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10-30-2007, 08:55 AM   #106
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QuoteOriginally posted by carpents Quote
Hmmm...I read your other posts, but did not put them together as yours - because they seem to be at odds with one another. You sandwich the post about 'possibly banning' someone by saying that you do not favor banning, so you'll have to forgive me for misinterpreting the post, not for selectively reading it!

One of the main reasons I abandoned dpreview was the Draconian rules regarding banning (or not) of participants. So I'll admit to being easily trolled into responding when it comes to this!

Okay, back on topic...
Not my intention to hijack the thread anymore so... PM sent. Lets the game continue


Last edited by Not Registered; 10-30-2007 at 08:56 AM. Reason: mispelling
10-30-2007, 10:34 AM   #107
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QuoteOriginally posted by RiceHigh Quote
My guess is the SDM *might* have less inertia and that it *might* stop faster than screw driven motor for the lens during focusing but my experience with MZ-S and those SDM lens on K10D is that both control can be achieved to be very good if the AF system is good enough. In the case of SDM on K10D, I just found the motor is just felt to be quite a bit "difficult" to turn and focus the lens fast enough and at least the MZ-S is much faster and start/accelerate much faster and stop also faster and more precisely with less hunting.

Well, people would then say that it is unfair to compare different cameras or even the same camera with different driving methods, but this point is irrelevant as the main point is the DRIVING SPEED of the SDM motors are now found to be slower or simply slow IMO.

As a final question for thought for all you folks and all we Pentaxians: DON'T YOU want the next SDM to be faster (and the AF to be better/improved)??
Really, the MZ-S comparison are useless.

The AF Canon EOS3 smokes the 30D with the same USM lens (70-200 f2.8) mounted on both: I've seen it with my own eyes and the difference is quite evident (try it with your 5D if you have a friend with a last generation film camera from Canon).

What do you make of that?

The only explanation I can find is that designing an AF system for a film camera is a different game than designing one for a digital camera and that the later requires more precision and hence is slower.

But if you're comparing drive speed on the same camera with both driving mechanisms (which you can only do on the K10), it is the speed of focusing (ie getting from one end of the focusing range to a focused position or from a near focusing point to a far away one) that matters and I am not sure we can relate this test to this.

You also seem to be implying that the focusing is found to be slow also on the 16-50 but I didn't get this feeling when I tried them back to back on the K10: the 16-50 was really fast, the 50-135 not so.

As for your final question, of course I want next Pentax SDM lenses to be faster: I'm planing to buy the damn thing! (60-250)
10-30-2007, 11:06 AM   #108
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QuoteOriginally posted by Maxington Quote
To recap, the slowest (by far) lens of the 3 I tested, is the fastest (by far) at actual AF. Everyone with a few different lenses, or even different cameras, go do the simple test, you'll see that the travel time is just meaningless, the same as this test is.
Now that would be an interesting video rebuttal of the end-to-end travel test, but to do the test properly, you would have to start each lens from the same point, then focus on the same object. I've always wondered if the focus speed comparisons did this...
10-30-2007, 03:56 PM   #109
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QuoteOriginally posted by kenyee Quote
Now that would be an interesting video rebuttal of the end-to-end travel test, but to do the test properly, you would have to start each lens from the same point, then focus on the same object. I've always wondered if the focus speed comparisons did this...
No, it was a lens-cap on test, same as the original test, not an actual AF focus test. Thus the big problem everyone has with Ricehigh taking this and running blindly with it.

Its simply NOT a test of AF, and can't even be correlated with AF speed.

10-30-2007, 04:22 PM   #110
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QuoteOriginally posted by RiceHigh Quote

My guess is the SDM *might* have less inertia and that it *might* stop faster than screw driven motor for the lens during focusing but my experience with MZ-S and those SDM lens on K10D is that both control can be achieved to be very good if the AF system is good enough. In the case of SDM on K10D, I just found the motor is just felt to be quite a bit "difficult" to turn and focus the lens fast enough and at least the MZ-S is much faster and start/accelerate much faster and stop also faster and more precisely with less hunting.
MZ-S is much faster? Hmm, I've had two MZ-S, and three K10D, but I haven't seen that MZ-S is MUCH faster than the K10D as far as AF goes. And I've tested several DA* zoom lenses on three different K10D cameras, the K10D can lock to a target from infinity to close target within half a second (less than 1sec in low but not dark condition) with either the DA*16-50 or DA*50-135 lens mounted, how MUCH faster the MZ-S can be? 0 second?

I think this time it's your title of this thread that puts some people off: K10D+SDM=(much) Slower AF Speed? Many users have confirmed that the two release SDM lenses don't seem to help with much faster AF speed, but definitely not MUCH slower!

Thought I shouldn't reply this thread, but just like some said above, you can't ignore some lies all the time.

Besides, why you always quote something from your blog instead of directly link to the original source? Playing the peacock? Sorry if this offends you.



To the other friends here, cheer up guys. SDM is great, it's a big step forward from previous screw driven lenses. I'm sure Pentax would get it improved in the future. BUT even at this stage, it definitely ISN'T much slower
10-31-2007, 06:57 AM   #111
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QuoteOriginally posted by frank Quote
And I've tested several DA* zoom lenses on three different K10D cameras, the K10D can lock to a target from infinity to close target within half a second (less than 1sec in low but not dark condition) with either the DA*16-50 or DA*50-135 lens mounted, how MUCH faster the MZ-S can be? 0 second?
If it is 0.5s, faster timings means anything less than 0.5s (but greater than 0s, of course). So, it can be 0.49s, 0.4s, 0.3s, 0.2s or even 0.1s but not "0 second", which is impossible.

Moreover, if 0.5s or one second could mean "fast", then I'm afraid that any of my Pentax SLRs or DSLRs is faster, according to the timings I measurbated and recorded long ago:-

RiceHigh's Pentax K100D Full Review

The above timings are under moderately bright situation and for a contrasty target, though.

Finally, the AF cannot be done faster than what the lens can travel alone, so what's the "lie"?
10-31-2007, 07:31 AM   #112
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Thank you Ricehigh for your most informative expression of your opinion and the facts regarding Pentax auto focus speed.

I personally didn't understand a word of it but I am sure that many of the more knowledgeable contributors to this forum will be in bewildered wonderment at your contribution as well as thrilled with your concise reporting of the facts.

I have seen the error of my ways and wish to thank all those who pointed out my very naughty behaviour, I am reformed and will show ricehigh the courtesy and respect he deserves for his selfless contribution to the betterment of Pentax.

Through his consistent exposing of the irrefutable scientifically sound factual evidence that proves Pentax is inferior we must applaud this saint, ricehigh, for ensuring the world is warned of the dangers of a slow AF system and the damage it can cause.

Once again Thank you Ricehigh.
10-31-2007, 07:39 AM   #113
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QuoteOriginally posted by RiceHigh Quote
so what's the "lie"?
Well, the most obvious one is the thread title.

The experiment described does not measure AF speed so the claim in the thread title is extremely misleading.

A lie is a statement of a falsehood with intent to deceive.

In that context, the thread title is either a lie, or strong evidence of scientific incompetence.

10-31-2007, 08:03 AM   #114
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QuoteOriginally posted by ChrisA Quote
Well, the most obvious one is the thread title.

The experiment described does not measure AF speed so the claim in the thread title is extremely misleading.

A lie is a statement of a falsehood with intent to deceive.

In that context, the thread title is either a lie, or strong evidence of scientific incompetence.
Well, Chris, I do admit my subject title in this thread maybe not exact and accurate enough. But what I meant is as what my blog article's subject title indicates - SDM lacks speed (and the driving is slow(er)), which should be more accurate for the exact meaning and what the experiment shows.
10-31-2007, 08:34 AM   #115
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QuoteOriginally posted by RiceHigh Quote
Well, Chris, I do admit my subject title in this thread maybe not exact and accurate enough.
It most certainly isn't, and this partial admission, I'm afraid, goes nowhere near far enough.

It is not just "not exact and accurate enough". The opening post on this thread makes a claim that not only is not proved by the experiment it cites, but cites an experiment that doesn't even test the subject of the claim.

Indeed your blog entry starts with this:

"A K10D user has carried out a scientific test on the AF speed (variation) of his DA* 50-135 SDM lens"

.. which is factually untrue.

For someone that portrays himself as a careful and neutral reporter of unbiased measurement, this is a grave failure, and casts serious doubt on the general credibility of his claims.

I've seen a lot of tabloid journalism masquerading as science in my time, and it often contains one or both of intellectual dishonesty, or outright incompetence. I have insufficient evidence to choose between the two, in this case.
10-31-2007, 09:12 AM   #116
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QuoteOriginally posted by ChrisA Quote
It most certainly isn't, and this partial admission, I'm afraid, goes nowhere near far enough.

It is not just "not exact and accurate enough". The opening post on this thread makes a claim that not only is not proved by the experiment it cites, but cites an experiment that doesn't even test the subject of the claim.

Indeed your blog entry starts with this:

"A K10D user has carried out a scientific test on the AF speed (variation) of his DA* 50-135 SDM lens"

.. which is factually untrue.

For someone that portrays himself as a careful and neutral reporter of unbiased measurement, this is a grave failure, and casts serious doubt on the general credibility of his claims.

I've seen a lot of tabloid journalism masquerading as science in my time, and it often contains one or both of intellectual dishonesty, or outright incompetence. I have insufficient evidence to choose between the two, in this case.
Okay, I will amend the statement to "AF driving speed" from "AF speed" by adding one word. However, you query of dishonesty or "outright incompetence" on me is somehow over the top I think. I have provided all the source information for you and any readers on the net to judge the whole story. How come you should impose such a strong accuse to me personally even if the short sentences I wrote are not perfect? (Okay, I think I shall stop here on the point and if you want to discuss further on the technical issue, it will still be welcomed)
10-31-2007, 11:28 AM   #117
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Did ANYONE, including Ricehigh read what this scientific "test" is stesting?

All bold text added by me to highlight the important bits.

Excerpted quote from original post by BTG308 on dpreview forum.

"Last week, I finally took delivery of a slightly used SMC Pentax DA* 50-135mm F2.8 ED [IF] SDM lens. I got it from an eBayer who was switching brands. As I had the 1.20 firmware in my K10D, a video camera and a tripod, I figured I'd tape the lens while focusing back and forth and then measure the focus speed from the video clip."

Excerpted quote from pentax usa.
"VERSION HISTORY

Version 1.30
Added compatibility with the supersonic motor drive of Pentax SDM lenses.

Version 1.20
Added the required programming for compatability with the Pentax Remote Assistant 3 software."

So according to Ricehigh, the end of the world is nigh once again, pentax and their SDM suck, and everyone who claims that SDM is fast and quiet is a big fat liar and puppet of the great pentax conspiracy. All this because SDM used in a very "scientific" test with a camera with THE WRONG FIRMWARE TO SUPPORT THE THING SUPPOSEDLY BEING TESTED.
10-31-2007, 11:37 AM   #118
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QuoteOriginally posted by raz-0 Quote
Did ANYONE, including Ricehigh read what this scientific "test" is testing?
Well I did. It seems you might have missed an important part of the DPR post though.

Here is the relevant text - emphasis mine:

QuoteOriginally posted by DPR post:
Last week, I finally took delivery of a slightly used SMC Pentax DA* 50-135mm F2.8 ED [IF] SDM lens. I got it from an eBayer who was switching brands. As I had the 1.20 firmware in my K10D, a video camera and a tripod, I figured I'd tape the lens while focusing back and forth and then measure the focus speed from the video clip.

I setup the video camera looking down on the lens' little focusing window and proceeded to half-pressing the shutter button (via cabled remote) with the lens cap on in the AF-S mode to make the AF system go all the way from infinity to close focus and back again. This way, I'd see the "raw" focusing speed by which the focus motors could drive the lens. I did this ten times for the screw-drive, flashed the firmware and tried it in SDM mode, fully expecting the SDM mode to be slightly faster than the screw-drive.
I read this as meaning that he did it with 1.2 first using the screw drive, then upgraded to 1.3 and tried it again.

It's no good accusing RH of bad science if we then proceed to abandon the moral high ground by failing to read things carefully enough to make a reasoned rebuttal.

Last edited by ChrisA; 10-31-2007 at 11:49 AM.
10-31-2007, 01:52 PM   #119
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QuoteOriginally posted by RiceHigh Quote
If it is 0.5s, faster timings means anything less than 0.5s (but greater than 0s, of course). So, it can be 0.49s, 0.4s, 0.3s, 0.2s or even 0.1s but not "0 second", which is impossible.

Moreover, if 0.5s or one second could mean "fast", then I'm afraid that any of my Pentax SLRs or DSLRs is faster, according to the timings I measurbated and recorded long ago:-

RiceHigh's Pentax K100D Full Review

The above timings are under moderately bright situation and for a contrasty target, though.

Finally, the AF cannot be done faster than what the lens can travel alone, so what's the "lie"?
Yeah, well, how much difference you'd feel in real world shooting between 0.5sec to 0.4sec? or even 0.1 sec? MUCH faster on the latter? Oh I forgot, you never do real world shooting but some measurebating ones.

The "lie" is: SDM lens isn't MUCH slower but faster or at least similar to most other Pentax AF lenses, MZ-S isn't MUCH faster than K10D, especially under good light. Your title and some words in your statement are just wrong and misleading, that's the "lie".

What kind of impression would your title give a future SDM lens buyer? Especially consider it is NOT TRUE! If you love Pentax as you claimed (but I really doubt about that simply base on what you've been saying about Pentax stuff), then don't trash it!


Sorry, I don't care about YOUR review of the K100D camera on YOUR BLOG. Got the camera myself, and I know how good and bad it is. I love the K100D camera (and the K10D too), your review won't change that.

I'll stop here on this case. There is no one in this world who can convince some guy like you that you are sometimes wrong, like this time. That'll be all. Good luck in your future measurabation, and getting more hits on your blog.

Last edited by frank; 10-31-2007 at 04:50 PM.
10-31-2007, 04:21 PM   #120
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QuoteOriginally posted by ChrisA Quote
Well I did. It seems you might have missed an important part of the DPR post though.

Here is the relevant text - emphasis mine:



I read this as meaning that he did it with 1.2 first using the screw drive, then upgraded to 1.3 and tried it again.

It's no good accusing RH of bad science if we then proceed to abandon the moral high ground by failing to read things carefully enough to make a reasoned rebuttal.

I did not read the whole thread, but I did miss that he flashed it while reading the original post. Sorry.

It's still not a good test for determining anything other than the speed of the motor from lock to lock. In reality, achieving focus on the pentax appears to be something along the lines of 1) determine focus direction 2) make large adjustment 3) make 2 fine adjustments to check focus and call it done. It does seem to be smoother and this may lead to less overshoot. It also seems that the pause at lock is the same or a little bit faster, which means the fine focus steps, especially in low light, might actually take less time than with the screw drive. THe screw drive seems to be slamming into the physical limitations of the lense mechanism, which might result in worse overshoot and greater distance traveled by the lens in a rela focusing situation.

My guess is that it delivers speed on par with the screw drive overall by moving a little bit less in the same ammount of time.

PErsonally I wish I could afford a DA* 500-135 to test that idea out on.
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