April 21, 2014, 09:17:22 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 - Meh

Pages: 1 ... 37 38 [39] 40 41 ... 46
571
EOS Bodies / Re: 1DX Review
« on: October 25, 2011, 11:49:25 PM »
Image noise goes up with higher ISO, fact of life.

Well that's one way of looking at it.

I would prefer to look at it as the noise being reasonably constant (within limits) but the signal being reduced due to the lower light levels available when you have to use higher ISO settings.  The end result is a lower signal to noise ratio (SNR) leading to a noisier image.   The post-capture ISO amplification applied gets you back to the correct image brightness, but as it boosts signal and noise equally, cannot do anything to correct the already impaired SNR, hence the noise that was there all along becomes relatively more visible.

Impaired SNR is the natural result an under-exposed sensor which of course is what you get if you use an ISO setting higher than base ISO.   The exposure meter may say you are not under-exposed, but that is because it is adjusted in advance to allow for the amount of post capture ISO amplification which is going to be applied later.  By going above base ISO you are effectively accepting under-exposure at the sensor.

I would therefore say that high ISO noise performance is a somewhat mythical concept, as in reality the performance at any ISO setting is largely dictated by the SNR ratio at base ISO.  The better this is to start with, then the better the results as you start losing signal due to low light levels. 

Fred

Yes, SNR is what matters most to what we see as image noise and you're absolutely right, ISO amplification happens after the sensor is exposed and amplifies the recorded signal at each pixel which includes the noise component... the camera doesn't know what the true signal was and how it was affected by the noise.  When shooting in low light the input signal is much lower so the SNR is in turn lower and the image looks noisy.

On the issue of thinking of noise as a constant, that depends what kind of noise we're talking about.  There is noise from the electronics (read noise) which is fairly constant and photon noise (aka shot noise) that is not constant.  Both contribute to the total noise (random variation) in the recorded signal.

Photon noise scales as the square root of input so the noise goes up with input signal in absolute terms (not constant) but is a smaller percentage of the input (higher SNR).   With very low light levels (dark shadows, night photos) photon noise can be significant.

Read noise is fairly constant for a given ISO setting and is in the range of around 2-20 electrons for most CMOS sensors.  Again, in dark scenes when the input signal is low (which is when we use higher ISO) the read noise becomes much more significant relative to the input signal (lower SNR) and we can see the noise in the dark areas of the image.

Even when we look at an image we can't "see" or know that a particular pixel (or any area in the image) was supposed to be say 500 photons but was recorded as 495 or 510.  What we see is the unnatural variation in adjacent pixels or groups of pixels that wasn't in the true input.  So say a group of 20 pixels were supposed to all be 500 photons but they were recorded due to noise anywhere from 470 to 530 we can see that variation and because it's random variation we know intuitively that the image isn't supposed to look that way and it's therefore noise.

572
EOS Bodies / Re: 1DX Review
« on: October 25, 2011, 10:56:35 PM »
@Chris_BC

Good points.  Given the slight drop in MP rather than an increase over the last generation FF sensor, the increase in standard ISO range, the fact that technology has progressed, and Canon's statements I would also hope for more than 1 stop increase.  My comment was meant more generally... that a full stop improvement over a predecessor body is a significant improvement.  Two or more stops would be even better of course.  As far as what body to compare to as the predecessor we could just as easily compare to the 1D4 since that was the most recent 1-series body but your point is still valid because the increase to 18MP FF from 16MP APS-H alone should result in improvements even if there were no other tech advancements.  How much improvement in noise and DR will "cut it" will depend on the user.

573
Lenses / Re: The price 300mm 2.8 IS--is just greed--maybe?
« on: October 25, 2011, 05:22:44 PM »
It's strange that there is such emotion on the pricing of things we want but can't justify the price.  It turns into a rant about corporate greed... there is such a thing as corporate greed but the pricing of products is an open and transparent thing and they aren't taking advantage, if you don't like the price don't buy.   What do you think the cost to produce any Apple product is... what's the markup on an iPhone... yet Apple and Steve Jobs are heroes.

There is so much to running any business far beyond just the cost to manufacture a product.  Who's to say what Canon spent on R&D to improve any given lens, re-tool the manufacturing process, etc.  Then there's marketing, distribution, overhead.

Even if Canon is making a killing on any particular product, so what?  If the market doesn't like the price and no one buys they will lower the price after a while.  Ultimately they're going to sell it for what the market will bear.  I wonder if the people who complain so much about corporate greed would sell their house for 20% less than market value because the business press reported widespread over-valuation in the housing market?

574
Lenses / Re: The price 300mm 2.8 IS--is just greed--maybe?
« on: October 25, 2011, 05:11:56 PM »
Time to "Occupy Canon?" :)

Nice one!  +1

575
EOS Bodies / Re: 1DX Review
« on: October 25, 2011, 01:08:50 PM »
Image noise goes up with higher ISO, fact of life.  Of course images at 51,200 are going to be noisy... but if those noisy images are usable, if only just barely, and you wouldn't have gotten the shot at lower ISO then it's a useful ISO setting.  I'm not saying it will be useful, have to wait and see what the real world images look like.  Even the marketing images Canon will show will be optimum and controlled situations.

Realistically, if the 1DX or any new body, gets even even a full stop of better ISO performance (i.e. ISO 3200 of the new body look as good as ISO1600 on its predecessor) then it's a significant improvement.  In general as technology matures, big advances from one generation to the next get harder to achieve.  If what Canon has claimed so far is even part way true they've made some significant improvements.  Whether worth the upgrade to any given user depends on their needs and preferences.

Other than a non Canon employee getting to touch the 1DX and tell us about that, there's nothing new in the Engaget review but still worth the read and a quick look at the product shots.

576
EOS Bodies / Re: Feedback on 1D X from 1-series users?
« on: October 24, 2011, 10:28:39 PM »
But to start a thread that assigns qualifications for contributors based on who can afford high end equipment from those who can't -- which is what this individual did -- is elitist and discriminatory.

English is not my native language, so maybe I'm missing something, but I just hear someone (neuroanatomist) saying, hey, we heard the crowd and they're in title to their layman opinion, but I like hear what the experts (as far as 1D or 1Ds) are thinking about the new tool.  That’s not “elitist and discriminatory” where I live.

This issue that drew complaints was not the request for comments from 1-series owners/users.  That was a great topic that neuro started.  The part that drew complaints was the Camry analogy that implied (although probably not what neuro intended, he has since said it was an attempt at humour) that most of the members commenting on the 1DX up to that point had never used a 1-series body and probably wouldn't ever buy a 1DX because they couldn't afford it even if they wanted to.  It came across as elitist because everyone knows neuro can afford a 1DX and will be getting one as soon as it's available.  Most of us will just stare dreamily at it in the window until the kids are done college (or drop out and we liquidate their college fund).

It was an attempt at humour and we've all said things that came out wrong or were interpreted in ways that were not intended.  Neuro's comments and all the sharing of knowledge from testing lenses, micro-adjusting every lens and sharing his experience, and proving us wrong with tack sharp images from lenses we complain about are valuable contributions to the forum.  So he has lot's of credit stored up to be forgiven for the odd failed humour... even Seinfeld bombed every now and then.  :)

And thanks to all the 1-series users who have contributed their comments.  Appreciated by everyone I'm sure.

577
EOS Bodies / Re: Feedback on 1D X from 1-series users?
« on: October 23, 2011, 09:50:23 PM »
So far, we've heard a lot of feedback, mainly complaints, from people who are not currently using 1-series bodies, and don't seriously plan to get one.  Sort of like people who say, "I was going to buy a Ferrari California, but now I'm not since they didn't put a V12 in it," and then just keep on driving their Toyota Camry, or at the most take out a 5-year loan on a newer model of the same car.


Nice elitist attitude.
So I guess Camry owners can't have opinions with regard to how the new Ferrari will effect their next Camry?
This IS an opinion message board, remember?
[ok, lets hear your real snappy comeback...)

Yes you can - there are enough threads on this site to cover that. The OP asked specifically for those who already have one of the Pro bodies. If you check his sig. he does not and is therefore asking from those that do.

Sorry, don't do snappy at 2am  :D

Well... neuro did ask for those opinions along with a smattering of a slam against those expressing opinions that may not intend to buy one.  He could have left out the whole Ferrari/Camry thing of course it would be less fun if he did.   Neuro gets some credit since we all know he's in the camp of those not currently using a 1 series as well as being in the camp of those that may in fact buy a 1DX.  I am in both those camps as well but for me not likely a 2012 purchase unless the retail price turns out to be below $6k which is doubtful.

So neuro, in your analogy was the Camry equivalent to any particular level of body or would even a 5D/5D2 be included.   Or maybe you were only taking a shot at people who talk like they want one but can't actually afford it?   Sorry, you may not have meant it but your comments come across a little elitist.  You might get credit for your honest viewpoints and credible statements about buying the 1DX as soon as it's available but you're also on record as stating that any piece of gear you want is "only X number of hours of consulting work" to you.

Great idea though to ask for more 1D users to weigh in.


578
Canon General / Re: Birders don't use Canons?
« on: October 20, 2011, 11:03:35 PM »
One thing I bet makes us all laugh is the photo editing software on cop shows or spy shows. I like how they will bring up a totally blurred image and type a couple of keys and suddenly the image creates data that was not there and suddenly the image looks great. Or when they magically hit a single key and the editing software turns an object around or creates a face that is behind a post or tree or something.


apparently they have access to the Adobe de-blurring tool!  http://tv.adobe.com/watch/max-2011-sneak-peeks/max-2011-sneak-peek-image-deblurring/ ... I still can't believe this is real, but Adobe seems to be pretty serious about it.


There are a few algorithms that can sharpen images but most likely this is just an implementation of a Richardson-Lucy Deconvolution.   Already available for free in RawTherapee.  It works best for simple camera movements that caused the blur... it's less effective or non-effective for complex or multiple movements (for example camera shake + lateral movement).

579
EOS Bodies / Re: The EOS 1D X Sensor Demystified...
« on: October 20, 2011, 10:24:32 PM »
Larger pixels giving more Dynamic Range is not a myth just an oversimplified statement because there is more to it than just pixel size.  It is true when those other things are equal.  DR is the ratio of the largest signal to the lowest signal that can be measured .  That ratio can be expressed as a simple ratio, stops/EV, or dB.

The maximum signal is the most electrons that can be stored in the photosite (one electron is release for each photon absorbed).  This is also referred to as saturation value or full-well capacity.  Note that it's the size of the photosite that matters... the area of each pixel that is sensitive to light which in the past I believe has been as low as 30% but in recent years was up to about 50%.  This is called the fill-factor 

The lowest signal is taken as the noise floor.. which is the read noise at whatever ISO your using.  Most CMOS sensors up until the most recent generation actually had higher read noise at ISO 100 but the Sony sensor used in the D7000 greatly improved on this and the read noise is fairly constant with ISO settings.

The Sony also has much higher full-well capacity even though the pixels are smaller.  This is most likely because they were able to increase the fill-factor... i.e.  a higher percentage of the pixel area is used for the photosite.  In other words, even though the pixels are smaller the photosites are larger (higher max signal).  Combined with the lower read-noise at ISO 100 (lower noise floor) the ratio of largest to smaller signal is much larger giving the very high 13.9 stops of DR.

Hopefully, we'll see these advances in the 1DX sensor as well but there are many other tradeoffs in designing a sensor to optimize for speed, heat, minimizing blooming (current leakage), etc. that the Sony sensor may have sacrificed... I don't know that's the case just stating the possibility.




580
EOS Bodies / Re: What's Next?
« on: October 19, 2011, 10:57:55 PM »
I thought that the 200-400 1.4X was a reality?

Yes, I am confused too. It's a lens that was announced some time ago, just that the release date is delayed (much like what happened with the 8-15 fisheye).

What I want to see: 24-70 f/2.8L with better optics and 14-24 f/2.8L

What I personally wish to have: FF with pentamirror or mirrorless. Just want to have a cheap, low weight Rebel type FF camera. :) That's just me.

I believe the 200-400 was announced to be "in development" and as yet not an officially announced product.

581
EOS Bodies / Re: What's Next?
« on: October 19, 2011, 04:22:08 PM »
I have been waiting to transition into DSLR filmmaking.  My holding out for the 5DmkIII is over...  I will get the 7D and some better glass while I wait for mkIII.  Then sell back the 7D.

At least wait until Nov 3rd. It's only 2 weeks away. Trust me as someone who has shot a lot of DSLR video the last few years. The moire and alias and soft video image can drive you crazy. It was good when it came out 3 years ago, but now compared to Sony and Panasonic, it's very dated.

Just give it 2 weeks before you buy. I think something good will come.

It may not change your mind about DSLR film making, since the alternatives are prohibitively expensive, but check out the 3-part series "The Great Camera Shootout 2011" at www.zacuto.com

The third in the series shows the motion artifacts that DSLRs are prone to due to the rolling shutter of CMOS sensors.  It will be interesting to see if what Canon announces on Nov 3rd will address this issue and if they announce something affordable for indie film makers or only cameras to compete with RED.

582
EOS Bodies / Re: What's Next?
« on: October 19, 2011, 04:05:15 PM »
Common 14-24 lens!

+1. I think we're the biggest fans of this idea.

I must be missing something. The 14-24 is a common lens?
Nikon makes one, but does anyone else?

I think it was mean to say "come on 14-24 lens" ?

583
So, after a useful discussion I think we are coming to an understanding/consensus that the DxOMark tests are representative of the DR the sensor is actually capable of and the DPR tests are an attempt to test what DR we can expect in final images but may be coming in low by somewhere in the range of 1-2 stops due to testing limitations, in particular the use of jpegs that by definition lose some detail in the shadows and highlights.  And perhaps the rest of the difference is due to say another half stop on either end (shadows and highlights) that the sensor can detect but can't be seen anyway.

The original comment that started this conversation was that DR has been Canon's Achilles heal.  In both sets of measurements it would seem that they are in fact behind by about a half to a full stop of DR when comparing sensors from the same point in time and that is most likely due to Canon's emphasis on higher resolution.  The 1DX will likely change that though.

Does that sound about right?




584
EOS Bodies / Re: What's Next?
« on: October 19, 2011, 02:14:34 PM »

The whole thing is pure comedy, becasue as I've been saying Nikon and Canon are switching. All the Nikon shooters are used to low MP sensors. All the Canon users are used to high MP sensors. And the two companies are going in opposite directions.

Unless both Canon and Nikon have each realized that there is a need, and more importantly a market, for both high resolution sensors and lower resolution sensors (along with the inherent trade offs of each) and will now try to have both types in their respective lineups?

It would be interesting to know what conversations happened in the engineering and marketing departments at each of Canon and Nikon as recently as 5-6 years ago.  You can almost imagine both companies with a concept of an ideal digital sensor (high res, low-noise, high DR, etc.) that technology couldn't deliver and laying out a road map of what properties to focus on first with the intent of improving over time towards the ideal.  Canon went with working on increasing resolution and Nikon went the other way.  Each marketed their choice as "better" and "more important" but knowing it's really just a matter of how an image would be used that defined what mattered most.

585
Last time looked, DPR's numbers for DR were based on in-camera JPG shots of a step wedge. If that's no longer the case, happy to hear it. If they're still doing that...need I say more?

Actually that´s (imho) closer to reality then the 12-13 Stops from DXO Mark.

8.x EV (9.x with Raw Headroom) seem to be what i can achieve with my 1D MK4.
But i sure come nowhere near the 12 Stops from DXO Mark.

Quote from: DPreview
Our Dynamic Range measurement system involves shooting a calibrated Stouffer Step Wedge (13 stops total range) which is backlit using a daylight balanced lamp (98 CRI). A single shot of this produces a gray scale wedge from the camera's clipped white point down to black (example below). Each step of the scale is equivalent to 1/3 EV (a third of a stop), we select one step as 'middle gray' (defined as 50% luminance) and measure outwards to define the dynamic range. Hence there are 'two sides' to our results, the amount of shadow range (below middle gray) and the amount of highlight range (above middle gray).



Quote
That would explain why every camera was measured to have around 8 stops of DR... no matter what the actual dynamic range recorded by the camera they are all converted to the standard jpg file format with 256 levels per colour channel.

Sonys Sensor is measured with 9.4 EV.

I think the point is more about the fact that DPR is using jpeps for the test rather than the fact they're doing a real world visual test by shooting the step wedge and counting the number of stops above and below middle gray before detail is lost.  My understanding (and feel free to correct me if I'm wrong) that the jpeg transfer function sacrifices shadow and highlight detail in favor of preserving detail in the middle tones.  Something has to be lost to reduce file size and highlight and shadow detail is the least important.  The earlier clipping of the shadow and highlights reduces the DR that was captured in the RAW file and this is precisely why by shooting RAW we can pull more detail out of the shadows in post than working with the in-camera jpegs.

When I stated that all the DPR results all came in at 8.x stops I was making the point relative to the numbers in Gothmoth's post (I have not looked for the DRP results for all cameras) and my point was that they were all reduced to about the same level lower than the DxoMark tests.  If the Sony sensor was measured 9.4 then perhaps it started with more DR in the RAW file, perhaps the Sony in-camera jpeg applied a less aggressive transfer curve?  I don't know, I'm asking because you seem to know about the details of their testing?

Another question I have is, if DPR is shooting the wedge and visually counting the stops what are they viewing it on (monitor, print) and what is the DR of that viewing medium.  This I have no clue about so perhaps you know more about that.  My understanding though is that modern sensors can record more dynamic range than can be printed and only very high-end expensive monitors can display DR greater than about 10 stops which perhaps DPR was using.

Since you imply you've tested what you can achieve with your 1D4, how did you do your test?  Do you have access to a monitor that can display more than 8-9 stops of DR?

Pages: 1 ... 37 38 [39] 40 41 ... 46