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  1. #61
    Join Date
    Feb 2006
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    Des Plaines, IL
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    Red face M.F.D. may be involved

    Like I said ... it is the real punch for having the TAMRON ... clearly, it's not perfect, but it is darn good!

    There also might have been a little bit of back-focusing involved, because I was really close to its M.F.D. ... which can trip a lens up. The camera may "approve" a shot, even though the focus is a little off. The PRIME is good down to 8-inches, where the 17-50 is around 18-inches. I will conduct other analysis, as time permits ... but the thrust of this was that the PRIME is really good ... and obviously, would be a clear asset on the α900.
    Last edited by DonSchap; 06-04-2009 at 11:40 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

  2. #62
    Join Date
    Dec 2006
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    God's Country - Australia
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    don under the conditions you tested almost any lens is gonna perform well. you could test out the kit lens, stop it down, add light and you have case for just sticking with the kit lens. if you;re buying a 20/1.8 lens to use in a light tent for product photography then you've wasted your money. where the sigma will shine is in low light. it will have better sharpness, better contrast, better AF and better colour than the tammie...by some distance.
    D800e l V3 l AW1 l 16-35 l 35 l 50 l 85 l 105 l EM1 l 7.5 l 12-40 l 14 l 17 l 25 l 45 l 60 l 75
    flickr

  3. #63
    Join Date
    Feb 2006
    Location
    Des Plaines, IL
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    Well, I am pressed for set-up time. I'll have more next week. This weekend is shot, already ... and it is not even Friday ... well, at least not HERE!

    f/2.8 is not all that closed down ... and I was not shooting the examples for noise determination, just a comparative focus test. Adequate lighting ... just makes it easier to see.

    Yes ... bigger tests lie in the future and it should be kind of fun to see "how low can you go."

    Thanks for the chime in ... we'll get there.
    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

  4. #64
    Join Date
    Feb 2006
    Location
    Des Plaines, IL
    Posts
    9,560

    Thumbs up Even wider ...

    Okay ... I finally got the TAMRON SP AF 14mm f/2.8 Aspherical (IF) Rectilinear lens. This one really pulls it wide on the A900 ( oh yeah, I still am missing the FF body ... hmmm, have to work on that. ) So my wide lenses are filled in ... with seriously wide aperture.

    Name:  SPAF14mmf28.jpg
Views: 50
Size:  343.8 KB

    I am not a big proponent of "second-hand" glass, and got this one off ebay ... but, this was purchased by the 'source' at a "close-out" sale and it is effectively "brand new" in the box w/ receipt. Yeah! Six-year warranty, starting now!

    I want to thank 'jimr-pdx' for the inspiration to seek out and obtain this lens.

    A couple examples ... soon.
    Last edited by DonSchap; 06-08-2009 at 04:35 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

  5. #65
    Join Date
    Jun 2008
    Posts
    2,204
    Wow, that would be ridiculous on an A900!
    flickr

    Canon 7D - 5D | 550EX - 430EX II - (2) PW FlexTT5 | 24-105 f4L | 70-200 f2.8L IS | 100 f2.8L IS | 50 f1.8 II

  6. #66
    Join Date
    Jun 2008
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    2,204
    Don't like to bump old threads, but I found myself trying to understand full frames better today and they really are just a larger frame. APS-C sensors are literally crops of the full frame, the bokeh is the same (the DOF is also the same). As Don pointed out however, the FOV (field of view) is different, much larger and wider. See here

    http://www.have-camera-will-travel.c..._sensor_-.html
    flickr

    Canon 7D - 5D | 550EX - 430EX II - (2) PW FlexTT5 | 24-105 f4L | 70-200 f2.8L IS | 100 f2.8L IS | 50 f1.8 II

  7. #67
    Join Date
    Feb 2006
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    Des Plaines, IL
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    Thumbs up Opening the history books ...

    There is nothing wrong with resurrecting old threads. In fact, that's how the research is done and newbies get a chance to review important aspects of the craft. Not everyone had a SONY A100 three years ago. A lot of what is relevant can be pulled right back into the forefront for all of the members.

    I had a member recently write me an IM and reference a posting of mine from 12/2007. It concerned lens repair, but is still just as pertinent NOW as it was then. So, relax about opening the door to the past. It is from there we often decide our future.
    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

  8. #68
    Join Date
    Dec 2006
    Location
    God's Country - Australia
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    Quote Originally Posted by dr4gon View Post
    APS-C sensors are literally crops of the full frame.
    what did you think it was ?
    the bokeh and dof are not quite the same either.
    D800e l V3 l AW1 l 16-35 l 35 l 50 l 85 l 105 l EM1 l 7.5 l 12-40 l 14 l 17 l 25 l 45 l 60 l 75
    flickr

  9. #69
    Join Date
    Jun 2008
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    2,204
    Quote Originally Posted by Rooz View Post
    what did you think it was ?
    the bokeh and dof are not quite the same either.
    Wait, what? I thought the DOF and Bokeh were pretty similar. Are they not supposed to be the same ? You would know now owning a D700.
    flickr

    Canon 7D - 5D | 550EX - 430EX II - (2) PW FlexTT5 | 24-105 f4L | 70-200 f2.8L IS | 100 f2.8L IS | 50 f1.8 II

  10. #70
    Join Date
    Dec 2006
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    God's Country - Australia
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    nope, not the same. if i take a photo with my 50mm lens at 1.4 its not the same bokeh or dof as if i took it with the d300. there are small differences in things like smoother colour transition, light to shadow transitions etc. small yes, but having shot the d300 i know when something looks a tad different. sometimes for the good, sometimes for the worse.

    while in essense what you said is correct, its not quite as simple as saying that aps-c is simply a smaller image circle. for example, the pixel photosites are completely different sizes on aps-c you are squeezing 12mp's into a smaller area. on FX you are squeezing the same amount of MP's onto a larger surface area. so it would make sense that there are small variations in the way these photosites respond to light etc.
    D800e l V3 l AW1 l 16-35 l 35 l 50 l 85 l 105 l EM1 l 7.5 l 12-40 l 14 l 17 l 25 l 45 l 60 l 75
    flickr

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