[séamuis]

It was supposed to be a joke. IQ was so bad Cindy Crawford was mistaken for a seal.

Sorry, I'll do better next time.

i got the joke about cindy, but the rest just seemed to be a legitimate circumstance... hrmm went right over my head.

[Quicksand]

IQ was so bad Cindy Crawford was mistaken for a seal.

I want a lens that does the reverse. Who has that?

[jsherman999]

I want a lens that does the reverse. Who has that?

That's the famous Tokina Beer lens. I think some goggles were made using the same technology.

[asdf]

So what your telling me is to hang on to my Nokton 58/1.4?

Pretty much. Nokton's AF speed blows FA 50 and DA* 55 out of the water.

[GaryM]

It was supposed to be a joke. IQ was so bad Cindy Crawford was mistaken for a seal.

I want a lens that does the reverse. Who has that?

Making animals look like supermodels could have unfortunate consequences, especially for the animal.

[asdf]

That actually wasn't a seal in water, that was Cindy Crawford at Cannes. Yes, there were some problems. Olympus fired an entire shift at their Philippines assembly plant after that one.




.

----------

[Rico]

In regarding the slower focus speed of the DA*55 it could be possible that the K20D might need a firmware update for it.

Maybe the DA*55 was made around a newer autofocus system that will be present in the next line of bodies.

[regor]

... last year's 300mm and this year's 55mm are the two worst Pentax primes I've used in many years.

I don't know about the 55mm, but I find your remark wrt the DA*300 rather surprising as this is the first negative comment I've read about it. All the reviews I've seen rated the 300mm as good if not better than the FA* equivalent, and from my own experience, this is one outstanding lens and there's 100's of images published to prove it. Perhaps you'd care to detail why you were so disappointed by it?

[blende8]

we are comapring micromotor and screwdrive here not micromotor and ring. and here there is not much difference (if any) in overall speed concerning the mechanics. its about more quiet focusing, which micromotors and electrical coupling allow. its this ignorance of what SDM is and is for, which leads to people complaining about AF speed after dropping cash on a DA*.

This is what PENTAX itself is saying about SDM:

From the DA 50-135 factsheet by PENTAX:
"Super fast autofocus through Ultrasonic technology"

From the DA 55 factsheet:
"SDM focusing: fast and silent with Ultrasonic Technology"

From the PENTAX lens glossary:
"PENTAX SDM lenses drive the autofocus system significantly faster and operate more quietly than conventionally driven AF lenses."

Perhaps they should remove the word fast from these statements.

[wlachan]

This is what PENTAX itself is saying about SDM:

From the DA 50-135 factsheet by PENTAX:
"Super fast autofocus through Ultrasonic technology"

From the DA 55 factsheet:
"SDM focusing: fast and silent with Ultrasonic Technology"

From the PENTAX lens glossary:
"PENTAX SDM lenses drive the autofocus system significantly faster and operate more quietly than conventionally driven AF lenses."

Perhaps they should remove the word fast from these statements.

Ouch!

[asdf]

This is what PENTAX itself is saying about SDM:

From the DA 50-135 factsheet by PENTAX:
"Super fast autofocus through Ultrasonic technology"

From the DA 55 factsheet:
"SDM focusing: fast and silent with Ultrasonic Technology"

From the PENTAX lens glossary:
"PENTAX SDM lenses drive the autofocus system significantly faster and operate more quietly than conventionally driven AF lenses."

Perhaps they should remove the word fast from these statements.

How exactly did you test focus speed? EDIT: For example, you could have two targets, one "near" and one "far" and then try locking onto each one of them, one after the other couple of times. Letting the lenses hunt and timing as they travel through their range is a slightly bogus test.

EDIT2: Here's an example: http://www.youtube.com/watch?v=j25VPu9-i3s

[lol101]

How exactly did you test focus speed?

Maybe by waiting for the lens to focus...?

Seriously though, the speed difference between two lenses is not something that requires complex test procedures to assess: it either focuses fast or ... not!

If you can feel the difference, it's what matters.

[blende8]

If you can feel the difference, it's what matters.

Right.
I have now word from three owners of the lens who confirm that it is slower than the FA50.

Here's my test procedure anyway:

I put the camera on a tripod.
Distance to target about 50 cm.
I turned the focus ring to infinity.
I attached a microphon to the lens.
I pressed the shutter.
I measured the duration of focussing using AUDACITY.

I did this in low light.
The time was about 1.5-2 s for the DA and 0.5-0.6 s for the FA.
I even had a 3 s DA focus. It depends, I don't know on what.
In brighter conditions the values are shorter.

[séamuis]

This is what PENTAX itself is saying about SDM:

From the DA 50-135 factsheet by PENTAX:
"Super fast autofocus through Ultrasonic technology"

From the DA 55 factsheet:
"SDM focusing: fast and silent with Ultrasonic Technology"

From the PENTAX lens glossary:
"PENTAX SDM lenses drive the autofocus system significantly faster and operate more quietly than conventionally driven AF lenses."

Perhaps they should remove the word fast from these statements.

im not going to go into a debate about pentax marketing terms and definitions. that's a whole 'nother animal. all I can say is look up the two different types of 'ultrasonic' focusing and compare them. read about the two types employed by canon and the differences in speed based on the mechanics.

though for what seems like the millionth time. its unfair to compare the FA 50 and the DA 55, concerning AF speed. they are two completely different lenses, the 55 is larger, heaver, has more glass elements, more electronics and mechanics inside the lens barrel. infact the only thing these two lenses really have in common is the similar focal length.

I refrained to comment because I don't feel it's fair to do so without having the DA* lens first. As a previous FA50 owner I want to say that sometimes the fast focus speed means nothing more than a constant whirl as lens struggles to lock focus. But seeing in the detail the procedure you used to determine the AF speed difference I think it's clear that the "3 times slower" sentence has less to do with the truth in more real working circumstances.

Right.
I have now word from three owners of the lens who confirm that it is slower than the FA50.

Here's my test procedure anyway:

I put the camera on a tripod.
Distance to target about 50 cm.
I turned the focus ring to infinity.

As the lens (both of them actually) have a 45 cm min focusing range in fact you did a full stroke test and in the day to day usage I think while this may happen it's not the norm.

I attached a microphon to the lens.
I pressed the shutter.
I measured the duration of focussing using AUDACITY.

This puzzles me a bit because I don't understand something about your procedure: the time needed to focus is between the shutter button is half pressed (or even better the dedicated AF button on the back to eliminate the possibility of error) and the moment the AF hexagon lights and camera beeps.

I did this in low light.

At what aperture? And speaking about aperture while I don't want to impose and I apreciate your tests I guess at least one intermediate value between wide open and F5.6 would of been very helpful.

The time was about 1.5-2 s for the DA and 0.5-0.6 s for the FA.
I even had a 3 s DA focus. It depends, I don't know on what.
In brighter conditions the values are shorter.

Again something interesting: you say that in good light you have less than 1.5 s values for the DA* or that they are close to 1.5s and in low light above 2s and closer to 3? Because IF in good light the values are under 1.5s its logical that the SDM is powerful enough and the problem is elsewhere. I am very curios about this!

And one final remark is that you used a K20D with a more powerful in body motor than the lower models. I assume it's fair to say that the DA* will have similar AF speed on any Pentax body with SDM ability while FA50 will focus slower on some. So the speed differential could be even less in some circumstances.

Thank you!
Radu