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Thread: Auto Focus in Floresent Ligt

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    Default Auto Focus in Floresent Ligt

    Can anyone explain why I have a hard time getting Focus Lock under good fluorescent lighting, such as an office or school classroom. I can get fairly quick, if not instant, lock in my den (about 18x25 feet) which has dark paneling, two 100w tungesten table lamps, textured ceiling, basically a poorly lit cave. But in a well lit, office, store or classroom, sometimes it seems as if I will never get a lock. I am using the E-450 with 14/42 and 40/150 kit lens. This happens at all f stops and focal lengths. It also occurs with a minolta 1.4 50mm with an AF confirm adapter, that is to say, when I manually focus, the focus confirm led may never come on. Additional info, added focus screen from jinfinance. But had the same problem before adding screen. Also using Auto WB. Any info, as to cause and/or cure would be greatly appreciated. I am getting embarassed by cankion owners who have about the same speed lens but get really fast focus in same lighting conditions. Really embarassed by my wife who has a Cannon A470 PS and keeps asking me to tell her again why my camera cost so much more than hers.

    Your assistance will be greatly appreciated.
    Last edited by Burcham; 08-24-2012 at 08:55 PM. Reason: spelling
    Dave

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    Kodak Brownie Bullet, and 1 E-450 of the 7 ever sold.

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    Default Re: Auto Focus in Floresent Ligt

    I cannot provide a technical explanation, because I do not understand how Phase-Detect-AF works. The problem you describe probably happens due to the fact that fluorescent lighting is not continuous, but rather strobes of light at twice the AC supply frequency.

    Moshe

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    Default Re: Auto Focus in Floresent Ligt

    Try to carefully blow out the AF trench (at the bottom of the mirror box) with a Rocket Blower.
    Motto: Wildlife won't come to me unless I go to it.
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    Default Re: Auto Focus in Floresent Ligt

    Thanks Moshe and Jebir,
    I have cleaned out the mirror box as suggested, there was very little dust in there, and also blew out the trench I didn't see anything, but blew it out just in case. It will be tomorrow before I can check to see if the problem I have was cured by the actions suggested and preformed. I did notice that the mirror had some kind of residue on it as from cleaning and the solution used dried in streaks from the top to the bottom. I bought the camera new, and have never cleaned the mirror and never noticed this streaking before, but have not really inspected it very closely. I suppose it could be the result of humidity condensing and drying on the mirror. Does any one suggest cleaning this off. If so what to use for a cleaning solution?

    Thanks for Your Help
    Dave

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    Kodak Brownie Bullet, and 1 E-450 of the 7 ever sold.

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    Default Re: Auto Focus in Floresent Ligt

    That must have been the problem, I went to the same location I had problems focusing last week, and had no problems whatever. There must have been more dust than I thought. Any Ideas about cleaning the mirror?

    Thanks
    Dave

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    Kodak Brownie Bullet, and 1 E-450 of the 7 ever sold.

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    Default Re: Auto Focus in Floresent Ligt

    Your'e welcome!

    Regarding the mirror, I strongly recommend NOT to clean it by other means than gentle blowing.

    Could you please clarify where how you see the specks? I would not bother if they are not seen through the viewfinder. If they are seen through the viewfinder - then it is not the mirror that needs cleaning but the focusing screen (in the ceiling of the mirror box). Also the focusing screen should only be blown off unless you take it out - then it can be wet cleaned and blown dry. The fine pattern is very sensitive to scratches.

    Cheers, Jens.
    Motto: Wildlife won't come to me unless I go to it.
    --------------------------------------------------------
    My Wildlife Photos: jensbirch.smugmug.com

    E-5, E-3, E-510, IR-E-1 ,E-P2
    ZD: 7-14, 14-54, 50, 50-200 SWD, 90-250/2.8, 300/2.8, EC-14, EC-20
    Peleng 8mm fisheye, shift Tamron SP 17/3.5, Tokina AT-X 300/2.8
    FL-50R, FL-40, FL-20, HLD-2, HLD-4, cleaved ZD EX-25 w. electric bypass, 250D, 500D, KatzEye Plus OptiBrite
    Feisol CT-3472LV and CM-1471

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    Default Re: Auto Focus in Floresent Ligt

    Thanks for your Interest Jebir. What I am seeing is streaks on the mirror, sort of like washing a crystal glass with water, and letting it air dry. The only way I can see the streaks is with a high intensity flashlight shining at an angle on the mirror. There are no "specks" visible, and when I point the camera at the sky, or bright light, no specks are visible in the view finder.

    Thanks
    Dave
    Dave

    ____________________________________________

    Kodak Brownie Bullet, and 1 E-450 of the 7 ever sold.

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