August 28, 2014, 03:15:18 AM

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Messages - dgatwood

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1
EOS Bodies / Re: Do Sensors Make the Camera?
« on: August 27, 2014, 07:24:32 PM »
Can Canon change their ADC arrangement to eliminate deep shadow noise without running afoul of Sony's patent? Can they do so with their current fab situation (whatever that might be)? Are the yields economical at this time given that this is a feature much debated on forums, but only actually used by a small minority?

Which Sony patent, specifically?

2
EOS Bodies / Re: F8 AUTOFOCUS
« on: August 27, 2014, 03:13:43 PM »
And, to further confuse the issue, the 70D will autofocus f/11 lenses.  This is only possible while using live view, autofocusing of that 400mm f/5.6 lens with a 2X TC attached is allowed.

I'd expect to see this feature on the 7D MK II, but no live AF beyond f/11.

Even the current 7D will AF an f/11 lens (e.g. 100-400L + 2x) with live view, using contrast detect AF.

I've used my 6D's live view autofocus at almost f/24 (an f/5.6 lens with stacked 1.4x and 3x TCs).  It has a bad miss rate (mostly because I can't hold the camera still enough at 1260mm even with the 70–300L's IS system), but it does function....

3
EOS Bodies - For Stills / Re: 5DIII dual cards
« on: August 27, 2014, 03:07:17 PM »
The SD slot is hooked up to the internal USB so no real writing/reading speed implemented by Canon.

If so, then Canon still chose what USB SD reader chipset to use, which defines the speed of the reader.  And if it really is a USB-based reader, then there's absolutely zero excuse for Canon doing what they did, because upgrading to UHS-I would be as simple as swapping in a different chip, with little or no wiring or design changes on Canon's part....


I would assume that the circuitry was copied straight out of the 5D Mark II, and that they just didn't bother to update it for the 5D Mark III because they figured nobody would bother to use the SD card anyway.  :)

erm, but the 5D2 uses CF only :P
The SD + CF combo is new to the 5D3, right? Or have they used it in other cameras (and if so: there's the practical reason)?

In that case, the only plausible explanation is that they deliberately crippled the SD card slot so that the 1DX with its dual CF slots would look more valuable by comparison.  Which is just sad.

4
As I said, my MkIII's (though they are 1Ds's) slow down when I put SD cards in them, the fastest rates I get with the various cards I actually own are when I just have Sandisk CF cards in the CF slot and nothing in the SD slot, every SD card I own is slower than the various CF cards I own.

You are correct.  Even the fastest SD cards are blown away by a fast CF card.  In a mark III, the fastest write speed you will get with SD is 10mB/sec, most are 5.  The card specs are misleading to a extreme.

No, the specs of the flash card aren't misleading.  Fast speeds simply require you to have a device that supports that speed.  Unfortunately, the 5D Mark III doesn't support UHS-I, so the flash card falls back to pre-UHS-I speeds.

AFAIK, the only Canon DSLRs that support UHS-I speeds are the 6D, the 70D, the SL1, the T4i, and the T5i.  On the 6D, the difference between a 30 MBps Sandisk card and a 95 MBps Sandisk card is like night and day.

5
EOS Bodies - For Stills / Re: 5DIII dual cards
« on: August 27, 2014, 03:53:20 AM »
I am presuming the associated circuitry was finalised in advance of UHS because I don't see how intentionally leaving it off would benefit them. I could obviously be wrong, but I can not come up with a scenario where the program manager made a decision to go with a slow secondary slot when a better option was viable and cost effective. I understand the notion of crippling, but that seems like a silly way to do it. The second card is nice but not strictly necessary. If you want the fastest performance, pull the SD. The 5D3 demographic isn't going to buy a 1dx due to a slow secondary slot, nor is 1dx demographic going to buy a 5d3 instead had it a faster secondary slot. Ergo I have to assume a more practical reason, such as timing.

I would assume that the circuitry was copied straight out of the 5D Mark II, and that they just didn't bother to update it for the 5D Mark III because they figured nobody would bother to use the SD card anyway.  :)

6
EOS Bodies / Re: Do Sensors sell the Camera?
« on: August 25, 2014, 10:55:14 PM »
I fully expect Sony/Nikon cameras to have 15, if not 16, bit ADCs in 4 years time.

I am amazed that they don't have them already...

The 7D has a full well charge of 24,800. you need 15 bits to properly read that.... and in the last 5 years full well charges have increased, particularly with FF. Only having 14 bits is a choke point.

The full well charge on the full-frame bodies won't even fit into 16 bits.  In an ideal world, they'd dispose of the downstream amplifier and go to at least a 17-bit DAC (or cut costs and use an off-the-shelf 18-bit DAC).

With that said, given that we're talking about an analog voltage level, they'd probably be better off using a higher-precision DAC even though strictly speaking there are fewer discrete levels, if only because you'd expect some charge decay over the course of longer shots, and having a more precise measurement of the voltage would allow you to adjust for that in post processing.

Also, there's the issue of noise floor.  You want the digital floor to be way below the analog floor so that you guarantee that anything that qualifies as signal gets captured.  Right now, the digital floor is considerably above the analog floor (as you pointed out), which is bad.  Pushing it several bits below makes for a nice safety margin.

Personally, I don't really understand why all the camera manufacturers don't just standardize on a 20-bit DAC and be done with it.  Storage is cheap.  Quality is irreplaceable.  Why cut corners?

7
Lenses / Re: lifespan of IS motor?
« on: August 25, 2014, 10:42:40 PM »
Most people accept that their car may not be trouble free for less than 5 year.

I expect my car to be trouble-free for at least five years, too.  I've never had a DSLR that didn't still work after 5+.  The only lens I've ever had fail (ignoring the shattered filter threads and scratched front of one lens that I dropped) was my original Digital Rebel kit lens.  It died after only 9 months.  In hindsight, it was probably under warranty, so I should have had Canon fix it, but the thought didn't even occur to me at the time.

Of course, I didn't really care enough about that lens to bother with shipping it to Canon to fix it.  The day it failed, I borrowed a 20mm prime from one of my coworkers and used it to shoot all day.  I was so shocked at how much sharper the photos were that I ordered a 17–85 and never looked back (except to swap out the bad ribbon cable with a part from a broken copy of that lens just to have a "safe for use at the beach" lens).

8
Photography Technique / Re: Is RAW worth it?
« on: August 25, 2014, 10:12:13 PM »
i see it like the difference between getting your film developed at the local drugstore, and doing it yourself in your own darkroom. the photo tech gets it pretty good, but you can get it exactly how you want.

More like the difference between keeping the negatives and keeping only the prints.  If the prints aren't quite right, assuming you have the negatives, you can always reprint them from the negatives and adjust them quite a bit.  If you don't have the negative, you don't have nearly as much wiggle room.

Then there was the time when the developer didn't bother to print several photos that I needed, presumably because the prints were way too dark using the default process.  We thought the photos had gotten lost, but I got the idea to dig through the negatives from that time period, figured out which almost-white negatives were relevant, and had them printed anyway.  Had I kept only the prints... well, you get the idea.

9
Photography Technique / Re: Cropping
« on: August 25, 2014, 10:06:35 PM »

Don't forget that most printers also require bleed, which is a certain amount of extra content that deliberately gets thrown away to ensure that you don't end up with white edges.

10
EOS Bodies - For Stills / Re: 5DIII dual cards
« on: August 25, 2014, 07:39:31 PM »
Yah, I know. It's not crippled, it just pre-dated faster SD.

Not even close.

  • March 2010: UHS-I spec released.
  • September 2010: First UHS-I flash cards shipped.
  • March 2012: Canon 5D Mark III shipped

UHS-I had been final for two years when the 5D Mark III shipped, and UHS-I cards had been available on the market for a year and a half before the 5D Mark III shipped.

Not supporting UHS-II is justifiable, as the cards didn't hit the market until April of this year.  But not supporting UHS-I?  That's corner cutting at its finest.

11
EOS Bodies / Re: Do Sensors Make the Camera?
« on: August 25, 2014, 03:57:03 PM »
@dgatwood. Thanks. With respects to those technical differences between the 5DIII and 6D you alluded to, could you point me to that source or white paper?

I can point you to an article that demonstrates the difference in high ISO noise levels pretty easily:

    http://petapixel.com/2012/12/13/canon-6d-and-5dmk3-noise-comparison-for-high-iso-long-exposures/

As for the reasons for the differences... that's mostly speculation, albeit reasonably informed speculation.  :)

12
EOS Bodies / Re: 6D MKII
« on: August 25, 2014, 03:53:12 PM »
I very much doubt this because there is an *absolute* "good enough" to shoot most scenes. The current 6d already does ok for a lot of them, but there's still a lot of incentive to upgrade to the "real deal" 5d3. If the 5d3 is the baseline, Canon would pull a rabbit out of the hat to make 6d2(=5d3)->5d4 as attractive.

Sure, the 5D Mark III has better autofocus in most circumstances, higher resolution, and faster max FPS.  On the other hand, you could also say that there's a lot of incentive to upgrade from the 5D Mark III to the "real deal" 6D.  It has lower and more consistent dark noise levels (which means you can brighten it by more stops before it becomes unusable), better ultra-low-light focusing (at least with the center point), GPS, Wi-Fi....

Either one is an upgrade, depending on your needs.  Canon would do well to ensure that the hypothetical 5D Mark IV is in every way more capable than the hypothetical 6D Mark II, not just better at some things.

13
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 25, 2014, 03:28:16 PM »
Hehehe! I do remember how it was slated as a piece of crap. In fact, the very guy who told me he'll never exchange his 5D2 for a 6D, now has a 6D and sold the 5D2...

Doesn't the 6D match or exceed the 5D Mark II's specifications in every way except for resolution (and only slightly lower in resolution)?  It has much lower noise at high ISO, faster FPS, more autofocus points, many more features....

14
EOS Bodies / Re: Do Sensors Make the Camera?
« on: August 25, 2014, 03:17:15 PM »
I think that the number of iPhone photos that are being published are a strong indication that the sensor is far less important that the photographer.

Both are important for different reasons.  Yeah, you can take great photos with an iPhone under ideal conditions.  Lower the light level to indoor levels and it starts to struggle.  You'll almost certainly never see many published photos outdoors at night taken with an iPhone.  You'll never see any significant number of published sports photos coming from an iPhone.  And so on.  Basically, there's nothing the photographer can do to fix the extreme motion blur of a half-second exposure.

And there are shots that simply cannot feasibly be taken with an iPhone, because it is not practical to physically place the phone close enough to the subject to get a decent shot.  I mean yes, ostensibly you could build a remote shooting helicopter rig for your iPhone, but really, what's the point?  Zoom lenses matter.

To answer the topic question, yes, IMO, sensors make the camera.  You can work around a weak autofocus system by learning to use a manual focus lens effectively.  You can work around a slow repeat rate by learning to time your shots better.  You can't work around a poor quality sensor; the sensor quality fundamentally defines the quality of the resulting image.  And you can't change the sensor; you're stuck with it.  This means that the sensor is the single most important attribute of the camera itself.  All else is secondary—important, even useful, but secondary to the quality of the sensor.

To be fair, beyond the point at which the sensor is "good enough" for a particular purpose, you do start to see diminishing returns from sensor improvement.  Therefore, it is not necessarily the case that improving the sensor is more important than improving other aspects of the camera.  The answer to that question depends entirely on your starting point.  If you start with a lousy sensor, improving the sensor is the most important thing; if you start with a great sensor, improving it is mostly unimportant, and other factors start to dominate.  But if you stick a crappy sensor in a 5D Mark III, it would be a crappy camera, whereas Canon stuck a crappy AF system in the 6D, and it's still a great camera.

If you're looking at camera systems, the availability of glass whose quality is good enough to fully take advantage of the sensor's performance is of equal importance to the quality of the sensor.  And again, all else is secondary, for the same reasons.

Pedantically, I should also add that the rest of the analog image pipeline is critical for the same reason that the sensor is.  For most modern cameras, the analog image pipeline is part of the sensor, but for some reason, Canon hasn't made that leap yet.  So for Canon cameras, there are other parts of the camera that are just as important as the sensor, solely because they're years behind the rest of the industry in terms of the way they design their image acquisition hardware.  But I digress.

And the main differences between the 5D Mark III sensor and the 6D sensor are that the 6D sensor is slightly lower resolution, and its downstream amplifier circuitry seems to have a lower and more consistent noise floor from channel to channel, resulting in less banding and dark noise.  Either that or the analog signal path is better shielded from noise sources.  Either way, the result is the same.

15
EOS Bodies - For Stills / Re: 5DIII dual cards
« on: August 25, 2014, 02:20:33 PM »
People use JPEG on SD on the 5D Mark III because the SD card is crippled (no 1.8V signaling), and thus can't do UHS-I speeds.  It makes a less than ideal backup, but the alternative is massively reduced shooting speeds.

From this point onwards, any new cameras should be doing UHS-II, which requires about four times as many signal lines, IIRC (two channels of differential signaling instead of one channel of non-differential signaling).  AFAIK, no DSLR manufacturer has adopted that standard yet, though (unless that has changed very recently).

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