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Thread: Pentax 645D questions

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    Pentax 645D questions

    Just purchased a 645D and was wondering about write times.
    I have it set up for DNG and using a 16gig Sandisk Extreme 30mb/s class 10 card in slot 1. From the time I take the shot until it is displayed on the LCD is a few seconds. Counting slowly after taking the shot the image appears after a count of 10 and the light stays on until about 12 is this normal writing time? Also is there a difference speed or quality wise between PEF and DNG?

    Thanks

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    Re: Pentax 645D questions

    Yes, the write times are slow--the problem of large image files (but still faster than Polaroids). The auto lens correction can add to that time. Disable that in the menu. There is no difference in write time for PEF and DNG. However the buffer is fairly large and so capture rate is not really affected by write time until the buffer fills. I have yet to hit that.

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    Re: Pentax 645D questions

    Ok good. The write times are similar to my M9 before they corrected it with a firmware update. Does it make a difference if you turn off lens correction to the raw image? I do have that turned on but it seems that LR recognizes the 55mm lens I have and there is a correction profile for it, not sure if it does the same for the 120 macro I have. Thanks for the info. Any other tips I should know as I am going into this camera blind?

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    Re: Pentax 645D questions

    I have heard that auto correction does change RAW write speed--I have not tried it. ACR has a lens correction for the FA lenses. If you have the A 120, I think you can ask ACR to use the FA setting.

    I think many Pentax users are still finding out about the camera, but slowly the secrets are coming out. I have been pushing it with long exposures and high ISOs. The good news is I am impressed and pleased. The Pentax Forum is another good place to go for answers.

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    Re: Pentax 645D questions

    Great, I will try it out. Thanks again.

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    Re: Pentax 645D questions

    HI Tim,

    Nice to see another 645D shooter. Tim I recently did a test with a variety of SDHC and SDXC cards to see if I could find one that would increase write times (shooting DNG). Unfortunately compared to my middle of the road Transcend 16 or 32 GB SDHC cards, I couldn't find a single other card that wrote images faster nor displayed the image quicker on the LCD screen. That was whether I timed with taking a single image or a burst of images till the buffer was full and processed them all. Some of the cards I tried were the fastest (and most expensive) on the market, including the most recent Sandsik and Lexar cards...and not one helped. The bottle neck seems to be the 645D processor and associated electronics, unfortunately. Since you also shoot with the M9, you're well aware of a similar situation. Anyhow, the buffer size in the 645D is pretty good, so at least that helps quite a bit. It appears Pentax, in order to keep the price down on this camera, had to economise in certain catogories and this appears to be one of them. Still all in all a great camera to shoot with. Enjoy it!

    Dave (D&A)
    Last edited by D&A; 25th June 2011 at 06:31.

  7. #7
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    Re: Pentax 645D questions

    I have just bought a new Pentax 645D. Can anyone tell where in the camera menu I can find info about the FW version installed?

    thanks in advance,

    Jeff

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    Re: Pentax 645D questions

    Quote Originally Posted by Shashin View Post
    Yes, the write times are slow--the problem of large image files (but still faster than Polaroids). The auto lens correction can add to that time. Disable that in the menu. There is no difference in write time for PEF and DNG. However the buffer is fairly large and so capture rate is not really affected by write time until the buffer fills. I have yet to hit that.
    It's not be accurate to say that's a "problem with large file sizes".

    Other higher-end systems produce much larger files and write them much faster. It just requires equally increased hardware/firmware/design to accommodate the larger files.

    A lot happens between the shutter release and the image being stored. The Phase One IQ series has a Phase One designed custom quad-core processor and auxiliary processors dedicated specifically to processing, displaying, and storing the image. Phase also uses dedicated hardware to compress the image prior to it entering the buffer (a method which is patented) which greatly increases potential throughput. They will also soon be releasing firmware to support UDMA7 (which supports up to 100 megabytes per second).

    This is Pentax's first foray into dealing with medium format sensors and the files that go along with them. Much like Leica's M8 first foray into a high res digital sensor. The process of tweaking hardware, firmware, and interface to maximize throughput often takes a full generation of equipment.

    Hopefully the hardware in the 645 will support better performance through firmware tweaking and implementation of e.g. the UDMA7 spec for CF cards. But it's impossible to tell in advance how far a system's overall performance can be improved until the work is actually done.

    And to be fair, Pentax specifically markets this camera to landscape photographers (not that they 100% ignore other markets, but this is their primary push). So for them to include the R+D, and hardware, to increase performance in this area would either increase the price or decrease the resources available for other features - all for a feature not especially important to their main market.

    As another reference point compare the Pentax 645 to a Mamiya ZD. Even though the Pentax is twice the resolution it is significantly faster in writing to the card and reviewing the image.

    So anyway, it's not just the size of the image.

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    Re: Pentax 645D questions

    Doug, thanks. I did understand that, but my point was folks focus so much on the hardware, they sort of let the fact slip that the files are also a lot bigger than their DSLRs make and they tend to think processing is a free ride. Pentax had to keep prices down somewhere along the image chain.

    But I am glad I caught you. Since I would also need a body, could you get me a new IQ140 for about eight grand?

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