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Messages - jrista

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46
EOS Bodies / Re: Canon Confirms Development of High Megapixel Camera
« on: December 29, 2014, 03:19:12 AM »
And yet wildlife guys sure seem to love the high density sensors.

Do they?  Are 'wildlife guys' flocking to the D800/810 or a7R?  Not that I've seen.  But I do see a lot of crop bodies used by 'wildlife guys'.  Now...is that because of the higher pixel density, or is it because of the real crop factor advantage – lower cost?  I suspect the latter, even if not everyone is willing to admit it.


Quite a few birders now use the D810 for it's higher resolution and "crop mode" option with higher frame rate. The results are pretty amazing, especially with dark birds with white highlights, like Loons, against brighter backgrounds.

47
EOS Bodies / Re: Canon Confirms Development of High Megapixel Camera
« on: December 28, 2014, 08:54:18 PM »
Heh...clearly business as usual here on CR...  ::)


I'm going to get back to my photography. I like not being here so much anymore...

48
EOS Bodies / Re: Canon Confirms Development of High Megapixel Camera
« on: December 28, 2014, 07:35:23 PM »

In practice, does pixel size affect low light performance for the same sensor area?

In practice, for moderate to high ISOs, smaller pixels do better.
Why is the red line above the orange line?

Different sensors, entirely.  The A7S has higher QE and lower read noise, neither of which goes with larger pixels.
How about "5D-III vs 1D-X" or "A7R vs D4"? (see attached)
Are those equal sensor technologies?

Virtually identical as you can see, plus DXO's testing doesn't for why smaller pixels win, which I posted up thread with samples.
Virtually the same... So how exactly is it that small pixels are better in low light? ??? I remind you that you earlier said: "In practice, for moderate to high ISOs, smaller pixels do better."

In general smaller pixels appear to be ever-so-slightly-worse with SNR.  If you consider the Dynamic Range you'll see that larger pixel are clearly superior at higher ISO. Colour sensitivity is virtually identical. I'm failing to see how smaller pixels (with equivalent technology) are any better in low light.  In what way are they doing "better"?

As for your post on why smaller pixels win, how about this: 20MP, at 200mm f/4 which is sharper?
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=458&Camera=963&Sample=0&FLI=0&API=3&LensComp=458&CameraComp=819&SampleComp=0&FLIComp=0&APIComp=3


The image comparison there is flawed, as it is same-framing, rather than same subject distance. It doesn't matter what you do, if you put more pixels on subject, then your going to get a better result. The 6D has larger pixels AND more pixels, so when that test chart is framed identically, your putting more pixels, and more sensor area, onto the chart. Of course it is going to be better.


When you frame such that the subject fills the same absolute sensor area (in other words, the chart would have to fill only the central 1.6x crop area of the FF sensor that matches an APS-C sensor), then the smaller pixels are going to resolve more detail (all else equal...the 6D uses newer pixel technology, so all else is NOT equal.)
When I say same sensor area I mean when comparing:
a) full-frame to full-frame
b) APS-C to APS-C

The 6D was released in September 2012, 7D-II has a newly developed sensor and was only just released in 2014. 7D-II also has been reported to have a higher QE than the 6D. Is it really fair to say that the 6D has newer pixel technology? Also, I just opened some CR2 files to look at the actual flie resolution. 6D resolution is 5472x3648 (19.96MP) and the 7D-II resolution is 5472x3648 (19.96MP). So in practical terms, no difference.

On my "flawed" normalizing:
1) Would you agree that a photographer should frame the subject as they intend to print it?
2) Should photographers use different composition rules when shooting on Full frame than they do when shooting APS-C? (i.e. Should Full frame users only frame their images in the tiny APS-C-equivalent portion of the frame?)


I didn't say it was your flawed normalizing, simply that the comparison itself was flawed, in the context of determining if one sensor resolves more than another, because the comparison was "same framing" rather than "same distance." Simple distinction, very important.


Regarding the 7D II, as far as I know the camera in discussion thus far was the 7D, not the 7D II. Still, it doesn't matter much. In a same-framing comparison, even if you have the same pixel count, the 6D is a full-frame sensor. Again, pixel size is irrelevant here...the larger sensor gathers more light. Period. More light, stronger signal, less noise. It's a very simple equation. Pixel size is immaterial to noise on an absolute-sensor-area basis in the grand scheme of things. Other factors about the pixels or sensor design, such as presence or strength of a CFA, the use or lack thereof of an AA filter, etc. can affect such comparisons...but when it boils down to pixel size and pixel size alone, it doesn't matter as far as noise goes. Bigger sensor, more light, stronger signal, less noise. That's all there is to it.


If you put more pixels onto a sensor, FF vs. FF or APS-C vs. APS-C, or FF vs. APS-C in a same-distance comparison, smaller pixels resolve more. Again, it's relatively simple. This should be obvious, of course smaller pixels resolve more. The key, when comparing FF to APS-C, is to make sure you've properly normalized. If you compare a full-frame camera to an APS-C camera in a same-framing context, then, relative to the scene, the pixels of the FF are smaller on a relative basis, thus they resolve more. Hence the reason it is important to compare FF and APS-C in a same-distance context. You could have fewer pixels on the APS-C, more pixels on the FF even, it doesn't matter. What matters is the total light gathered in your crop area. If the APS-C had larger pixels than the FF, and the FF was cropped to 1.6x size then downsampled, your STILL going to have the same noise...only the downsampled FF crop is going to be sharper.


Pixel Size <==> Resolving Power
Sensor Size <==> SNR/Noise


As for your two questions, they are irrelevant in the context of comparing two sensors on an objective basis. However, not everyone has the ability to always fill the frame with every sensor. Birding and wildlife are two great examples of reach-limited photography. You aren't always able to fully utilize the entire sensor surface with a FF sensor....sometimes you are FORCED to use only the central region (and possibly even less than a 1.6x crop equivalent area.) If you always have the ability to more tightly frame your subject, then the bigger the sensor, the lower the noise. Simple as that. If you are reach limited, then more resolution in a smaller sensor isn't going to hurt you over using a larger sensor with less resolution at the very least, and at best it would mean you have more detail with the same noise if you normalized (which, if your publishing to web, is pretty much always going to be the case.)


In a comparison of the 7D II vs. the 6D, which one wins? It entirely depends on what your shooting, and what your options are when shooting. The 6D will do better when you can utilize all it's pixels. The 7D II will do better when you are forced to shoot at a distance (and certainly when you need faster, more accurate AF.) The 7D II is packing the same pixel count into half the sensor area, so of course it's going to resolve more detail in a reach-limited situation. Conversely, of course the 6D is going to have less noise in a same-framing situation. If you had a 6D II with the same pixel size as the 7D II yet was still a full-frame and had an awesome AF system, then you would have the best of both worlds...resolving power, light gathering power, cropping power, sheer resolution.


This is pretty elementary stuff. I am always surprised that everyone has such a hard time with it. Not everyone shoots the same things, not everyone has unlimited budgets. Therefor, some people are always going to be able to fill the frame given what they shoot (portraits, weddings, street, studio, etc.), thereby maximizing the benefits of ever larger sensors. Concurrently, other people are always going to be reach-limited, always needing longer focal lengths and/or higher resolution sensors given what they shoot (birds, wildlife, landscapes, sports, etc.), thereby maximizing the benefits of ever smaller pixels. (Note, ever smaller pixels, damn the sensor size, it doesn't matter...you could have 7D II pixels in an APS-C or FF package...the reach-limited will always be able to use more resolution.) There will also always be some who want the best of every world, and those are the most demanding customers...wanting a balance of frame rate, AF performance, sensor size and pixel count. If it was possible to build a 15fps FF sensor with 80mp, someone would have done it, they would sell it for a mint, and they would have ecstatic customers from every walk of photographer life. :P

49
EOS Bodies / Re: Canon Confirms Development of High Megapixel Camera
« on: December 28, 2014, 06:46:41 PM »
Utterly meaningless without the camera details. So which two same generation crop and ff cameras were these?
They are cameras that came out within three months of each other but have pixels different in size by a factor of 16.

Your unwillingness to answer a direct, specific question with a direct, specific answer says a lot about your credibility.  I have little respect for anyone who conducts a test but refuses to fully disclose their methods, nor do I accept at face value the data from such 'tests'.

Well, this Private guy is such a dork that he'll pick some irrelevant detail of the test and declare the whole thing invalid, so I'm not giving this particular person any information that isn't relevant to the test.  They are both Bayer sensors of the same generation with very similar performance per unit of area, and they were both shot in the same way in the same conditions.  No tiny changes in read noise or quantum efficiency or anything else will mean anything compared to the enormous difference in pixel size (factor of 16 in area).  But Private will latch onto something irrelevant and ignore the relevance.


Why not just provide the names of each camera? That isn't difficult to do, and Private isn't the only one who cares. Being specific about your test is the only way for it to be taken seriously. Personally, I agree with you that smaller pixels are not a bad thing, but don't be so obscure...it really DOES make you seem like you are hiding something, and that does go to your credibility. (Especially on these forums...  ::) )

Fine, S3, 5D, not that it matters at all.


Well, it matters enough that it stopped the conversation. ;P At least now we can move forward.

50
EOS Bodies / Re: Canon Confirms Development of High Megapixel Camera
« on: December 28, 2014, 06:40:43 PM »
Utterly meaningless without the camera details. So which two same generation crop and ff cameras were these?
They are cameras that came out within three months of each other but have pixels different in size by a factor of 16.

Your unwillingness to answer a direct, specific question with a direct, specific answer says a lot about your credibility.  I have little respect for anyone who conducts a test but refuses to fully disclose their methods, nor do I accept at face value the data from such 'tests'.

Well, this Private guy is such a dork that he'll pick some irrelevant detail of the test and declare the whole thing invalid, so I'm not giving this particular person any information that isn't relevant to the test.  They are both Bayer sensors of the same generation with very similar performance per unit of area, and they were both shot in the same way in the same conditions.  No tiny changes in read noise or quantum efficiency or anything else will mean anything compared to the enormous difference in pixel size (factor of 16 in area).  But Private will latch onto something irrelevant and ignore the relevance.


Why not just provide the names of each camera? That isn't difficult to do, and Private isn't the only one who cares. Being specific about your test is the only way for it to be taken seriously. Personally, I agree with you that smaller pixels are not a bad thing, but don't be so obscure...it really DOES make you seem like you are hiding something, and that does go to your credibility. (Especially on these forums...  ::) )

51
EOS Bodies / Re: Canon Confirms Development of High Megapixel Camera
« on: December 28, 2014, 06:36:52 PM »
Lee Jay, the 7D had 18 megapixels...not 12...

52
Landscape / Re: Deep Sky Astrophotography
« on: December 28, 2014, 05:34:52 PM »
Thank you for the answers, well i agree with you, but as you said you are stretching the data beyond what anyone would do in other types of photography, maybe ask Canon for an astro camera? but yeah i want a better sensor as well, though currently i am very happy with the jump to FF :)


Eh, no point in asking Canon for an astro camera. They are the only DSLR manufacturer that has produced any, the 20Da and the 60Da. They don't filter out as much red, so they pass a lot more hydrogen alpha emissions (the primary reddish/pink emission of hydrogen gas nebula.) The problem with DSLRs is they have rather non-linear data. There is always some kind of in-camera processing. Canon used to be more linear than all the alternatives in the past, but they have been doing more processing in-camera lately, particularly with the 7D II (and DIGIC 6).


DSLRs make ok stop-gap astro imagers, but for anyone who is as serious as I am, the only real option is a CCD. CCDs have excellent data linearity and for the better manufacturers (i.e. QSI, FLI) they have perfect gaussian read noise (no banding, very few if any hot pixels), which is vastly superior for astro. The other benefit of a CCD is you can get them monochrome, and use various filters like LRGB (luminance + RGB) or narrow band (Ha, SII, OIII, NII, Hb, and a variety of other bands). The mono sensors have a far higher fill factor, no color noise to speak of, and are overall much more sensitive regardless of the filter used (simply because your using all of the sensors pixels for all bands.)


I'll probably be getting a QSI 683WSG-8 soonish here. It's an APS-C sized sensor, the KAF-8300, full mono, with an 8-position filter wheel (LRGB, Ha, SII, OIII and unfiltered), off axis guider port, and has a perfect gaussian read noise distribution. It's a very expensive camera though (with the filters and the various necessary adapters for use with my Canon lenses and standard telescope equipment)...about five grand. So I won't be buying any other cameras any time soon...least of all Canon, Canon sensors, even their newest ones, are just too darn noisy with poor noise characteristics.

53
Landscape / Re: Deep Sky Astrophotography
« on: December 28, 2014, 05:27:23 PM »
It's some kind of diffraction effect caused by the lens. Those are indeed stars. I'm not sure what causes it, but it's always been that way. I've noticed recently that my stars are not flat across the field, which has me worried that my lens has a decentered or tilted element. Frustrating, as if that's the case, it's probably going to cost me a fortune to get it fixed...and I don't know when or how it happened.


Anyway, here is an updated version:








http://jonrista.com/2014/12/28/orions-sword-wide-field-dust-and-reflections/

54
EOS Bodies / Re: Canon Confirms Development of High Megapixel Camera
« on: December 28, 2014, 05:12:57 PM »

In practice, does pixel size affect low light performance for the same sensor area?

In practice, for moderate to high ISOs, smaller pixels do better.
Why is the red line above the orange line?

Different sensors, entirely.  The A7S has higher QE and lower read noise, neither of which goes with larger pixels.
How about "5D-III vs 1D-X" or "A7R vs D4"? (see attached)
Are those equal sensor technologies?

Virtually identical as you can see, plus DXO's testing doesn't for why smaller pixels win, which I posted up thread with samples.
Virtually the same... So how exactly is it that small pixels are better in low light? ??? I remind you that you earlier said: "In practice, for moderate to high ISOs, smaller pixels do better."

In general smaller pixels appear to be ever-so-slightly-worse with SNR.  If you consider the Dynamic Range you'll see that larger pixel are clearly superior at higher ISO. Colour sensitivity is virtually identical. I'm failing to see how smaller pixels (with equivalent technology) are any better in low light.  In what way are they doing "better"?

As for your post on why smaller pixels win, how about this: 20MP, at 200mm f/4 which is sharper?
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=458&Camera=963&Sample=0&FLI=0&API=3&LensComp=458&CameraComp=819&SampleComp=0&FLIComp=0&APIComp=3


The image comparison there is flawed, as it is same-framing, rather than same subject distance. It doesn't matter what you do, if you put more pixels on subject, then your going to get a better result. The 6D has larger pixels AND more pixels, so when that test chart is framed identically, your putting more pixels, and more sensor area, onto the chart. Of course it is going to be better.


When you frame such that the subject fills the same absolute sensor area (in other words, the chart would have to fill only the central 1.6x crop area of the FF sensor that matches an APS-C sensor), then the smaller pixels are going to resolve more detail (all else equal...the 6D uses newer pixel technology, so all else is NOT equal.)


55
EOS Bodies / Re: Canon Confirms Development of High Megapixel Camera
« on: December 28, 2014, 05:09:52 PM »
It is funny I have been saying this same thing for years, nearly 7, when I first compared the 7D to the 1Ds MkIII and I used to get no end of crap for saying it. Probably the most vocal maths oriented poster here used to crucify me, he was a 7D owner and insisted that his camera had vastly more 'resolution' than mine, he has since got a 5D MkIII and done the tests, guess what? His estimation of the crop cameras 'resolution advantage' has gone from >60% to around 15% at best on manual focus bench tests.


You are taking so many things I've said way out of context there, it's unbelievable. First, I've never said the 7D had a mere 15% advantage over the 5D III. I did say it might be about 25% on average for the average use case (i.e. no tripod, less than ideal focus, etc.) The 60% statement was qualified with the fact that ignores the bayer array or AA filter...i.e. it's the raw, monochrome mathematical advantage of the 7D's pixel size.


I believe under more ideal conditions, the 7D can realize about a 45% advantage over the 5D III. That is just a resolving power advantage, which when were talking about micrometer sized pixels, isn't something that jumps out of the screen at you...that would be something more like a 200% or 300% advantage, which at the moment only small form factor sensors have with 1.0-1.2 micron pixels.


You and I see different things, which is why subjective comparisons are useless. Maybe I sit closer to my screen than you do, who knows. I see the advantage of the 7D, you do not. Neither of us is right until someone actually does a proper test with proper testing tools and gets some actual resolution numbers. However we all know how well real numbers go down here on these forums as well...so again, it's all entirely pointless.


Simple fact: smaller pixels resolve more detail. I think that has been demonstrated thoroughly well over the last decade, throughout the continual march towards ever smaller pixels paired with frequently improving optics.
I agree that smaller pixels can resolve more detail if the lens has sufficient resolving power.

In practice, does pixel size affect low light performance for the same sensor area?


By "for the same sensor area", I assume you mean when your subject fills the same absolute area of sensor (i.e. you would need to crop the FF to get the same FoV as the APS-C). In  that case, the pixel size isn't really going to affect things much. Assuming same lens, same aperture (which would be necessary for identical subject size and DoF at the sensor), then your going to gather the same amount of light in total for your subject, regardless of which sensor you use. The FF could have bigger pixels, or it could have the same size pixels as the APS-C. The pixel size doesn't really matter...it's just an arbitrary factor. In the end, for an APS-C sized crop of an FF sensor, you gathered the same amount of light as the APS-C itself. Therefor, noise should be the same once the results are normalized. If the FF has the same pixel size as the APS-C, then simply cropping would be enough to normalize. If the FF had larger pixels than the APS-C, then downsampling the APS-C to the same image dimensions as the FF would average pixel data together, resulting in the same noise.


Now, if you framed the subject the same with both cameras, and used the same aperture with both, then the FF camera, regardless of pixel size, is going to perform better.


Pixel size, ultimately, affects resolving power. Smaller pixels, higher resolving power. If you move from an FF sensor with 10 micron pixels to an FF sensor with 5 micron pixels, your going to resolve more detail. Strait out of camera, the image made with smaller pixels will appear noisier...unless you downsample it to the same dimensions as the 10 micron image. Then noise will appear the same, however the 5 micron image will still be sharper and more detailed.


Smaller pixels, assuming same or better technology, can never be a bad thing. On a normalized basis, smaller pixels mean more detail (all else being equal.)

56
EOS Bodies / Re: Canon Confirms Development of High Megapixel Camera
« on: December 28, 2014, 01:13:56 AM »
It is funny I have been saying this same thing for years, nearly 7, when I first compared the 7D to the 1Ds MkIII and I used to get no end of crap for saying it. Probably the most vocal maths oriented poster here used to crucify me, he was a 7D owner and insisted that his camera had vastly more 'resolution' than mine, he has since got a 5D MkIII and done the tests, guess what? His estimation of the crop cameras 'resolution advantage' has gone from >60% to around 15% at best on manual focus bench tests.


You are taking so many things I've said way out of context there, it's unbelievable. First, I've never said the 7D had a mere 15% advantage over the 5D III. I did say it might be about 25% on average for the average use case (i.e. no tripod, less than ideal focus, etc.) The 60% statement was qualified with the fact that ignores the bayer array or AA filter...i.e. it's the raw, monochrome mathematical advantage of the 7D's pixel size.


I believe under more ideal conditions, the 7D can realize about a 45% advantage over the 5D III. That is just a resolving power advantage, which when were talking about micrometer sized pixels, isn't something that jumps out of the screen at you...that would be something more like a 200% or 300% advantage, which at the moment only small form factor sensors have with 1.0-1.2 micron pixels.


You and I see different things, which is why subjective comparisons are useless. Maybe I sit closer to my screen than you do, who knows. I see the advantage of the 7D, you do not. Neither of us is right until someone actually does a proper test with proper testing tools and gets some actual resolution numbers. However we all know how well real numbers go down here on these forums as well...so again, it's all entirely pointless.


Simple fact: smaller pixels resolve more detail. I think that has been demonstrated thoroughly well over the last decade, throughout the continual march towards ever smaller pixels paired with frequently improving optics.

57
EOS Bodies / Re: Canon Confirms Development of High Megapixel Camera
« on: December 28, 2014, 12:48:10 AM »
Quote
There is no problem of pixel size.

<physics>There is. </physics>


The only physical limitation on pixel size is when they become as small or smaller than the wavelengths of light you need to image. Outside of that, there are no physical limitations on how small pixels can be. We can always benefit from smaller pixels...although beyond a certain point, at common apertures (f/2.8 and smaller) you enter the realm of severely diminishing returns.


At diffraction limited fast apertures, lenses will always resolve more than the smallest physics-limited pixels, which is around 800nm (0.8um)...manufacturers are already wary of implementing 900nm pixel sizes...the smallest so far are 1000nm, which are already smaller than the 1100mm infrared limit for silicon based sensors.

58
Landscape / Re: Deep Sky Astrophotography
« on: December 27, 2014, 11:23:16 PM »
Thanks. :)


So, there is noise. Lots of noise. It's only 2 hours of integration, and I probably need a minimum of 5 to really do it justice. It's just not easy to get that data, since there are only a handful of dark nights a month, and Orion is really racing towards the western horizon. I hope to gather another three hours at some point, which should help.


The 5D III, as I've tried saying so many times on these forums, is one craptastically noisy sensor! It is NOT, buy today's standards, a low noise sensor, at all. Which is a little sad, for a camera barely three years old. That's where the color noise comes from.


As for electronic noise overall, it's actually fairly low. I used ISO 1600 specifically to get read noise low. Its around 3.x e-. I was also imaging at around 3C (it's the heart of winter here, nights are 15-18F), so the dark current is very low. The reason the darker regions look noisy is they have been very significantly stretched. I had 21.3mg/sq" skies where I imaged this, which is getting pretty close to the darkest possible 22mg/sq" skies on earth. That was necessary to even get a reasonable amount of photons on those dark areas. Still, on a per-sub basis, the darker areas probably only had maybe 5-8 photons/pixel/minute tops! :P


So, yeah...there is noise. There is always noise, and when you do a ludicrous stretch like I did, that noise can present a bit of a problem. The only solution is to expose long enough to swamp read noise, and integrate more and more. I need three and a half more hours of integration for my minimum, and I would really prefer another 7 hours.


Regarding dark subtraction, you have to match the dark frame temps to the light frame temps. That can be a major PITA, so I stopped bothering and now use dithering instead. Along with Winsorized Sigma Clipping integration, that takes care of the hot and cold pixels, sat tracks, etc. I still use biases and flats, though...and flats actually tend to increase noise a bit as it removes LP and vignetting.

59
Landscape / Re: Deep Sky Astrophotography
« on: December 27, 2014, 05:06:32 PM »
Bad weather has basically shut me down lately. Decided to start spending my clear nights at a dark site, as it's vastly more efficient to gather photons without LP than with. Here is my latest:





Orion's Sword - Wide Field with additional Dust and Reflections


Canon 5D Mark III
Canon EF 600mm f/4 L II
Orion Atlas EQ-G (Belt Modded)


Acquisition with BackyardEOS, processing with PixInsight and Photoshop. Total of 2h 20m integration for the background, grand total of ~4h total image data for bringing out the core (manual blending, this target has MASSIVE dynamic range.)



60
EOS Bodies / Re: Canon Confirms Development of High Megapixel Camera
« on: December 27, 2014, 05:01:14 PM »
Nope - Zeiss will never, ever make anything to compete with the Big Whites.

Really? 



Do you think Canon will ever make anything to compete with the Zeiss 1700mm f/4?   ;)


I wouldn't say there is any "competition" going on between that Zeiss and Canon lenses at all. Look at that Zeiss thing...that's a funktastically wackadillyc monstrosity of a lens there...and it was a special order design that required very special focusing mechanisms and only works with one particular Hassy 6x6. That isn't a mainstream product that has regular availability. If Canon wanted to, they could special-order something up like that as well (that's basically what the 1200mm lenses were.) I think the comparison here is irrelevant.

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