Slow SDM is it normal?

Sorry about the title but it got you attention

My K5 is in for repair so my kind lady let me use her Kx for a major swim event this weekend.

I was using it with SDM glass and what a disaster (over dramatization permit) SDM was so sloooow, Not faulty slow or failing SDM judder , juts slow compared to my K5 .

I wondered if anyone else has seen this and why it not been reported before

I can see why, SDM is designed for the 7.2 V supplied by li-ion or the 7.2 supplied by 6aa's in the k5 grip.

The 4.8 that 4 Enloops/ni-mh can deliver in the kx are bound to produce slower results

Going out with my screw 400 and 70-200 today , SDM on the Kx is not usable for sports shooting

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If it were true, would be a simple solution for this.

4 AA Energizer Lithium Ultimate.

But I'm not so sure, that only voltage is the problem.

I used to think that, on my *istD, even the in body screw drive motor, is significantly influenced by voltage.
So I used to use 4 AA Lithium Ultimate....

But at some point, I tried Eneloop, and I have not looked back since.

AF wise, smc-F 28-80 f 3.5-4.5, and smc-F 35-70 f 3.5-4.5, are still many times faster than SDM, even with low voltage eneloops.

I don't use zoom lenses often, but my prime lenses, are also happy with eneloops.

Eneloop or Lithium energizer are the only choices ofr good use of K-x

It generated a number of threads about it in the times of the launch of the K-x and I personaly experienced that and therefore can confirm.

--
Regards
Francois

loock said:

If it were true, would be a simple solution for this.

4 AA Energizer Lithium Ultimate.

Click to expand...

how would that help though they have a 1.5v no load there 1.2 after a very short period load.

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CDMQFjAC&url=http%3A%2F%2Fdata.energizer.com%2FPDFs%2Fl92.pdf&ei=98RmUOP5BY-PswatmYHwCw&usg=AFQjCNFKY-13qke6r4y3_7qhi3i4rdYrZw&sig2=6UfyKWARLtNMQ1RzzP1y4w&cad=rja

loock said:

But I'm not so sure, that only voltage is the problem.

I used to think that, on my *istD, even the in body screw drive motor, is significantly influenced by voltage.

Click to expand...

Screw drive lens are unaffected but then they don't take a direct power feed from source and motor can be designed for operating voltage

loock said:

So I used to use 4 AA Lithium Ultimate....

But at some point, I tried Eneloop, and I have not looked back since.

AF wise, smc-F 28-80 f 3.5-4.5, and smc-F 35-70 f 3.5-4.5, are still many times faster than SDM, even with low voltage eneloops.

Click to expand...

Not sure of you point here .?

loock said:

I don't use zoom lenses often, but my prime lenses, are also happy with eneloops.

Click to expand...

Not sure I mentioned any Zoom lens.? (DA* 300 )

Don;t think it some preconceived conception I'm seeing I;ve shot 10,000+ image with the DA* in exactly the same environment but last night my adjust > focus > snap was pre-Jumping the camera being in focus (af-c)

The only reasonable reason for that is SDM is slower on 4AA's, But I'll try with screw drive today and report back.

I'm confident the issue will have vanished .

4AA's can only deliver 60% of the power compared with 7.2v given the same load.

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Villamarcel said:

Eneloop or Lithium energizer are the only choices ofr good use of K-x

It generated a number of threads about it in the times of the launch of the K-x and I personaly experienced that and therefore can confirm.

Click to expand...

Were getting off topic rapidly.

I you read my opening paragraphs I specifically mentioned eneloops to stop this

"I swear by XX there great" type responses

To clear it up

Last night I had with me and used
1 set Lithium ultras'
2 set Enloops
2 Sets 2900 Nimh

The results were very consistent so I don;t for one second believe all the eneloops/Lithium/nimh are best posts

the batteries providing properly charged and maintained perform almost identically in the camera.

The Technology best would IMHO be a personal thing, I use exclusively eneloops in my flashes not for performance but being charged over long shelf time

I use Ni/mh in my external flash charger as the extra grunt (2900Ma Vs 2200) reduces charge times to bellow 2secs, Downside always charge before use.

And the Wifes Kx always has Lithiums in it due to long periods of non use.

So you can see why I had such a collection of Technology with me last night

but they all did not drive SDM with the speed as the K5.

The same batteries in the K5 grip (6) don;t produce the same lack lustre performance ergo its the Kx not Battery technology selection.

I have no reason to suspect this is my KX only so would not recommend SDM use on KX or older cameras, Newer base models I would recommend using the supplied li-ion when suing SDM.

It also goes someway to explaining my experience of SDM being its plenty fast enough even the DA*55 for sport whereas some people moan about their sluggish AF.

Villamarcel said:

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Click to expand...

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I tried all SDM lenses on K-5, and I also tried 18-135 DC motor.

DA 18-70 f 4 is so-so, but not great.

All other, are stupid slow.

I also tested 4 K-5 bodyes.

K-5 AF is not realy very fast, (more like a poor, and very bad joke compared with eos 1n from 1994...), but the bigger problem is in the lenses.

AF wise, smc-F 28-80 f 3.5-4.5 and smc-F 35-70 f 3.5-4.5, are the fastest Pentax lenses I tried - many times faster then any current SDM implementation.

F*300 f 4.5 is faster then FA 300 f 4.5, which in turn, is also faster then DA* 300 f 4 ( all tested on K-5)

FA* 24 f 2 is fast, but not blazing like some F lenses are.

My K200D (using 4 eneloops) + DA*60-250mm f4 (SDM) is extremely slow as compared to my K-5.

Cheers.

Ron

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My DA* 50-135 is the slowest focusing lens I have used. My enormous F* 600 F4 focuses faster, much faster.

Recently I had occasion to dig out my old SMC F 70-210 F4-5.6. I was amazed as how quickly it focuses on my K-5.

Joe

brandrx said:

My K200D (using 4 eneloops) + DA*60-250mm f4 (SDM) is extremely slow as compared to my K-5.

Click to expand...

Thanks went with the 70-200 screw on the kx today like a different camera, Still not as fast as SDM on the k5 but not far off what teh 70-200 screw achieves on the K5.

Made the day considerably more enjoyable, quite fun th enippy little KX when it gets into its stride.

As I say I don;t get these slow SDM on k5 comments as it not been my experience at all, Tracking AF is considerably faster and more accurate with SDM than Screw on the K5.

brandrx said:

Cheers.

Ron

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Click to expand...

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My experience has been closer to that related by awaldram. I don't posses many DA* glass but have seen the 55mm DA* to be fast enough for sports on K5. It doesn't have quite the reach for me here, however, but it is super sharp. I don't consider the K5 particularly slow as you do and I've had a lot of experience with it and other brands in which individual copies can perform worse than others (or the user hasn't calibrated the lens ).

Going out with the 35-80 today, Would usually use the DA*16-50 for these environment social shots but want screw fro Kx.

Should be fun the camera is so light !!

I have a number of other options in this range but the 35-80 has the closest focus and AF speed.

If the weather stays bright should be OK but is it get dull I could be in bother f5.6 will not deliver.

Have a 70-300 Apo with me so can get to f4 @80mm if needed.

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Sorry for disturbing your thread,
Next time I keep my experiences and advices for myself big chief !

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Regards
Francois

I wonder if this would apply to Sigma HSM as well? I use it on my K-x and have been pleased. Perhaps I should avoid borrowing a K5! I may be disappointed going back to my K-x! What I don't know can't hurt me?

Interesting find, I own a K-x and a K100Ds but no SDM lenses though.

This should be an easy test for people having a K-r/K-30 with dual battery support. I think the D-Li109 is 7.4V also.

--
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Villamarcel said:

Sorry for disturbing your thread,
Next time I keep my experiences and advices for myself big chief !

Click to expand...

I don't mean to upset you, There are plenty of posts on Eneloop,Nimh and lithium most conjecture and wrong.

This weekend using freshly charged Ni-MH 2500 and eneloops
Nimh = 600 Shots approx 6hrs use
Enelopps = 450 shots over approx 3.5hours

I'm 100% confident of the results as the environment did not alter and shooting conditions identical.
Previously under SDM load both battery type struggled to deliver 300 shots

The Eneloops are not the best option for user who can ensure fully charged batteries before the event/shoot, Eneloops are the best performing battery for the casual shooter who does not constantly use the camera.

Lithium are the best option for occasional shooter whose camera may sit for prolong periods.

Pentax have made the best use of available 4xAA technology but it doesn't come close to the performance of the propriety LI-ions, Going to Six batteries and dropping alkanline support would deliver but weight would then be an issue.

Villamarcel said:

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Francois

Click to expand...

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awaldram said:

4AA's can only deliver 60% of the power compared with 7.2v given the same load.

Click to expand...

Your maths/physics is wrong mate.

power = current * voltage
or
power = voltage ^ 2 / resistance

And what's to say that the resistance is the same in both cases? I don't know for sure but I'd consider it MOST UNLIKELY that, in both cases, the raw battery voltage is fed directly to the SDM motor. There will be some sort of current or voltage limit in the way so completely dismissing your assertion that everything is dependant on voltage alone.

Ever stopped to wonder why flash guns with their huge peak current demand still use AAs? It's because you cannot draw huge currents from lithium-ions without risking a fire. On the other hand Eneloops are happy to pump out 10 amps apiece.

If the SDM lens is slower on the Kx then I'm sure this has absolutely nothing to do with the voltage of the battery.

Villamarcel said:

Sorry for disturbing your thread,
Next time I keep my experiences and advices for myself big chief !

--
Regards
Francois

Click to expand...

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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Your getting it all about face.

The load is the SDM lens its resistance (at the PZ contacts) is constant in either case

What electronics and current limiting behind the Pz contacts is irrelevant.

The efficiency of the Piezo Motor is directly related to the power (watts) capability of the source.

There is no free lunch if the stall load of the USM is 1 amp then at 100% efficiency

4.8v can delivered 4.8watts of motive power
7.2v can deliver 7.2 watts of motive power

In reality will be considerably lower and speed/torque will be dependent on Frequency and amplitude

Never the less 4.8v can only deliver 60% of the power in to the SDM lens as 7.2v

As you correctly pointed out this assumes a constant load and 100% efficiency .
The load is the SDM lens and is constant so that has to be correct.

Two statement you make confuse me
1

altis said:

completely dismissing your assertion that everything is dependant on voltage alone.

Click to expand...

I asserted that ?? where

I thought I was saying the lower voltage necessitated delivering less power less power by necessity means either lower frequent or less amplitude from the USM oscillator which in turn means slower operation to the users perception either because of less torque or lower rotational velocity.

2

altis said:

Ever stopped to wonder why flash guns with their huge peak current demand still use AAs? It's because you cannot draw huge currents from lithium-ions without risking a fire. On the other hand Eneloops are happy to pump out 10 amps apiece.

Click to expand...

Not sure what your point is here so yes if I wanted to deliver massive amperage into a low load the Nimh would be appropriate.
But whats you point.?
You are getting confused over battery technology and application.

Stuff NiZN batteries in a flash and watch it scream recharge time will be reduce by 2-4 seconds , Did you ever stop to think why increasing the battery voltage from 4.8 to 6.4 could have such a dramatic effect on the flash.? some flash even destroy themselves in their eagerness to charge

People often confuse Load and source when playing with Ohms law and you seem to have fallen in that trap

the camera is the source the SDM the load . The SDM provide identical current and resistance demand to the source.

altis said:

awaldram said:

4AA's can only deliver 60% of the power compared with 7.2v given the same load.

Click to expand...

Your maths/physics is wrong mate.

power = current * voltage
or
power = voltage ^ 2 / resistance

And what's to say that the resistance is the same in both cases? I don't know for sure but I'd consider it MOST UNLIKELY that, in both cases, the raw battery voltage is fed directly to the SDM motor. There will be some sort of current or voltage limit in the way so completely dismissing your assertion that everything is dependant on voltage alone.

Ever stopped to wonder why flash guns with their huge peak current demand still use AAs? It's because you cannot draw huge currents from lithium-ions without risking a fire. On the other hand Eneloops are happy to pump out 10 amps apiece.

If the SDM lens is slower on the Kx then I'm sure this has absolutely nothing to do with the voltage of the battery.

Click to expand...

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GPGeneralPhoto said:

Villamarcel said:

Sorry for disturbing your thread,
Next time I keep my experiences and advices for myself big chief !

--
Regards
Francois

Click to expand...

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.

Click to expand...

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.

GPGeneralPhoto said:

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awaldram, who says it's a constant current load?

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.

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.

Mean time shut up and stop confusing folks.