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Messages - jrista

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1621
EOS Bodies / Re: dual pixel tech going forward
« on: April 26, 2014, 12:25:42 AM »
On the 70D, canon has two photo-diodes per pixel almost across the entire sensor. The fact that they can get useable phase information from them suggests that they can read them independently.

So, could they change the bayer filter out and double resolution rather than get sensor level phase detection? Perhaps being co-located they couldn't use a traditional bayer design, but could they for example have green AND either red or blue at every pixel?

If so, that could be a cost-effective way forward to producing 1DmkV and 1DmkVs cameras once DPAF is perfected to the point that it equals or betters SIR AF. The former could have a traditional bayer filter with the second processor dedicated to amazing autofocus; the latter could have double the resolution and use a simpler last-gen SIR AF unit.

I am probably fundamentally misunderstanding the implications of having two photo-diodes per pixel, though. More likely DPAF is their way into high end mirrorless.

Having two photodiodes per pixel means the photodiode pair exists underneath the CFA filter and the microlens(es). That is actually the only way DPAF really works...to be able to detect a phase differential, you need to check the HALVES of each PIXEL. If you just shrink the pixel size and put different color filters over those smaller pixels...well, now you have smaller pixels (and an odd image ratio), and you no longer have DPAF. It's a tradeoff...resolution or a focus feature, which do you want/need? (Or, as the case may be, you get a cross between both, slightly smaller pixels (i.e. 20mp 70D vs. the 18mp that came before) AND DPAF.)

I know everyone likes to speculate about all the wonderful things that DPAF might potentially bring to the table...but so long as it is Dual-Pixel Autofocus, that's all your really going to get. There really isn't any magic bullet here, no trickery that you can pull of by somehow using one half of the pixels at ISO 100 and the other half at ISO 800 for more dynamic range, etc. Pixel area is pixel area, and phase detect is phase detect. DPAF pixels serve one purpose when read out for AF, and another purpose when the halves are binned and read out for an image. Those are really the only two functions DPAF will ever serve, and while I'm sure the Magic Lantern guys will figure out something cool about the specific mechanism of DPAF's implementation...they will still only be able to work within the bounds of the sensors design. The ML DR increases was ultimately thanks to an OFF-die downstream amplifier that allowed them to control the readout process, not really due to any specific nuance of Canon's actual sensor design.

Assuming Canon does not remove that downstream amp in favor of some kind of on-die parallel ADC and readout system, I honestly don't expect them to be able to do anything more radical with DPAF. They may find a way of doing creative focus things with AF, maybe add the ability to remember AF positions for video purposes, things like that...but the design of DPAF doesn't really mean Canon suddenly has some amazing wildcard on their hands that can give them a significant edge in the stills photography department.

1622
Third Party Manufacturers / Re: Zeiss Otus Initial Impressions
« on: April 24, 2014, 03:52:53 PM »
Thanks Jrista, I need some support.

I have just returned from a heated debate with my boss (or wife if you like). She was not overly enthusiastic when I said I would change all light sources in the house to either candles, halogen point source or gas light bulbs, to avoid onion ring bokeh in my out of focus light source images ...  ::) What happened to sickness & health, support and encouragement and all that ...  :-\

Eldar, have you tried the same test using a different lens?  The TDP review linked below shows how different bokeh is affected by the different lens designs.  If you use a light source that produced the known effect with the Otus and then tried your S35, then you can compare the results with each other and to TDP to see whether or not it is a lens design/manufacturing issue.  The S35 isn't as clean as the new 35 f/2 IS, but the pattern should be different if the effect is dominated by the lens manufacturing technology and not by wavefront interference that jrista mentioned.

http://www.the-digital-picture.com/Reviews/Canon-EF-35mm-f-2-IS-USM-Lens-Review.aspx

This is an excellent idea. At least it would generally settle the matter with some hard evidence.

1623
Third Party Manufacturers / Re: Zeiss Otus Initial Impressions
« on: April 24, 2014, 03:19:18 PM »
I got an answer back from Zeiss, which seems to be an honest one.

Apparently onion rings are normally indicators for aspherical elements, showing the structures of the manufacturing process. They also say that visibility and intensity of these structures depend on various factors in the scenery, such as the intensity of the light source compared to the surroundings, the exposure, the spectral built-up, the amount of "unsharpness" and many other factors. They also mention that some bright light sources in the out-of-focus areas may be clean, due to light intensity (saturating the sensor).

So, without starting a new series of unfocused shots of all the various light sources I have available at home  ::) I think it is fair to conclude that this has to do with the lens. But! I made lots of shots where I deliberately used very fast shutter speeds at low ISO, to make sure I didn´t saturate the sensor. And in the cases where I had a clean light source, being a candle, a halogen point source or a gas filled bulb, I did NOT get onion rings.

So, I am still puzzled.  :-\

I still disagree. None of your OOF light sources were saturating the sensor. If I understand what Zeiss was saying, you REALLY need to saturate the sensor (i.e. have pure white full value OOF blur circles, blown blur circles...i.e. what you might get from spots of sunlight streaming through the leaves of a tree) to get solid color. The candles for sure were not even remotely close to saturating, yet they don't exhibit onion ringing. I am also 100% certain that the rings you see in my sample photo taken with my camera were due to the bulbs of the Christmas Lights I was photographing, not the lens (which does not have any aspheric elements.)

I truly believe your lens is fine, and that the aberrations in *some* of your OOF blur circles are due to other things.

1624
Animal Kingdom / Re: Show your Bird Portraits
« on: April 24, 2014, 03:11:58 AM »
Mourning Dove

Canon EOS 7D
Canon EF 600mm f/4 L II IS
Gitzo GT3532LS + Jobu Pro 2 Gimbal

I love the iridescent feathers they get around the back of their necks.

1625
Animal Kingdom / Re: Show your Bird Portraits
« on: April 24, 2014, 02:31:40 AM »
Wonderful shots, Don! You are indeed a lucky man. At best, I get rare glimpses of Ospreys far overhead, well beyond the reach of my lens. To have three nests...truly lucky man. :)

1626
EOS Bodies / Re: 1d IV vs. 7D II
« on: April 23, 2014, 10:24:24 PM »
I hope that was understandable. I never realize how long these posts are until I've actually posted them. They always end up longer than I expect.

I should caveat my last post with one thing. When I say pixel size doesn't matter, I do mean pretty strictly in context of noise, pixel size doesn't matter much. I don't want anyone to misinterpret that to mean that pixel size doesn't matter at all. On the contrary, pixel size does matter. Depending on what you shoot, it can matter a whole hell of a LOT! Pixel size determines resolving power (spatial resolution). When your photographing landscapes, birds or wildlife at a distance, even sports at a distance, you can always use more pixels. More pixels means more detail.

This should actually give even better context to the reasons why larger total sensor area is important when you are not reach-limited. If you can frame your subjects as you want to frame them, a larger sensor with smaller pixels means the best of both worlds...you can gather more total light, AND you can resolve more detail. There is really nothing wrong with that. Even if we eventually get to the point where sensors are oversampling lenses more often than not (which, unless we eventually see the "average" lens quality equal the quality the Otus delivers at fast apertures (at least f/4, even up to f/2.8), is rather likely), it's actually better to oversample than to undersample.

If we can oversample our images by about two fold at the lens' ideal aperture, then I think we would finally reach a point where AA filters would fundamentally be UNnecessary. The lens would be doing the necessary high frequency blurring for us, there would never be a chance (with the possible exception of the Otus Next :P) that the lens would resolve detail fine enough to create moire patterns and aliasing with the sensor. At that point, it would simply be a matter of practice to always downsample our images by a factor of two (at least, obviously significantly more for publication online) to get the ideal result. In the case of print, sensors with that kind of resolution (and were talking some pretty serious resolution here, 120-150mp FF at least) would be natively producing quality results that don't need to be upscaled (which effectively produces similar results to a sensor that oversamples a lens) unless your printing at some pretty extreme sizes...40x30 or larger (however even then...you wouldn't need to upscale as much, so it's a wash.)

1627
EOS Bodies / Re: 1d IV vs. 7D II
« on: April 23, 2014, 10:46:43 AM »
I thought this topic was going to be ideal because I have a chance of getting a mint 1dmk 1v with no more than 7500 clicks. I will trade my 7d against this camera. I am no longer prepared to wait for the fabled 7dmk11.
Given the number of pages posted here on the merits of full frame v crop ( I already have the 5dmk111 and love it) could anybody confirm whether the 1dmk iv will be better than the 7d in terms of overall image quality.

I know build quality will be improved and noise as well as autofocus will be better. I will be using this body with either the 300f2.8mk11 or 70-200f2.8mk11 + extenders.

Guys and girls a simple reply would be appreciated without going into the theorem of Pythagoras. I get lost with some of the technical stuff you all come up with.

So long as you compose your shots the same with the 1D IV as you would with the 7D II (i.e. the subject is framed the same), then yes, the 1D IV should perform better in pretty much every case. The only time a smaller sensor is better is when you are reach-limited, in which case your subject would be reproduced at the sensor the same size with both cameras. You'll get the same amount of light on the subject, as far as sensor area goes, however with the smaller pixels that are usually used with APS-C sensors, you'll generally get more detail.

If the 7D II hits the street with a strong AA filter, or a less than ideal full well capacity, then it is unlikely it would even perform as well as the 1D IV in reach-limited scenarios. (The 7D has a 20187e- FWC, where as the 70D has a 26726e- FWC DESPITE having smaller pixels...so it is likely that the 7D II will also have a better FWC.) I think it is most likely that the 7D II will hit with a slightly weak AA filter, as that's been the trend, I think it will also have improved Q.E., so I think it will have an FWC between 26ke- and 28ke-. For what it is, it should perform quite well...but regardless of how well, if your filling your frame with the subject, the 1D IV is still going to outperform it.

1628
EOS Bodies / Re: 1d IV vs. 7D II
« on: April 23, 2014, 10:33:15 AM »


There have been strides in sensor technology, however pixel size still dominates the determination of how much noise you have. Smaller pixels will always have more noise, that's a simple matter of physics. We have improved READ noise with better sensor technology, but read noise is only a small contribution to total noise (especially at high ISO)...photon shot noise is the primary source of noise in images. The larger pixels of the 1D IV will always win out against smaller pixels of APS-C sensors. The only way the 7D II could do better is if it had larger pixels than the 1D IV, however that would make it something like a 10mp sensor...highly unlikely.

A smaller pixel generates less read noise, correct. For example, the 7D has 8e- read noise, vs. the 1D X's 35e- read noise. But read noise is a tiny, tiny, tiny contributor to overall noise. The lower FWC means TOTAL noise (including photon shot noise) is higher, because your maximum signal (as dictated by that lower FWC) is lower.

The overall sensor area is what dictates total noise in the image, and in that respect it doesn't really matter what the pixel size is. Smaller sensors have more noise than larger sensors due to their smaller total area/less total light gathered.

Jrista, I'm a little confused by your two statements - which seem at odds with each other, unless I misunderstand them. 

My understanding is noise is determined by the total light gathered by the system, and that is a function of the sensor's area and its quantum efficiency.  That would mean changing the 7D sensor for one which is the same size but has a smaller number of much larger pixels (which otherwise performed the same) wouldn't help with noise, because you wouldn't change the total light gathered by the system.  Larger pixels would presumably have a larger FWC, which might enable more subtle colour/brightness gradation (and perhaps increase dynamic range?), but wouldn't actually reduce noise.

Am I missing something?

That is essentially correct. Pixel size doesn't matter much because you can always downsample, which is effectively the same as either binning or having larger pixels. Let's say you have a 32mp APS-C and a 8mp APS-C. Both sensors have a Q.E. of 50%. Neither sensor has an AA filter. These two sensors are a factor of four difference in pixel size...you can fit four of the 32mp sized pixels into one 8mp sized pixel. If you take the 32mp image and downsample it to 8mp (8000x4000 pixels downsampled to 4000x2000 pixels), the results are the same. The per-pixel noise of the 32mp image is higher, however once downsampled, basic averaging effectively nullifies the increase in noise, and largely nullifies the increase in detail, resulting in nearly the same detail and exactly the same noise as the 8mp sensor. The detail will be slightly higher as you started out with a finer level of detail, and the multi-sampling process of downsampling means that while you are concurrently averaging out noise, you are also compounding the quality of detail in each pixel.

Now, let's say the 8mp camera has 40% Q.E. and the 32mp camera has 80% Q.E. Now the 32mp camera only has noise that is 50% worse than the 8mp, rather than twice as bad. If you downsample the 32mp image to the same dimensions as the 8mp image, the downsampled 32mp image will have less noise and will show the same advantage in detail. It is highly unlikely we will ever see a consumer-grade sensor with 80% Q.E. I've only seen those levels in Grade 1 scientific sensors (the kinds of sensors you find in astrophotography cameras or the stuff they ship up to the Hubble.) We may see sensors with 65% Q.E. or so, however that is only about a half-stop improvement over the ~50% most current sensors have now.

Now, let's say we have two sensors of differing size. Let's say we have a 16mp mp FF sensor, and an 8mp 24x16mm sensor (exactly half the area of the FF sensor, slightly larger than APS-C). Both cameras have exactly the same pixel size. If you frame your subject in one vertical half of the FF sensor with the camera oriented vertically, and crop out the other half, you will have identical results to the 8mp APS-C sensor. If you frame the same subject horizontally using the full area of the FF sensor, you are putting twice as much sensor area on the subject. You have gathered double the amount of light with the FF sensor as you are with the APS-C sensor...and it has nothing to do with pixel size. If you downsample the FF image to the same dimensions as the APS-C image, your going to trounce it in both noise levels and detail levels.

The total amount of light gathered is really what matters. Assuming the same sensor size, then the actual pixel size does not really matter all that much. There are things that may result in improved performance of one sensor with one pixels size or another. Improved quantum efficiency is one way. There are also caveats with pixel size. If you want more pixels, that also means more wiring. In FSI sensors, the increased wiring with smaller pixels means there is even less total light sensitive area than with larger pixels. Theoretically, assuming an identical fabrication process is used, our 8mp camera from above will actually have more total photodiode (light sensitive) area than the 32mp sensor. If they both have the same Q.E. then the 8mp sensor will actually perform slightly better due to the slightly greater total photodiode area. This would be the only way I think a 7D II could perform as well as or better (highly unlikely) than the 1D IV. By reducing pixel count significantly, one can increase the total amount of light-sensitive sensor area. I'm not exactly sure where the cutoff point would be...however you would have to pretty drastically reduce the wiring area of the 7D II. You would probably also need to use a process shrink (500nm to 180nm). Another way to do it would be to move to a BSI design. (This all assumes that there is enough wiring in the 1D IV sensor that total light sensitive area is still not greater than the area of an APS-C sensor...if it is, then actually there wouldn't be any way the 7D II could actually perform better.)

In this respect, you are indeed correct about color fidelity and dynamic range...larger pixels do have an edge here. However you are still going to find that greater total sensor area still has a greater impact on those aspects of IQ than larger pixels do in the long run (for example, the D800 has phenomenal color fidelity, however it's pixel size is only marginally larger than the 7D, which has pretty terrible color fidelity in the grand scheme of things...the greater total light gathering capacity, benefited by both higher Q.E. and being FF, of the D800 is it's real edge here.)

Other technology may be employed to increase the total light sensitivity of a sensor pixel. Currently sensors are effectively two dimensional...the only thing that really matters for total charge capacity is the area of the photodiode. Foveon-type sensors stack photodiodes, resulting in an increase in total charge capacity for each pixel. The same technique could theoretically be employed for monochrome and bayer sensors. Blue pixels would be least sensitive, as silicon will filter out most of the bluer wavelengths before they penetrate deeply. Green and red pixels would be most sensitive, allowing for two or three, maybe even four layers of photodiodes. Such technology could be employed in higher megapixel sensors to increase FWC and sensitivity. There is nothing that says the same techniques couldn't be employed with larger pixel sensors, though.

1629
Canon General / Re: $10,000
« on: April 22, 2014, 04:46:36 PM »
Also means I have $ 8K of equipment just for hobby. WTF!!!  :o

Ain't it scary when you realize exactly HOW MUCH you've spend on your hobby? :P

After I got my 600mm lens, I calculated all of mine. Without the lens it's over $10,000, and with the lens it's almost $23,000!  ??? Throw in the new astrophotography gear...

It's way too easy to spend ridiculous amounts of money on photography.  :o

Yours is justified by the time you spend on it, and the photos you have created.

Well thanks. :) I'm pretty critical of my own work. I always feel I could do way better. I could probably count on one hand the number of photos of my own that I think are really good. :P

I have less control over the quality of the end product, but at least I need to spend a lot more time shooting. Which means I need to manage my time better...  :-[

I too need to spend more time. I haven't photographed birds in months (largely because we were in the dead cold of winter until about two and a half weeks ago...now suddenly it's 75° during the day! :P) I guess I should get out there and start photographing nature again. It's galaxy season right now, and I need a bigger/longer scope to image those in any reasonable fashion. Nebula won't be back until the middle of next month, so it's an ideal time to get back out into nature...

1630
Canon General / Re: $10,000
« on: April 22, 2014, 04:21:40 PM »
Also means I have $ 8K of equipment just for hobby. WTF!!!  :o

Ain't it scary when you realize exactly HOW MUCH you've spend on your hobby? :P

After I got my 600mm lens, I calculated all of mine. Without the lens it's over $10,000, and with the lens it's almost $23,000!  ??? Throw in the new astrophotography gear...

It's way too easy to spend ridiculous amounts of money on photography.  :o

1631
Canon General / Re: $10,000
« on: April 22, 2014, 02:47:58 PM »
I have really...I mean....REALLY...expensive hobbies....  :o

Look at it this way, cheaper than collecting cars or yacht racing.   Or are those your other hobbies?   :o

Well, let me fill in a few holes. Here is my "other" hobby (still photography...just a much more complex form: astrophotography). My ideal rig would be:

10Micron GM2000HPS: $20,850
PlaneWave 20" CDK: $32,500
FLI Proline 16801 Mono CCD - 65mm, Grade 1: $27,000

Then you have all the various accessories....robotic filter wheels, robotic focusers, robotic field rotators, off-axis guiders, etc. To use all this equipment, you need to build an observatory for it (it is not portable.) That's anywhere from $30,000 to $50,000, and if you want it out under consistently dark, clear skies, you gotta buy the land for it, too! :P

Die-hard astrophotography is probably about as expensive as fixing up old muscle cars or yacht racing in the end.

Okay, you're right.  You're just nuts.   ;D

Nope. I'm pre-nuts. Totally Nuts will come once I actually literally blow that kind of money on that kind of equipment. :P  ;D

1632
Canon General / Re: $10,000
« on: April 22, 2014, 02:00:38 PM »
you slowly start buying gear and one day your gear is more expensive than your first car.

…and then one day, you buy a single lens that is more expsnsive than your first car.   ;)

BTDT :P

1633
Canon General / Re: $10,000
« on: April 22, 2014, 01:59:52 PM »
I have really...I mean....REALLY...expensive hobbies....  :o

Look at it this way, cheaper than collecting cars or yacht racing.   Or are those your other hobbies?   :o

Well, let me fill in a few holes. Here is my "other" hobby (still photography...just a much more complex form: astrophotography). My ideal rig would be:

10Micron GM2000HPS: $20,850
PlaneWave 20" CDK: $32,500
FLI Proline 16801 Mono CCD - 65mm, Grade 1: $27,000

Then you have all the various accessories....robotic filter wheels, robotic focusers, robotic field rotators, off-axis guiders, etc. To use all this equipment, you need to build an observatory for it (it is not portable.) That's anywhere from $30,000 to $50,000, and if you want it out under consistently dark, clear skies, you gotta buy the land for it, too! :P

Die-hard astrophotography is probably about as expensive as fixing up old muscle cars or yacht racing in the end.

1634
EOS Bodies / Re: 1d IV vs. 7D II
« on: April 22, 2014, 01:23:54 PM »
On the basis of better IQ and lesser noise at high ISO, there's a good chance the 7D II will be at least as good as the 1D IV. In there last few years, there have been great strides made in sensor technology. Let's hope the camera that finally comes to market doesn't have too many, hence smaller, pixels to negate that virtue.
On the other hand, the reliability and durability of the 7d II will likely not come close to the 1D IV (nor any others in the 1D family) unless it's sold at a price point above the 5D III. Since it's being billed as a prosumer camera, we can  be pretty certain THAT's not going to happen.

There have been strides in sensor technology, however pixel size still dominates the determination of how much noise you have. Smaller pixels will always have more noise, that's a simple matter of physics. We have improved READ noise with better sensor technology, but read noise is only a small contribution to total noise (especially at high ISO)...photon shot noise is the primary source of noise in images. The larger pixels of the 1D IV will always win out against smaller pixels of APS-C sensors. The only way the 7D II could do better is if it had larger pixels than the 1D IV, however that would make it something like a 10mp sensor...highly unlikely.

This statement is not true, a smaller pixel generates less noise but also have a lower FWC due the psycial size.
http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p3.html

A smaller pixel generates less read noise, correct. For example, the 7D has 8e- read noise, vs. the 1D X's 35e- read noise. But read noise is a tiny, tiny, tiny contributor to overall noise. The lower FWC means TOTAL noise (including photon shot noise) is higher, because your maximum signal (as dictated by that lower FWC) is lower.

The overall sensor area is what dictates total noise in the image, and in that respect it doesn't really matter what the pixel size is. Smaller sensors have more noise than larger sensors due to their smaller total area/less total light gathered.

1635
Canon General / Re: $10,000
« on: April 22, 2014, 01:11:18 PM »
Hmm. If I had ten grand. Well, ignoring the "jack of all trades" bit, I'd buy this:

FLI ProLine 16803 CCD

One of the best Astro CCD imagers on the market, used by the masters. :P

For an actual camera setup, from scratch...I don't think I could buy what I need with a "mere" $10,000:

Canon 1D X
Canon 5D III
Canon EF 600mm f/4 L II
Canon EF 300mm f/2.8 L II
Canon EF 70-200mm f/2.8 L II
Canon EF 85mm f/1.2
Canon EF 50mm f/1.2
Canon EF 8-15mm
Canon TS-E 24mm
Canon MP-E 65mm 1-5x Zoom Macro

That would be my ideal kit. It's...WAY more than ten grand...more like FIFTY GRAND.

??? :-\ :(

I have really...I mean....REALLY...expensive hobbies....  :o

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