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Thread: Sigma DP2M colour casts/filters

  1. #1
    Senior Member Tim's Avatar
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    Sigma DP2M colour casts/filters

    Hi all,

    There has been a lot of discussion on the web with regards the Sigma DP2 Merrill and green/magenta casts.
    Many believe the IQ from the DP3 to be a little better than the DP2M, the files being cleaner more neutral.

    I generally don't notice much in the way of casts in my DP2M images but have seen some bad examples here and there. I am wondering if a possible reason is the use of a UV or skylight filter? I did apply one on my DP2M for a while. I would leave the lens cap off, camera at the ready, all I had to do it power up and shoot. I did notice a change in the files. I've since removed the filter.

    Over on Photographers Lounge it was noted that a Sony RX1 was yielding distortion on the left and right edges of the image. The culprit was no other than the UV filter. It somehow making people and items on the frame edges fatter. Strange but it was reproducible effect.

    This led me to ponder what effects a UV filter has on any sensor/lens, but in particular if DP2M users would chime in. Do you use a UV on your Sigma? Have you tried images with and without?

    The filter I had used was a Kenko. Perhaps some brands are more suitable.
    I think I am now a no filter convert.

    On another note I recently tried an older Olympus polariser, it was a circular type but the resulting images looked like there was haze or fog. The reverse of what was wanted was achieved.

    Thanks in advance.

    Tim

  2. #2
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    Re: Sigma DP2M colour casts/filters

    For a long time I dont use UV or skylight filters, if I want my DP2m to be ready without cap I have the sunshade attached.

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    Senior Member darr's Avatar
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    Re: Sigma DP2M colour casts/filters

    A cheap filter can change the quality of the light that hits the sensor and produce bad results. I use Rodenstock filters on my Sigma Merrills, and have used B&W UV filters at one time with no negative results. Quality filters are expensive, but so are good lenses.
    "Creativity takes courage." ~ Henri Matisse
    Darlene Almeda, photoscapes.com

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    Re: Sigma DP2M colour casts/filters

    Funny timing, this thread - I am about to post a foveon/filter question myself, but I won't hijack this one, I'll start another.

    I did do some general tests a few years ago and found that stacking filters was a really bad idea. My results showed that one filter alone only made the slightest difference to sharpness (on film, this was) but two filters gave a loss in resolution of over 10%.

    Because of this I got into the habit of not using filters at all, unless absolutely necessary.

  5. #5
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    Re: Sigma DP2M colour casts/filters

    b w mrc ones are the best, i cant tell the difference between no filter and b w filter.

    the non mrc ones might not be good, ive got a couple and they deffo affect things and make things "glowy".

    i had a sigma branded one that caused nasty flairs, but the larger 77mm one on my 10-20 has been ok.

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