Pentax k1x0D long exposures (astro photography)

Discussion in 'Pentax' started by mirceaar, Sep 13, 2006.

  1. mirceaar

    mirceaar Guest

    It is yet quite hard to find at least several expert reviews on one of
    the 2 new Pentax DSLRs, so behavior at high ISO and long exposure i.e.
    5-10-15+ minutes is to me so far unknown.
    Is it better or worse than the Nikon's D50/D70 or one of the *ist
    series camera?
    Is it "improvable" by any means?
    (I am not discussing the Canon CMOS DSLR's on this issue, everyone
    interested knows they are the best for this kind of work)
    The Nikon's workaround for not having the dark frame extracted is, tho'
    efficient, quite barbaric IMHO. :)
    If I know well, the D80 has the possibility to disable this dark frame
    extraction feature. Also, from what I've read in the K100D's manual,
    there is also possible to disable Noise Reduction. If I know wrong,
    please correct me. How much improvement does that bring, if any?
    The low price on these cameras, together with the overall kit lens
    optics, construction and handling quality makes my wish gland drool.
     
    mirceaar, Sep 13, 2006
    #1
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  2. mirceaar

    Pete D Guest

    I have only done a few ten minute exposures but on my DS (and it should be
    similar) the DFS works quite well. I did some testing in a dark room and had
    some flare particularly at the edges that was dealt with apparently quite
    nicely by the DFS. Probably fairly similar to the Nikons with DFS.
     
    Pete D, Sep 13, 2006
    #2
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  3. mirceaar

    atasselli Guest

    High ISO is useless in any DSLR for astrowork. As for reports
    unfortunately I know of no one.
    I bet they're better than the *ist (far too noisy) and probably with
    more noise than the D50.
    They're not, except maybe the Da.
    Is not about the dark frame but rather about median filtering. Besides,
    it can be automated.
    Difficult to say without knowing exactly what it is supposed to do and
    what effectively does, isn't it?
    If you're happy with QE at best 2x of high end film than yeah,
    otherwise yawn..

    Andrea T.
     
    atasselli, Sep 13, 2006
    #3
  4. High iso (800 to 1600) is the preferred iso in DSLR
    astrophotography. E.g., see:
    http://www.dl-digital.com/astrophoto/Astro-Galaxies.htm

    quantitative analysis:
    Night and Low Light Photography with Digital Cameras
    http://www.clarkvision.com/photoinfo/night.and.low.light.photography
    Why? Until a test is done, you don't know. The two
    factors include read noise and dark current.
    Here are a couple of comparisons; I'll be adding more
    soon:
    Digital Cameras and Long Exposure Times:
    Noise and Dark Current Comparisons
    http://www.clarkvision.com/imagedetail/long-exposure-comparisons

    Scroll down to "Sensor Analysis" on this page:
    http://www.clarkvision.com/imagedetail

    Random noise is not filtered unless you average pixels.
    Do have actual info on the QE? If so, please provide
    a link. I would like to add data to my sensor analysis
    pages referenced above.

    Roger
     
    Roger N. Clark (change username to rnclark), Sep 14, 2006
    #4
  5. Take a look at what Buil says about the D70 (scroll down to "Raw file
    quality"):
    http://www.astrosurf.com/buil/d70v10d/eval.htm

    The D200 does the same thing (at least in my limited experimentation
    before finding more interesting things to do).
     
    achilleaslazarides, Sep 14, 2006
    #5
  6. Note followup.


    Of noise and such in digital cameras for astrophotography:
    Would you care to elaborate on that? I expect to make that decision in
    the medium term. I have a certain amount of Nikon glass and no Canon
    anything. If a Nikon D-80 lets me get reasonably close to a Digital
    Rebel XT I will be a happy camper.
    How is it automated? A pointer to some information would be fine.

    Question for mirceaar:
    May I ask where you got that information? It would be of considerable
    interest to me to be able to follow-up on it.

    - Shankar
     
    Shankar Bhattacharyya, Oct 16, 2006
    #6
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