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Thread: Focus issue with DF

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    Focus issue with DF

    Hi all,
    I just wanted to post a quick note that I was having the DF hunt for focus a fair amount. Basically I could mount the camera on a tripod and point it at something fairly clear to focus on, and each press of the shutter would cause it to choose a different focus point, it seems to cycle through three imaginary focus points. A few attempts could get a decent focus.

    It felt annoying to use, but after a while I realised something was wrong. A ton of images were focused behind the subject (which seems to be the second press)

    Anyhow I carefully cleaned the mirror and the problem was solved as it seemed a little hazy. After that, focusing on the same object, same point it was bang on and would not hunt at all. Each shutter release simply did not change the focus and it remains fast and precise.

    Just for the record in case anyone else has similar issues.

    Paul

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    Administrator, Instructor Guy Mancuso's Avatar
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    Re: Focus issue with DF

    I can see that happen but never experienced it. Great info
    Photography is all about experimentation and without it you will never learn art.

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    Senior Member Thierry's Avatar
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    Re: Focus issue with DF

    Useful info, indeed.

    Thierry
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    Workshop Member Wayne Fox's Avatar
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    Re: Focus issue with DF

    Quote Originally Posted by wentbackward View Post
    Anyhow I carefully cleaned the mirror and the problem was solved
    Paul
    Just curious how you cleaned the mirror ... mine tends to change focus every time I press the button even when on a tripod ... sounds similar to what you described.
    Last edited by Wayne Fox; 28th July 2011 at 18:58.
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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Focus issue with DF

    I avoid the problem by setting up the rear AE lock button as my AF-ON select. Once it's focused using that button the AF doesn't move between shots. i've never really got on with auto-focus select from the shutter release for anything other than wildlife or action shooting with a 35mm DSLR.

    I use accurate mode, single selection. It wheezes in & out and eventually latches on to something ... eventually. (I'm not a big fan as you know ). If I'm shooting from a tripod I prefer to slip it into MF anyway.
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    Workshop Member Wayne Fox's Avatar
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    Re: Focus issue with DF

    Quote Originally Posted by GrahamWelland View Post
    I avoid the problem by setting up the rear AE lock button as my AF-ON select. Once it's focused using that button the AF doesn't move between shots. i've never really got on with auto-focus select from the shutter release for anything other than wildlife or action shooting with a 35mm DSLR.

    I use accurate mode, single selection. It wheezes in & out and eventually latches on to something ... eventually. (I'm not a big fan as you know ).
    Yes I use that button as well. But the camera will change focus with multiple presses. After 3 or 4 presses it seems to quit changing, so my current habit is press it over and over until it stops changing focus. I've never tested to see if that is more accurate than just pressing once and trusting it.
    wayne
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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Focus issue with DF

    Wayne, I tend to hold the AF-ON until focus is selected where I want it. I understand what you mean about the different selections when you press the button multiple times. For me, when I press and hold AF-ON it will typically hunt around a bit unless the subject is an easy lock. If I just press the button it'll find the first lock position. If I hold it for a bit longer and there are other valid targets it'll then zip between the other targets or take a firm lock. If the focus mode is on continuous then it'll start off again but I very seldom use that mode.

    The idea of cleaning the mirror and getting better focus response/accuracy actually doesn't sound unreasonable. If the image path to the AF sensor is dimmer or diffused than it should ideally be then I could see there being a drop off in contrast which I would easily believe would negatively affect AF lock performance.

    I still maintain that the best AF lens that Mamiya/Phase One make is the 120 macro.
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"

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    Re: Focus issue with DF

    Quote Originally Posted by Wayne Fox View Post
    Just curious how you cleaned the mirror ... mine tends to change focus every time I press the button even when on a tripod ... sounds similar to what you described.
    Hi Wayne, Yes this is quite a relevant point. I used a 35mm full frame sensor swab with the methanol based fluid that comes with them. I wiped it a few times (unlike the one time one side as with a sensor) as the main 'idea' was really to cover the whole mirror effectively and that the fluid leaves no residue.

    Paul

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