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Thread: Sony 24-70 F2.8 GM Tests

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    Re: Sony 24-70 F2.8 GM Tests

    Seb, if Shaun says that it is sharp in the center, it is obvious where he focused it. No?

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    Re: Sony 24-70 F2.8 GM Tests

    Quote Originally Posted by Vivek View Post
    Seb, if Shaun says that it is sharp in the center, it is obvious where he focused it. No?
    I did see sharpness thests where that was not given. Or there was something in the center that was not flat at all. To judge DOF and field curve it's vital to know where exactly was the focus peaking point. And if the shot is at f8 I don't want to guess if he did focussed on the wall or at the bird house just next to it or the front side of the car to the left or...

    I rather want to use this time to find out what the issue is and help. Therefore it's good to see a picture and know how the test was done.
    Last edited by seb; 7th September 2017 at 11:33.

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    Re: Sony 24-70 F2.8 GM Tests

    I had no idea focusing was that complicated with a Sony camera! So much for "live view" and focusing off the sensor plane!

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    Re: Sony 24-70 F2.8 GM Tests

    It may sound funny that I'm asking about the focus point but...
    1. A lens can have different center-midframe-corner sharpeness, distortion (the correction will reduce sharpness) and a curved focus field. And all that may differ with FL, aperture and focus distance.
    2. And it may have a quality-issue because it is decentered or has a tilt-shift: https://www.lensrentals.com/blog/201...-lens-testing/
    3. But there can be also just a bad test setup.

    A quality-issue:
    Here is an example of a 24-70/2.8 GM "testshot". The lens is heavily tilted (https://www.dpreview.com/forums/post/58681273):


    Especially with tilted lenses it's very difficult to judge the lens if you don't know where the focus point was.

    A bad setup:
    Another one. This was with the 28/2. The guy complained that the head is sharp but not the feet of the model and said his lens may be tilted:


    But it was probably only a bad test setup (blue lines does show the additional blur due to the heavy distortion):


    Thanks to the picture and he said where the focus point was, it was possible to find out the reason. If the focus point was on her hip (which is as sharp as the head and is in the center of the picture) the feet should be as sharp as the head.

    or just a lens with soft corners:
    If you look at Philipp Reeves Review, the lens has soft corners on certain FL+aperture combinations: https://phillipreeve.net/blog/review...2-824-70mm-gm/
    Lens Rentals shows also some softness after the first third between center and corners at FL24: https://www.lensrentals.com/blog/201...ariance-tests/

    Without a comparison shot, it's difficult to say if the lens is more soft or not.

    edit: here is a good test beside the test of Roger Cigala on lens rentals: Lens screening testing

    Quote Originally Posted by Vivek View Post
    I had no idea focusing was that complicated with a Sony camera! So much for "live view" and focusing off the sensor plane!
    @Shaun: your page is very inspiring. It's a very nice portfolio. I hope I would come close to such a mood and quality once.
    Last edited by seb; 8th September 2017 at 08:57.

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    Re: Sony 24-70 F2.8 GM Tests

    Most issues you list, Seb, relates to the QC of the lens. The other stuff related to set up is from lack of basics.

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    Re: Sony 24-70 F2.8 GM Tests

    Ah well... a nice summary!

    Quote Originally Posted by Vivek View Post
    Most issues you list, Seb, relates to the QC of the lens. The other stuff related to set up is from lack of basics.

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