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  1. #21
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    Don, as often happens you fail to appreciate the minutiae of the discussion.
    I never claimed that your Tamron lens was either in or out of tolerance, how could I know? I am quite prepared to accept the likelihood that it isn't for reasons I mentioned earlier.
    My point was that the lens or camera can be within tolerance but not "perfect" which seems to be what you are expecting.

    Quote Originally Posted by DonSchap View Post
    Peter, I know from where I speak, so please to be offended when I say, "Are you, like, on something?".......had to be absolutely, without a doubt, dead-on and within tolerance. Otherwise "REJECT!" with a big red tag...........
    I give you credit for thinking you know "from where you speak" but here you claim the item of equipment was "dead on" yet in the same sentence claim it was "within tolerance".

    Implicit in the statement, "within tolerance", is that the item is not "dead on" but lies within an acceptable deviation around the ideal. We also know that tolerances can accumulate in a very negative way. That's why stock engines get blueprinted for racing at extraordinary expense (for example).

    The simple fact is perfection cannot be achieved at any sensible price in the manufacture of a lens particularly at Tamron prices. Zeiss get closer but at a much higher price which some are prepared to pay whilst others won't.

    If you can't recognise these simple facts of life there is no hope for you. It's necessary to understand a problem before you can deal with it.

    A statement from one of your earlier posts really says it all...
    Quote Originally Posted by DonSchap View Post
    One of the benefits (if you could call it that) on the two Full Frame SONY DSLRs (α850/α900) is the Micro-Focus Adjustment, ..........

  2. #22
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    Between you and me and the four walls ...

    Quote Originally Posted by Peekayoh View Post
    A statement from one of your earlier posts really says it all...
    Micro-Focus adjust was only added to the higher-end DSLR camera to compensate for variations you encounter from older glass and the range that some ZOOM lenses go through to correct the problem of focal variations from one extreme to another. Personally, my lenses go back to the depot for alignment to a standard, when a problem like that is detected.

    If you can live with this misalignment on a camera that CANNOT correct it (e.g, every SONY dslr other than the a850/a900), fine ... it's your photography and you are welcome to it. I, admittedly, am a little more conscious of these problems. I did not find it by accident, I sought it out, after several years of experience with many different manufacturers.

    Like I said, once the lens is "tweaked" to its correct alignment, we are off to the races. I will wait and see what comes back, as usual. It's new, it should work 100%, OOTB. You have my pity (more like my disdain) if you are too lazy to get off your duff and correct the problem.

    Again, if I am going to bother to buy a lens, you can be sure, we are going to see what it is made of ... and darn quick. Let the chips fall where they may.
    Last edited by DonSchap; 05-10-2011 at 06:29 PM.
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

  3. #23
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    Quote Originally Posted by DonSchap View Post
    Micro-Focus adjust was only added to the higher-end DSLR camera to compensate for variations you encounter from older glass.........
    Don, you never fail to astonish me. That's an outrageous statement which is completely UNTRUE.
    What you are now saying is that Manufacturers have spent a fortune to equip high end DSLRs with Micro Adjust in order to support Old Glass. B***s***, they would have publicised the fact that old glass is inferior to the latest offering, sold you the new glass and laughed all the way to the Bank.

    Quote Originally Posted by DonSchap View Post
    ..... and the range that some ZOOM lenses go through to correct the problem of focal variations from one extreme to another. Personally, my lenses go back to the depot for alignment to a standard, when a problem like that is detected.
    Yes, It's true that many Zooms suffer from the problem of focus shift as the focal length is changed. However, sending the lens back for adjustment is a complete waste of time. This behaviour is a design issue that no amount of adjustment can nullify.

    Quote Originally Posted by DonSchap View Post
    ..... If you can live with this misalignment on a camera that CANNOT correct it (e.g, every SONY dslr other than the a850/a900), fine ... it's your photography and you are welcome to it. I, admittedly, am a little more conscious of these problems. I did not find it by accident, I sought it out, after several years of experience with many different manufacturers.
    Isn't that a bit condescending? You make it sound as if you and you alone had the perspicacity to ferret out a problem. Isn't it the truth that many seasoned Pro's (and seasoned Amateurs) wrestled with the issue for a long time? Isn't it the truth that Canon and Nikon spent an inordinate amount of time and money looking for a solution, calibrating the systems of Pros, whole systems that is, all of their lenses to individual camera? Isn't that the reason why Micro Adjust was developed?

    Quote Originally Posted by DonSchap View Post
    .....Like I said, once the lens is "tweaked" to its correct alignment, we are off to the races. I will wait and see what comes back, as usual. It's new, it should work 100%, OOTB. You have my pity (more like my disdain) if you are too lazy to get off your duff and correct the problem.
    Seeing as I don't fit that description, I won't pretend offense.
    Let me restate my position. A faulty or poorly adjusted lens should be returned to the Manufacturer for correction; it's a no brainer, right? Everyone should assess a new lens for proper function (see my earlier post for a link as to how).

    Let me also restate my position when the lens is within tolerance but still exhibits some B/F focus. Returning it for adjustment is likely to yield no benefit and just as likely to be counterproductive. This is an incontrovertible fact.

    And again, if your camera does not have micro adjust and you have a B/F focus issue, send both the camera and lens for calibration as a unit. This is the only way be be sure of a fix. Well, that's not strictly correct, if you are handy with an Allen key, you can adjust the camera yourself but most won't choose that option.

    Let me also reassure Junior members that this is not a big issue for most users. It only becomes apparent with a fast lens at high magnification with the lens wide open (or near to). This makes the DOF so thin that focus errors become significant. Use the same lens at f/5.6 and you are unlikely to see a problem.

  4. #24
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    313
    Don: you should spend less time worrying about the gear (and telling everyone how you know better than all engineers at Nikon, Canon and Sony) and more time improving your photography.
    Just saying...

  5. #25
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    Dec 2006
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    [QUOTE=Peekayoh;427545]Yes, It's true that many Zooms suffer from the problem of focus shift as the focal length is changed. However, sending the lens back for adjustment is a complete waste of time. This behaviour is a design issue that no amount of adjustment can nullify.
    /QUOTE]

    Have never really understood focus shift properly. I mean i know what it is but i dont know why it happens. What part of the lens design contributes to the issue and why so prevalent on some lens' and non existent in others ? Have you got a good link about it ?
    D800e l V1 l AW1 l 16-35 l 35 l 50 l 85 l 105 l EM1 l EP5 l 7.5 l 12-40 l 14 l 17 l 25 l 45 l 60 l 75
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  6. #26
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    Cool Oh yeah ... it can wait!

    Quote Originally Posted by jr_rodriguez View Post
    Don: you should spend less time worrying about the gear (and telling everyone how you know better than all engineers at Nikon, Canon and Sony) and more time improving your photography.
    Just saying...
    You make it sound like this is something novel or new. It's not! It's just par for the course and needs to be made better, so we all can enjoy opening our little lens gifts on Christmas Day, popping it out of the box, popping it on the camera and taking well focused images.

    Right now, its "Oh, hold on, kids ... I just checked and I need to send this wonderful gift you gave me BACK to __________ (<- Insert your favorite lens manufacturer's name here) and we should be good in about 2-3 weeks, after they do what they should have done when they made it and put it in the box, in the first place. Just go back to bed and we'll open the rest of the gifts on January 20th." (okay, take a breath). Yeah, that's gonna happen. So, you get crappy stuff from your BRAND NEW LENS ... so what, right?

    Sorry, as a flagrant consumer of things photographic, I demand a better QC ... and so should you, despite your silly and disappointing protestations to the contrary. You want let them off the hook. See ya. It is not going to happen with this guy.
    Last edited by DonSchap; 05-11-2011 at 11:08 AM.
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

  7. #27
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    Nov 2008
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    [QUOTE=Rooz;427556]
    Quote Originally Posted by Peekayoh View Post
    Yes, It's true that many Zooms suffer from the problem of focus shift as the focal length is changed. However, sending the lens back for adjustment is a complete waste of time. This behaviour is a design issue that no amount of adjustment can nullify.
    /QUOTE]

    Have never really understood focus shift properly. I mean i know what it is but i dont know why it happens. What part of the lens design contributes to the issue and why so prevalent on some lens' and non existent in others ? Have you got a good link about it ?
    Sorry Rooz, I can't point you to any useful link on the subject.
    A parfocal Zoom (as opposed to varifocal) is one that maintains focus when magnification/focal length is changed. This is real handy, but parfocal zooms are about as common as hens teeth.
    Unfortunately it's more difficult and more expensive to design a Parfocal zoom.
    When you start moving an element group any distance, as happens in a zoom lens, it affect the focus plane as well as the focal length and perfect compensation is difficult.
    For obvious reasons, you will find Parfocal Zooms in Cinematography, but they really cost, an arm and a leg job.

    Similar thing happens when you focus a prime lens, the focal length is affected but to a lesser degree. Most obvious in a Macro lens because of the bigger extension.

    It would be nice if there were a list of Parfocal Zooms somewhere. Maybe there is.

  8. #28
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    Feb 2006
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    Thumbs up It is on the way ...

    Well, I spent the dough to insure this lens and get it there in a decent amount of time. Hopefully, TAMRON will be indulgent and return a truly "tweaked" piece of work.

    Again, that 90mm f/2.8 Di is about the sharpest lens in the pile. The SONY CZ 135mm f/1.8 comes real close. It is just a little long for a less than 10' room.

    So, it is off to the zoo, tomorrow, if the weather permits. Time to try out that SIGMA 85mm f/1.4 and see what shakes out.

    Ah, photography ... do you see what I see?
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

  9. #29
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    Nov 2010
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    Apopka, FL
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    447
    85mm isn't that much of a distance for a zoo.
    Sony A33 | Sigma 70-200mm f/2.8 II EX DG APO Macro HSM | Sony 30mm f/2.8 DT AF Macro | Tamron SP AF 28-75mm f/2.8 XR Di LD

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  10. #30
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    Well, at the exhibit I have been shooting with the bears (polar & grizzly), it may be too long. I will keep the 50mm f/1.4 and the 28mm f/2.8 handy. Outdoors, I have the 70-400mm f/4-5.6 G SSM to do the heavy-lifting. The 85mm and the 70-400mm use the same size filter, so there is that benefit.
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

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