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Thread: Multi-minute exposure with the P25

  1. #1
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    Multi-minute exposure with the P25

    I'm aware the P25 has some issues in design and therefore cannot do long exposures in the same way as P25+ despite using the same sensor. Heat transfer from battery and LCD I suppose. I'm after a low cost second hand back, and while I'd prefer the P25+ it is hard to come by second hand unlike the P25.

    With ISO50, f/11, center filter, early morning the official 32 second limit of the P25 is a little tight. I don't need 30 minutes, but 2 - 4 minutes would be nice.

    It looks like the P25 can be powered via the firewire cable, which might resolve some heat issues. Has anyone tested to do longer exposures in this mode?

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    Re: Multi-minute exposure with the P25

    IF you are trying to reduce battery heat it does help to have multiple batteries powering your Phase One back connected via a cable. You can do so with the Canon CH-910A



    You can also put much bigger batteries on the Canon CH-910A. Clean power makes quite a difference.

    Also there chargers are way better than the junk you get from Phase One.
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    Re: Multi-minute exposure with the P25

    Where online can I buy this new, not used? B&H and others indicate that this product has been discontinued but the Canon site still lists it on their site.

    Jack

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    Re: Multi-minute exposure with the P25

    Quote Originally Posted by FredBGG View Post
    IF you are trying to reduce battery heat it does help to have multiple batteries powering your Phase One back connected via a cable. You can do so with the Canon CH-910A
    How, exactly, does running remote batteries reduce the amount of heat at the sensor? Personally, I've never noticed the battery getting particularly warm, even during long exposures.

    The reason I ask is because, as it happens, I have one of these Canon chargers (it came with my used P30+ in lieu of the factory charger) and do a lot of long-exposure night photography in the desert southwest, where even at night, the ambient temps can be high enough to be problematic for digital backs.

    Thanks!

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    Re: Multi-minute exposure with the P25

    FredBGG posted this on LL around a year ago:

    "You could also get yourself one of these chargers by Canon.
    Dual charger with an external battery option. Lets you use even bigger batteries
    and keep the batteries warm if you are shooting in a cold climate and shooting long exposures.
    The dummy battery plate need a small modification so as to lock into the IQ and Credo backs.
    The dummy battery plate is thinner on one end so you need to take a shell off an old battery and
    attach it to the dummy battery plate.
    The charger also comes with a belt clip."

    Could you tell me the specifics or show me a picture of a CH-910A dummy battery modification for Phase One IQ backs? I know I will miss this ability for extra-long battery life when I upgrade from the P series and have the ability for very long exposures.

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