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02-03-2010, 11:26 AM   #46
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QuoteOriginally posted by PentaxPoke Quote
Someone posted these video comparisons that I found interesting:
http://www.youtube.com/watch?v=ngUcQUchHEU
EDIT: What the... The guy has 70-200 f/4 on the canon but a crappy slow super zoom (note it's "zoomed in") on the K-7.

Yes and someone posted a video of the Tokina:
http://www.youtube.com/watch?v=l5FgZToE7uQ

It's not meaningful to compare two camera systems with two lenses of different construction.


Last edited by asdf; 02-03-2010 at 11:31 AM.
02-03-2010, 11:29 AM   #47
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QuoteOriginally posted by asdf Quote
You made a sweeping statement about SDM. Didn't I say that it depends on the lens and construction? DA 17-70 and DA 16-45 have pretty much the same focus ring travel time--and both are slower than the kit lens (you can find quick tests on youtube).
Well it is a misunderstanding then. I meant that it was slower than screwdrive in the same lens. That is a direct comparison of SDM to SD. I never meant to compare different lenses and different camera companies.
02-03-2010, 11:34 AM   #48
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QuoteOriginally posted by PentaxPoke Quote
Well it is a misunderstanding then. I meant that it was slower than screwdrive in the same lens. That is a direct comparison of SDM to SD. I never meant to compare different lenses and different camera companies.
OK, I see. ...they can definitely increase the torque in the built-in motor (EDIT: in successive camera models). I wonder if that's why FA 50's are falling apart.
02-03-2010, 11:41 AM   #49
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QuoteOriginally posted by asdf Quote
OK, I see. ...they can definitely increase the torque in the built-in motor (EDIT: in successive camera models). I wonder if that's why FA 50's are falling apart.
That is a good point. When I used to use my 35 and 50 on my K-7, it seemed like the camera used to hammer the ring against the stops at the end of travel. I think the k-7 body AF motor has more torque and voltage.

02-03-2010, 12:33 PM   #50
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First thing I noticed when I tried out my DA* 50-35mm for the first time: super quiet focusing.

Second thing I noticed: My screw-drive kit lens focuses faster. Especially the delay between the time I half-press the shutter button and the lens starts moving. My kit lens reacts immediately, the 50-135mm takes half a second or so.

Accuracy is about the same between the two.

Actually, the very FIRST thing I noticed with the 50-135mm was that it didn't work. It took a good 5 minutes before the SDM even deigned to kick in. At first, I was convinced it was DOA, and then it sllooowwwlllyyy started moving, and then it seemed to work fine.

There was a post recently about someone who started having apparent SDM troubles, then he changed his generic 3rd party battery for a genuine Pentax one and his SDM lens woke right up and went back to its old self. I have a feeling low voltage has a lot to do with SDM motor life. Any electric motor strains under inadequate current and can fail prematurely, and a lot of us use 3rd party batteries because they're so much cheaper.

Last edited by GoremanX; 02-03-2010 at 03:50 PM.
02-03-2010, 07:15 PM   #51
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Voltage could indeed be an issue, but you would also have to take into account battery life and the occasionally defective battery, OEM or otherwise.

Wonder if anyone currently having SDM issues could possibly test this theory with fresh, new batteries or perhaps with the AC adapter!
02-03-2010, 07:49 PM   #52
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QuoteOriginally posted by Frogroast Quote
Voltage could indeed be an issue, but you would also have to take into account battery life and the occasionally defective battery, OEM or otherwise.

Wonder if anyone currently having SDM issues could possibly test this theory with fresh, new batteries or perhaps with the AC adapter!
Surely, if that were the issue, Pentax would be delighted to make an announcement to that effect. It would shift the blame from themselves to the customer. It also doesn't explain the occasions where Pentax have repaired or replaced a failed lens.
02-03-2010, 09:34 PM   #53
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QuoteOriginally posted by Damn Brit Quote
Surely, if that were the issue, Pentax would be delighted to make an announcement to that effect. It would shift the blame from themselves to the customer. It also doesn't explain the occasions where Pentax have repaired or replaced a failed lens.
Exactly. Pentax service said mine were SDM failures. That is why they sent be brand new lenses. I also have never used a third-party battery.

02-04-2010, 03:18 AM   #54
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No issues with DA* 50-135mm

I'm using the DA* 50-135mm with the K7. I'm amazed at how well the lens does. Focus is very fast Almost instant. Even in the dark i get focused fast. for those who are focusing on a plain wall or on something that may confuse the camera, focus may have trouble searching, but that is normal with any top of the line lens.

I've had the lens for 2 weeks now and i'm amazed at how well it does. Took great shots every time i used it. I was worried before i bought it reading few of the issues people had. But i'm glad i got it.

See photos below. The second picture is a cropped version of the first one so you can see the details. Posting the photos here do not do justice. Bu you should be able to see the quality.
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02-04-2010, 03:40 AM   #55
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I am still unsure that the speed difference that we talk about is related to perception and/or quality variation.

My 50-135 is reasonable for speed... focus throw is quite long so if you change focus point from min to infinity it does take some time to get there... but is this not why we have "quickshift"? I find that in normal operation that the 50-135 is slightly faster than the kit lens but hunts less.... If I set the centre point on a decent point of contrast it does not hunt at all (i.e. If I can see the contrast thorugh the VF the AF finds it also...)
I do find the 16-50 to be significantly faster focussing.... this is all on a K20D

I would hope Pentax would not remove either of these lenses from the roadmap.
02-04-2010, 03:57 AM   #56
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I did try to focus from min to infinity and did not notice the delay you taking about. I tried focusing on tree leaves, focused immediately, then pointed to the sky, also focused immediately. I did not notice any focus hunting, i would say 1 second or so. Could it be that k7 handles differently then the k20 or other models. I don't know. I noticed most users who complained do not have the k7. I will do more testing for min to infinity tomorrow.

Last edited by Alex00; 02-04-2010 at 04:04 AM.
02-04-2010, 05:14 AM   #57
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There are definitely two issues. First of all, there is focus throw length. Pentax over time has kept a longer focus throw length to please manual focusers. The lenses where they haven't (like the DA 40) are really fast focusers, but really tough to manually focus. The second thing is the SDM issue. As far as I can tell, SDM is equivalent to screwdrive, not really faster or slower. To focus accurately and lock, they both require contrast. I don't find that the DA 50-135 is particularly slow in real life shooting, just because I don't usually turn my lens to infinity before I lock focus. The distance the lens has to travel is less than the maximum it could travel.

Now, it is clear that the Canon 7D is a better focuser than any Pentax offering and that the ring driven USM is faster than SDM by a significant margin. I just don't think that SDM is actually slower than screwdriven lenses, just less reliable.
02-04-2010, 08:51 AM   #58
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QuoteOriginally posted by Alex00 Quote
I'm using the DA* 50-135mm with the K7. I'm amazed at how well the lens does. Focus is very fast Almost instant. Even in the dark i get focused fast.
You are just blinded by that beautiful new baby you have. Even the most ardent Pentax fan must admit that the 50-135 is a slow focuser. (I seem to remember a post from someone long ago about things that move faster than the 50-135. Like the earths rotation, the seasons, etc.) You are the first person I have ever seen post say that the 50-135 is an "almost instant" focuser. It gets much worse when the lights are low.

I think the only way the 50-135 could be described as "almost instant" is if you were already in focus.

This is the way I remember my 50-135's focusing:
http://www.youtube.com/watch?v=ngUcQUchHEU

Last edited by PentaxPoke; 02-04-2010 at 09:01 AM.
02-04-2010, 10:16 AM   #59
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QuoteOriginally posted by PentaxPoke Quote
You are just blinded by that beautiful new baby you have. Even the most ardent Pentax fan must admit that the 50-135 is a slow focuser. (I seem to remember a post from someone long ago about things that move faster than the 50-135. Like the earths rotation, the seasons, etc.) You are the first person I have ever seen post say that the 50-135 is an "almost instant" focuser. It gets much worse when the lights are low.

I think the only way the 50-135 could be described as "almost instant" is if you were already in focus.
kind of speaks to what I was referencing... either it is about individual perception, e.g. I dont much real experience with other systems to compare so maybe what I perceive to be "decent speed" is "slow" for others with different experiences... although I do have a Nikon shooting friend who also found the focus speed decent in real usage.
Other side is that maybe not all 50-135s are build equal... is it possible you had a slow/defective copy? I only have seen mine in action so have had no other 50-135s to do a side-by-side.
02-04-2010, 11:14 AM   #60
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QuoteOriginally posted by gazonk Quote
Which "reps" are saying this? Sounds like utter nonsense.
Its from several reps from our main suppliers in the Uk, 2020 who are the main suppliers of Pentax Equipment to independent firms have been unable to confirm deliveries or whats is even coming in. And after searching around i've found alot of the main retailers who deal direct with Pentax are out of stock on most lines and have no details of when they will be getting new stock. The largest Camera retailer in the UK dropped Pentax at the begining of last year.
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