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10-28-2017, 09:42 AM   #961
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QuoteOriginally posted by biz-engineer Quote
It is a video cam. It is very easy to pull 17ev of dynamic range out of a 36Mp sensor down sampled to 8K, especially when the sensor is about 22x44mm large. There is an array of larger pixels interwoven with an array of smaller pixel both having different sensitivities, the two data set are merged after conversion. With regards to resolution it doesn't stack-up to still camera sensors.


That doesn't work, there would be way too much moire patterns.
This 8K video, not 4K. Resolution is 8192 4320, so 35.4MP... Your K1 is 35.9MP. I think you amphatize a bit too much the superiority of your still camera that does 4.5 FPS for a few seconds while the other one does 60FPS without limitation.


Last edited by Nicolas06; 10-28-2017 at 10:01 AM.
10-28-2017, 10:12 AM   #962
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QuoteOriginally posted by normhead Quote
Exactly how does reducing the size of the image either lower the lowest value recorded, or extend the highest value recorded.
It's not the size of the image that directly impact dynamic range, it's just that given the size of the sensor there is more space allowed to waste some area. For example using 2 small sensel instead of a single one, with 1 of the 2 elements having less efficiency. Under exposure to light, each sensel charges at a different speed, it's like having a sensor operating with 2 different base ISO values, you convert both into digital and use the one that doesn't clip, the downside being less final resolution but for RED it doesn't matter , the final image is downsampled to 4K or 8K video.
10-28-2017, 10:15 AM   #963
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QuoteOriginally posted by normhead Quote
Dynamic range is the difference between the lowest level recorded and the most intense level recorded. Theoretically, I don't see how reducing the size of the image affects those metrics.

So, I'm not buying it, until I see a theoretical explanation and images to show the difference is observable.

Exactly how does reducing the size of the image either lower the lowest value recorded, or extend the highest value recorded. That is a function of the sensor not image size.

I'm sure someone will correct me if i'm wrong.

Saying if I reduce my image size from 7200 pixels to 1080 pixels increases my dynamic range to 17 EV of more, sounds like science fiction.
Reducing your image size by averaging the adjacent pixels doesn't change the theoretical dynamic range of the photosites one bit, i agree. But your image have noise that reduce the signal quality and the practical measurable dynamic range. By averaging many pixels, you average the noise and be more near the theorical dynamic range of your photosites.

As per DxO, the measured dynamic range at full resolution of the K1 is 13.5 EV. At 8MP, with 4X less pixels, the dynamic range is 14.6 EV. Reducing the resolution allowed to get 1.1EV. In theory it could have given up to 2EV if the photosites were actually capable of that. Maybe actually the max dynamic range of that K1 is near this 14.6 measured dynamic rnage.

The RED camera I was speaking of is capable of recording at 17+EV of dynamic range. (WEAPON BRAIN with MONSTRO 8K VV Sensor | RED Digital Cinema store (US)). What is not clear is if it at its native resolution of 35.4MP or downsampled. In all case that's better than 14.6 the K1 manages or the 14.8 the D850 manages.
10-28-2017, 10:17 AM   #964
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QuoteOriginally posted by Nicolas06 Quote
This 8K video, not 4K. Resolution is 8192 4320, so 35.4MP...
Yes you are right. Sorry for my mistake.

Anyway , with regards to increasing DR, there is no secret, it's only about trade-offs.

10-28-2017, 10:26 AM   #965
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QuoteOriginally posted by Nicolas06 Quote
Reducing your image size by averaging the adjacent pixels doesn't change the theoretical dynamic range of the photosites one bit, i agree. But your image have noise that reduce the signal quality and the practical measurable dynamic range. By averaging many pixels, you average the noise and be more near the theorical dynamic range of your photosites.

As per DxO, the measured dynamic range at full resolution of the K1 is 13.5 EV. At 8MP, with 4X less pixels, the dynamic range is 14.6 EV. Reducing the resolution allowed to get 1.1EV. In theory it could have given up to 2EV if the photosites were actually capable of that. Maybe actually the max dynamic range of that K1 is near this 14.6 measured dynamic rnage.

The RED camera I was speaking of is capable of recording at 17+EV of dynamic range. (WEAPON BRAIN with MONSTRO 8K VV Sensor | RED Digital Cinema store (US)). What is not clear is if it at its native resolution of 35.4MP or downsampled. In all case that's better than 14.6 the K1 manages or the 14.8 the D850 manages.
OK, I'll go with that. It sounds a bit reasonable. I'm still not sure I'm buying this or DxO measurements. If at some point I really care I'll look into this. Thanks for your logic.
10-28-2017, 10:30 AM   #966
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QuoteOriginally posted by Nicolas06 Quote
By averaging many pixels, you average the noise and be more near the theorical dynamic range of your photosites.
You can improve up to a point, that is the resolution of A/D conversion, for K1 it is 14bits , so 14ev is the max because the A/D can't code anything smaller than its LSB, if some labs give more than 14ev that come from their measurement errors. To achieve 17+ ev, there is certainly more than one conversion gain on the sensor. Explained here : https://en.wikipedia.org/wiki/High-dynamic-range_video

Last edited by biz-engineer; 10-28-2017 at 10:38 AM.
10-28-2017, 02:10 PM   #967
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QuoteOriginally posted by biz-engineer Quote
You can improve up to a point, that is the resolution of A/D conversion, for K1 it is 14bits , so 14ev is the max because the A/D can't code anything smaller than its LSB, if some labs give more than 14ev that come from their measurement errors.
By definition, if you measure there are errors, fully agree. But not all are necessarily inputable to the DxO measurement. I guess even the best A/D may not have a perfectly linear transfer function neither...
10-28-2017, 09:50 PM   #968
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QuoteOriginally posted by Nicolas06 Quote
I guess even the best A/D may not have a perfectly linear transfer function neither...
:-) not sure how good are ADC need the bottom of the curve. I believe not every pixel use a dedicated ADC, eventually there is one ADC per column (would explain banding from some sensors + time required to convert all lines limits the burst rate), some noise would eventually cancel out by averaging (improving the dynamic range) and the non linearity of ADCs would remain. Should do some research on sensor topology.


Last edited by biz-engineer; 10-28-2017 at 09:59 PM.
10-28-2017, 11:02 PM - 1 Like   #969
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For the price of a D850 (B&H prices) I could buy a K-1 and a KP, and have $400 left to pay toward a D FA28~105. Aside from 4K video, what can't I do with those two Pentax cameras that I can do with a D850?
10-28-2017, 11:13 PM   #970
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QuoteOriginally posted by monochrome Quote
For the price of a D850 (B&H prices) I could buy a K-1 and a KP
Yes, and that would be doubling up on what you already have,but you would have lots more weight to carry too.

Last edited by surfar; 10-28-2017 at 11:29 PM.
10-28-2017, 11:23 PM - 4 Likes   #971
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QuoteOriginally posted by monochrome Quote
Aside from 4K video, what can't I do with those two Pentax cameras that I can do with a D850?
With the D850 you can unleash your LBA and ruin your bank, with K1 you can't, there is a financial security bundled with the K mount. The good thing about Pentax is they space new lens releases in time so that the users has time to save money for their next lens, when a new lens is released no one can claim "I did not have time to save money for that lens".
10-28-2017, 11:32 PM   #972
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QuoteOriginally posted by surfar Quote
Yes, and that would be doubling up on what you already have,but you would have lots of weight to carry too.
Conceded, assuming I need to have all the combined capabilities available to me at all times. So far I have not carried both cameras plus 8 primes, 2 zooms and 2 telephoto lenses on one outing, and I don't feel that I've missed anything. Do I need to carry every capability all the time?

This is a serious line of questioning. What can one really do with a D850 that one can't do with what I own?
10-28-2017, 11:37 PM   #973
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QuoteOriginally posted by biz-engineer Quote
With the D850 you can unleash your LBA and ruin your bank, with K1 you can't, there is a financial security bundled with the K mount. The good thing about Pentax is they space new lens releases in time so that the users has time to save money for their next lens, when a new lens is released no one can claim "I did not have time to save money for that lens".
I can ruin my bank in the Marketplace alone.

I'm asking about the cameras. Assume I can have any legacy Pentax lens that will approach the capability of any Nikon lens up to 600mm, given that I'm not good enough to use any differential capability of a better Nikon lens.
10-28-2017, 11:40 PM   #974
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You can pray and spray 7 frames per second with a D850, you can't do it at 7FPS with a K1 but you can do it with two K1 bodies at a time one in each hand. Does this answer your question?
10-28-2017, 11:51 PM   #975
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QuoteOriginally posted by monochrome Quote
This is a serious line of questioning
I was being non-serious,sorry!

Now on the serious side, apart from the crappy 4K....what you own is more than adequate but not quite as fast as the D850.

What i consider more viable is...

If i was spending that sort of money, i'd wait until the latest 42mp $$$ony has been tested by consumers(as opposed to reviewers) and consider it.At the moment it looks the closest to a FF hybrid as there is....I know $ony is a 4 letter word around here but bit by bit every body they put out progresses.

My personal choice for Dslr is Pentax,all my other stuff is mirrorless and the name on the fronts not important,its the capability that interests me.

$$$$$$$$$$$$$$$$$$$$$ony native lenses are not necessary either, the techart Pro adapter makes most mounts compatible.
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