics .... [Sarcasm key off]
    Actually Hasselblad did stop the production of Proxars quite some time ago and if I'm not mistaken (i.e. if what I've read is correct) their reason was the degradation in image quality.


    Anyways, I think it is a well established fact that close-up lenses have some sort of deteriorating effect on image quality. However, that doesn't exactly mean that a Proxar will turn a Hasselblad into a Holga.

  5. #15

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    Sticking a lens element in front of a camera lens degrades the optics to some point. It is physically impossible for it not to. With just a small amount of magnification, the degradation is not going to be as noticeable as it is with higher magnification. If you stack them to get close to 1:1, the difference between close up filters and extension tubes is like night and day in my experience. Degradation in image quality also becomes more noticeable with a higher enlargement factor.

    According so some testing I just did, it's also incorrect to say that close up filters don't reduce the amount of light that passes through the lens. I have a set of Tiffen close up filters that came with a camera outfit that I bought, and I just did some testing to see if there is any change of the meter reading on my Nikon (they are too small to use on my RZ). Using just one filter, the difference was less than 1 stop with fairly bright light, and more than 1 stop with low light. Apparently, the difference is in the percentage of light that is reflected off the surface vs the percentage of light that passes through.

  6. #16
    df cardwell's Avatar
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    The light loss is due to flare. A diopter does NOT change the effective aperture, as does a bellows extension. Tiffen diopters may not perform as well as a Proxar, Nikon, or Leitz diopter. This is a coating, and materials problem.

    A #1 diopter on a 150 lens results in a 130mm lens. SO, you get closer. The lens often performs better at close distance with a diopter than it does at its close focus limit because the lens is corrected for a greater working distance, and the diopter causes the image rays to enter the lens as though the lens was focussed further away.

    The increased image magnification of the Proxar+Lens gives a higher quality print than using the lens alone, with a lower magnification on the film, because the higher enlargement degrades the image more than did the Proxar.

    A Macro Lens will beat a Proxar by a mile.
    But many times, a Proxar is more than enough to make the picture.

    Reference: View Camera Technique, 5th edition, by Leslie Stoebel. Focal Press, 1986. Chapter 5.5: DIOPTERS
    Last edited by df cardwell; 05-11-2008 at 06:00 PM. Click to view previous post history. Reason: typos, halfwittedness

  7. #17
    Andrew Moxom's Avatar
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    wow, thanks for the comments. Seems like extension tubes are the right way to go.
    Please check out my website www.amoxomphotography.com and APUG Portfolio .....

  8. #18
    Ed Sukach's Avatar
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    Quote Originally Posted by max_ebb View Post
    Sticking a lens element in front of a camera lens degrades the optics to some point. It is physically impossible for it not to.
    A good illustration of the trouble one can get into via an overgeneralization. If you will remember, the Hubble telescope was corrected - MADE BETTER - by installing a supplementary lens into - I dobn't know where, in front of? over? the optical system. It is possible - to to do the same with camera lenses. Adding elements will not NECESSARILY degrade the system

    According so some testing I just did, it's also incorrect to say that close up filters don't reduce the amount of light that passes through the lens. I have a set of Tiffen close up filters ....
    It would surprise me - a lot - if the amount of light passing through additional glass did NOT decrease. No matter what, some light will be absorbed by the glass and transformed into heat.

    What I said was that the f/stop will not be affected by the addition of Proxars - the aperture remains where it always is - so the ratio f(focal distance)/ aperture diameter remains the same. The amount of light passing through would be indicated by the "T/stop" ... an entirely different story.

    Can anyone recall a 35mm still camera with a lens employing "T/stops"?
    Last edited by Ed Sukach; 05-11-2008 at 07:10 PM. Click to view previous post history. Reason: @#$ Typo
    Carpe erratum!!

    Ed Sukach, FFP.

  9. #19

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    I have both, but I expect to use tubes more, as my 150 is a CF Bay 60, and my 80 is a B 50 C model. I have Proxars for the 80 but I can use the same tubes with either lens.

    As for sharpness, for portraits, some consider the Hasselblad optics too sharp anyway. So a bit of softness introduced by using a Proxar might not be a big problem.

  10. #20

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    Quote Originally Posted by Ed Sukach View Post
    Changes "correction"? Properly, affects the characterstics of the optical system...
    Playing games?
    You said that the only thing that "changes" was the focal length. That's not right.

    Quote Originally Posted by Ed Sukach View Post
    ??? In any lens, no single element is 'even an achromat'.
    Right. Proxars are single element lenses, therefore not even achromats.
    Not too difficult, is it?

    Quote Originally Posted by Ed Sukach View Post
    Where does it say that 'being at least an achromat' is an absolute necessity?
    In a number of places. Unless of course you don't think that performance is a necessity.

    The single lens you are adding to a perfectly balanced design introduces a number of faults, that were 'designed away' in the lens you put it on.
    You can (and common sense says you should) reduce that ill effect by doing whatever you can.
    Turning the close up attachment into a (two lens) achromat - like other manufacturers than Zeiss do - is the simplest and easiest way of doing so.


    Quote Originally Posted by Ed Sukach View Post
    "Hard"? "Can ever be..." ?? For Zeiss, manufacturer of the Hasselblad Proxars?
    Indeed.
    Should they do what should be done to keep such a combination as good as the lens alone, or as good as their other products, they can only do one thing: design a lens that incorporates the Proxar. A close up lens that can do what you want it to do, do it well, without needing such a crappy bit of glass in front.
    And they do: they make Makro-Planar lenses, that still need tubes, but do so much better than a lens with Proxar, that they do not even bother to change those crappy, single lens close-up attachments so they at least eliminate the additional chromatic aberrations a bit.


    Quote Originally Posted by Ed Sukach View Post
    Note that the Proxars ARE designed for a "matched" purpose ... the Hasselblad lens system.
    That's completely untrue.
    The Proxars are not designed to match anything.
    They are even simpler thingies than the lenses Zeiss produces for eyeglasses.

    Quote Originally Posted by Ed Sukach View Post
    "Impossible ..." ? Uh ... no, not impossible. Not even close.
    That's what you think...


    Quote Originally Posted by Ed Sukach View Post
    [Sarcasm key on] Of course ... Hasselbad sanctifies Zeiss Proxars by allowing their name on them ... Hasselbad LIKES products that screw up their optics .... [Sarcasm key off]
    Maybe you should turn on the "i'll make sure that i'm well informed before i turn on the sarcasm key"-key?

    Quote Originally Posted by Ed Sukach View Post
    Ah ... a little mind game. How does one tell if an image is of "bad quality" if one cannot perceive that the image is of "bad quality"? - And, specifically, why should I care?
    Who said you "cannot perceive" that the image is bad?
    You can.

    The mind game is still played though, in the minds of people who prefer to not see it, and tell themselves they should not care.

    Quote Originally Posted by Ed Sukach View Post
    There is nothing wrong with the use of either extension tubes or bellows ... but they both require additional work to determine proper exposure. There is nothing wrong, in my opinion with using dedicated supplementary lenses, Proxars", either.
    In your opinion not. That's clear.

    Quote Originally Posted by Ed Sukach View Post
    "Lazy" ....? OK. What is wrong with avoiding extra effort, and related potential for error?
    What's wrong is that you accept "error" (you paid lots for a fine lens, only to reduce it to a less good one).
    That's not just being lazy. Other terms apply too.


    Quote Originally Posted by Ed Sukach View Post
    Add to signture: Optical Quality Assurance Specialist - in a "previous life".
    You shouldn't have.
    Only helps to make you look worse ...

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