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Author Topic: Canon EOS 7D Mark II Information [CR1]  (Read 33370 times)

K-amps

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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #120 on: March 08, 2013, 01:03:13 PM »
I don't want to put it down too much simple but let's try:
P=Vi
where "P" is power,"V" is voltage and "i" is the current. (Units of measure [Watt], [Volt], [Ampere] )
if we keep "i" costant, we have:
11,1 * i > 7,6 * i
e.g. 11,1 V * 1A = 11,1 W  > 7,6V * 1A = 7,6 W

The result is that a 11,1V battery can spin the lens motor phisically faster than a 7,6V battery,
if there are no differences in circuits, I mean, amplificantions, cuts, stabilizations etc etc etc, and obviously the lens must be designed to accept a certain range of potentials.
Things are not so simple, but this is only for exemplification purposes.

The stepping motors have a set resistance on the windings. It does not matter which camera or battery you are using.... the resistance stays the same.

The pertanant equation is P=E^2/R, or Power = Voltage times voltage divided by resistance. I don't know what the resistance is, so we can not compute what the power is, but we can calculate the ratio of power using an 11.1 battery against a 7.6 volt battery. We get (11.1*11.1)/(7.6*7.6) or 2.13.

A camera using an 11.1 volt battery has twice the power to drive a lens stepper motor than a camera with a 7.6 volt battery....... but remember that this is only one factor in AF speed.... there is how accurate the af sensor is, how fast the camera's computer can interpet the results, the search algorithm, and probably a dozen other things that I am unaware of. The battery voltage is just one part of a very complex system.

Since the motors are USM, it means they are driven by an AC current rather than DC. (In this case >20kHz.)

Strictly speaking; AC motors/ transducers have an impedance, not a resistance.... An Impedance changes with Load and drive frequency (in this case torque needed to move an element) so the same motor may present a different impedance, there would be other factors like the angle of the load... all this complicates things a bit.

Seems that the Canon USM motors have a good spread of voltage tolerances, this would enable them to use similar motors (volume/ scale efficiencies) in many different lens designs... would also explain why the larger element lens may sometimes perform worse than their smaller brethren perhaps.

It should be fairly easy for Canon to tweak the control circuitry to deliver larger voltages in bodies with larger power supplies to drive some of these lenses AF quicker... more voltage would spin the motor faster (assuming current holds up).

Which begs the question....

Would you wear out a lens motor on a 1 series body; sooner than you would on a smaller body?
« Last Edit: March 11, 2013, 11:10:13 AM by K-amps »
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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #120 on: March 08, 2013, 01:03:13 PM »

jrista

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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #121 on: March 08, 2013, 01:53:22 PM »
I don't want to put it down too much simple but let's try:
P=Vi
where "P" is power,"V" is voltage and "i" is the current. (Units of measure [Watt], [Volt], [Ampere] )
if we keep "i" costant, we have:
11,1 * i > 7,6 * i
e.g. 11,1 V * 1A = 11,1 W  > 7,6V * 1A = 7,6 W

The result is that a 11,1V battery can spin the lens motor phisically faster than a 7,6V battery,
if there are no differences in circuits, I mean, amplificantions, cuts, stabilizations etc etc etc, and obviously the lens must be designed to accept a certain range of potentials.
Things are not so simple, but this is only for exemplification purposes.

The stepping motors have a set resistance on the windings. It does not matter which camera or battery you are using.... the resistance stays the same.

The pertanant equation is P=E^2/R, or Power = Voltage times voltage divided by resistance. I don't know what the resistance is, so we can not compute what the power is, but we can calculate the ratio of power using an 11.1 battery against a 7.6 volt battery. We get (11.1*11.1)/(7.6*7.6) or 2.13.

A camera using an 11.1 volt battery has twice the power to drive a lens stepper motor than a camera with a 7.6 volt battery....... but remember that this is only one factor in AF speed.... there is how accurate the af sensor is, how fast the camera's computer can interpet the results, the search algorithm, and probably a dozen other things that I am unaware of. The battery voltage is just one part of a very complex system.

Since the motors are USM, it means they are driven by an AC current rather than DC. (In this case >20kHz.)

Strictly speaking; AC motors/ transducers have an impedance, not a resistance.... An Impedance changes with Load (in this case torque needed to move an element) so the same motor may present a different impedance, there would be other factors like the angle of the load... all this complicates things a bit.

Seems that the Canon USM motors have a good spread of voltage tolerances, this would enable them to use similar motors (volume/ scale efficiencies) in many different lens designs... would also explain why the larger element lens may sometimes perform worse than their smaller brethren perhaps.

It should be fairly easy for Canon to tweak the control circuitry to deliver larger voltages in bodies with larger power supplies to drive some of these lenses AF quicker... more voltage would spin the motor faster (assuming current holds up).

Very true, AC power involves some different dynamics, and can be more complicated. I'm decent with DC power, not as good with AC power.

Which begs the question....

Would you wear out a lens motor on a 1 series body; sooner than you would on a smaller body?

Good question. I figure it probably depends on the lens. The big white telephotos are built like tanks.

I accidentally dropped one from about 6 feet up when I had my camera slung over my shoulder on a tripod. It was my "heavy duty" tripod from about four years ago that had a removable center riser pole. I remove it whenever I use telephoto lenses. Sheath inside the tropod base cracked, apparently led to too much strain on the latch underneath the head that kept the whole entire assembly attached to the tripod legs...and my 7D with one of the new (rented!) supertelephoto lenses droped strait to the ground! I literally think my heart stopped for a moment when that happened, but it landed on ground that was partly covered in about 1" of snow, and relatively "soft" lightly damp earth and matted grass underneath.

The hit sounded really hard...but after some extensive testing....not a single thing seemed to be wrong! The lens was still tack sharp, focused instantly, the camera still operated perfectly...everything seemed to be ok. There wasn't even a scratch on either the lens or body...no dents, nothing. Everything was physically, electronically, and even mentally...in perfect shape. :P (Suffice it to say, I no longer use that tripid...I locked it down as tight as possible that day, but I've moved on to a Gitzo GT3532LS now, which is just a phenomenal tripod!) So, I'd figure that Canons most expensive lenses can handle the power from a heavy duty body like the 1D X. It seems as though they have explicitly designed circuitry to provide better AF drive performance when attached to more powerful bodies than lesser bodies.

I am not sure that would be true about all Canon lenses, though. There are definitely lesser L-series lenses, and even though they are "professional grade", they are not quite the same build quality as the better lenses.

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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #122 on: March 08, 2013, 01:58:52 PM »
A 7d2 would meet my meager needs for FPS. 5D3 & 2 stuff is getting some pub, albeit, in a niche publication.
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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #123 on: March 08, 2013, 02:36:28 PM »
J: I agree... Super tele's must have specialty parts. Glad you didnt have to dig deep in those pockets to make up for any damages.

I was referring to those motors that "cross-pollinate" across similar lines perhaps ...  :)
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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #124 on: March 08, 2013, 02:40:20 PM »
From a marketing perspective, it seems like they'd go backwards in that sense. Bringing back the era of 1D and 1Ds lines but with new names and APS-C instead of APS-H.

Exactly.

... it feels like a step backwards- what will Canon achieve with a low-light capable, excellent AF, fast frame-rate APS-C body- didn't they have all that in an APS-H body in the 1DIV already? What can be gained additionally other than the ability to use EF-S lenses?

It is hilarious that people get hooked to the argument they like and ignore the main forum topic. I think if Canon wanted to, they could implement a higher voltage battery in the current 7D-sized body. I do believe they have a reason to move away from APS-H and a non-FF 1d-style body. It is possible that 7DII will have an integrated grip, maybe as one variant, but I feel it is highly unlikely Canon will sell an APS-C body at a higher price point than the 5DIII merely on the basis of fps and AF speed.
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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #125 on: March 09, 2013, 04:20:47 PM »
I do believe they have a reason to move away from APS-H and a non-FF 1d-style body. It is possible that 7DII will have an integrated grip, maybe as one variant, but I feel it is highly unlikely Canon will sell an APS-C body at a higher price point than the 5DIII merely on the basis of fps and AF speed.

one standout feature of the 1DX is that I now have a sports camera (high frame rate, good AF) on which my wide angle lenses are now wide angle again.  I don't use telephoto lenses for sport, so don't feel like i'm missing out with lost reach.

in moving the 1-series to FF some people will loose out on reach, so that movement of the 1-series to FF creates a gap the 7-series can move into.
also, the increase in price of the 1-series creates a gap for the 7-series

in some respects, the 5-series and 7-series could fill the space that was occupied by the 1d and 1ds series.
could make sense if canon have gone down that route.

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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #126 on: March 09, 2013, 04:39:45 PM »
This doesnt seem to be a 7D II concept but a 3D or whatever concept since it would sit between the 1d and the 5d much like the 1dm3 did. Thus Like neuroanatomist mentioned about $4000.

I would expect an excellent game changer 7DII to be $3000. Who nows really, only Canon.

Its nice to see CR posting about focus speeds being related to voltage output, it seems to not be understood by many as the reason why a 5dm3 and 7d can't focus as fast. But then there are also many that do. I am re-stating it to continue the awareness.
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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #126 on: March 09, 2013, 04:39:45 PM »

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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #127 on: March 10, 2013, 06:16:06 AM »
This doesnt seem to be a 7D II concept but a 3D or whatever concept since it would sit between the 1d and the 5d much like the 1dm3 did. Thus Like neuroanatomist mentioned about $4000.

I would expect an excellent game changer 7DII to be $3000. Who nows really, only Canon.

Its nice to see CR posting about focus speeds being related to voltage output, it seems to not be understood by many as the reason why a 5dm3 and 7d can't focus as fast. But then there are also many that do. I am re-stating it to continue the awareness.

whilst I see you point, I think that canon has made the 1-series "universal" in going high-speed and full-frame.

this does leave a gap in the line that can be filled; a cropped sports camera.  the 7-series is such a camera

as for the 3-series, that's been desired for years but with little basis in reality.  a new 7-series is somewhat more likely

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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #128 on: March 10, 2013, 12:54:32 PM »
Referring to new battery issue...  8)

My question, did you guys ever use the "AA" batteries (6 pieces) tray into grip when your LP-E6 run out? Any different in focusing??? Sometimes i use good batteries like Energizer, sometimes I used my Eneloop from 580EXII... Basically I dun feel any lag in focusing...

When I've used alkalines, I've noticed a drop in performance. Alkalines have a continuous voltage drop over their lifetime, so you only really get "good" performance within the first few minutes. When I use Eneloop or Imedion LSD batteries, performance is FAR better, nearly or as good as the Canon batteries, and consistent until the last few minutes before the batteries become depleted. One thing I have noticed is that the Imedions (which I actually like a lot, more so than Eneloops, but the problem occurs with both brands) is that continuous shooting is not quite as fast. With the Canon battery at full charge, continuous shooting (assuming a fast enough shutter) is very good, very consistent, and I can keep shooting at about 2-4fps even after the buffer is full. With Imedion/Eneloop, continuous shooting tends to start lagging after a few seconds of sustained continuous, and buffer-full performance is not quite as good.

Oh too bad, i never drain my alkalines - just used it while waiting for LP-E6 to recharged.. Eneloop just did fine till the last minute. Perhaps i should take an experiment on burst mode.

jrista

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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #129 on: March 10, 2013, 02:54:31 PM »
Referring to new battery issue...  8)

My question, did you guys ever use the "AA" batteries (6 pieces) tray into grip when your LP-E6 run out? Any different in focusing??? Sometimes i use good batteries like Energizer, sometimes I used my Eneloop from 580EXII... Basically I dun feel any lag in focusing...

When I've used alkalines, I've noticed a drop in performance. Alkalines have a continuous voltage drop over their lifetime, so you only really get "good" performance within the first few minutes. When I use Eneloop or Imedion LSD batteries, performance is FAR better, nearly or as good as the Canon batteries, and consistent until the last few minutes before the batteries become depleted. One thing I have noticed is that the Imedions (which I actually like a lot, more so than Eneloops, but the problem occurs with both brands) is that continuous shooting is not quite as fast. With the Canon battery at full charge, continuous shooting (assuming a fast enough shutter) is very good, very consistent, and I can keep shooting at about 2-4fps even after the buffer is full. With Imedion/Eneloop, continuous shooting tends to start lagging after a few seconds of sustained continuous, and buffer-full performance is not quite as good.

Oh too bad, i never drain my alkalines - just used it while waiting for LP-E6 to recharged.. Eneloop just did fine till the last minute. Perhaps i should take an experiment on burst mode.

Well, what I was trying to say about alkalines is they have a continually and progressively declining voltage. It may start out at the highest level, like 9v, but within the first few minutes its down to around 8v, and it drops progressively from there over the life of the battery. It is like of like a reversed S curve that you usually use to tweak the contrast on a photograph, only high at the left end and low at the right end....the "foot" for alkaline battery voltage can go on for a LONG time, hovering just above unusable. I used my 7D for quite a long time on alkalines once...I could hear the shutter and mirror really struggling. It's probably quite bad for the electronics, to work with too little voltage like that, so I no longer use alkalines in my camera body (only Imedeon and Eneloop, in the off chance it ever comes to that...which it only has twice the entire time I've owned the camera.)

When it comes to flash, another drawback with alkalines is recharge time. Near the beginning of their life, an alkaline actually has nearly instantaneous recharge. But as that voltage drops, recharge takes longer and longer until you can only get one pulse every 15-30 seconds. With an LSD like Imedeon or Eneloop, recharge is never quite a fast as alkalines are right at the beginning, but sustain a far faster recharge time throughout the life of the charge. I think there are some Eneloops that are better for use in flash than others. They have a lower maximum charge, but they support a faster flash recharge (I found that out by reading comments on Eneloops on Amazon...not sure which specific variety it was.)

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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #130 on: March 10, 2013, 04:09:39 PM »
Neither can I see the APC sensor matching the current FF in noise quality.

Oh no, you didn't...you just got jrista's dander up...he's gonna beat you up  ;D ;D

You can't compare a new technology APSC to an old technology ff. it's a lot like saying that since my new Nikon is better than your four year old canon, that nikons are better than canon... it is possible that a new technology APSC will beat old tech Ff, but wait until new technology ff comes out.....
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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #131 on: March 10, 2013, 04:24:12 PM »
Neither can I see the APC sensor matching the current FF in noise quality.

Oh no, you didn't...you just got jrista's dander up...he's gonna beat you up  ;D ;D

In terms of noise, I'd agree, APS-C cannot match FF. I spout a lot of theory, and theoretically if an APS-C sensor could get three times as much light on the photodiode, some hypothetical future APS-C sensor could match today's ~22mp sensors. But...that is all just theory.

Realistically, if you want low noise, the best way to get it is to spend the big bucks, get a FF camera (at least a 5D III), pick up a couple of those fancy new Mark II EF lenses, and fill the frame. Do that with any camera, and no way around it...FF will beat APS-C in terms of IQ.

That said...if you need reach and can't afford to drop fifty grand on the kind of gear that will make it happen with FF...APS-C is more than a viable alternative. :)

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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #132 on: March 10, 2013, 06:56:40 PM »
You can't compare a new technology APSC to an old technology ff. it's a lot like saying that since my new Nikon is better than your four year old canon, that nikons are better than canon... it is possible that a new technology APSC will beat old tech Ff, but wait until new technology ff comes out.....

A pretty simple concept isn't it :D
not sure why it escapes alot of people

If the 7D2 comes out with a blazing new sensor that has eqaul IQ to the 5Dmk3 it will be awesome, doesnt make my 5Dmk3 cameras any worse but man can you imagine what the next FF would be like? usable 512K iso?
the concept sounds insane but 4 years ago no one considered 51K iso usable and now look what the 1Dx can produce at that iso with some clever NR not just hamfisted smeared jpgs
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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #132 on: March 10, 2013, 06:56:40 PM »

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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #133 on: March 11, 2013, 01:25:02 AM »
This doesnt seem to be a 7D II concept but a 3D or whatever concept since it would sit between the 1d and the 5d much like the 1dm3 did. Thus Like neuroanatomist mentioned about $4000.

I would expect an excellent game changer 7DII to be $3000. Who nows really, only Canon.

Its nice to see CR posting about focus speeds being related to voltage output, it seems to not be understood by many as the reason why a 5dm3 and 7d can't focus as fast. But then there are also many that do. I am re-stating it to continue the awareness.


whilst I see you point, I think that canon has made the 1-series "universal" in going high-speed and full-frame.

this does leave a gap in the line that can be filled; a cropped sports camera.  the 7-series is such a camera

as for the 3-series, that's been desired for years but with little basis in reality.  a new 7-series is somewhat more likely
I wasn't denying the 7d2 possibility just the specs being a 7d2. These specs make me think of 1dm3 and 1dm4 at $4000 or more. A 7D2 should be around $2500/$3000 in my guestimate.
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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #134 on: March 11, 2013, 10:56:07 AM »
If Canon wants the next 7D to focus as fast as 1-series bodies, they only have 2 choices: use an integrated grip body to accommodate the higher-voltage 1D-series batteries or develop a smaller version of that higher-voltage battery that can fit in the handgrip of a 7D body (lesser capacity obviously).

To those who still have not figured out why 1D-series bodies AF faster than lesser bodies even with the same lens, here's a simple yet clear comparo between a 1D2 body and a 5D using the same lens (85L with lenscap on, measuring how fast the lens spins from MFD to infinity):

https://www.youtube.com/watch?v=8Yr0BaYYCnQ

Of course, only Canon knows if it's just firmware, AF CPU, higher lens driving voltage, or a combination of all 3 that is responsible for the performance delta.

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Re: Canon EOS 7D Mark II Information [CR1]
« Reply #134 on: March 11, 2013, 10:56:07 AM »