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09-20-2007, 11:25 AM   #1
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Is manual focus on 18-55mm DA rough?

I just bought a K10D with the kit lens. I find that the manual zoom makes a scratching sound when I manually focus the lens. Is this normal?

It is making the kind of noise that I have heard after accidentally drop kicking a lens , but not as bad as burying a lens in the sand.

I have to say, I haven't bought a new Pentax lens in over 20 years. I have never had a new lens that would make this kind of noise, but maybe they aren't as smooth as they were in the distant past?

Is a scratchy sound and feel normal when manually focusing?

09-20-2007, 11:44 AM   #2
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Yeah, it feels like sand in there, but actually there isn't. I have 2 of the kits and both make a little scraching or smth sounds when MF. I think you shouldn't worry about it.
09-20-2007, 01:02 PM   #3
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I don't experience that at all on any of the newer generation Pentax lenses I own. Zooming or focusing. Focusing feels alright to me--it's a little freer than zooming, but no scraping or sandy sounds. The DA40 is a little difficult to focus, but only because it was meant for tiny hands.
09-20-2007, 01:11 PM   #4
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I have that on my da 18-55, but not my da 50-200.

09-20-2007, 02:58 PM   #5
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Pentax-Tokina Vietnam Fab Comodity Polycarbonate Lenses

QuoteOriginally posted by bobwired Quote
I just bought a K10D with the kit lens. I find that the manual zoom makes a scratching sound when I manually focus the lens. Is this normal?
It is making the kind of noise that I have heard after accidentally drop kicking a lens , but not as bad as burying a lens in the sand.
I have to say, I haven't bought a new Pentax lens in over 20 years. I have never had a new lens that would make this kind of noise, but maybe they aren't as smooth as they were in the distant past?
Is a scratchy sound and feel normal when manually focusing?
AFAIK, all new DA lenses (not sure about DA*) are coming out of the Pentax-Tokina (Tokina, not Tamron, correct?) Vietnam polycarbonate fab.
From what I can tell, and based on my engineering product management experience, they are utterly focused on massive, commodity production.
That's not to say they are "cheap" in construction, and it seems to be a "state-of-the-art" facility producing "quality at commodity."
But all DA models (non-DA* at least) should be considered focused on commodity, "inexpensive" production costs.

My DA 18-55 "kit" is not bad, and seems to be on-par with what most people have.
My DA 50-200 and DA 16-45 are outstanding, and better than what the PhotoZone.DE samples were (especially the DA 50-200).

With that said, the build quality of the DA 16-45 is stellar, the DA 50-200 also outstanding, no "scratch feel" to the focus, and the quick release "feel" is just perfect.
I haven't used my DA 18-55 much at all, not much before the DA 16-45 when I used the AF 28-105 more (which didn't have quick release), and not at all now.
But I don't think my DA 18-55 had a "scratch" feel to it either, although it wasn't "perfectly smooth" at all.

In any case, don't expect these DA (non-DA*) lenses to hold up forever though.
It will be interesting to see how well my DA 16-45 and DA 50-200 hold up long-term.
Maybe they will fair better, especially with the plastic design, who knows.
09-20-2007, 03:44 PM   #6
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The focus feel has improved

Thanks for the feedback.

In the first 4 hours of use, the focus scratchiness has gone away.

Perhaps the lubricant had dried out or wasn't applied everywhere it needed to be.

The 18-55mm lens is very light weight compared to my old non-autofocus 40-80 f/2.8-4 macro zoom.

The old zoom cost me $159 in 1980. Taking inflation into account, that's worth $440 in today's dollars. Probably not many people would pay that today!

Maybe plastic lenses are OK, even if they aren't as durable? (and, the newer lens doesn't have to illuminate a full 36 x 24mm frame,)

Guess I'll have to take some pictures with both and see how they work.
09-20-2007, 04:05 PM   #7
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QuoteOriginally posted by bobwired Quote
In the first 4 hours of use, the focus scratchiness has gone away.
Perhaps the lubricant had dried out or wasn't applied everywhere it needed to be.
Actually, I would guess it was plastic being smoothed out by mechanical use.
I.e., these lenses are mass produced, and it would not surprise me if the plastic molds have some slight "spillover" at some edges.
Those "edges" are then "sticking out" and after a little mechanical use, become "smoothed down."
No different than a car engine, edges get "smoothed out" within the first few uses.

QuoteOriginally posted by bobwired Quote
The 18-55mm lens is very light weight compared to my old non-autofocus 40-80 f/2.8-4 macro zoom. The old zoom cost me $159 in 1980. Taking inflation into account, that's worth $440 in today's dollars. Probably not many people would pay that today!
The latest in plastic and polycarbonate material science combined with the latest manufacturing techniques, the fab is relatively new as I understand it.
You get lightweight, but fairly durable units at a very, very commodity cost.
The question then becomes, how good are the yields, and what QA measures are in place to determine the specifications and acceptable results?

My only, current complaint is that Pentax's (Tokina's as well?) QA specifications are too loose.
I.e., I've been "guestimating," based on reports from various boards, that about 20% or so DA units are barely "within specification."
I wish Pentax would tighten those specifications, reducing yield about 20% or so, but everyone would get a good sample.

I'd be willing to pay 25% more for that, especially since my DA 50-200 unit is outstanding in quality.
My DA 16-45 seems to be the same as well, and even my DA 18-55 was nothing to sneeze at.
But people are getting some faulty DA 18-55 units, and DA 50-200 units (PhotoZone.DE definitely got a bad, but "within specifications" DA 50-200 from their shots).

QuoteOriginally posted by bobwired Quote
Maybe plastic lenses are OK, even if they aren't as durable? (and, the newer lens doesn't have to illuminate a full 36 x 24mm frame,)
Material science has drastically improved not just in the last decade, but even the last 5 years.

E.g., NASA shut down the X-33 project as the Shuttle Transport System (STS) replacement some 5 years ago because the carbon fiber cryogenic tanks failed, and they didn't think material science would solve the problem soon enough.
Well, they did last year, but the X-33 remains canceled (and Lockheed Martin's commercial VentureStar endeavor with it .

QuoteOriginally posted by bobwired Quote
Guess I'll have to take some pictures with both and see how they work.
The DA 18-55 seems to be consistently weak at the corners, a result of the design, not so much the fabrication.
The DA 16-45, on the other hand, seems to be outstanding, and even the limited CA issue doesn't result in purple fringing (PF).
And my DA 50-200 has been quite the performer, and I know others have seen similar with theirs, despite its size.
09-20-2007, 04:46 PM   #8
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Mine makes that same noise, but seems to be great otherwise. The focussing itself isn't rough -- it just makes a subtle noise when being turned.

09-20-2007, 05:23 PM   #9
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yup, its seems common in all slotted screw drive (Conventional AF lenses).

When you turn the focus ring, you hear a faint whrrrring sound right? Its the AF slot screw at the bottom of the lens turning.
09-20-2007, 06:12 PM   #10
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Ah, no, unless I'm not understanding about DA lenses ...

QuoteOriginally posted by FotoPete Quote
yup, its seems common in all slotted screw drive (Conventional AF lenses).
When you turn the focus ring, you hear a faint whrrrring sound right? Its the AF slot screw at the bottom of the lens turning.
Ah, no, unless I'm not understanding something.
The DA lenses are supposed to have "quick release."
My DA 16-45, DA 18-55 (now sold) and DA 50-200 all do.
Although my older, full-frame AF 28-105 (now sold) does not.
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