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06-24-2009, 03:20 PM   #61
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QuoteOriginally posted by Haakan Quote
in simplified audio terms your proposal would be similar to having variable frequency generator or known white noise (=fractal pattern covering all frequencies)
I guess you grasp my idea very well

Yes, the fractal pattern would be a fractal gray rather than a fractal binary pattern. Or if possible, even a fractal color pattern. It may be challenging to develop a corresponding test pattern. Or not. I haven't really thought thru this detail.

06-24-2009, 04:59 PM   #62
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I certainly hope not!

It's the specific high-ISO noise produced by Pentax's DSLR's that is one of the attributes that keeps me with Pentax. Yes, I'm an old fart from the days of B&W film and I just don't want my images to look like screen grabs from a high definition TV.

Here are my thoughts in a previous thread about why I love Pentax:

"I know I am alone but I will be sadly disappointed if the K7 high-ISO performance is on par with Canon or Nikon. Yes, I know, I can always add noise or digital "grain" to an image but, to me, that's like sucking and blowing at the same time. After 30+years of shooting film, I'm no fan of absolutely smooth, plasticky high-ISO images. If I shoot at ISO 800 or 1600, I want my image to show the imperfect character of those sensitivities (can you tell I don't shoot for stock agencies?!)."

As for making equipment purchase decisons based solely on DXOMark scores (or any other printed specifications/ performance rankings), let me use the car analogy. Who here would a buy a new car based only on a spec sheet and a magazine review? Surely we all test drive the new car we are thinking of buying.

I will be "test driving" a K7 when my local dealer has them in stock. If I like the dreadful image noise it produces, I'll keep it. Until that day, I'll be enjoying my K20D and the images it produces rather than sitting here wringing my hands about whether or not the competition has a "better" camera than the K7.
06-24-2009, 07:05 PM   #63
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You can always underexpose and that'll help bring in the noise you desire.
06-24-2009, 07:19 PM   #64
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QuoteQuote:
As for making equipment purchase decisons based solely on DXOMark scores (or any other printed specifications/ performance rankings) ...
Agreed. Buying something on the basis of performance data or a spec sheet alone is not always advisable.

But to continue the car analogy, it is also not always advisable to just go by how something feels in a test drive. If a car *feels* fuel efficient, that's not an impression likely to be as valid as a lab test of same.

06-24-2009, 09:58 PM   #65
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QuoteOriginally posted by pingflood Quote
You can always underexpose and that'll help bring in the noise you desire.
Agreed, pingflood .. underexposure will definitely amplify image noise. I work mostly in B&W and I find this technique also pushes the blacks down beyond the sensor's noise floor thus reducing dynamic range. I much prefer maintaining the full tonality the sensor can deliver.
06-25-2009, 08:16 AM   #66
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Yeah, it's a tradeoff. I usually aim for "clean black/white" in which case I want minimal noise and maximum tones, or "gritty" where I'm ok letting the darks go to get a little roughage in the image.
07-07-2009, 04:12 PM   #67
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nice discussion; I have not gone thru all of it but I see many of you are fond of the grain our Pentax gear delivers. So am I with K20d that I own for a few months now.
I had a chance to do some testing with a 300d prior to purchasing K20d and exactly as some of you support, there is less fine detail at high ISO compared with K20D and images look little smeary then, yet stll clean, which seems a little disparate, yet Nikon manages somehow. So far, K20D matches 300d except for the speed and some fancy features like conectivity with GPS ans Wireless
It is never the grain that K20D makes even at lower ISO, especially in shades, it is solely the almost complete lack of ability to brighten up dark areas that makes a noticible difference. Due to the lesser dynamic range of K20d (which was also visible in the illustrated comparison with d40 on page 3 of this thread, there is often need to brighten up shadows a bit or more. Then K20D comes to get smeary, grainy, greyish, flat and undifferentiated, while 300d still shows colors, contrast and distinct outlines. In fact, K20d performs worse than K100D and of all the models I have, ist DL is the best with regards to that use model.

Hopefully K7 performs better here. A few test shots I had seen do support my hope, however, I have yet to see a real comparison. If anyone could contribute to that soon ...
07-07-2009, 06:04 PM   #68
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Really? I have a tendency to hit the "shadows" slider pretty heavily in RAW conversion and in most exposures I see very little noise as a result. Mind you, this is working with RAWTherapee, which isn't doing any noise reduction at all to the image... then again, sometimes other exposures can be simply awful as far as noise, even at base ISO. I'm really not sure what causes the difference, often they seem to be pretty well exposed. Maybe it has to do with camera usage and sensor heat; that samsung chip runs pretty hot.

07-07-2009, 08:52 PM   #69
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Good discussion.

I await the DXOLabs results for the K7's sensor with renewed interest.

We shouldn't have long to wait, I think, now that the K7 is commercially available.
07-08-2009, 03:29 PM   #70
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Now that Imaging Resource has put up their standard suite of test shots taken with a production K-7, for me at least the answer to your original question is "no". I was hoping for some last minute magic with the sensor changes they supposedly made, but no such magic is forthcoming. ISO 1600 is still very good, while 3200 is still not good enough. That's my view anyway.

Looks like I'll be sitting this one out. I had such high hopes, probably unrealistic ones now that I think about it.
07-08-2009, 03:56 PM   #71
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QuoteOriginally posted by Yohan Pamudji Quote
Looks like I'll be sitting this one out. I had such high hopes, probably unrealistic ones now that I think about it.
The photons must still come in, right?

Backlit sensors may give you another stop, and a higher quantum efficiency, or the removal of the color filter, or wavelet-based noise reduction software, of full frame. Maybe, 5 stops altogether and then you hit physics.

None of the above five magic tricks is applied in any 2009 camera (except full frame in some). So, what were you expecting? And the next one will still be the same as I see none of the five measures be happening in the next 18 months.
07-08-2009, 04:57 PM   #72
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QuoteOriginally posted by Yohan Pamudji Quote
Now that Imaging Resource has put up their standard suite of test shots taken with a production K-7, for me at least the answer to your original question is "no". I was hoping for some last minute magic with the sensor changes they supposedly made, but no such magic is forthcoming. ISO 1600 is still very good, while 3200 is still not good enough.
In looking at those test shots at:
Pentax K-7 Digital Camera Thumbnails - Hands-On Preview - The Imaging Resource!

the K7 still does pretty well all the way up to 3200. Quite creditably in fact.

Some quality differences are discernable (eg between the D90 and the K7) in some areas, of course.

For example, in looking at the shadowing in a 3200 (NR =off) K7 image like:

Digital Cameras, Pentax K-7 Digital Camera Test Image

and comparing it side by side to the same scene taken by the D90 with it's NR turned off, shadows in the K7 image seem 'clumpier' with less gradations of tone and more visible coarse grain - eg the shadows behind the scale on the right hand side of the K7 image.

The K7 3200 shot is still a good image with a degree more resolution too, given the extra pixels, and perfectly usable, but the D90's do seem cleaner.

I do wish though that Imaging Resource would do their tests across a wider light gamut (like DXOLabs do). It has always struck me (with the Imaging Resource tests and others like DPreview) that testing a sensor's high ISO performance under conditions of brilliant studio lighting seems hardly the point. You want to test high ISO under low-light conditions, one would have thought.
07-08-2009, 05:00 PM   #73
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QuoteOriginally posted by falconeye Quote
So, what were you expecting?
Magic, man. MAGIC!

As I said--unrealistic expectations. At ISO 3200 noise levels are more or less even with 50D for instance, which isn't shabby. FF has me spoiled rotten I suppose.
07-08-2009, 05:09 PM   #74
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QuoteOriginally posted by Yohan Pamudji Quote
Magic, man. MAGIC!

As I said--unrealistic expectations. At ISO 3200 noise levels are more or less even with 50D for instance, which isn't shabby. FF has me spoiled rotten I suppose.
Yeah, when I got my 50D I was concerned about high ISO since people bitched so much about it having more noise per pixel than the 40D. Then I printed an ISO 1600 shot and it was incredibly clean. If the K-7 is as good I can't imagine anybody complaining.

But yeah, FF still rules. Even my 5 year old one puts the current APS-C gear to shame by quite a margin -- not so much in the measurable sense but in the final print.
07-09-2009, 11:02 AM   #75
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Several people have already made the point that static numbers and synthetic benchmarks are only moderately good as predictors of real-world behavior. They're so bad, in fact, that the only reason we use them is that nobody has come up with another way. The fractal color/resolution/bandwidth map sounds like an excellent solution to me, but if cameras follow audio and computers, it wouldn't be long before manufacturers were building sensors specifically to perform well on those particular charts - and they would cease to correlate to real-world performance.

After hours and hours and hours of poring over images from pixel-peeper.com and various review sites, I've come to a somewhat heretical conclusion: There is far more difference from photographer to photographer than from camera to camera or lens to lens.

Additionally, people make trivial differences sound as though they're penultimate, conclusive analyses. The difference between some of the sensors that people are so religious about is less than the differences between some of the films of the 70s and 80s that people were so religious about.

If your photography is a laboratory activity, then all these numbers might be critical. But if it's an artistic endeavor, then all of these numbers are naught, as art is subjective. Well, not completely irrelevant, but they should be only suggestive rather than decisive. Pick the platform that meets your artistic requirements - whether that's noiseless low-light performance or stunningly sharp macro images or grainy B&W images. Then take some pictures!
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