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  • 14-54 circular aperture - Ian eats humble pie!

    I have been asked a few times about the circular aperture 'feature' of the new Mark II Digital Zuiko 14-54 f/2.8-3.5, as changes to the optics comparared to the original we all know and love.

    I contacted Japan and the answer was that the optics were unchanged. It made sense and so I assumed that the old and new lenses also had the same aperture iris designs. This is what I have been telling people, but I was WRONG! Here's the evidence:


    At full aperture (f/3.5 @54mm) the iris shape is circular for both. This is because the iris blades don't come in to play when the lens is wide open.

    But in the lower pair of images, you can see that the Mark I lens, at f/5, definitely has a hexagonal outline, while the Marek II is still almost circular.

    So I apologise for my mistake and thank you to Kuifje and geohsia for prompting me to test the lens again in this thread:

    http://www.fourthirds-user.com/forum...ead.php?t=2886

    Ian (stuffed with humble pie - yum)
    Founder/editor
    Four Thirds User (http://fourthirds-user.com)
    Digital Photography Now (http://dpnow.com)
    Olympus UK E-System User Group (http://e-group.uk.net)
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    Twitter: www.twitter.com/ian_burley
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  • #2
    Re: 14-54 circular aperture - Ian eats humble pie!

    Interesting factoid, Ian, and explains a technical advance so that even I can understand it.
    Question, though, why are the images @ f5 so much brighter than those at f3.5?
    I would not expect any difference.


    The picture is the story, it is your history. dw.

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    • #3
      Re: 14-54 circular aperture - Ian eats humble pie!

      Originally posted by Imageryone View Post
      Interesting factoid, Ian, and explains a technical advance so that even I can understand it.
      Question, though, why are the images @ f5 so much brighter than those at f3.5?
      I would not expect any difference.
      Operator error (me!) I didn't use manual exposure. Sorry (again!)

      Ian
      Founder/editor
      Four Thirds User (http://fourthirds-user.com)
      Digital Photography Now (http://dpnow.com)
      Olympus UK E-System User Group (http://e-group.uk.net)
      Olympus camera, lens, and accessory hire (http://e-group.uk.net/hire)
      Twitter: www.twitter.com/ian_burley
      Flickr: www.flickr.com/photos/dpnow/
      Pinterest: www.pinterest.com/ianburley/

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      • #4
        Re: 14-54 circular aperture - Ian eats humble pie!

        or simply kinda logical guessing here... Assuming taken in A mode and figure the camera meter and set the shutter speed accordingly

        the lights in the F5 circular bokeh is more concentrated, and thus brighter?

        the light source emit costant amount of light, with wide open Aperture, those lights need to be spread through a bigger area, thus dimmer and more diffuse, vs the stopped down more concentrated and bigger?

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        • #5
          Re: 14-54 circular aperture - Ian eats humble pie!

          I can see a logic in your reply, bitslizer, but on the flagship camera of the range and all other factors being exactly the same in both sets of images. I would have expected the camera to automaticaly compensate to the same brightness.So I don't actually see how Ian could be at fault.
          You have to remember, I still use an old E-300 for certain types of image, so am very well used to slight deviations in exposures.
          It would be of interest to me to see the shutter timings for a comparison, Ian.


          The picture is the story, it is your history. dw.

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          • #6
            Re: 14-54 circular aperture - Ian eats humble pie!

            Originally posted by Imageryone View Post
            I can see a logic in your reply, bitslizer, but on the flagship camera of the range and all other factors being exactly the same in both sets of images. I would have expected the camera to automaticaly compensate to the same brightness.So I don't actually see how Ian could be at fault.
            You have to remember, I still use an old E-300 for certain types of image, so am very well used to slight deviations in exposures.
            It would be of interest to me to see the shutter timings for a comparison, Ian.
            Mk1 14-54 - f/3.5 @54mm, 0.6 sec
            Mk1 14-54 - f/5 @54mm, 1.3 sec
            Mk2 14-54 - f/3.5 @54mm, 1 sec
            Mk2 14-54 - f/5 @54mm, 2 sec

            My reason for being self-critical, is that both sets of exposures should have been identical. But I subscribe to the light concentration theory to explain why the smaller aperture discs appear brighter than the larger ones.

            Ian
            Founder/editor
            Four Thirds User (http://fourthirds-user.com)
            Digital Photography Now (http://dpnow.com)
            Olympus UK E-System User Group (http://e-group.uk.net)
            Olympus camera, lens, and accessory hire (http://e-group.uk.net/hire)
            Twitter: www.twitter.com/ian_burley
            Flickr: www.flickr.com/photos/dpnow/
            Pinterest: www.pinterest.com/ianburley/

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            • #7
              Re: 14-54 circular aperture - Ian eats humble pie!

              Thanks for the information, Ian, I in no way disagree with the theory, just thought the electronics should compensate.
              Very interesting to note, however, that in both tests, the Mk11 required a slower shutter speed than the Mk1 to obtain the same image.
              .4 @ f3.5
              .7 @ f5.0

              With .7 delay, I would expect the light emitted to the sensor would be enough to round the iris anyway, so is it a technical advance, or a little bit of flim-flam?
              So, on that note. if you were to reset the test using the same apertures and shutter speeds on both lenses, what would be the comparison then?.


              The picture is the story, it is your history. dw.

              Comment


              • #8
                Re: 14-54 circular aperture - Ian eats humble pie!

                Originally posted by Imageryone View Post
                Thanks for the information, Ian, I in no way disagree with the theory, just thought the electronics should compensate.
                Very interesting to note, however, that in both tests, the Mk11 required a slower shutter speed than the Mk1 to obtain the same image.
                .4 @ f3.5
                .7 @ f5.0

                With .7 delay, I would expect the light emitted to the sensor would be enough to round the iris anyway, so is it a technical advance, or a little bit of flim-flam?
                So, on that note. if you were to reset the test using the same apertures and shutter speeds on both lenses, what would be the comparison then?.
                OK, I will re-do the test under better controlled conditions, over the weekend.

                Ian
                Founder/editor
                Four Thirds User (http://fourthirds-user.com)
                Digital Photography Now (http://dpnow.com)
                Olympus UK E-System User Group (http://e-group.uk.net)
                Olympus camera, lens, and accessory hire (http://e-group.uk.net/hire)
                Twitter: www.twitter.com/ian_burley
                Flickr: www.flickr.com/photos/dpnow/
                Pinterest: www.pinterest.com/ianburley/

                Comment


                • #9
                  Re: 14-54 circular aperture - Ian eats humble pie!

                  Maybe also good to note that there seems te be a difference in maximum apperture in respect to focal length. The MK II seems to hold its brightness longer then the MK I.

                  Looking forward to the result (and ofcourse of it bests the PL 14-50 .. )

                  Martin

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                  • #10
                    Re: 14-54 circular aperture - Ian eats humble pie!

                    Originally posted by Kuifje View Post
                    Maybe also good to note that there seems te be a difference in maximum apperture in respect to focal length. The MK II seems to hold its brightness longer then the MK I.

                    Looking forward to the result (and ofcourse of it bests the PL 14-50 .. )

                    Martin
                    I've decided to expand the scope a bit and to test defocussed aperture disc shapes for a range of lenses:

                    DZ 14-42
                    DZ 14-45
                    DZ 17.5-45
                    DZ 14-54 I & II
                    DZ 14-35
                    DZ 12-60
                    DZ 50-200 (old and new versions)
                    Panasonic Leica 14-50 f/3.5-5.6

                    I'd like to include the old and new versions of the DZ 40-150, but I don't have either at the moment. If anyone reasonably local to me can help, do let me know.

                    The idea is to test at full aperture and f/8 at as close to 50mm focal length as possible.

                    Hopefully I can get this done by the end of the coming week.

                    Ian
                    Founder/editor
                    Four Thirds User (http://fourthirds-user.com)
                    Digital Photography Now (http://dpnow.com)
                    Olympus UK E-System User Group (http://e-group.uk.net)
                    Olympus camera, lens, and accessory hire (http://e-group.uk.net/hire)
                    Twitter: www.twitter.com/ian_burley
                    Flickr: www.flickr.com/photos/dpnow/
                    Pinterest: www.pinterest.com/ianburley/

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                    • #11
                      Re: 14-54 circular aperture - Ian eats humble pie!

                      Will be looking forward to the results!

                      Ehh .. not really helpfull but incase you hop over to the Netherlands I have the DZ 40-150 bright version and the 14/50 Elmarit (old version) here

                      Can I maybe suggest to include the "master of dof" at 50mm, the 50mm f2 macro? Hope I am not over asking, ..

                      Martin

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                      • #12
                        Re: 14-54 circular aperture - Ian eats humble pie!

                        Originally posted by Kuifje View Post
                        Will be looking forward to the results!

                        Ehh .. not really helpfull but incase you hop over to the Netherlands I have the DZ 40-150 bright version and the 14/50 Elmarit (old version) here

                        Can I maybe suggest to include the "master of dof" at 50mm, the 50mm f2 macro? Hope I am not over asking, ..

                        Martin
                        Yup - I have the 50 f2

                        Ian
                        Founder/editor
                        Four Thirds User (http://fourthirds-user.com)
                        Digital Photography Now (http://dpnow.com)
                        Olympus UK E-System User Group (http://e-group.uk.net)
                        Olympus camera, lens, and accessory hire (http://e-group.uk.net/hire)
                        Twitter: www.twitter.com/ian_burley
                        Flickr: www.flickr.com/photos/dpnow/
                        Pinterest: www.pinterest.com/ianburley/

                        Comment


                        • #13
                          Re: 14-54 circular aperture - Ian eats humble pie!

                          A pedantic issue, Ian, but isn't the shape of the oof areas on the old 14-54 octagonal, rather than hexagonal?

                          edit...or rather perhaps heptagonal? Since there are seven blades?

                          Last edited by Hokuto; 5th January 2009, 09:26 AM. Reason: added info
                          "...and only the stump, or fishy part of him remained."
                          Green Gables: A Contemplative Companion to Fujino Township

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                          • #14
                            Re: 14-54 circular aperture - Ian eats humble pie!

                            Originally posted by Hokuto View Post
                            A pedantic issue, Ian, but isn't the shape of the oof areas on the old 14-54 octagonal, rather than hexagonal?

                            edit...or rather perhaps heptagonal? Since there are seven blades?

                            Hehe! Yup - I now count seven blades so I think we agree on heptagonal

                            Ian
                            Founder/editor
                            Four Thirds User (http://fourthirds-user.com)
                            Digital Photography Now (http://dpnow.com)
                            Olympus UK E-System User Group (http://e-group.uk.net)
                            Olympus camera, lens, and accessory hire (http://e-group.uk.net/hire)
                            Twitter: www.twitter.com/ian_burley
                            Flickr: www.flickr.com/photos/dpnow/
                            Pinterest: www.pinterest.com/ianburley/

                            Comment


                            • #15
                              Re: 14-54 circular aperture - Ian eats humble pie!

                              Originally posted by Ian View Post
                              Hehe! Yup - I now count seven blades so I think we agree on heptagonal

                              Ian
                              What beats me is why the first version was not equipped with these rounded blades, there is only one extra blade and the actuator looks the same so it can't have been the extra cost.
                              Regards,
                              Henk

                              http://mordisco.smugmug.com

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