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07-08-2014, 09:54 AM   #31
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QuoteOriginally posted by Kunzite Quote
ISO 800 -> 1600 -> 3200 -> 6400. 3 stops difference.
That's what norm is saying the extra sensor is worth. What the sensor is ACTUALLY worth is two stops of performance.

Equivalent Crop Factor = sqrt((44*33)/(23.7*15.7)) ~= 2.

Equivalent ISO = crop factor^2 = 4.

So the actual equivalent performance will be 2 stops difference. K-3 ISO 800 will be roughly 645Z ISO 3200, assuming no profound leap forward in sensor/read technology for the 645Z.


Assuming same sensor tech, the difference between the K-3 and the D810 is more than the difference between the D810 and the 645Z. Throw in the fact that the available lenses for the D810 are generally two stops faster than the lenses for the 645Z, and there's absolutely no reason to purchase the 645Z for low-light.

We don't like it, but it's the truth.

07-08-2014, 11:17 AM - 1 Like   #32
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I thought that one should get A7s for low light. But one might be lucky, because ISO3200 is not good for low light. ISO 51200 is. And especially with good clean and professional quality.

That's what I like, and it is true too.
07-08-2014, 11:51 AM - 1 Like   #33
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QuoteOriginally posted by ElJamoquio Quote
That's what norm is saying the extra sensor is worth. What the sensor is ACTUALLY worth is two stops of performance.

Equivalent Crop Factor = sqrt((44*33)/(23.7*15.7)) ~= 2.

Equivalent ISO = crop factor^2 = 4.

So the actual equivalent performance will be 2 stops difference. K-3 ISO 800 will be roughly 645Z ISO 3200, assuming no profound leap forward in sensor/read technology for the 645Z.


Assuming same sensor tech, the difference between the K-3 and the D810 is more than the difference between the D810 and the 645Z. Throw in the fact that the available lenses for the D810 are generally two stops faster than the lenses for the 645Z, and there's absolutely no reason to purchase the 645Z for low-light.

We don't like it, but it's the truth.
Oh, boy - this nonsense again.
07-08-2014, 11:52 AM   #34
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You'd may have to be willing to accept an adaptor for the A7S to be the best at low light, or be unwilling to have narrow DOF. A F/1.4 lens with a D810 will have better SNR than the A7 with the F/1.8.


Of course I haven't taken into account color reproduction, etc.

---------- Post added 07-08-14 at 11:54 AM ----------

QuoteOriginally posted by Kunzite Quote
Oh, boy - this nonsense again.
Take it this way then - 800 ISO * 4 is 3200.

You don't have to understand the math.

07-08-2014, 12:03 PM - 1 Like   #35
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And the usual follow up. I understand "the math" perfectly, it's application is nonsense.
07-08-2014, 12:05 PM   #36
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QuoteOriginally posted by Kunzite Quote
And the usual follow up. I understand "the math" perfectly, it's application is nonsense.
I notice you didn't mention that "the application is nonsense" to Norm when he brought it up, or correct him when he got the math wrong.





I don't like the result. I think a lot of people don't.
07-08-2014, 12:09 PM   #37
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I think he was talking about actual results (we have high ISO samples taken with the 645z, and they're impressive); and there's nothing in his post to suggest the nonsense being used. Norm, am I wrong?
07-08-2014, 12:10 PM   #38
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QuoteOriginally posted by Kunzite Quote
I think he was talking about actual results (we have high ISO samples taken with the 645z, and they're impressive); and there's nothing in his post to suggest the nonsense being used. Norm, am I wrong?
I haven't seen any ISO-sequence shots comparing the K-3 to the 645Z. Got a link?

07-08-2014, 12:26 PM   #39
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It doesn't have to compare directly the K-3 and the 645Z; all that's needed is a known value (e.g. the D800), or reasonable knowledge on how your camera would behave in similar conditions.
We're not talking about precise measurements here, but a ballpark estimate.
07-08-2014, 12:39 PM   #40
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Off an entire stop doesn't sound like the right ballpark to me. That's more than the difference between the D810 and the 645z.
07-08-2014, 12:39 PM   #41
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QuoteOriginally posted by marmaduke Quote
no rampant religious chanting for a FF?? where are my pentax cultists FFS?
It's all 645z all the time over there. Rumor was 645z shoved everything else aside for the time being - so there was nothing else to rumor about.

asahi man says a new superzoom, a holiday season just like last year and a glorious future for Pentax including all sizes of camera. Translate that as you want.
07-08-2014, 01:39 PM   #42
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Just had a thought - since the fastest K-3 lenses are two stops faster than the fastest currently-available 645 lenses, it's basically a wash in terms of SNR between the two cameras, all else the same. Thankfully the 645 will be sharper, and I suspect the 645 lenses perform better as well.
07-08-2014, 01:58 PM   #43
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And here I thought this was a Photokina thread, and not a 645z vrs K-3 vrs DWhatevs thread...
07-08-2014, 02:17 PM   #44
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QuoteOriginally posted by Doundounba Quote
And here I thought this was a Photokina thread, and not a 645z vrs K-3 vrs DWhatevs thread...
Godwin's Law of Pentax Forums says the thread has to become a FF thread eventually...
07-08-2014, 02:22 PM - 1 Like   #45
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Godwin's Law, of course, AND...

QuoteOriginally posted by rawr Quote
Getting back to Photokina, I have the feeling that the tight opsec Ricoh is maintaining about it's plans for Photokina may be a positive sign. Putting the best possible spin on it, they may actually have a big news cargo enroute to Photokina that they want to protect.
QuoteOriginally posted by boriscleto Quote
Godwin's Law of Pentax Forums says the thread has to become a FF thread eventually...
What???! No full-frame at Photokina...AGAIN??!!!?? Pentax is doomed...DOOMED!!!

...says he, carefully clutching his cache of pristine FA* glass, just in case...



I just love this place. They just gave us the APS-C camera of the year, the magnificent K3, performing to or exceeding the standards of the Nikon full-frame at a ridiculously low price, small size, great battery life, and still we bitch and whine...


Cheers,
Cameron
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