March 06, 2015, 11:46:41 PM

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Messages - jrista

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1
Animal Kingdom / Re: Show your Bird Portraits
« on: March 04, 2015, 08:50:47 PM »
Portrait of a Goose

First bird photography I've done in a while, from a couple weekends ago. It's been cold here in Colorado, VERY cold, teens and lower most of the time. Lot of snow lately as well...the past week and change has been one snow storm after another...we've got a solid, persistent foot everywhere. Having a slightly "warm" break in all the cold was nice, and gave me the opportunity to get back into bird photography, prep for the coming migration.

Canon EOS 5D III
Canon EF 600mm f/4 L II + 1.4x TC III
Gitzo GT3532LS + Jobu Pro II

Full frame, uncropped:


Closeup:


Full detail (1:1 crop, unscaled when you click for full size):


In case anyone was wondering, this is why you spend $12,000 on a 600mm lens. ;) Even with the 1.4x TC, the detail from 30+ feet away is just amazing.

2
Landscape / Re: Deep Sky Astrophotography
« on: March 01, 2015, 03:41:59 PM »
I agree that bigger is always better but the point is what are you going to travel with? Often times we have to make due with less. So while a 600mm on a star adventurer is not ideal, you can make due but have to shoot a lot of subs and weed out the bad ones. I could not see traveling with anything larger than the sky watcher astro package.


I've traveled with my Atlas to dark sites about a dozen or so times now. It isn't as portable as an AstroTrac or StarAdventurer, but it is still quite portable. I usually get it physically set up in about 10-15 minutes, including all connections to batteries and the laptop.


The mount I am looking at now is the Astro-Physics Mach 1 GTO. It is a high end mount, $8000 new (less used, maybe by a grand or so), but it is actually even more portable than the Atlas, and has a true 45lb imaging capacity. The Mach1 breaks down into several parts, the base, the two axes, and the CW shaft (which is very thick for stability). I think the heaviest part of the Mach1 is 16lb, which is quite a bit less than my Atlas (which doesn't break down outside of the mount coming off the tripod).


You can get good portability with higher end mounts and higher capacities. I use the Atlas in a certain way. I have marked up everything, the mount, the dovetails, the scope rings, even my lens itself (tape on the body) so that I can just put everything together, rotate parts as necessary to get everything aligned identically every time, and setup is very quick and easy.


The Sirius is a smaller version of the Atlas, basically, with a smaller capacity (30lb), lighter mount, and cheaper cost. If you want the most reliable and portable mount for the lowest cost, I would say look for a used Orion Sirius. It'll handle a 600mm lens and 5D III (and guide scope and camera and all the cables hanging off them), and you can usually find one for about $700 used. That isn't even $200 more than an AstroTrac, and it's more portable than the Atlas. For those who want to spend a little money as possible, but want some room to grow, I would offer that the Sirius is probably the best option. Intermediate imagers have used that mount (which is also upgradable with a belt mod) up to 20lb capacity with good results, so if you ever wanted to eventually move up to a larger OTA like an AT8RC or a small 6" newtonian, you could.

3
Landscape / Re: Deep Sky Astrophotography
« on: February 28, 2015, 10:47:40 PM »
I prefer this tracking system for travel use.

http://www.bhphotovideo.com/c/product/1092106-REG/sky_watcher_s20510_star_adventurer_motorized_mount.html

thanks, seems like a good value.

Holds a lot of weight too.  I can get my 600 F4L with my gripped 5D3 on it but need extra counter balance.  But it works.  With my 300mm F2.8L it's a perfect balance with only one counterweight.  You would likely need the wedge and a couple of other things so if that seems like a good value, make sure you get everything you need.


While you can barely fit a 600/4L and 5D III on the Star Adventurer, it is not recommended. The rule of thumb for imaging is to use only half the rated capacity. More than that, and your tracking accuracy will suffer, which will affect your stars. You shouldn't put more than 5-6 lb on the Star Adventurer for best results. You might get away with 7-8lb, but with longer lenses your star profiles will suffer (you'll have bloated stars, and you'll lose the benefits of the increased resolution of a large lens like the 600mm f/4).


I use an Orion Atlas, a $1500 mount with a 40lb capacity, and at barely 20lb I am still not able to get ideal stars. I've reached the point in my imaging where instead of obsessing over things like just getting tracking working reliably at all, I am now obsessing over maximizing my mount's performance to get the tightest stars. I've come the the simple conclusion that a $1500 mount with 40lb capacity is simply not capable of giving me sub-arcsecond performance, even when guided, with a mere 20lb load.


There are two levels of alternatives. There are the $5000 mounts, like the CGE Pro, the Orion HDX110, the Losmandy Titan. These can perform well, and have higher capacities, but they aren't engineered much better than the entry level mounts that run for $1500-$3000. They can get to 1-2" guided performance, but still can't get to the holy grail of true sub-arcsecond performance (where the worst case performance is still less than an arcsecond peak-to-peak (P2P) periodic error (PE).) Only the high end mounts, which start at $8000 for 45lb worth of imaging capacity, can give you tracking performance that averages >1" PE and 0.1" or better guided performance (which is necessary when you start imaging at a scale of 1"/px or larger...in my case, I am trying to image at 0.73"/px and simply can't do it with my mount.)


The 600/4 and 5D III is 2"/px image scale, and to get the best stars, you really want to keep your guided tracking at around 1-1.25" RMS. The 11lb capacity of the Star Adventurer is not going to give you that kind of performance, not even at half load, let alone full load. You might be able to get away with a 5D III and 300mm f/2.8 on that mount, but I think it would be difficult to get good performance out of it. The 5D III and 400mm f/5.6 would probably do much better.


For beginners, the best recommendation is to get the biggest mount you can possibly afford, and get a small, short, fast refracting telescope (or lens) as your first telescope. That maximizes the mount capacity (i.e. an Orion Sirius or Atlas), and minimizes load, thus maximizing your potential to get the most out of the equipment without a lot of hassle. Focal lengths ranging from 300mm to 600mm are generally recommended for beginners. Once your up over 800mm through 1200mm, your image scales drop to the point where mounts like the Sirius or Atlas are barely going to deliver what you need without extra work (i.e. most Atlas users who are imaging at 1200mm or longer have hypertuned and possibly belt modded their mounts...or, they skipped the Atlas and went strait to the Atlas Pro, which is basically hypertuned and belt modded right out of the box, for another $500 tacked onto the price.)


If your looking at something like the Astro Trac or Sky adventurer, you should be thinking much more wide field. Anything from ultra wide (14mm through 80mm), maybe 100-200mm. To give you guys and idea of how big these fields are (assuming a FF camera like the 5D III or 6D). The ultra wide focal lengths like 14-80mm are either "whole sky", "constellation", or "asterism" in terms of the field coverage. After that, up to 200mm or so, then you can start zeroing in on the really large regions of nebula, like the greater Cygnus region, or the entire Orion Belt+Sword complex, or both Heart and Soul nebulas in Cass, etc. At 600mm your down to just Orion's Sword or the end of his belt where Horsehead is, or just Heart or Soul nebula, or just California and Pelican nebulas in Cygnus, Andromeda Galaxy, etc. At 1000mm, your down to portions of nebula, small nebula (Wizard, Elephant Trunk,  Crescent, Tulip, etc.), medium sized galaxies like Triangulum, and beyond that your into bulk (small) galaxy ultra high resolution nebula imaging. Much beyond 1200mm, and you have to start explicitly looking for scopes that have truly massive apertures, and much larger sensors with gargantuan pixels, just to get a reasonable image scale. It's not uncommon to find FF sized CCD sensors with 9 micron pixels being used at 1600-3000mm. A lot of the larger scopes support 65-70mm image circles, which cover 37x37mm and 49x37mm "large format" sensors that have 9, 12, and even 24 micron pixels.


So, as beginners, you should be thinking what is the shortest telephoto lens you can use, and what is the biggest mount you can possibly afford. Shortest Scope + Biggest Mount = Least Hassle, Most Fun. With an AstroTrac or Star Adventurer, I'd say 400mm f/5.6 or around there should be the limit. If you are willing to deal with some frustrations, you might be able to work a 300mm f/2.8 on a Star Adventurer, but just prepare yourself for dealing with tracking issues and other problems about half the time.

4
Landscape / Re: Deep Sky Astrophotography
« on: February 28, 2015, 10:25:26 PM »
Thanks jrista!  Maybe I'll go back and see if I can do some better processing on this data.  I used Lightroom on the tif output from DSS.  Do you see any limitations with Lightroom for this type of post processing?  Would Photoshop be better?  Do you know of any good tutorials for post processing in either Lightroom or Photoshop with the output tif from DSS?  Thanks in advance.

I'd have to say, looking at the images you have produced is making me want to get into this a bit more.  I'll have to work on convincing the wife about getting a tracker...


I wouldn't use Lightroom for processing. Photoshop is significantly better, and there are a number of actions packages out there that can make things easier (Look for Carboni's Astro Actions).


Ultimately, Photoshop isn't even the most ideal tool for astro processing. It's great for beginners as many beginners already have it, but if you end up serious about the hobby, I highly recommend looking into PixInsight. It's a program designed specifically for astro image processing, including integration (the stuff DSS does, only PI is WAY better at it.)


Rodger Clark at clarkvision.com has some photoshop advise and alot of other astro related info, most above my paygrade but intresting. If you get serious or just have free funds the dedicated programs can really be worthwhile for getting every last drop from the data.


Roger Clark has some good baseline information, and some good basic tips. Clark does most of his imaging with pure DSLR equipment, and a lot of his recommendations, while aiming for simplicity, only work with pure Canon-branded DSLR equipment. He effectively bypasses image calibration by using camera features like LENR and lens calibration and very high ISOs to get decent images, without any real work. If that's in line with your own goals, Roger's method is great.


That said, Roger's image processing is not top notch. His astro images often have artifacts, color balance issues, and other things, probably because of his "light touch." If you want to get better results, I recommend joining Cloudy Nights forums, find the Beginner and Intermediate Imaging forum, and start reading. That is probably the most helpful forum on the net for beginner astrophotographers, it's where I hang out myself (I'd call myself intermediate now, far expert or advanced...but I have enough knowledge to help true beginners get rolling.)


Once on the CN BII forum, you can start asking questions, and  you'll quickly be directed to the best resources on the net for beginners, from making the hardware choices, to learning acquisition, to guiding, to processing.

5
EOS Bodies / Re: Possible Canon EOS 5D Mark IV Spec Talk [CR2]
« on: February 26, 2015, 09:42:05 PM »
This is the way I see it.  And of course Lee Jay and PBD can add/correct me if needed.

To increase high ISO performance to me is to increase DR at high ISO/light-limited situations.  I need to increase FWC or max signal per pixel or QE, however you look at it.  You need to lower read noise.  HOW you do those two things I'm not really commenting about but if you can do that you can increase S/N at high ISO.  You already have less read noise with smaller pixels so why can't you increase the size or efficiency of the photodiode in the pixel?  I've been in discussions about smaller parts in and around the pixel to make way for larger photodiodes, for instance.  I can also see where the FWC could be more important than read noise and overcome the higher read noise by adding more signal because signal is additive whereas noise is added SQRT.  So in that case, larger pixels might still win.  This of course is all at equal sensor size and equal technology.


Increasing FWC (probably a poor term to use, max saturation is probably better) is definitely a way that you can improve DR at higher ISO. Reducing read noise can certainly help, but at higher ISO read noise is already quite low, 3e- or less these days usually, and it's tough to complain about that. The saturation point at higher ISOs is usually only a couple thousand e-, sometimes as little as a few hundred e-, so increasing the charge capacity of each pixel is probably the better way to improve SNR at high ISO.

You aren't thinking about this correctly.

At high ISO, FWC is limited artificially by all the gain.  The cells are fully capable of holding a lot more charge, and they do, but the A-D saturates because of all the analog gain.

Assuming you are at high ISO because you are light-limited (not a bad assumption, IMHO), then the ONLY way to increase DR is to reduce read noise (assuming Bayer dyes, same QE, etc.).


I understand it perfectly.

I agree that if you are light limited (a possible use case for high ISO), then you would need lower read noise to increase DR. I disagree that's the only use case for high ISO. I frequently shoot at high ISO when there is plenty of light, easily enough to saturate the entire sensor in a fraction of a second, because I need motion-stopping shutter speeds for very fast motion (just watch a Chickadee or Bushtit sometime...those things NEVER stop moving, and they make these ultra fast micro-moves that blur with shutter speeds lower than around 1/2000th or so). Increased EQE and increased FWC would result in greater IQ at the higher ISO settings I often need to use for these birds. Personally, I would rather not go with larger pixels to achieve that higher FWC though...I want my resolution.

So, I disagree that the only way to increase DR at high ISO is to reduce read noise. Just look at the A7s...that sucker has a MASSIVE FWC (true full well capacity, the base ISO maximum charge capacity of the photodiode) of 155557e-! It's saturation point at say ISO 12800 is 1298e-. Now that's thanks to having a greater fill factor...more total light sensitive surface area in the sensor, and per pixel, because the pixels are huge. The saturation point at the same ISO for the 6D is 604e-. Both cameras have similar read noise at that ISO, 1.8e- and 1.6e- respectively, but one has 9.7 stops DR and the other has 8.4 stops. Why does one have more DR than the other, if the only way to improve DR at high ISO is to reduce read noise? The camera with the higher DR actually has higher read noise! The 6D has a lower fill factor, less total light sensitive surface area.

The capacity of a photodiode is primarily limited by it's area, and the sensitivity is limited by area and EQE. Sensor sensitivity is affected by total light sensitive area in the sensor. So if Canon had made the 6D with the 65nm process Samsung is using, they could have increased the photodiode area. I don't have time at the moment to actually calculate how much area increase Canon could achieve without changing pixel size, but suffice it to say they could increase light gathering capacity and sensitivity by increasing photodiode area. There are still EQE losses due to the use of microlenses and CFA. Improve microlenses (aspheric lenses have been researched to better focus off-axis light onto photodiodes), replace the CFA with color splitters, move to BSI and basically gain nearly the entire surface area of the sensor as light sensitive area, and you increase the amount of light reaching each photodiode, which makes them saturate faster, thus utilizing that increased capacity, therefor allowing you to reduce gain further (which reduces the amplification of everything, noise included.) That improves IQ, even at high ISO.

6
Landscape / Re: Deep Sky Astrophotography
« on: February 26, 2015, 09:07:52 PM »
Nice work, Schmave. :) Glad you gave it a try. I would be willing to bet, with a little bit more tolerance for some noise, that your data has more information in it than you think. It's a classic beginner "mistake" to try and make the background totally black. Thing is, space isn't black (very, very few areas of the sky actually have a black background, and none of the areas with emission nebula, which are all along the milky way, have a black background at all...there is tons of faint dust and filaments of emission nebula scattered all about the milky way.)


I would work on keeping your background level above black...maybe 20-30 levels. You should be able to bring out more of the nebula then. You will have more noise, but noise is just a fact of life with astrophotography...we work with such weak signals. ;) Keep it up! You've just started a very long journey. The next step would be to get some kind of tracking mount...be it a Polari or AstroTrac, or something larger and more expensive, once you can track, you'll see your ability to get deeper exposures increase dramatically.

7
EOS Bodies / Re: Possible Canon EOS 5D Mark IV Spec Talk [CR2]
« on: February 25, 2015, 02:58:15 PM »
This is the way I see it.  And of course Lee Jay and PBD can add/correct me if needed.

To increase high ISO performance to me is to increase DR at high ISO/light-limited situations.  I need to increase FWC or max signal per pixel or QE, however you look at it.  You need to lower read noise.  HOW you do those two things I'm not really commenting about but if you can do that you can increase S/N at high ISO.  You already have less read noise with smaller pixels so why can't you increase the size or efficiency of the photodiode in the pixel?  I've been in discussions about smaller parts in and around the pixel to make way for larger photodiodes, for instance.  I can also see where the FWC could be more important than read noise and overcome the higher read noise by adding more signal because signal is additive whereas noise is added SQRT.  So in that case, larger pixels might still win.  This of course is all at equal sensor size and equal technology.


Increasing FWC (probably a poor term to use, max saturation is probably better) is definitely a way that you can improve DR at higher ISO. Reducing read noise can certainly help, but at higher ISO read noise is already quite low, 3e- or less these days usually, and it's tough to complain about that. The saturation point at higher ISOs is usually only a couple thousand e-, sometimes as little as a few hundred e-, so increasing the charge capacity of each pixel is probably the better way to improve SNR at high ISO. There is also the simple fact that you really want to improve the signal, and reducing noise doesn't exactly do that per-se...only increasing the charge capacity and the charge accumulated per unit time does. Increasing Q.E. can certainly help, but at very high ISO, you suffer from clipping problems (so, while with high Q.E. you might have the necessary sensitivity, if it isn't paired with a capacity increase, it might be a useless improvement to sensitivity.)


Increasing photodiode size is certainly one way to improve charge capacity, but there have been other recent innovations (usually for super small pixel sizes) that use layered photodiodes to capture deeper penetrating photons and convert them to charge as well (not for the purposes of color, just increased charge capacity). There have also been innovations in photodiode design...charge accumulates at a layer at some particular depth inside the PD, around where N-type and P-type silicon interface. I've read of a couple patents that have been changing the curve of that interface layer to increase capacity without increasing PD size, or to change the structure of that layer. A curved or shaped layer has more surface area, and thus more room for electrons and electron holes to accumulate.


If you could double your signal with the same read noise, you could certainly gain some DR. For example, if you have 300e- saturation at ISO 12800 and 3e- RN, you would have ~6.67 stops DR. If you increase saturation to 600e-, you would have ~7.67 stops of DR. You gained a stop. Doubling charge in a photodiode without increasing it's size could be tough, so it's unlikely to see quite that much of a change without some other technological innovations. A reduction in process size, use of a curved N/P interface layer in the PD, use of BSI, etc.

8
Landscape / Re: Deep Sky Astrophotography
« on: February 22, 2015, 05:13:35 PM »
Here is another. I just had a run of six clear nights...something I've never seen before...and got a ton of data on several targets. Most were galaxies, the one nebula was Rosette. This is an 11 hour integration (164x240s subs).

5D III + 600mm f/4 + 1.4x (840mm 1.55"/px) on Atlas mount

Two versions, one "narrow band" like and one "natural color":

This is my longest integration to date, at 11 hours. I did this from my back yard with an IDAS LPS-P2 light pollution filter. That's replacing my Astronomik CLS filter, and it's actually quite amazing. Not entirely dark site quality data, but quite good data nevertheless.

John, 

Outstanding Details!  This must look great at 1:1.  One comment, on the second image the blue halos around the stars are a bit detracting.  Cleaning those up, and a little color correction (less blue) in the stars would really strengthen that image. Im guessing these are left over from your Light Pollution Filter.   Excellent work!


Actually, the first image is more what I got strait out of camera. The IDAS LPS-P2 actually produces great stars with great color balance, but it doesn't handle the deeper pinks of emission nebula as well. The blue halos are due to the processing, which I am working on. I need to figure out how to properly reduce the stars in both the luminance and RGB images before combining them. I am also working on doing some pre-stretch masking on the stars in the second color version to prevent them from becoming overly blue (a more neutral white-based would be ideal.)

9
EOS Bodies / Re: Possible Canon EOS 5D Mark IV Spec Talk [CR2]
« on: February 22, 2015, 05:09:25 PM »

Not sure why no one else has suggested this, but:


18mp x3 layer sensor?


That would make it 54 million photodiodes, but spatially an 18 million pixel sensor.

Seems a bit odd, but it is afterall a test prototype. I dont see Canon reducing the MP in a 5 series unless they plan on using the 20.2 MP sensor from the 6D but with DPAF. 12FPS would nice but would they really bring the frame rate into the 1DX realm? Current 5D3 is 6FPS. 8-10FPS seems more realistic in a final product.  A "quantum leap" in DR and FPS in a 1 body would be fantastic, not that the current model is a slouch whatsoever. And no, you dont need mirrorless to do it. None of them do it now. 20FPS doesnt do a lick of good without a reliable AF system and mirrorless isnt there yet.


They might reduce it if it is a layered sensor. If it is 18mp x3, then it would have 54 million photodiodes. If Canon is pairing the camera with a DIGIC 7...then they should have the necessary throughput (each DIGIC 7 chip would need to handle around 600MiB/s throughput, which is a little more than double the current DIGIC 6 chips.)


It seems more logical to me that it would be 10fps, in which case each DIGIC 7 (or whatever they call it) would end up handling 500MiB/s throughput, or exactly double the current DIGIC 6.

10
EOS Bodies - For Stills / Re: Coincidence or?? MP/SEC
« on: February 17, 2015, 03:25:29 PM »
Hmm, yeah, calibration with the bias signal might benefit from a higher bit depth. You would more accurately represent the differences in each column of the bias... Interesting.


Regarding the 7D II, as far as I know the dual pixel read for AF is a literal dual pixel read. That would be 40.2mp in that case. I wonder if there are two separate reads, though...one for one half of each pixel, then another for the other half? It is also possible each AF read is converted to only 7 bits as well. Dunno. The specifics on that might be contained within the DPAF patents, though...

11
EOS Bodies - For Stills / Re: Coincidence or?? MP/SEC
« on: February 16, 2015, 07:43:30 PM »
Output data at 14fps would be JPEG, but the input data from the sensor would still be 14-bit. I don't believe Canon does any kind of downgrading on the bit depth of the ADC units (I've never found any information indicating as much anyway), so I don't believe there is a 12-bit 14fps read mode. The output data rate for JPEG (when writing to the memory card) would certainly be lower, but the input rate into the DIGIC processor would still be 14-bit.

It's difficult for anyone outside of the development team to do any more than speculate, but I'd argue that if the camera can really handle 14 bit readout at 14 FPS, then why force JPEG only on users? The buffer is still there, and if the readout and JPEG engine can keep up with 14 bits, the buffer should be able to too - so instead of forcing JPEGs on the user, why not give them a choice of a smaller buffer depth and raw? Card speeds only become relevant once the buffer fills up, and the target audience of the 1D X should in Canon's eyes be capable of deciding which trade off to choose.

I'm under the impression (falsely or not) that it's JPEG only as the readout doesn't support 14 bit CR2 files at 14 FPS.


The readout is simply transferring charge and converting it to digital numbers. JPEG doesn't come into play until that native signal information has already entered the DIGIC chip, since it is DIGIC that is actually performing the conversion to JPEG. The sensor isn't going to natively spit out 8-bit JPEG data, as that requires processing, like color space conversion, compression and encoding, etc.


Why does Canon limit 14fps to JPEG? I don't know the answer to that. I am just quite certain that neither the sensor nor the off-die ADC units are spitting out JPEG data natively. It could be possible that the ADC units are switching to 12-bit mode at 14fps. Samsung certainly doe it at 15fps. Why Canon even bothers with a 14-bit ADC in the first place when their data barely supports more than 11 bits worth of information because of system noise levels is beyond me. If a 12-bit ADC would allow them to process 17.5fps, without any loss in DR, I don't know why they don't. That said, I've never encountered any information anywhere, including in patents, that indicates Canon switches to 12-bit data output from their ADC units. There could very well be a different reason they had to limit 14fps to JPEG.

12
Canon General / Re: Decline in DSLR sales explained
« on: February 16, 2015, 03:54:01 PM »
Totally ridiculous that Canon (and Nikon) continue to refuse to put touch screens on top of the line DSLRs. I defy anyone who has used a 70D to argue that higher end cameras would not benefit from touch screens. Yet, we have this ridiculous concept that they aren't "professional."


I think that's the inverse of the question that needs to be asked. Do professionals WANT that stuff? Personally, I don't really care if Canon puts a touch screen on their xD lines or not...it might be useful in the menus, but the way I actually use the camera for actually doing photography, the LCD is off and black. I use the buttons and dials for everything, frequently without ever removing my eye from the viewfinder.


Adding more technology is fine, but why expend the resources doing it if the statistics (whatever they may be, just making a case here) show that most of your buyers wouldn't actually care about or use the feature much of the time, if any of the time? In the professional (or semi-pro or avid enthusiast) world, I think a lot of Canon's sales come from return buyers who are looking for something familiar. I also think that most focus more on the traits that actually affect IQ, vs. a new (and certainly potentially useful) way of interacting with certain features of the camera. If someone has all the necessary procedural memory to control Canon DSLRs because Canon has stuck with the same key button layout for each line for a while now, a touch UI suddenly becomes a backburner item.


I think the consumer grade lines are totally different. The xxD and xxxD/xxxxD Rebel lines are catering to an entirely different audience. Things like touch screens, or LTE and WiFi, internet accessibility, maybe some built-in app features like Instagram or Facebook, etc. are not only useful features, but as the video was getting at, essential features for that segment of the DSLR market to survive. But that's an entirely different market segment, at least the way I look at it. It's the segment that isn't catering to return customers who want familiarity and the ability to instantly access critical functionality at the press of a button, because having that procedural-memory/muscle-memory speed and accuracy when using the device isn't the most critical thing for consumers. The most critical thing for consumers is (apparently, these days) the social aspects of photography.


In that respect...even IF Canon and Nikon and the rest manage to somehow meld smartphone and DSLR into a usable device...are people actually going to give up the convenience of their existing and easily accessible pocket cameras (smartphones) for something larger, bulkier, and still more complex (interchangeable lenses, at the very least)? Smartphones are like the disposable camera of the modern age: Tough to beat for the average consumer.

13
EOS Bodies - For Stills / Re: Coincidence or?? MP/SEC
« on: February 16, 2015, 03:02:53 PM »
At full tilt, many Nikon bodies reduce the data per frame by dropping from 14 bit to 12 bit raw.

Canon don't offer that, but the 1D X does have compromises at 14 FPS other than the mirror staying up leading to viewfinder blackout and no AF tracking - the output is JPEG only. That's likely due to the sensor output dropping to 12 bit as a work around for the high data rate. If that's the case, the sensor readout and processing has gone from 12 FPS @ 14 bits to 14 FPS @ 12 bits - which is an identical data throughout.

Add bit depth into your calculations, and the 5Ds works out at ~443 MB/s.
The 1D X tops out at ~380 MB/s at both 12 and 14 FPS.

The 5Ds is no speed demon purely in terms of FPS, but that is an unprecedented data throughput for a Canon stills camera.


Output data at 14fps would be JPEG, but the input data from the sensor would still be 14-bit. I don't believe Canon does any kind of downgrading on the bit depth of the ADC units (I've never found any information indicating as much anyway), so I don't believe there is a 12-bit 14fps read mode. The output data rate for JPEG (when writing to the memory card) would certainly be lower, but the input rate into the DIGIC processor would still be 14-bit. That would mean the input throughput for the 1D X is basically the same as for the 5Ds, around 465mb/s plus any additional overhead.


I still believe that DIGIC5+ and DIGIC6 are 250mb/s input throughput per chip, or a total of 500mb/s total maximum input throughput.

14
EOS Bodies - For Stills / Re: Coincidence or?? MP/SEC
« on: February 16, 2015, 02:12:18 PM »
This is a ridiculous thought..

Canon 5DS / 5DSR - 50.6mp - max 5/sec burst = 253mp per sec
Canon 1DX - 18.1mp - max 14/sec burst = 253mp per sec

Two highest - when summed - figures from the Canon line-up in terms of image size.

As they use different processors is there another limiting factor? or is this just stupid?

My vote is stupid, but I wanted to share it nonetheless.


Remember, every frame read includes the masked border pixels for calibration purposes. That increases the megapixel count above the number of pixels that actually end up in your final images, usually by around 4-6%. The 1DX actually has 19 million pixels. The 5Ds is likely to have close to 53 million pixels. Total pixels, masked ones included. So total megapixel counts per second are more like 266mp.


Every pixel is converted to a 14-bit number, that whole chunk of data is read 14 times per second for the 1Dx, or five times per second for the 5Ds. The data throughput of the DIGIC chips MUST be able to handle the RAW PIXEL INPUT throughput, which is:


Canon 1D X: 19,000,000px * 14bit/px / 8bit/byte * 14fps = 465,500,000byte/s
5Ds: 53,000,000px * 14bit/px / 8bit/byte * 5fps = 463,750,000byte/s


When you throw in overhead, both cameras are very likely using DIGIC processors capable of handling an input throughput rate of 250mb/s (since two DIGIC chips are used).


The big difference between DIGIC5 and DIGIC6 is clearly not throughput. The 7D II requires less than 400mb/s total, so it only needs 200mb/s throughput for it's pair of DIGICs. The big difference with DIGIC6 is that the chips are doing a lot more onboard processing of each pixel, reducing noise and whatnot, than the DIGIC5 chips did. Overall processing power increased, even if data throughput did not. Supposedly that increased processing results in better images. Ignoring DR, I think that is the case...OOC images from the 7D II and 5Ds definitely look better. The DIGIC 6 processors don't seem to help at all in the area of read noise (and one wouldn't expect them to), but that doesn't change the fact that these chips are doing more processing than the DIGIC 5 chips.

15
Canon EF Prime Lenses / Re: Canon EF 600mm f/4L IS II USM
« on: February 16, 2015, 12:03:27 AM »
Yeah, the Atlas Pro is basically a ready-to-go version. It's about $500 more expensive, whereas the belt mod itself is $200. If you have mechanical skill, I would say get the original Atlas and the belt mod, save the $300. If not, the Atlas Pro is a good mount.


I'm also not really trying to discourage, just make sure you know exactly what's involved. If you are up for it, it's an awesome hobby, and it is most definitely rewarding.

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