August 28, 2014, 11:27:01 AM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - jrista

Pages: 1 [2] 3 4 ... 270
16
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 26, 2014, 12:15:14 AM »
I'd love the most verbose people to actually take the time to photograph a step wedge, it should take about 15 seconds, and post their results.
I had one back in the good old days of the B+W darkroom.... I kind of wish I had one now because this has gotten me very curious as to how my various cameras compare... I might have to order one :) (any recommendations?)

Please correct me if I am wrong, but I always thought of "stops" as an analog/perception scale and that it did not necessarily match up with a digital scale... perhaps part of the confusion here is that people are talking about two different things yet using the same terminology.

Whilst the Stouffer versions are the standard I know of, there is no reason decent results couldn't be got with a home printed version. With careful lighting and exposure I would think you could do very well.

Well I wouldn't get into a semantics argument here, it seems many have far more time than I do and that is all it takes to "win", but I think stops translates just as well to digital as analog, it is just much easier to read the values of the output now and they are finite, unlike the infinite variability of analog density. When we needed to know the density of negatives it was much more involved than moving a cursor over the relevant pixel  :)

Just out of curiosity, how did you determine the density of negatives? How accurate were the measurements?

17
Landscape / Re: Beautiful sunsets
« on: August 26, 2014, 12:13:36 AM »
1Dx
First Pic
16-35mm L F2.8II
ISO 100 
F13
51secs

Second Pic
16-35mm L F2.8II
ISO 100 
F11
88secs

Very nice! I particularly like the first one.

18
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 26, 2014, 12:11:55 AM »

0-16384 (14 bit ADC) is infinity?  ???



16,384 = 2^14.

The lowest value the sensor records, however, isn't 0.

It's 2^0. Were it zero, any increase would be infinite on a percentage basis.

But it isn't.

1-2-4-8-...2^bitdepth

The range is from 0 to (2^N)-1
it is 0 to 16383

I think what 3kramd5 was getting at was that no system has zero noise. When we convert the voltage of a pixel into an ADU with the ADC, we cannot convert a fraction of an ADU. If RN is 3e- and FWC is 60ke-, then 3e- RN, although in floating point precision is 0.8192, ADUs are integer (at least, they are in todays sensors...maybe at some point we'll have cameras that can convert directly into 32-bit float RAW. :D) Since ADUs are integer, you cannot convert any non-zero charge to zero...the minimum ADU is 1, or 2^0.

19
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 26, 2014, 12:05:58 AM »
Don, when people show no respect and just shout and argue over everybody, it becomes impossibly difficult to show them any respect in return.
It's a hard thing to do. I try to focus on the good things and ignore the bad.... after all, we all do stupid things from time to time..

I'd love the most verbose people to actually take the time to photograph a step wedge, it should take about 15 seconds, and post their results.
I had one back in the good old days of the B+W darkroom.... I kind of wish I had one now because this has gotten me very curious as to how my various cameras compare... I might have to order one :) (any recommendations?)

Please correct me if I am wrong, but I always thought of "stops" as an analog/perception scale and that it did not necessarily match up with a digital scale... perhaps part of the confusion here is that people are talking about two different things yet using the same terminology.

Stops is just a term used to describe differences by factor of two. We could just as easily replace stops with "powers of two", if you prefer...same thing. The raw calculations result in decibels, though. If we have 60ke- signal (in volts) and 3e- read noise (again volts):

Code: [Select]
20*log(60,000e-/3e-) = 86dB
We convert to stops by dividing by 6, since voltage in a signal changes roughly by a factor of two every 6dB, and it's ultimately voltage that were measuring (since incident photons, dark current, and amplification and readout all affect the number of volts per pixel), that gives us a number that corresponds to stops of change in exposure settings (shutter and aperture...not ISO). In the case of the above, we have:

Code: [Select]
86/6 = 14.33 stops
We can corroborate this by figuring out gain for a 14-bit ADC, and running the formula for power in a signal:

Code: [Select]
60,000/16384 = 3.662109375e-/ADU gain
To get read noise in ADUs, divide the read noise by gain:

Code: [Select]
3/3.662109375 = 0.8192
Calculating dynamic range from the digital signal:

Code: [Select]
10*log(16384/0.8192) = 43dB
Converting to stops:

Code: [Select]
43/3 = 14.33 stops

20
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 25, 2014, 11:49:11 PM »
...I started seeing this fundamentally mocking behavior.

Yep, it's just popping up all over the place!

Dur...oops... Infinity!

WOW...   :o  Well, clueless is as clueless does, I guess... You've definitely "clearly" proven your point...whatever your point actually is.

Heh, touche. Although, I tried the reasonable approach first, over and over, and he's been asking for it for days. He makes it very, very hard not to sometimes.

21
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 25, 2014, 11:47:02 PM »
Quote
Technically speaking, the lowest level in every sensor is black, or ZERO. By EVERY definition of dynamic range, the range from zero to any number is INFINITY.

0-16384 (14 bit ADC) is infinity?  ???

Do you need an education in basic mathematics?

What happens when you divide any number by zero? What happens when you take the logarithm of zero or infinity?

Mathematical formula for DR:

Code: [Select]
20*log(FWC/RNrms)
FWC divided by noise. Hmm, let's see:

Code: [Select]
20*log(16384/0)
Dur...oops... Infinity!

Introducing real math? How rude, he thought he had a zinger.  But seriously, try DualISO if you haven't already.

Yeah, I've thought about DualISO. I don't like the loss in resolution...and I've never been too sure about putting ML on a brand new camera.

22
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 25, 2014, 10:56:04 PM »
Quote
Technically speaking, the lowest level in every sensor is black, or ZERO. By EVERY definition of dynamic range, the range from zero to any number is INFINITY.

0-16384 (14 bit ADC) is infinity?  ???

Do you need an education in basic mathematics?

What happens when you divide any number by zero? What happens when you take the logarithm of zero or infinity?

Mathematical formula for DR:

Code: [Select]
20*log(FWC/RNrms)
FWC divided by noise. Hmm, let's see:

Code: [Select]
20*log(16384/0)
Dur...oops... Infinity!

23
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 25, 2014, 10:52:01 PM »
Again, it is painfully obvious you have zero experience producing these kinds of shots. You don't need an Exmor sensor. You need to:

* Stop arguing in this thread
* Do a Google search.
* Read and watch some of the many excellent tutorials out there.
* Download some HDR demo software.
* Go out and photograph some HDR scenes.

Hmm...really? I guess my time out in the field...literally...yesterday, gathering bracketed shots and doing HDR processing was just all a waste then:



I'm sorry. I'll sheepishly crawl back into my hole, cry some, then make another pitiful attempt at "learning" HDR. ;P


LOL, night d.

24
Landscape / Re: Beautiful sunsets
« on: August 25, 2014, 10:49:29 PM »
Thanks, guys. :) Glad you like. I'm still not entirely satisfied with it, but I think the warmer tone of the second version is better...things were too cold and almost lifeless feeling in the first.

25
Landscape / Re: Beautiful sunsets
« on: August 25, 2014, 09:05:55 PM »
@jrista:  John this is a fantastic photo. Could you share some process details that lead to this result?

The HDR result was pretty simple. I imported to Lightroom, then selected all five for this set, right-clicked and chose to "Merge to HDR Pro in Photoshop..." When that was done, I chose 32-bit, and "Tone in ACR". I then tweaked things a bit in ACR, mainly exposure, a little bit of curves, applied a gradient (like a digital GND) to the top to bring out the blues more, did some brushing around the sun (just to deal with some posterization), and that was pretty much it.

26
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 25, 2014, 08:09:54 PM »
Alright. Since it's clear you guys are fed up with the DR stuff, I'll leave the DR stuff out of this thread for now on. Here's to hoping the 7D II actually hit's the streets with something much better than rumored. We only have a couple weeks to wait before we know for sure. I am impressed with the AF and metering system rumors, and the frame rate. Hope it lands with all of those traits being true.

27
Landscape / Re: Beautiful sunsets
« on: August 25, 2014, 08:02:55 PM »
Wow, Jon you always go the extra mile. Thanks :)  That is very helpful in understanding what you're doing and why.  I'm still debating in my mind how I should interpret the photo.  Maybe sometimes I'm really not feeling I want that much detail in the shadows - could it be visual overload for me??  Again, I'm not qulaified to judge so don't mind me.

Ah, I understand your question now. I think it's just that your not seeing the benefits of the HDR at full size. Here is a comparison of the HDR in the "shadows" (not really shadows, it's definitely midtones, since it's the sunflowers, which are the primary subject of the image), and a single-frame shadow pull:



If I wanted to print this (I do, actually), the single-frame shadow pull is entirely unacceptable for that purpose. I already have people who want prints of this, family and friends, and I'm sure others will as well. At 13x19, the size I usually print at home, the difference in detail and detail clarity between the HDR and the shadow pull is totally obvious. There is a huge difference in detail, the HDR version has TONS more, and it's crisper and sharper and has more color fidelity. For larger prints, even gallery wraps up to 48x36", the better detail of the HDR is that much more important, because of the need to upsample.

28
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 25, 2014, 07:51:57 PM »
Well...to each is own, I guess. Me, I'm going to get vocal about Canon's crappy low ISO noise, and do everything I can to back up my claims with concrete, visual evidence...because, it's really freakin NASTY noise. STILL nasty...after all these years. And I think that needs to change (especially because Canon is still my preferred brand...I'd rather have a 5D IV with 50mp and 14 stops of DR than a D800.)

I see nothing wrong with jrista complaining about "Canon's crappy low ISO noise."

Anyone is welcome to complain about anything they want. But...

...doing it over and over and over and over again to the same audience becomes tedious.

...attempting to "prove" your point again and again to those who happen to disagree with your opinion becomes annoying.

...insisting that you are right and then attacking anyone who doesn't share your viewpoint is obnoxious.

...failing to recognize that what you perceive to be a major concern isn't necessarily even a minor concern of others is rude.

...hijacking every discussion to push your agenda with long diatribes that repeat the same basic points time after time is obsessive.

...demeaning others when they raise concerns about features that you don't happen to care about (as in touch screens) is narrow minded.

...making wild claims that unless your particular obsession is addressed by a major multi-national corporation they will be doomed is delusional.

And, most important of all...thinking that these discussions on an internet forum are anything more than trivial ineffective entertainment is just silliness.

It's far from hijacking every discussion. I've hijacked a couple. I also know I'm not alone in my desire for more DR from a Canon camera specifically. I think there are a lot of us. I'm also sure I'm not alone in getting tired of waiting for Canon to address the issue. I also think most who want more low ISO DR have given up on Canon and just added other brands to their kit, which I'll end up doing here myself. I think that's a bummer...people should figure out a way to get Canon to listen and respond, as in every other respect they have a better system. Guess landscape photographers and others who could really use more low ISO DR really are a small niche...

On the flip side, it's just as "annoying" to have people constantly say that Canon has no issues that need to be corrected again and again, or that there is no difference at all between Canon sensors and the competition (something some people here DO seem to do every time these debates start), especially now that I've noticed the highly mocking nature it's done in. There IS a difference...whether it matters to each individual or not is one thing, but to patently deny it exists at all is another. (I used to just pop into a thread, drop a few posts about technology or some such, then leave...I usually ignored all the other discussions that went on....I'm reading more posts now, and I'm getting a whole lot of flak myself....and now I notice the underlying attitude here. If ANYTHING is annoying...it's the mocking, often childish tones that everyone here takes when anyone has anything negative to say about Canon. Canon has their issues...IMO, better to acknowledge that, and see if you can do something to get them to recognize and resolve their issues if you, and any like minded individuals, can build up a strong enough voice to actually be heard. Seems clear such a voice won't be built here on CR.)

29
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 25, 2014, 07:38:25 PM »
So what are the engineering considerations involved in on-sensor ADC?

As Don stated, you need space on the sensor die. With 500nm transistors, on-die ADC will take up a lot of space. That reduces the yield from each wafer. Larger transistors, operating at a given speed, generate more heat, and heat results in increased noise from dark current.

Moving to a smaller transistor size, such as 180nm or 90nm, means you can pack a whole lot more transistors in a lot less space. Those transistors, being smaller, require lower voltage and current, therefor they don't produce as much heat.

The actual design of the on-sensor ADC matters as well. Who knows what's best there, companies would have to research that. Sony Exmor uses a column-parallel ADC with digital CDS, and a remotely located clock. This means there is one ADC unit per pixel column, the CDS (correlated double sampling) is performed AFTER ADC, so it operates on ADU's (digital numbers, rather than analog charge). Exmor also employs per-column ADC/CDS tuning, which effectively eliminates vertical banding. The ADC units, only having to process one column of pixels each rather than dozens of columns (and potentially hundreds of thousands of pixels each) can operate at a lower frequency, so you don't pick up noise from high frequency oscillations. The high frequency clock itself, which is usually a source of noise, is also remotely located on the Exmor sensor die, so the ADC units don't pick up any issues with noise from being close to the clock itself.

There are probably other ways of minimizing noise once you have die space to put a lot more transistors on the sensor die. Canon has patents for dual-scale ADC, which switches to a slower readout rate when possible, allowing even lower frequencies to be used during readout (the lower the frequency, the lower the read noise....this technique is frequently employed in astro CCD cameras...readout rates are often extremely low, requiring as much as 10 seconds to read out a single frame.) There are other patents out there that describe a variety of means for reducing noise, reducing dark current, etc.

30
Landscape / Re: Beautiful sunsets
« on: August 25, 2014, 07:24:13 PM »
Here is an alternate version of the HDR:


Pages: 1 [2] 3 4 ... 270