Thursday, October 25, 2007

Lack of Speed of the SDM

A K10D user has carried out a scientific test on the AF driving speed (variation) of his DA* 50-135 SDM lens and measurement was made for when the K10D was driving the lens by the body against by the SDM in-lens:-

http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=25309045

Well, the user has briefed the test procedures clearly and I do regard the test and the measurement made are to be quite systematic and scientific. Hence, the results obtained and presented should be quite reliable. Do note also that the user did repeat the test and measurement for ten times, too. Bottom line is that the user has also posted the video clip he took on the net to show the difference in the AF driving speed when screw motor drive is used against the SDM.

In fact, this is actually not the first report for K10D users discovering and found that the SDM is actually moving slower or simply slow. Now, the truth has been revealed again with solid evidence. So, I just wish to ask if SDM just stands for Slow Driving (AF) Motor?

Read Also:-

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17 Comments:

Up Your Kilt said...

Stands for Stupid Dumb Moron which is RiceHigh!

This is not a scientific test and nobody said SDM was going to be faster, just smoother and quiter which it is. How can a Canon convert like yourself say anything about a Pentax product you do not own or have even tested. It is nonsense blogs like yours that prove even STUPID people can have a blog. Have a nice day and learn to take pictures, not like your crooked, bland 5D photo on Dpreview.

RiceHigh said...

> nobody said SDM was going to be faster..

Nobody? Have you ever read Pentax's official statement here?

Quoted: "SDM technology for fast, accurate, quiet focus." Do note that "fast" is the first advantage they mentioned.

Anyway, you're right about the fact that SDM on the K10D is not going to be faster, but actually just slower. But if one replaces the term SDM by USM, then it surely is not the case! See?

Anonymous said...

Its not a test of AF speed, its a test of motor torque. Do you know for a fact that the SDM motor is slower than the Pentax AF system?

It doesn't MATTER if screw-drive speed is faster than SDM if both are capable of keeping up with AF does it? You really think Pentax engineers are as stupid as you?

Wheres the blog post about the K10D's raw files retaining more detail than the twice as expensive, latest model Canon 40D?

Oh wait, its Ricehigh's Anti-Pentax Blog. Home of no scientific reasoning or intelligence.

Anonymous said...

Fast is not FASTER you complete moron. They did not say FASTER!

Holy hell, shot yourself in the foot again, amazing.

RiceHigh said...

Boy, you look so silly to play with the words like what you have done. If Pentax tells us that the "SDM is fast, accurate and quiet". WHY we should not and cannot *expect* the SDM to be faster, more accurate and quieter? If it is really so, what's the point of the SDM? And how come people should spend much more to buy the SDM lenses??

As for the motor "torque" versus turning "speed", it is utter non-sense again for your this "argument". It has been proven that the SDM is moving more slowly which is the fact. What do you want to argue on and actually what is your "point"? And who on Earth tells us that ultrasonic motor "should be" with less "torque" and "should" turn the lens more slowly??

Once again, that's what blind brand loyalty shows up for how this unexplainable silly thing could make people blind like in your this case and simply can't look at things with any objectiveness and accept any fact. If ultrasonic AF motors are *really* slower and has "less torque", then Canon and Nikon should not make those lenses decade ago and Pentax need not to follow to introduce ultrasonic lenses! (Well, you can still loop back to keep saying that it is just for the quiet! (Noun here, quietER is not applicable, I know) LOL..)

Jaka said...

You're expecting a 800€ lens to perform like a 2k€ lens? Fascinating

I held and shot with the Mark III 1D with a 70-200mm f/2.8 USM and it focuses super fast.

I own a Pentax K10D and the 50-135mm f/2.8 SDM and it focuses fast.

The main difference is that the mentioned canon setup would make me sell my kidney(s) (probably wouldn't be enough). And the Pentax one is affordable.

If you ask me, the difference isn't worth the money if you REALLY don't need it.

I'm happy with the body and lens so far (very sharp even in low light, does lack sharpness close up, but it's still OK).

Focusing speed of the SDM is fast enough for that kind of money.

Go shoot with your Canon if you like it so much, some of us prefer Pentax.

PS: The 40D is a great camera after holding it and shooting with it for an hour or so. Would have to test it under different conditions to conclude anything tho. Haven't focused on RAW quality, so I can't say anything about that.

Anonymous said...

The speed of the motor means nothing as long as its as fast as the AF system, or do you deny that? It was not a AF test, it was a motor speed test, two different things, or do you deny that as well? Or is a camera supposed to be able to AF with the lens cap on in your world.

And you are the moron that brought up Pentax's statement, which did NOT say that SDM is faster than screw drive. YOU are the one playing word games. It said SDM is fast, as referenced in your own post. Point out where it said its faster. Come on, where? I'm waiting.

And please, its utterly laughable for you to say people should be objective. Your blog is the most biased unobjective site on the web. I notice you didn't say a word about DPReview pointing out that Pentax raw has more detail than Canon, did you? There's only one side of the story for you, thats attacking Pentax. I've no idea why, maybe the CEO of Pentax ran over your dog. Or maybe he dismissed the letters you sent to Pentax as the ravings of a uninformed lunatic.

Go ahead and ignore all these points, thats how your brain works.

RiceHigh said...

To jaka: I'm of course not expecting the SDM lenses on the K10D is as fast as the Canons as Pentax has never been famous for fast AF, whereas the reverse is true. Also, you're generally right about one would get what he paid for but this comparison is more applicable for comparisons within the same system. Universally, I do agree much for the statement, though, as actually there is no free lunch on this planet.

In response to "anonymous": I don't want to waste my time further to repeat arguing with you on the same argument "points" and "issues" endlessly with you, in my this blog post or just like in my previous ones. I shall opt to just leave it to all other readers who can read and will read to judge, by themselves.

As my only response to your one and only one just more sensible point about the total AF speed against the AF motor (turning) speed, one should note that the motor turning speed is one of the most important and crucial factors for a fast overall AF speed and performance - so, there is actually no true conflict afterall, as you seem to suggest. Enough said.

Anonymous said...

I just compared a DA* 16-50 against a Canon 135 f2.0 USM on a 20D body, my pro photographer housemates cameras. The Canon took TWICE as long to travel its full length. Sit them side by side with lens caps on, watch the travel in the plastic window. The DA* is done and waiting another second before the Canon is finished.

Same test, Canon 20D, Tamron 27-75 f2.8. DA* is done again, a second earlier than the Canon.

Both 20D bodies, with the aforementioned lenses sitting side by side. The Tamron beats the Canon lens.

By this I can conclude that SDM is better than USM, and Tamrons motor system is also better than USM, right?

No. There are far more factors in play than motor speed. The Tamron does not focus faster than the Canon lens, even though the Canon has a much slower motor/longer travel distance. I've used them both, and just tried it again. The Canon lens is MUCH faster, as expected.

Testing the DA* 16-50 against the Canon 135 in AF? The Canon kicks its ass. It focuses MUCH faster and hunts much less. Sound is about the same, except Canon has a quieter shutter slap naturally.

DA* 16-50 against the Tamron? I can't really tell with accuracy, the Pentax edges it out but its by a small margin. But damn is the Tamron noisier. Both the Tamron and the DA* have longer pauses at the end of hunting than the Canon. The Tamron being the worst at pausing before beginning to travel back.

Time taken for a lens to travel fully from one end to another is NOT an indicator of relative AF speed, which is all that test did. Anyone who has used a camera and swapped lenses knows this.

roentarre said...

Now I felt SDM might have been slower than screw driven AF, But it is dead silent though. I love it on my new 16-50

Anonymous said...

You don't have a clue man and I'm tired of your BS claims with very little to back them up.

First you make claims about the metering and then I use both an external meter and a gray card to determine that the K10D / GX-10 is actually only 1/3 stop difference max and this makes sense to save highlights.

Next you start leading people to believe the Sensor has been disclosed as a Sony Sensor and it was never specified anywhere that Pentax used that sensor in their camera.

Now you're telling us the SDM is slower than normal focusing motors and we're expected to believe you now when you don't even own the lenses.

Oh and for the record the quote said Fast focusing not Faster and thus your mastery of the english language is really showing as you prove yourself wrong with that quote.

At any rate, you're a joke and nobody that actually owns or cares about Pentax as a viable imaging alternative believes a word of what you have to say.

Anonymous said...

Oh great guru of arcane knowledge. I give you a riddle of sorts. How do you know that lenses w/ USM ONLY are actually faster than one that is designed as a screw drive??? Let's face it only Pentax allows you to do this "comparison" in the first place since the only way to do it is have the 2 systems in an identical lens. Re-engineered is not good enough...
BTW: I think your mixing up your anonymouses ;)
Fact is if some of Canon's/Nikons USM lenses were designed w/ screw mounts they may be faster. They could be pulling the wool over your eyes this very minute.....Think about it.

Richie said...

If I'd known the test would wind up here, I'd have saved me an hour of my life and shot some pictures instead... Yes, the DA* 50-135's SDM motor is slower than the K10D's screw-drive motor. Then again, the screw-drive is also very slow on this particular lens model. Only the much lighter 50-200 is in the same league. So, it's not an indictment of SDM per se, it's just a comparison for that particular lens. The DA* 16-50 focuses much faster by all accounts (although I don't know if it's SDM is faster than it's screw-drive). SDM is fast, but not really fastER. SDM does focus differently from the screw-drive; it doesn't overshoot and correct quite as much as the screw-drive.

RiceHigh said...

Richie, just wish to say thank you to you for your test and sharing. But as you should have known before you measurbated, measurbations are always a waste of our (valuable) time especially when you're comparing to use our time for picture taking! :-)

Well, btw, why not repeat your test for focusing a real target to see the difference(s) between the SDM and the screw drive body motor? Of course, I suggest you should let the lens to travel for enough span in order to see more the difference and to get more accurate and reliable results.

Nonetheless, I still consider that your test method is clever (with very simple setup and quick to conduct), correct and scientific. So, just looking forward to see your another true test on the actual AF speeds. But then you will waste another hour or even hours to measurbate and to publish your results (and for the discussion time wasted in the cyber space as well)! ;-D LOL

I shoot pics do you? said...

Rice High. You really must learn to read. The Pentax official comments about the lens system say nothing about FASTER. They say "fast" only. You can try as hard as you like to cram words down Pentax's throat and change the meaning of their statements but what it printed on the site is clear. Defend your position as much as you want. Your interpretation is still wrong. They don't compare SDM to screw drive or any other system. They simply say "fast". BTW the main point of SDM is to get the system quiet. AF screw drive is noisy and if you shoot weddings for example it can be distracting.

I'm not going to to get into the bogus "scientific" test here or any of the other oh so helpful Pentax foolishness you post. You sold your Pentax gear. Go bother Canon now till they get sick of you as well.

Bob said...

You were absolutely RIGHT about the slow AF of SDM. More people are catching on now. There are posts on youtube showing how slow Pentax AF is. Also, the drumbeat of QC problems with SDM continues and now there is an online petition to Pentax regarding SDM.

Would you be able to revisit this issue since your post on this is from 2007?

RiceHigh said...

Search the term "SDM" in my Blog and you'll be able to see the updates.

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