Dust in interior of new pentax lens

[randall_thomas]

Hi, I have searched the archives on this and don't see it mentioned; I have just moved up to medium-format from 35mm and noticed the new pentax 105m lens that came with the kit in promo now has a notable piece of dust on the interior of the bottom of the lens. I have put a test roll in for devolopment but wont have back for a few days; Is this reasonable/normal (I have never seen dust inside any other lens I have owned), should i wait to see if it is visible on results or going ahead and see about exchanging?

 

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Thanks,

 

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Randall

[ed_hoey]

I would say that this is unacceptable for any new lens from any

manufacturer. On an older lens, especially one purchases at a

discount this would be acceptable and would contribute very little

image degradation of sharpness, but I wouldn't accept it in a new

lens....

 

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Ed

[rolf_strasheim]

Let me begin by saying that you would have to pry my 6x7 equipment

from my dead hands.

 

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That said, I don't know that I have a lens that DOESN'T have some

residual dust in it.

[scott_laughlin]

Pentax 67, Mamiya 7, Nikon, Zeiss....all of them I've found at least

some measure of dust in them.

[rolland_elliott4]

I wouldn't worry about it. Almost all lenses have some dust in them.

It won't effect picture quality unless it is very big or there are a

lot of small pieces of dust

[steve_rasmussen]

Although it is quite common to have dust in new lenses, there is no

excuse for it by the manufacturers. It is simply a lack of attention

to detail. I once worked in a clean room environment(NASA) and can

assure you that it is entirely possible to have dust free lens(at

least not any particles that the eye can see). I don't think Pentax

finds the dust problem an issue. A friend of mine had to return a

Pentax lens because the dust was large and plentiful. The reason I

don't like dust inside a lens is that it causes diffraction. But, a

little dust doesn't really bother me.

[joachim_inkmann1]

Unfortunately, inadequate quality control becomes a frequent problem

with Pentax 67 lenses: I just had to return two brand new 67 lenses

because they had obvious flaws. The first (4/45mm) could not be

mounted on the camera body without excessive force and a noise of

scratching. The second (2.8/75mm) had a larger piece of dust (?)

melted into the bottom lens element - and I am not talking about the

usual dust particles found in every lens after a while. Adding the

2.8/90mm, which arrived with a piece of a fly (!) melted into the

front lens element, I had to return three of my four Pentax 67

lenses. I never achieved a similar score in my 35mm days. Pentax

really should consider the quality issue more seriously. While I

finally always get the quality that I can expect at this price level,

the transaction costs are really frustrating. By the way, this

experience keeps me away from mail ordering - the trouble would be

doubled.

[steve_rasmussen]

Joachim, this situation has gotten worse with the 67 lenses. I have

stated before in this forum that the older Super Takumar and Takumar

lenses were of better quality than the recent Pentax ones. The 105mm

comes to mind. I've had some problem with the mount area on my zoom

and a couple of others. It was not so bad that I had to return them

however. I have wondered about Pentax's process variability in their

machining operation for some time. I own two Leica SLRs and they have

perfect lens mount to lens fit. Pentax is crude in comparison. I own

two screw mount Pentax lenses(35mm) from years ago and the build

quality is really good compared with the newer 6x7 lenses. Pentax

needs to start using Statistical Process Control on their machining

before they lose customers! The contaminated glass is a disgrace! Not

only did the producer(Hoya?)make the bad glass but Pentax accepted it

into their plant and ground it. Obviously, there was no visual

inspection by Pentax at the end of polishing. An unacceptable

situation.