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12-12-2011, 08:59 PM   #1
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K-x vs. K-5 Low light, High ISO Rating

If you go to the end of the K5 or Kx review at dpreview.com, you'll find an interactive comparison chart to compare almost all active and some inactive cameras. Interestingly enough, the Kx is shown to outperform the K5 from a Low Light, High ISO standpoint. Does anyone believe this to be true?

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12-12-2011, 09:23 PM   #2
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That's more of a subjective rating- a better estimate would be to look at the DxO scores (which outrank the K-x in both dynamic range and sensitivity).

Basically, the IQ of the K-5 is the best of any Pentax DSLR to date.

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12-12-2011, 10:27 PM   #3
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Agreed, the K-x holds up very well against the K-5 in most purely visual comparisons, up to only the highest ISOs. As a cam, the K-x is a great little thing that has always punched above it's weight.

But as Adam says: if you want to look at it objectively, the guys at DxO Labs have done the measurements and lab tests, and the data shows that technically the K-5 beats out the K-x in every element of IQ.

The IQ differences between the K-5 and K-x may not always jump out at you, but they certainly are there.
12-13-2011, 12:40 AM   #4
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While I agree that objective measurements take any subjective bias out.
However photography is a visual media -
and more often than not our eyes are the final judge -
but I will take the point that one's own judgement may not necessarily apply to anyone else.

I like displaying these from dpReview.com on the Pentax K-5 -
ISO6400:

I find ISO6400 is about the highest practical limit for noise.

RAW:


ISO12800:


RAW:


12-13-2011, 06:27 AM   #5
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QuoteOriginally posted by careboy Quote
Ahh! I stand corrected then, Thanks for clearing that up.
Were you replying to a different thread?

In regards to the current discussion, I find it very hard to call a winner in some of the comparison images, especially the RAW images. I agree that the K-x is, and has been, an amazing value.

When I was upgrading from my Olympus e-510, I wanted something that excelled at high ISO. I originally bough the Canon T2i ($900) when it first came out. But then when I found out I could get the K-x for HALF the price, I bought the K-x and returned the t2i. I actually owned both cameras at the same time for a few days, and was able to compare the two cameras head to head, and found that the K-x did not give up any image quality to the t2i, even at high ISO. I used the money I saved with the K-x to buy the Tamron 28-75mm f2.8.

Last edited by Edgar_in_Indy; 12-13-2011 at 09:40 AM.
12-13-2011, 06:52 AM   #6
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I always like the K-x a few quirks but nice camera overall and a killer price/bang per buck ratio.
Maybe the colours a little strong at times I used to tweak that down in camera a bit.

High ISO whilst I think the 16mp CMOS is a bit better the 12mp CMOS is pretty close I never worried about shooting even up to ISO 6400 with care you could get some excellent results.
I did miss the lighting AF points a bit that meant I used the centre point more, battery indicator never really worked great but a minor complaint. I can see why the K-x was a hit killer IQ and good spec for a very modest outlay. In many ways it certainly put other maker's entry models to shame at the time.

And..the AF was actually pretty accurate in iffy light even in low kelvin light. I regret selling the K-x now
12-13-2011, 09:03 AM   #7
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I have a K-x & have no complaints. It's a responsive, petite little machine with good ergonomics & ripping good image quality. I'm also continually surprised at how good it's low-light performance is. Personally, I don't feel a need to upgrade.
12-13-2011, 09:36 AM   #8
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QuoteOriginally posted by rawr Quote
...as Adam says: if you want to look at it objectively, the guys at DxO Labs have done the measurements and lab tests, and the data shows that technically the K-5 beats out the K-x in every element of IQ.

The IQ differences between the K-5 and K-x may not always jump out at you, but they certainly are there.
The proof is in the pudding. Anyone with both a K-x and 5 willing to do some test shots for comparison?

12-13-2011, 09:53 AM - 1 Like   #9
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QuoteOriginally posted by JHD Quote
The proof is in the pudding. Anyone with both a K-x and 5 willing to do some test shots for comparison?
Again, I'm a big fan of the K-x, but upon further reflection I think that the Imaging Resource ISO test cited here is a little bit flawed. I've found that the true test of a camera's high ISO ability is found in dimly lit scenes, or scenes with some significant amounts of shadows. I don't hesitate to use my K-x at ISO 1600 when lighting is good, but when things are dim I've noticed that noise is more noticeable.

The Imaging Resource still life posted above is a very well-lit, bright scene. So if somebody is good enough to do an ISO comparison between the K-5 and K-x, I would suggest that one of the scenes photographed should have some darker areas.
12-13-2011, 10:12 AM   #10
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QuoteOriginally posted by GibbyTheMole Quote
Personally, I don't feel a need to upgrade.
Me neither. The 16mm sensor alone doesn't justify an upgrade--frankly, I haven't seen any image produced by a K-5 that's noticeably superior to K-x images, and online comparometers seem to justify my impression. Still, I might get K-x's successor just to have two bodies (and one with an assist lamp), because I'm skeptical the new 24mm sensor will yield better IQ. But I'm never going to sell my K-x jewel


QuoteQuote:
Edgar_in_Indy Quote
The Imaging Resource still life posted above is a very well-lit, bright scene. So if somebody is good enough to do an ISO comparison between the K-5 and K-x, I would suggest that one of the scenes photographed should have some darker areas.
True, and good suggestion.
12-13-2011, 10:20 AM   #11
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QuoteOriginally posted by causey Quote
Me neither. The 16mm sensor alone doesn't justify an upgrade--frankly, I haven't seen any image produced by a K-5 that's clearly superior to K-x images, and online comparometers seem to justify my impression.
It seems to be established that the K-5 has slightly better image quality than the K-x, and with more megapixels. I love my K-x, but I certainly wouldn't mind have more megapixels to work with.

I shoot a lot in my home studio, and more megapixels gives more headroom for cropping. I will sometimes take a full body shot of somebody, and will also want to do a tighter crop of their head/shoulders for a portrait in post processing. Having more megapixels facilitates this type of workflow. This is assuming, of course, that they are quality megapixels, which is certainly the case with the K-5.

This is the reason why I'm not opposed to increases in megapixels. Although the extra megapixels may not be useful at higher ISO's, the increased resolution is nice to have in the studio when shooting at low ISO. And the high ISO shots can always be down-rezzed.
12-13-2011, 10:54 AM   #12
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QuoteOriginally posted by Edgar_in_Indy Quote
This is the reason why I'm not opposed to increases in megapixels. Although the extra megapixels may not be useful at higher ISO's, the increased resolution is nice to have in the studio when shooting at low ISO. And the high ISO shots can always be down-rezzed.
Do people remember that video linked in the thread -

How can they print that big with only 12mp?

From the UK TV The Gadget Show -
where they blew up a shot from a 12Mp Nikon D700.
(I can't now view the video from the USA....
- but I had saved a copy back when the thread was current
Hopefully people in the UK may still be able to see it?)
but the gist is they printed to 17x10 metres(!)
and on the video the print looked not just "acceptable",
but great even on close ups, easily beating out the ISO400 35mm film shot......

The K-x is only 12Mp

I uploaded the .flv video for anyone who wants to view it -
it was very enlightening -

Link

Last edited by UnknownVT; 06-11-2012 at 08:30 AM.
12-13-2011, 01:22 PM   #13
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QuoteOriginally posted by UnknownVT Quote
The K-x is only 12Mp
I'm at work and can't watch the video, but I'll certainly check it out when I get home. But I gather that you're a little skeptical about anybody really needing more megapixels.

Now I can only speak for myself, but I do a lot of 8x10 prints, and I've seen where the print can become soft when cropping too much. Especially in the scenario I mentioned above where I want to crop a head shot from a full body shot. I usually try not to go lower than 1200x1500 for an 8"x10" print, and I only go that low when I don't have a choice. 1200x1500 works out to about 2 megapixels, so having 16mp or 24mp at my disposal would make it that much easier to crop out some detail, and still stay above that 2mp threshold for an 8x10 print.

One more thing I would point out in favor of more megapixels. I have occasionally had a shot I just loved, but was slightly out of focus. Sometimes those shots are able to be salvaged by down-rezzing them to the point where the focus problem is no longer noticeable. A larger image will provide more headroom for this type of fix.

Last edited by Edgar_in_Indy; 12-13-2011 at 01:34 PM.
12-13-2011, 01:53 PM   #14
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QuoteOriginally posted by Edgar_in_Indy Quote
But I gather that you're a little skeptical about anybody really needing more megapixels.

Now I can only speak for myself, but I do a lot of 8x10 prints, and I've seen where the print can become soft when cropping too much. Especially in the scenario I mentioned above where I want to crop a head shot from a full body shot. I usually try not to go lower than 1200x1500 for an 8"x10" print, and I only go that low when I don't have a choice. 1200x1500 works out to about 2 megapixels, so having 16mp or 24mp at my disposal would make it that much easier to crop out some detail, and still stay above that 2mp threshold for an 8x10 print.

One more thing I would point out in favor of more megapixels. I have occasionally had a shot I just loved, but was slightly out of focus. Sometimes those shots are able to be salvaged by down-rezzing them to the point where the focus problem is no longer noticeable. A larger image will provide more headroom for this type of fix.
I take and understand all those points -
it's like the argument for using only RAW -
to allow for mistakes at the shooting stage.
More than fully realize no one is perfect (me less so than others)
but the whole point of photography is to try to capture the image we see the best we can.

Having safety nets is all well and good -
but for me it is no substitute for careful work....

How did people shooting slides (virtually no pp ability, or RAW)
using manual focus and manual exposure settings
ever manage to take good photos?



on CD cover:

taken on 2Mp Canon Digital ELPH S100 p&s circa 2000

Last edited by UnknownVT; 12-13-2011 at 02:40 PM.
12-13-2011, 02:32 PM   #15
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QuoteOriginally posted by UnknownVT Quote
Having safety nets is all well and good -
but for me it is no substitute for careful work....
It don't think it's about not being "careful", and I don't consider it sloppy work when I take a shot of someone in the studio, and it works both as a full body shot and as a head/shoulders portrait shot. I don't know if you've ever worked with very small children in the studio, but with some kids you might only get a few shots with a nice smile, and it may not have been a shot where you were zoomed in on the face. You may be able to make a nice portrait from that shot, but only if you have the resolution to crop it tight and still remain sharp. Or when shooting the entire family, you may be able to crop individuals for separate portraits. Or a wedding photographer may take a nice picture of the couple holding hands, and from the same picture he could zoom in the on the hands and crop the rest out for a nice detail shot of the clasped hands.

I could see other scenarios where cropping could be useful. For example, you may take a nice photograph of a building, and from the same photo you might be able to crop a separate image of a detail on the building. Or if you're shooting sports or a stage performance, but your lens isn't as long as you would like, cropping can simulate a longer lens. But the amount you will be able to "zoom" will be limited by the resolution of your original image.

And I don't care how good of a photographer you are, you will sometimes get some soft shots. This can be caused by missing focus, or by your subject moving out of focus or being slightly blurred by movement. This happens a lot with kids since they sometimes have trouble holding still. With a very high resolution photo, some of these shots can still be saved.

All of the above reasons are why I'm annoyed when people moan about the "megapixel" wars. There seems to be a knee jerk reaction among some people to "just say no" to more megapixels, without fully considering the advantages of increased resolution.

Last edited by Edgar_in_Indy; 12-13-2011 at 02:50 PM.
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