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Slow SDM is it normal?

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I have a degree Digital Electronics, Computing and Communications attained in 1991 from No1 Radio School RAF locking with additional modules in my spare time.

If you look back-in my history you'll find published prints of my certificates.

I worked 14 years in the Air-force, 3 years Open systems Engineering , 14 Years Siemens/ATos.

So I would return the offer put up or shut up.!

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altis said:
awaldram, who says it's a constant current load?
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Again your confusing what I'm saying probably me not clear enough.

Constant load as compared to changing batteries ie. if the SDM is requiring X watts of power then that remains the same load under the same environment whether you using 4.8v or 7.2.
altis said:
I've found an application note for you about driving a piezo motor here:
http://cds.linear.com/docs/Design%20Note/dn436f.pdf

I have no idea whether Pentax use the LT3572 but it must be something like this.
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I would think so, Fitted in the lens to reduce capacitive effect of long cable runs at high frequency.
Not sure of your point though .?
altis said:
When you understand about internal resistance, impedance matching, have an honours degree in electronics and over 30 years experience in the industry then you can question my understanding of Ohm's law.
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See my previous reply.
altis said:
Mean time shut up and stop confusing folks.
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Well your certainly confusing me. ??

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Of cause neither qualification or web links prove you or I are correct but the symptoms tend to favor my thoughts.

i.e sluggish SDM under 4.8v, considerably reduced battery life under 4.8v.

Would indicate that SDM is designed to operate efficiently under a higher voltage than 4.8 and that a dc-dc converter is either present in the camera or lens.

Probably as your linked example shows in the actual SDM drive circuit.

I must admit to being confused why your so against the idea that lower voltage source causes lower efficiency in hi power devices.
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Don't be too serious, I was joking.
But your experience is quite relative like all of us.

Congratulations for your score for number of posting, you are running it very well
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Regards
Francois
 
Villamarcel said:
Don't be too serious, I was joking.
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I didn't think I was being serious :)
Sorry if I came across all grumpy
Villamarcel said:
But your experience is quite relative like all of us.
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I'm not trying to say I'm right everyone else is wrong but I do point out the eneloops are only a variant of NiMh.

I personally use hybrids for most of my AA needs accept where I need/want serious grunt then I use hi-current Nimh.

I agree with you all that eneloops are then best average batteries for AA totting cameras.

But my wife's KX has lithium in it as they will last her over a year and are ready for use when she wants to use the camera.

As you say experience is relative to environment.
Villamarcel said:
Congratulations for your score for number of posting, you are running it very well
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Thats nothing 84 in the olden days (cue sandbags and swinging lights ) would not have got you mid table.

I don;t even feel I've posted that much :) But guess there has been a number of interesting threads lately I've contributed to.
Villamarcel said:
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Regards
Francois
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awaldram said:
GPGeneralPhoto said:
Villamarcel said:
Sorry for disturbing your thread,
Next time I keep my experiences and advices for myself big chief !

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Regards
Francois
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Keep on disturbing us. I like to read all the opinions about a topic that interests me. I own an ist DL that won't even start up with 2500 mAh Nimh batteries, but works fine with Eneloops.
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Given eneloops are 2100mAH Nimh batteries but with improved electrode separator you must have faulty 2500mAH nimh batteries or charger

The lower capacity of hybrids (eneloops) is a direct result of better electrode separation giving slower self discharge the chemical technology is identical.
awaldram said:
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I'm thankful to still be able to...
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No. Neither batteries nor charger are faulty. The problem is inrush current. This could be off topic for your lens problem, but I don't know anything about SDM.

http://en.wikipedia.org/wiki/Inrush_current

The Eneloops are able to deliver more current than the standard Nimh in a very short amount of time. My DL has a failed capacitor on the main board that would normally allow the standard batteries to work. But, without the capacitor the inrush current demand at start-up is too high for standard batteries. The extra amperage that Eneloops have available IN THAT SHORT AMOUNT OF TIME allows the DL to start up.
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I'm thankful to still be able to...
 
I have noticed SDM on my DA 17-70 is not as fast on my K-x as it is on my K-5. So... I'd say it's normal. In particular, Liveview AF with SDM is HORRIBLE on the K-x and not nearly as bad on the K-5.

Of course IMO screw drive is faster in any case. Not a big SDM fan here. :-)

For the shots you did get... notice that the little K-x turns in basically the same detail level as the K-5. Still an amazing camera value that K-x was.

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Any government that has the power to correct any injustice and level any inequality also has the power to do ANYTHING it wants.
 
SRT201 said:
I have noticed SDM on my DA 17-70 is not as fast on my K-x as it is on my K-5. So... I'd say it's normal. In particular, Liveview AF with SDM is HORRIBLE on the K-x and not nearly as bad on the K-5.

Of course IMO screw drive is faster in any case. Not a big SDM fan here. :-)

For the shots you did get... notice that the little K-x turns in basically the same detail level as the K-5. Still an amazing camera value that K-x was.
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I'd love to reject that but have to agree the little KX is an awesome little camera :)

Psst don;t let my wife hear me say that.
SRT201 said:
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Any government that has the power to correct any injustice and level any inequality also has the power to do ANYTHING it wants.
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I won't tell. :-)

Yeah, I was all ready for a dramatic new level of detail when I popped my K-5 out of the box. However, after doing same-lens, side-by-side shots with the K-x determined that the the extra detail simply wasn't there. The K-5 MIGHT get a little extra detail but it is subtle at best.

Lot's of things are better on the K-5 but when it comes to real resolution the K-x is neck-and-neck. The nice thing about that is I can shoot with both bodies and not worry about getting inferior imagery from the K-x.

Some claim it's low ISO is actually a little cleaner than the K-5. Haven't really compared that. They are both top-notch in that department.

--

Any government that has the power to correct any injustice and level any inequality also has the power to do ANYTHING it wants.
 
You just have to love that mirror CLACK! :-)

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Any government that has the power to correct any injustice and level any inequality also has the power to do ANYTHING it wants.
 
Sanyo don't quote any figure for peak current but this R/C stack doesn't indicate they behave well

Perhaps thats why your camera starts with it they die under extreme load .?

Which is what I would expect improved self discharge must logically increase internal resistance and lower peak current.

http://www.rcgroups.com/forums/showthread.php?t=1629435

Of cause its only conjecture.

The other things that might help is at 1/2 rated load (1A) they are able to maintain terminal voltage better than standard Nimh so that might be whats helping you.

(The Utube eneloop v Nimh flash comparisons have to make you laugh, proving the obvious or what : ) )

Only other thing I found out, there is no such thing as 'standard' Nimh these days all manufacturers are messing with build and chemical composition so it almost impossible to define how 1 manufacturers battery will behave in a given environment.
awaldram said:
Interesting thanks

I would have thought with the reduced capacity so would the peak current be lower than equivalent Nimh

Off to Google peak current and internal resistance of eneloops and Nimh(how sad am I :) )
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awaldram said:
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SRT201 said:
You just have to love that mirror CLACK! :-)
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Was scaring me silly, As my K5 is in for stuck shutter felt like the Kx was taking the pxss :)

As to ISO I'd say the K5 has about 1/2 - 3/4 of a stop advantage to1600 then 1-1.5 3200 and beyond.

Reality, happy with results with Kx @1600 where would have shot 3200 with K5.
SRT201 said:
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Any government that has the power to correct any injustice and level any inequality also has the power to do ANYTHING it wants.
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awaldram said:
Interesting thanks

I would have thought with the reduced capacity so would the peak current be lower than equivalent Nimh

Off to Google peak current and internal resistance of eneloops and Nimh(how sad am I :) )

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I believe that Eneloops have a lower internal resistance than standard Nimh batteries and thus can deliver higher peak current.
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I'm thankful to still be able to...
 
At last found what I was looking for , Different version but same data (updated)

At 9A load Standard Eneloops are about the worst option available Eneloop XX and Sanyo nimH 2700 the best.

I don't know what the inrush current requirement is for your camera though.

http://www.candlepowerforums.com/vb/showthread.php?298090-The-AA-NiMH-Performance-Test-Thread
GPGeneralPhoto said:
awaldram said:
Interesting thanks

I would have thought with the reduced capacity so would the peak current be lower than equivalent Nimh

Off to Google peak current and internal resistance of eneloops and Nimh(how sad am I :) )

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I believe that Eneloops have a lower internal resistance than standard Nimh batteries and thus can deliver higher peak current.
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I'm thankful to still be able to...
Click to expand...
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Here is a link to a thread in the other forum about the DL battery problem.

http://www.pentaxforums dot com/forums/pentax-dslr-discussion/13335-ist-dl-batteries-5.html

Replace the 'dot' to view.

Seems others have had the same problem and found that Eneloops work and standard Nimh don't.

In that thread, I read about the addition of a capacitor solving the problem with standard batteries and I can not think of any reason other than in-rush current demand being too high. I read the page from your link and I'm not sure I understand completely what it is saying. I'm not an Electrical Engineer, just a lowly service tech (retired). I'm not sure that a test for battery life powering flashlight bulbs is equivalent to a test for batteries powering up a CPU main board as found in a DSLR.

All I can say is that, in real-world testing, the Eneloops work and the standard Nimh batteries don't.
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I'm thankful to still be able to...
 
Ahh

Were not talking large inrush current were talking voltage sag under initial load.

I see why eneloops help I was there a few posts previous :)

" The other things that might help is at 1/2 rated load (1A) they are able to maintain terminal voltage better than standard Nimh so that might be whats helping you."

What I thinks happening is on switch on Batteries Sag many batteries will fall below whatever threshold the camera detects for empty prob 1.1v.

En-loops being able to hold Voltage as you surmised probably due to internal resistance don;t know for sure but stay above 1.1v so voilà camera starts.

I was barking up the wrong tree looking for large current handling which enloops don't have (XX do though)

Clever stuff batteries, I also know little about them with only some dabbling in hi-current mobile transmitter use and R/C hobby use as a youngster.

Basically your camera is causing a brownout in the batteries during charge detection :)

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awaldram said:
awaldram wrote:

I have a degree Digital Electronics, Computing and Communications attained in 1991 from No1 Radio School RAF locking with additional modules in my spare time.

If you look back-in my history you'll find published prints of my certificates.

I worked 14 years in the Air-force, 3 years Open systems Engineering , 14 Years Siemens/ATos.

So I would return the offer put up or shut up.!
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I am pleased to see two other electronics people weighing in on this question!
I'm not brave enough to venture an opinion, because I don't know the design. Perhaps you have some experience in these matters.

I assume a voltage limiter would be used?

If so then I would assume a higher capacity batter would be more useful than a higher voltage batter.

I would of course defer to any owners practical experience.
 
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