# 1D X FPS limiting factor?



## Malte_P (Dec 28, 2012)

what is limiting the maximum FPS for the 1D X?

is it the bandwith/processing power of the DIGIC5+ CPU´s?

or is it the mechanical shutter construction?

could a dual digic 5+ powered camera deliver 10 FPS for a 21-24MP sensor?


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## neuroanatomist (Dec 28, 2012)

The shutter limits it to 12 fps, the dual Digic 5+ apparently limits it to 14 fps, but it's possible that's a card writing limitation.


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## Mt Spokane Photography (Dec 28, 2012)

Malte_P said:


> is there any info on how many pixels per second the digic 5+ can process?
> any bandwith specs?


Its not specified. However, many things tend to be limiting, the shutter speed, the card speed, the processing speed. In a good design, they all tend to be reasonably close in capability. For example, a faster processor would eat up battery life and give no benefit, a faster shutter would not help if the processor was incapable of faster speeds, and none of this would matter if Card and internal memory speeds were not fast enough. It is likely that mechanical limitations (Shutter, Autofocus / lens speed) come into play earliest.


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## neuroanatomist (Dec 28, 2012)

Malte_P said:


> all fine and correct but does not answer my question.



Well, this:



Mt Spokane Photography said:


> Its not specified.



...seems like a pretty succinct and accurate answer, to me. Digic 5+ is _relatively_ spec'd as 17-times faster than Digic 4, but since there aren't absolute specs for the latter, that's fairly useless. 



Malte_P said:


> the shutter as limiting factor is what i guessed too.. but i would like confirmation.



As I stated above, the 1D X can shoot 12 fps normally, but 14 fps with the mirror locked up. Since 14 fps mode requires JPG and doesn't support RAW, I infer that card writing may be a limiting factor.


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## tpatana (Dec 29, 2012)

neuroanatomist said:


> As I stated above, the 1D X can shoot 12 fps normally, but 14 fps with the mirror locked up. Since 14 fps mode requires JPG and doesn't support RAW, I infer that card writing may be a limiting factor.



At that speed it's mostly writing to buffer, and just trying to empty to card as fast as possible. So card speed is not the limiting, but buffer memory speed could be.

My bet would be one of the data-lines, so sensor -> digic, or digic -> buffer (or is the buffer between sensor and digic? I haven't seen block diagram). 18MP x 12fps is plenty of data to haul across a data-line.


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## PackLight (Dec 29, 2012)

Is this not answered in Canons 1D X white paper;

"A full-frame, 18 Megapixel sensor shooting at 14 frames per second produces a large signal stream that needs to be removed from the sensor rapidly. To enable this, the EOS-1D X uses a 16-channel high-speed output with two-vertical-pixel simultaneous readout. It is around 1.4 times faster than the readout system found in the EOS-1D Mark IV and it's this that allows the 14 frames per second shooting speed — a first for a camera with a 35mm full-frame digital sensor. Note that at ISO 32,000 or higher the frame rate will be reduced to 10fps (which still equals the fastest shooting rate of the EOS-1D Mark IV)."


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## PackLight (Dec 29, 2012)

Malte_P said:


> could a dual digic 5+ powered camera deliver 10 FPS for a 21-24MP sensor?



I am going to speculate not yet.

The reason the 1D IV exists, is that the high speeds couldn't be obtained because of processing power. Processing power and frame rate is why we have crop sensors at all.

I bet the reason the 1D X has an 18mp sensor is that it couldn't have kept up with a 24mp sensor.


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## tpatana (Dec 29, 2012)

Freelancer said:


> PackLight said:
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> > Processing power and frame rate is why we have crop sensors at all.
> ...



Smaller pixels = smaller amount of data, of course.


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## PackLight (Dec 29, 2012)

tpatana said:


> Freelancer said:
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Which makes smaller RAW files, which take less time to process.

There was an old article I read a while back, put out by Canon explaining why we have crop sensors at all. From memory the whole reason was file size and processor performance at the time. Cheaper sensor cost and other things were not an issue initially.


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## tpatana (Dec 29, 2012)

PackLight said:


> tpatana said:
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Um, what?

I guess you missed my last line there.

21mp from crop = 21mp from ff

the actual data don't care of the sensor dimensions, it only cares about the number of pixels (and some other crap, but not the sensor size).

So I think you've either mis-read, or remember only parts of the explanation. E.g. for same pixel _density_, FF would yield more data thus needing more processing power. But for same MP count, it's the same between crop and ff.

I don't know if yield makes the difference between ff and crop, I know in ICs the big components get much lower yield.


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## PackLight (Dec 29, 2012)

tpatana said:


> PackLight said:
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Yes, but what does it matter. If you are making the point that the 1D X could have used a larger sensor it probably could have and gotten 10fps vs 12fps.

The 1D X normal RAW file is about 23mb, the 1D IV's is 22mb. However the 5D II's is 25.8mb. They apparently opted to get 2 more fps rather than offer a slightly larger sensor.
Still I think the limiting factor here is the processors. 

It could be said that it is mechanically limited. But there were cameras shooting a high mechanical frame rate for years. Processors are catching up now.

And you can get a higher frame rate: Enter the 1D C.....


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## tpatana (Dec 29, 2012)

Ok, now I have no idea what you're saying.

But it seems you still didn't understand that the sensor size, crop or not, does _not_ affect the file size, thus it doesn't affect the processing power required.



PackLight said:


> They apparently opted to get 2 more fps rather than offer a slightly larger sensor.



Sensor size itself has nothing to do with the fps.


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## PackLight (Dec 29, 2012)

tpatana said:


> Ok, now I have no idea what you're saying.
> 
> But it seems you still didn't understand that the sensor size, crop or not, does _not_ affect the file size, thus it doesn't affect the processing power required.
> 
> ...



Slightly larger in this statement meaning a 21mp sensor rather than the 18mp they used. A 21mp sensor file wouldn't have written as fast.


http://cpn.canon-europe.com/content/education/technical/eos_1d_x_explained.do


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## PackLight (Dec 29, 2012)

PackLight said:


> Ok, now I have no idea what you're saying.
> 
> But it seems you still didn't understand that the sensor size, crop or not, does _not_ affect the file size, thus it doesn't affect the processing power required.



Please show me the specs of the 21mp crop sensor you are talking about, and which camera it is in. Then we can compare to see how it matches up to Canon's 21mp sensor in the 5D II.

It doesn't exist because Crop sensors were made smaller so the files would be smaller. Of course if you made a FF sensor as dense as the 7D's the file would be huge. 

The sensor you speak of may exist in the near future. Why camera makers started making 35mm bodies in the start, isn't the reason they will keep making them. I hope the 7D II does have a larger sensor.


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## neuroanatomist (Dec 29, 2012)

PackLight said:


> ...Crop sensors were made smaller so the files would be smaller.



Ahhh, so the crop sensor in my 7D will give me smaller files than the FF sensor in my 1D X? Hmmmmmm...that doesn't seem to be the case. :


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## PackLight (Dec 29, 2012)

neuroanatomist said:


> PackLight said:
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> > ...Crop sensors were made smaller so the files would be smaller.
> ...



Sure not, but then the 7d isn't the first crop sensor is it? Amazing what a few years of crop evolution wil produce.


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## neuroanatomist (Dec 29, 2012)

PackLight said:


> neuroanatomist said:
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You seem to be intentionally missing the point. Sensor size is irrelevant for file size. Only MP count matters. APS-C crop sensors were made smaller not to produce smaller files, but to produce cheaper sensors - a 10-fold greater yield per wafer. APS-H was made because, at the time, that was the largest sensor that could be imaged in a single stepper pass during lithography. Canon has stated those rationales in white papers.


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## Mt Spokane Photography (Dec 29, 2012)

Malte_P said:


> Mt Spokane Photography said:
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You ask, and I told you its not specified. That means no specs. Apparently you are hoping someone will fabricate numbers for you?


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## Don Haines (Dec 29, 2012)

An 18mp sensor produces the same size file if it is a full frame sensor or if it is an APS-C sensor. Smaller pixels do not make smaller bits 

Write time to your card is based on lots of factors, but the two main ones are processing delay and the slower of card speed and camera write speed. 

Processing delay is not as simple as faster processor beats slower processor.... What is the algorithm? Does it take the same time for an iso100 image as an iso 51200 image with lots of processing to correct noise.... Does a 60D run a simple algorithm on a clean picture faster than a 1D X on a noisy picture??? This is why there is no answer to how fast can a digic 5+ process pixels.... The answer varies based on the algorithm used.

Write time is the slower of camera write speed and card speed. I don't know how fast the 1D X write speed is to the card, but you can bet that the published specs were with the fastest card available. Nice and simple...... And wrong! After the image is processed it is stored in high speed memory, which is then dumped to the card. The bottleneck occurs when the read/process/dump to high speed memory occurs faster than you can write to the card.

A 1D X has something like 34 times the processing power of a 60D and we all know how the mighty compact flash beats the tar out of the lowly SDXC cards, yet the 1D X is only able to take 12 frames per second compared to the 5.3 of the 60D....... There are no easy answers here.


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## PackLight (Dec 29, 2012)

neuroanatomist said:


> PackLight said:
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Not really intentionally missing the point. My original point was sidetracked intentionally. The "mp determine file size" was a clarification that was made that really didn't matter to the overall point of the original post.

Yes sensor size is a factor in determining file size, take the 7D sensors pixel density and make the sensor FF size. See how that affects file size.

The reason Canon used the APS-H sensors in the 1D bodies is so they could get the increased frame rate and maintain a reasonable IQ. Did the APS-H have fewer pixels than the 1Ds sensors? Did the APS-H have smaller file sizes than the 1Ds sensors? Was the APS-H smaller than the 1Ds sensors?

A question would be why didn't they put a FF sensor in the 1D IV instead? Probably because of IQ and file size. It looks like Canon thought they had the right balance to make the move.

Also your statement that "only MP count matters" for file size. Your 1D X at 18.1 mp lists the large Raw file as 23.2mb, where the 7D at 18mp large Raw file size is 25.1mb. Sounds like there is a few other things involved.


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## PackLight (Dec 29, 2012)

Don Haines said:


> Write time is the slower of camera write speed and card speed. I don't know how fast the 1D X write speed is to the card, but you can bet that the published specs were with the fastest card available. Nice and simple...... And wrong! After the image is processed it is stored in high speed memory, which is then dumped to the card. The bottleneck occurs when the read/process/dump to high speed memory occurs faster than you can write to the card.



A point might be, would any of the bodies write to the buffer at 12 fps? Write speed to the card would have nothing to do with the initial frame rate. Other than once you hit the buffer your fps falls to 2 or 3, there about.


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## neuroanatomist (Dec 29, 2012)

PackLight said:


> Yes sensor size is a factor in determining file size, take the 7D sensors pixel density and make the sensor FF size. See how that affects file size.



Clouds block the sun. Clouds produce rain. An umbrella blocks the sun, therefore, an umbrella produces rain? Correlation isn't causation. The 1DII and 20D were contemporary, same MP count. Same for the 1DIII and 40D. By your logic, where does the relatively tiny 41 MP sensor in the Nokia phone fit into the picture?

FWIW, here's what Canon says:

"_With all these benefits, it’s only natural to wonder why all DSLR cameras aren’t full-frame. Ultimately, the issue is money. Research, development, manufacturing and distribution costs are all independent of camera size, so a smaller camera will not cost appreciably less than a larger one for any of these reasons. The end cost difference between small mirrors, mirror boxes, chassis and so forth, and larger ones is not that great. The difference is the sensor._"

Not file size, money. Smaller sensors are cheaper.


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## neuroanatomist (Dec 29, 2012)

Speaking of APS-C sensors evolving, does the much newer T3/1100D APS-C sensor produce smaller files than the older FF 5DII?


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## Don Haines (Dec 29, 2012)

PackLight said:


> Don Haines said:
> 
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> > Write time is the slower of camera write speed and card speed. I don't know how fast the 1D X write speed is to the card, but you can bet that the published specs were with the fastest card available. Nice and simple...... And wrong! After the image is processed it is stored in high speed memory, which is then dumped to the card. The bottleneck occurs when the read/process/dump to high speed memory occurs faster than you can write to the card.
> ...


Regardless of the card speed, the 1D X is supposed to be able to write 12 frames per second to the buffer.... If the card speed is not enough to keep up, it eventually fills the buffer and then the speed drops to what the card can support. That's why the 60D starts off at 5.3 but when the buffer fills drops down to less than 2. Same problem, just a lot more dramatic difference


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## Don Haines (Dec 29, 2012)

neuroanatomist said:


> Speaking of APS-C sensors evolving, does the much newer T3/1100D APS-C sensor produce smaller files than the older FF 5DII?



But to further complicate the issue..... Newer cameras MIGHT be running a better compression algorithm....so it is possible that a new 18M camera produces a smaller file than an old 18M camera.... And then there is 14 bit d/a compared to older 12 bit and even 8 bit........


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## PackLight (Dec 29, 2012)

neuroanatomist said:


> FWIW, here's what Canon says:
> 
> "_With all these benefits, it’s only natural to wonder why all DSLR cameras aren’t full-frame. Ultimately, the issue is money. Research, development, manufacturing and distribution costs are all independent of camera size, so a smaller camera will not cost appreciably less than a larger one for any of these reasons. The end cost difference between small mirrors, mirror boxes, chassis and so forth, and larger ones is not that great. The difference is the sensor._"
> 
> Not file size, money. Smaller sensors are cheaper.



Canon's white paper on FF sensors, August 1st, 2006

Has Canon ever told us one thing at one point then something different a few years later?

This was my original comment on the sensors:
"There was an old article I read a while back, put out by Canon explaining why we have crop sensors at all. From memory the whole reason was file size and processor performance at the time. Cheaper sensor cost and other things were not an issue initially."

I am not sure if it was one of the Canon books I have, or somewhere on their website. I would like to find it as a curiosity, it really doesn't matter.


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## tpatana (Dec 29, 2012)

PackLight said:


> Yes sensor size is a factor in determining file size, take the 7D sensors pixel density and make the sensor FF size. See how that affects file size.



Sensor size *does not *determine file size. How many times we need to tell you this?


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## tpatana (Dec 29, 2012)

PackLight said:


> This was my original comment on the sensors:
> "There was an old article I read a while back, put out by Canon explaining why we have crop sensors at all. From memory the whole reason was file size and processor performance at the time. Cheaper sensor cost and other things were not an issue initially."



Yes, and we've replied you at least 10 times now that you are mistaken, the crop sensor [size] doesn't affect the file size. Either you just remember incorrect, or read incorrect, misunderstood, or the article you read was incorrect. But sensor size doesn't make the file size. It's the MP count (mostly, plus bit-depth and algorithm and stuff, but not sensor size)


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## PackLight (Dec 29, 2012)

neuroanatomist said:


> Speaking of APS-C sensors evolving, does the much newer T3/1100D APS-C sensor produce smaller files than the older FF 5DII?



What I think this is a real indication of, is how much effort Canon put in to the Crop bodies compared to the 1D X's smaller files. It's easy to use up file space, tougher to clean it up and make it better and smaller.


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## Don Haines (Dec 29, 2012)

tpatana said:


> PackLight said:
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> > Yes sensor size is a factor in determining file size, take the 7D sensors pixel density and make the sensor FF size. See how that affects file size.
> ...


Are you measuring size in area, or size in number of pixels...... One of you is arguing with one definition, one with the other....

Given the same degree of compression and a/d bit depth, an APS C sensor and a FF sensor with the same number of megapixels will produce the same size file.

BUT....
If you are arguing based on area, then to scale up an 18M APS C to FF physical size, you could fit 46M pixels into the area of a FF sensor and of course the file would be bigger


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## PackLight (Dec 29, 2012)

Don Haines said:


> tpatana said:
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All Crop sensors have less MP than full frame. They do not like me saying file size has anything to do with the physical size of the sensor. Of course two sensors with equal pixel density, the larger produces a larger file. Were not supposed to relate these two in this discussion though. They want to be hard core sticklers and say file size is controlled only by the number of MP, which is somewhat correct except there are a few other factors involved.


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## tpatana (Dec 29, 2012)

PackLight said:


> They want to be hard core sticklers and say file size is controlled only by the number of MP, which is somewhat correct except there are a few other factors involved.



Argh... it's pretty much correct.

Crop size 18MP and FF size 18MP give exactly same file sizes, assuming algorithm and such is same.


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## lethalfalcon (Dec 29, 2012)

To answer the OP, I'm pretty sure the limit is in the mechanical shutter, however, like Mt. Spokane mentioned, it's likely that the capabilities of the processors and the buffer are matched to the limitations of the shutter mechanism. It makes no sense to over-engineer something if it can never be used. If they could get 14FPS with the shutter moving, they wouldn't have needed it locked, and it would have been better for them if they could have allowed focusing at 14FPS. Saying JPEG only is not dependent on whether the shutter moves, either. Also, it should have been (relatively) easy to slap more buffer RAM on the board if it were needed to handle more data.

Card speed is definitely a limiting factor, though, but more on the continuous shooting side. If you put 1GB of buffer memory into the camera, but it takes 8 seconds to clear it (and that's with Lexar 1000x cards), once you fill that buffer you're going to be waiting if you want to burst again. They might be able to fit 4GB on there, but then you need to wait half a minute to write the whole buffer out. I think the processors can handle a bit more than the 150MB/s of data the card can, especially if you're shooting clean images (ISO 100). The more noise and the more cleaning functions you turn on, the more you'll tax the logic. And they could always go for more chips if they can find the room. Think quad Digic 5+. 

As to the later posts about file sizes, consider this: a 7D and a 1DX are really close to the same MP (same written image size of 5184x3456). However, a 1DX takes FAR cleaner images under almost all circumstances. Cleaner images = better compression. The idea is that a cleaner image is likely to have more pixels that have the same value, so the compression algorithm can more efficiently store that. If every pixel is a different color (because it actually is or because of noise changing the output just slightly), compression falls apart. I just took two pure white images (.6" ISO100 no lens, shot at a lit wall) from a 7D and a 1DX. Both show they're completely blown out in LR. Results: 14,498,781 bytes for the 1DX and 14,223,956 for the 7D. I'd guess that 200KB is mostly extra metadata.


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## rs (Dec 29, 2012)

PackLight said:


> All Crop sensors have less MP than full frame. They do not like me saying file size has anything to do with the physical size of the sensor. Of course two sensors with equal pixel density, the larger produces a larger file. Were not supposed to relate these two in this discussion though. They want to be hard core sticklers and say file size is controlled only by the number of MP, which is somewhat correct except there are a few other factors involved.



Not all crop sensors have less MP than full frame. The original Canon 1Ds was full frame with 11MP, the original Canon 5D had 12MP, whereas the latest generation of APS-C Canon's have 18MP.

However, if what you're on about is scaling up the current generation of crop sensors to FF, along with the appropriate increase in MP, then you'll end up with a 46MP FF sensor (18MP x 1.6h x 1.6v). That would result in more data, but the extra data is directly proportional to the MP increase. For two sensors of equal MP, the sensor size has no effect on the amount of data (other than the larger sensor potentially producing lower noise levels, allowing even the RAW files to be compressed more, as stated by lethalfalcon)


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## EchoLocation (Dec 29, 2012)

PackLight said:


> All Crop sensors have less MP than full frame. They do not like me saying file size has anything to do with the physical size of the sensor. Of course two sensors with equal pixel density, the larger produces a larger file. Were not supposed to relate these two in this discussion though. They want to be hard core sticklers and say file size is controlled only by the number of MP, which is somewhat correct except there are a few other factors involved.


As has been said above, All crop sensors do not have less MP than full frame sensors.
What do you want from this thread exactly?
There have been numerous discussions on numerous different aspects of files size in relation to sensor size, MP, compression algorithims, and whatnot... 
It was pretty clear from the second or third post that no one knows exactly which aspect of the 1DX limits the FPS. There are many different areas of concern that are all near (80%ish) of their capabilities. 
There are many different opinions on this but no hard facts, we've heard many opinions(many from good sources) so far, but obviously you haven't heard one that satisfies you. 
What exactly are you looking to hear? that the file size and Digic V's are the limiting factor(to corroborate the story you remember)? i'm a little confused on what we are arguing about at this point besides your lack of satisfaction from the answers given.


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## Don Haines (Dec 29, 2012)

PackLight said:


> All Crop sensors have less MP than full frame.


The T3i and the 1D-X have the same number of pixels...... That's right..... an obsolete rebel has the same number as the just released flagship.....care to restate that statement?


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## Don Haines (Dec 29, 2012)

PackLight said:


> They do not like me saying file size has anything to do with the physical size of the sensor. Of course two sensors with equal pixel density, the larger produces a larger file. Were not supposed to relate these two in this discussion though. They want to be hard core sticklers and say file size is controlled only by the number of MP, which is somewhat correct except there are a few other factors involved.



The file size produced by the sensor is 5184 pixels X 3456 pixels X 14 bits X 3 colors, all divided by 8 bits per byte for one of Canon's current 18M sensors. That's a 94M file. That is the size of the file an 18M sensor produces... Period! And does not matter if it is in a iD-X or in a point and shoot.

The camera then runs lossless compression algorithms to create the data for the raw file, plus adds in some overhead, such as the Exif data. The size of the .raw file depends on the algorithm used and the nature of the image. Complex algorithms will compress more than simpler algorithms, but at the cost of needing a lot more computing power.... But at the level we are talking about with Dslrs, the difference is minimal.

It is the nature of the image that has the most effect on .raw file size..... Look at the images on your computer and good luck finding two of he same size.... Try taking two images, one of a properly exposed scene with lots of variation (no big areas of the same color) and the other picture with the lens cap on..... That's the effect of image scene and that's about 99.9 percent of what affects file size


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## rs (Dec 29, 2012)

Malte_P said:


> what is limiting the maximum FPS for the 1D X?
> 
> is it the bandwith/processing power of the DIGIC5+ CPU´s?
> 
> ...



To return to the original question, the 1D X as far as I know is beyond any SLR before in terms of frame rate for a moving mirror at 12 FPS, and also beyond any DSLR's data throughput at 216 MP/s (18MP 12 times each second, it's max in RAW mode). 

While both of those are pushing the boundaries, as to which is forming the actual limit, only the Canon engineers will know. However, it's likely the mirror assembly is moving as fast as they could get working reliably at that price point, and the data throughput of the dual digic 5+ at 12 FPS would have been pushed too far with one of the many 20+ MP sensors they have put in every other full frame body released since the 1Ds mk III. 

Therefore they're probably both right up at their respective limits, in balance with each other. 

To answer your last question, based on the above assumption of an upper limit of 216 MP/s, at 10 FPS a dual digic 5+ camera could work with a sensor of up to 21.6 MP. Any more MP and the frame rate would have to drop further.

And the rumoured 46MP camera with the same processing pipeline would max out at 4.7 FPS - if it's 50+ MP, it'll be 4.3 FPS or less.


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