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12-23-2015, 08:58 PM   #16
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and here I thought the 'sports' measurement was reflection of noise measurements at higher ISOs - less noise = more usable higher ISO shots which is important in sports. Portraits = bit depth, Landscape = dynamic range, Sports = ISO noise. At least that's what I thought. Could be wrong.
I'm surprised that DR is just about equal between the Z and the D810.

12-24-2015, 12:18 PM   #17
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Seems like Sony and Nikon are the winners by that comparison, being that their cameras score just a tiny smidge lower than the Pentax at a much lower cost, and in more compact packages *puts on flame suit*
12-24-2015, 12:55 PM   #18
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And - the most important reason of all - they have the "right" brands
12-25-2015, 04:53 AM   #19
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QuoteOriginally posted by osv Quote
none of that is to say that the a7rii is the perfect ff camera; for example, some people have complained that it's not what they expected for astrophotography, to the extent that at least one a7rii owner bought a canon 6d for his night work... yes, it's bsi technology, but maybe it's fully wrung out because of the aptina technology? or perhaps the 42mp compromise because of video considerations was a factor.
Maybe it was the lossy RAW compressor that dimmed the single pixel spots in a noise reduction algorithm? Before it got lossless uncompressed (ridiculously large files) raw from a firmware update. 645Z, as all other Pentax DLSR, uses the best of both worlds, lossless compressed raw files.

---------- Post added 12-25-15 at 12:59 PM ----------

QuoteOriginally posted by hsteeves Quote
I'm surprised that DR is just about equal between the Z and the D810.
If we could compare apples to apples, ISO 100 to ISO 100, the Z would probably have better DR then D810. The difference is that D810 starts at ISO 64 while 645Z starts at ISO 100.

This is the same reason K-5 got on top of the APS-C DR scores with its ISO 80 vs the competitions ISO 100 or more.

12-25-2015, 11:42 AM   #20
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QuoteOriginally posted by Simen1 Quote
If we could compare apples to apples, ISO 100 to ISO 100, the Z would probably have better DR then D810. The difference is that D810 starts at ISO 64 while 645Z starts at ISO 100.
It was apples to apples.

645Z ISO 100 is 35mm-equivalent ISO 60 (100/1.68).

That's the reason why D810 with native ISO 64 both scores the same and why this is an apples to apples comparison.
12-25-2015, 04:01 PM - 2 Likes   #21
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QuoteOriginally posted by falconeye Quote
645Z ISO 100 is 35mm-equivalent ISO 60 (100/1.68).
You can't just say one ISO value is equivalent to another ISO value in a different format.

If you point a point-and-shoot and a 645Z at the same scene and choose the same aperture value and shutter speed, then dialling in the same ISO should produce an image of the same brightness. There is no equivalence here, it's the same.
12-26-2015, 01:19 AM   #22
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What's the sensor in the IQ250? Looks impressive at iso 200 and up...
12-26-2015, 02:52 AM   #23
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QuoteOriginally posted by sbh Quote
What's the sensor in the IQ250? Looks impressive at iso 200 and up...
The same sensor as in 645Z.

12-26-2015, 05:18 AM   #24
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QuoteOriginally posted by falconeye Quote
It was apples to apples.

645Z ISO 100 is 35mm-equivalent ISO 60 (100/1.68).

That's the reason why D810 with native ISO 64 both scores the same and why this is an apples to apples comparison.
I think you disagreed on something we actually agree on. I just formulated it different. Both at ISO 100, the Z would win DR. Both at lowest ISO (100, 64), DR is equal. Hypothetically both at 64, the Z would win. I'm not sure if the lowest ISO is hardcoded or possible to adjust via firmware updates. ISO is an amplifier, where 100 usually means no gain (1:1 inpututput). And current silicon technology limits the electron capacity per unit area to the same amount regardless of sensor size. Maybe we could call it the ISO 100 limit. Thats why I wrote equal ISO number means apples to apples. If I choose your approach, small sensors (phones/compacts) would have a very high real base ISO.
12-26-2015, 03:59 PM   #25
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QuoteOriginally posted by RonHendriks1966 Quote
The same sensor as in 645Z.
I thought so but wasn't quite sure. How come it performs so much better in the iq250? Is it a customised version or is that a software thing?
12-26-2015, 07:19 PM   #26
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QuoteOriginally posted by sbh Quote
I thought so but wasn't quite sure. How come it performs so much better in the iq250? Is it a customised version or is that a software thing?
i've seen speculation that the raw files on that model get tweaked? i wonder what sensor is in the iq260, because it's so much lower.
12-27-2015, 02:05 AM   #27
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QuoteOriginally posted by sbh Quote
I thought so but wasn't quite sure. How come it performs so much better in the iq250? Is it a customised version or is that a software thing?
No idea, is that so? They have 16-bit RAW don't they? Or is that lens performance?
12-27-2015, 04:21 AM   #28
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QuoteOriginally posted by FantasticMrFox Quote
You can't just say one ISO value is equivalent to another ISO value in a different format.
I just did. And I know what I am talking about. Although, to avoid another debate, I won't discuss. Please, google it up. Thanks.

QuoteOriginally posted by Simen1 Quote
I think you disagreed on something we actually agree on. I just formulated it different. ... Thats why I wrote equal ISO number means apples to apples. If I choose your approach, small sensors (phones/compacts) would have a very high real base ISO.
No, we disagree and we do because you didn't do your homework.

Actually, small sensors *DO* have a very high 35mm-equivalent base ISO although their base ISO is low. That's not a question of approach, that's how the terms are defined. However, it doesn't affect comparisons as you compare at the lowest available value of ISO anyway. It just explains why the results are so different. BTW, the results for an apples to apples comparison.

Base ISO isn't the same for all sensors, regardless of size. 645Z and D800 roughly have the same full well capacity per unit area and the same base ISO, correct. But the D810 (and here you missed to do your homework) has a different sensor significantly more expensive to build and not used in any other camera. It has a larger full well capacity per unit area which allows it to have base ISO of 64 (50 actually if calibrated the way DxO does). To estimate the effect, I computed the 645Z 35mm-equivalent base ISO to compare the effect of the two more expensive sensor techs: size vs. area capacity. That's an apples to apples comparison, your's was not.

Medium format has a special look (always had) because it captures more light before the medium saturates, film or sensor. Which leads to cleaner images, not only more detailed. In the digital age, this effect is expressed as 35mm-equivalent base ISO. And here, the D810 compares favourably because it has a different sensor tech effectively simulating this medium format effect, at least for cropped MF.

Last edited by falconeye; 12-27-2015 at 04:39 AM.
12-27-2015, 04:29 AM   #29
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QuoteOriginally posted by osv Quote
i've seen speculation that the raw files on that model get tweaked? i wonder what sensor is in the iq260, because it's so much lower.
A 60 Mpix full frame (40.4 x 53.9mm) CCD sensor designed and manufactured by Teledyne Dalsa.
12-27-2015, 04:39 AM   #30
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I would just say that the DXO Mark score is fairly unimportant. It is the break down of the score that means something. DXO Mark puts a lot of their score weight on base iso dynamic range, feeling that this is what is important to landscape shooters. Then, they factor in SNR and color depth. It seems that the easiest way for a sensor to significantly increase its score, at this point, is to bump its dynamic range at base iso. While increasing high iso performance is a lot tougher to come by.

Resolution is not factored into the DXO Mark score.

Based on this, the 645z still is an appealing camera for landscape shooters even if lowest iso dynamic range is equaled on a D810.
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