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07-29-2010, 10:51 AM   #1
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K-x owners - pls comment on negatives (per Dpreview)

So I ordered the Pentax K-x (as a supplement to my K20D). Its shipped out today.

But I could not help but wonder about the following negatives .... per the dpreview review.

  • Tendency to clip highlights in high-contrast scenes
  • Relatively little RAW headroom means it is difficult to pull back blown detail even when shooting RAW
  • Shake-reduction not too efficient
  • Unreliable Auto White Balance in artificial light (but very good presets and WB fine tuning)
  • ISO in movie mode is capped which can result in underexposed videos

Now FWIW ... I always shoot in raw and mostly in Manual Mode ... and I always shoot with center-point focus only and none of the above has been experienced with my beloved K20D.

With that in mind ... can some of the K-x owners give their take ? Thanks !!!

Max


Last edited by vulcanman; 07-29-2010 at 01:13 PM.
07-29-2010, 12:32 PM   #2
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High contrast scenes are bad for any camera.

WB has a tungsten setting - for a reason.

If you don't have issues, I would not worry about them.
07-29-2010, 01:06 PM   #3
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If you only shoot raw, why did you bother listing AWB as an issue?
07-29-2010, 01:11 PM   #4
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QuoteOriginally posted by Ira Quote
If you only shoot raw, why did you bother listing AWB as an issue?
Good point.

07-29-2010, 01:13 PM   #5
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Tendency to clip highlights in high-contrast scenes

Relatively little RAW headroom means it is difficult to pull back blown detail even when shooting RAW


OK, but only in Matrix metering mode. I use CW on the K-x to avoid these. The K20D meters much more reliably than the K-x in Matrix mode.

Shake-reduction not too efficient

I haven't seen the problem. I suspect the reviewer had shakey hands.

Unreliable Auto White Balance in artificial light (but very good presets and WB fine tuning)

I disagree. I find the K20D AWB better in natural light, but the K-x AWB easily beats the K20D in artificial light. I would say it's as good as any DSLR in artificial light.

ISO in movie mode is capped which can result in underexposed videos

What's movie mode?
07-29-2010, 01:38 PM   #6
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Regarding unreliable auto white balance under artificial lighting, I assume that the kx's awb range is 4000-8000K, just like the K100D and K-7.

Most artificial light has a color temperature that is outside this range.

It is not realistic to expect awb to perform reliably outside its range.
07-29-2010, 02:11 PM   #7
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Thanks all for your thoughtful responses. Have a wonderful day !
07-29-2010, 02:21 PM   #8
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The K20D, unless I heard wrong, and the K-X, have identical dynamic ranges. If anything, the K-X has a better dynamic range.

Makes me wonder if the reviewer was using the dynamic range 200% setting to his disadvantage, as it can cause problems with noise or blown highlights. I can also help, but you have to use it properly.

White balance is only an issue in JPEG land, but really, every camera has that issue to a certain extent and RAW obliterates the problem. Everything automated only works, at best, in 90% of cases, which is why you need to learn how to use your camera in manual no matter the feature set.

Finally, yes, in-body shake reduction is less effective. I've heard that it is about 1 stop less effective than lens shake reduction. But consider the pros!

1) I can buy a 20 year old, 50 dollar lens and it will have shake reduction.
2) In reality, in body stabilization works to a point where you would need to be shooting still subjects anyways for an extra stop to be useful.

So really, the shake reduction "problem" only occurs if you are indoors shooting a test chart or still life. In most situations, you need you shutter speed faster than 1/30, which is where I find shake reduction begins to break down. Furthermore, in long telephoto situations, where the extra stop is more helpful, you are talking about adding hundreds of dollars to a very expensive lens to get image stabilization.

I recently bought a cheap 70 - 210 mm zoom for 30 bucks, and it has stabilization thanks to my K20D. Sure it does not perform as well as a 1300 dollar canon zoom with stabilization in the lens but come ON.

Price performance dictates that in body stabilization is the way to go. If you are a paid sports photographer, you likely aren't considering the K-X anyways.

07-29-2010, 02:59 PM   #9
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Well, I find my Kx to behave more or less just like my K7 (got both) regarding highlights in bright, contrasty scenes (like sunny day out) : it needs -1ev to preserve them.

On the other hand, with overcast/shadow/indoor scenes, they both can take +1ev...

"Little RAW headroom" is just saying the same thing as "the camera renders highlights at the most of available data", that's all... Would be no point in having a camera capturing one extra stop but not using it in the JPG conversion...

What is important to me is the amount of data between highlights and shadows, and the Kx simply have one the the best APS-C DR around... OK, so you have to be careful in bright daylight, but that's ok by me...

AWB is not a problem for me, I find it does a nice job in tungsten, leaving a warm cast to the pic quite truthful to the scene...

Regarding the movie mode, well, I don't know if iso is limited, but the K7 behaves just like it (I made the test yesterday!)...
07-29-2010, 03:09 PM   #10
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QuoteOriginally posted by vulcanman Quote
So I ordered the Pentax K-x (as a supplement to my K20D). Its shipped out today.

But I could not help but wonder about the following negatives .... per the dpreview review.

  • Tendency to clip highlights in high-contrast scenes
  • You shoot in manual mode, this doesn't mean anything. This is a knock on the K-x's automatic metering and the fact that its ISO is closer to what it states. Many brands's ISO is less than what they state, and they push the shadows in order to get a non-linear highlight range. Fact is all sensors capture highlights linearly (film is different).
    QuoteQuote:
  • Relatively little RAW headroom means it is difficult to pull back blown detail even when shooting RAW
I believe this is another knock on the metering since they are only referencing blown detail (highlights, as opposed to black crush), since their figures show the total DR of the K-x is above all the other cameras compared. As long as you expose correctly, you will have MORE headroom.
QuoteQuote:

  • Shake-reduction not too efficient
  • True. Though it somewhat depends on your shake profile. There are other advantages to in-body IS, though, as you know.
    QuoteQuote:

  • Unreliable Auto White Balance in artificial light (but very good presets and WB fine tuning)
  • I find the K-x pretty spectacular in incandescent, and you're shooting RAW anyway.
    QuoteQuote:

  • ISO in movie mode is capped which can result in underexposed videos
  • Isn't this always the case? All cameras stop HW analog ISO amplification at 1600, but perhaps other cameras have more powerful processors.
    QuoteQuote:
    QuoteQuote:
    Now FWIW ... I always shoot in raw and mostly in Manual Mode ... and I always shoot with center-point focus only and none of the above has been experienced with my beloved K20D.

    With that in mind ... can some of the K-x owners give their take ? Thanks !!!

    Max
    07-29-2010, 04:52 PM   #11
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    Tendency to clip highlights in high-contrast scenes
    To a degree it does. Interestingly dpreview said the same of the Nikon D90, which shares pretty much the same sensor as the K-x.

    Relatively little RAW headroom means it is difficult to pull back blown detail even when shooting RAW
    Disagree. There is an awful lot of depth in the K-x RAW. More so in the shadows than the highlights perhaps, but there is useful info in there even in the highlights. This issue is also VERY dependent on the RAW processor you use. DCU4, DXO Optics Pro and LR3 do very well, I've found, working the K-x DNG's.

    Shake-reduction not too efficient
    Meh. The K-x results are the same for any Pentax in-body SR

    Unreliable Auto White Balance in artificial light (but very good presets and WB fine tuning)
    Disagree. Most times - even under stage lighting - the K-x nails the WB very well.

    ISO in movie mode is capped which can result in underexposed videos
    Not an issue I've ever seen. Maybe.
    07-29-2010, 06:14 PM   #12
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    QuoteOriginally posted by vulcanman Quote
    So I ordered the Pentax K-x (as a supplement to my K20D). Its shipped out today.

    But I could not help but wonder about the following negatives .... per the dpreview review.

    • Tendency to clip highlights in high-contrast scenes
    • Relatively little RAW headroom means it is difficult to pull back blown detail even when shooting RAW
    • Shake-reduction not too efficient
    • Unreliable Auto White Balance in artificial light (but very good presets and WB fine tuning)
    • ISO in movie mode is capped which can result in underexposed videos

    Now FWIW ... I always shoot in raw and mostly in Manual Mode ... and I always shoot with center-point focus only and none of the above has been experienced with my beloved K20D.

    With that in mind ... can some of the K-x owners give their take ? Thanks !!!

    Max
    1) Yes, it clips highlights. All models in this price range do. It's part of the sensor. As with film, there's tradeoffs.

    2) I see between 2 and 3 stops headroom. Less in very dark or very bright scenes. Not unusual.

    3) WB is OK, DPReview has way too high standards. WB will always be tricky without a site reference.

    4) ISO in movie mode errs on the side of underexposure. This is a good thing because you'll at least capture motion without getting the blinding, no detail glare. Again, it's a necessary tradeoff.
    07-29-2010, 06:55 PM   #13
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    Just to reiterate (please educate me if I am wrong), all digital sensors clip highlights just the same. Light levels are light levels, and sensors collect it all linearly (and not compressed like film).

    Now, JPEG processing is different. The reason why many cameras in this class, compared to the K-x, have compressed highlights, is because their ISO sensitivity is less than the K-x (see DxO mark) and they apply a different tone curve, effectively pushing shadows like "highlight correction" on the K-x but to a lesser extent.

    More headroom in the shadows? It's only because of metering. You apply -0.5 EV and that headroom shifts from the shadows to the highlights.
    07-30-2010, 06:39 PM   #14
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    QuoteOriginally posted by vulcanman Quote

    • Tendency to clip highlights in high-contrast scenes
    I'm probably not the best person to remark on this coming from a Panasonic FZ50 with rather limited DR, but I've personally found the DR of the KX to be excellent.

    QuoteOriginally posted by vulcanman Quote
    • Relatively little RAW headroom means it is difficult to pull back blown detail even when shooting RAW
    I don't shoot RAW very often.

    QuoteOriginally posted by vulcanman Quote

    • Shake-reduction not too efficient
    Don't know what the reviewer is used to, but I have found this to be true at all.

    QuoteOriginally posted by vulcanman Quote
    • Unreliable Auto White Balance in artificial light (but very good presets and WB fine tuning)
    I did find this to be the case -- my previous cameras (Panasonic FZ50 and Olympus E-500) had better AWB, but I have found the presets to be better in the KX than my previous cameras, so that's an easy work-around.

    QuoteOriginally posted by vulcanman Quote
    • ISO in movie mode is capped which can result in underexposed videos
    Well, I guess I'm not shooting video of a black cat in a dark room, because I haven't had a situation where 1600 ISO isn't enough.

    -- Chris
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