[elpolodiablo]

yes, it's official, mine got one spot, serial 3851xxx

[bobmaxja]

The big question , in normal photo do we see it? Up to now, I do not see it except in 1 photo, the rest look marveleous

[elpolodiablo]

only visible f16-f22

[bobmaxja]

But are we seing it in a normal photo? My question is Hoya is an optical company , I am sure they know about this. WE need to know what is their specification or standard. UNtil i see real life photo that are truly bad , for me it's a non issue

[geezer52]

I have to admit that much of this discussion is a bit over my rather inexperienced head. So hopefully this won't sound too dumb. But if the spot is only showing up in photos using very small apertures, does that pretty much automatically place the spot between the sensor and the cover glass? When I have dust it is usually evident at all apertures, but I have rechecked my K-5 and found one similar suspicious spot in f-22 and f-32 shots but nothing in any f-8 shots (I have many shots with clear blue skies where it would show up quite plainly).

I ask because if it is pretty much certain to be uncleanable, I don't want to try and maybe introduce other dust or otherwise compromise my ability to send it in for service.

I must admit to mixed feelings. I very rarely shoot at the affected apertures but it does bother me that it might be there at all. This camera was no small investment for me (nor for anyone else I would think). Feels a bit like getting that first big scratch a week after buying your new car.

[falconeye]

I have to admit that much of this discussion is a bit over my rather inexperienced head. So hopefully this won't sound too dumb. But if the spot is only showing up in photos using very small apertures, does that pretty much automatically place the spot between the sensor and the cover glass? When I have dust it is usually evident at all apertures

The original post answers your question exactly.

BTW, the particles are between the sensor cover glass and the AA filter, not between the sensor and the sensor cover glass. Both normally are sealed areas, the latter is already sealed in the chip fab's clean room.

Dust on top of the AA filter (more specifically, on top of the IR filter cleaned by ultrasonic waves) is invisible. You can check this using the equations given in the original post. The intensity is ~N^2/d^2 and if the distance d becomes large enough, dust disappears for all practical N.

What is visible on top of the IR filter is dirt, not dust. Large enough to be visible at all apertures and at 1/10" or 2.5mm distance to the sensor.

[Thorolf]

Hello Falk,

Kudos to you.

I just looked at an old optics/physics textbook .

Your explanation, although specific had wider implications. Your explanation of the issue was much easier to understand and apply in other areas e.g. astronomy, telescopes etc.

Should write one yourself - with Pentax photographs, of course .

Cheers,

Rod Worth.

[elle.e]

only visible f16-f22

Not true, noticed the spot when taking a close up with my macro lens @ f/4.5
:ugh:

[dgaies]

Not true, noticed the spot when taking a close up with my macro lens @ f/4.5
:ugh:

Agreed. Especially once you know where the spot(s) are, you can see them (very faintly) at f/4-f/5.6. At f/8 they start to get darker and at f/11 they are easy to spot.

[Rupert]

I don't have a K5 yet.......I have been waiting because of the price issue, which was supposedly addressed at Photokina by Pentax, but proved to be false.
Now this comes along and will further deter my purchase until it is resolved...if it is resolved.

I love my Pentax gear, have been very well pleased with my K20D and other Pentax products, excepting my SDM DA*50-135, which crashed, but supposedly "has no problems".......according to Pentax's non address of this issue.

Because I do favor Pentax, I am concerned that at the busiest buying time of the year, many like me will not be purchasing the K5. Not because it isn't a fantastic camera, it obviously is, but because of the uncertainty of how Pentax will handle this. Just like the SDM, will they fail to address the problem and offer a solution that will let buyers purchase with confidence? The record at Hoya for open and honest communications with their purchasers is not good, and this time it couldn't come at a worse time. The ads for the D7000 are everywhere, and word of problems travels fast in this internet age. I am not nearly as concerned about the current problem as I am about the reaction of Hoya and how they respond. It is an opportunity for them to make lemonade or suck on a lemon....their choice.
Best Regards!

[philbaum]

I agree with the overall point you're making. I also fully acknowledge that if Pentax were to hand inspect every camera, and reject each one what had even the slightest hint of an issue, that the camera could easily be several hundred dollar more expensive than it is now. ...

the phrase "penny wise, pound foolish" may apply here. This is begining to sound widespread enough (is that true - as usual we don't know because Pentax isn't talking) that a sampling program would have likely identified it.

To quote another source

PENTAX: Out, damned spot! out, I say! One; two: why, then, ’tis time to do ’t. Hell is murky! Fie, my lord, fie! a PHOTOGRAPHER and afeard? What need we fear who knows it, when none can call our power to account? Yet who would have thought SONY to have had so much DUST in him?

(my apologies to Shakespeare)

[falconeye]

Agreed. Especially once you know where the spot(s) are, you can see them (very faintly) at f/4-f/5.6. At f/8 they start to get darker and at f/11 they are easy to spot.

Actually, if you boost the contrast in an extreme manner against an extremely uniform background, you can see the dust/dirt particles on the lens. For one of my lenses, they appear as (still very faint) disk of about 400 pixels diameter (at f/32 close focus). Of course, nothing to worry about. And I could clean my lens

[hut234]

I've read somewhere (although it was related to cell phones, but I think it applies here even more) that all modern equipment has flaws. That is, if you buy a new cell phone, camera, etc, they would have some problems, be it something like this, or a bit of a body that chips off the K10D or misaligned electronic level or infamous SDM problem. I hardly shoot at f/11 and less, but if you do - it may a problem for you. If not, just be happy and take many pictures... That's my approach.

I think the bigger picture is: how much is simply within spec for a dealable imperfection now and how much of these get worse over time? Will the affected cameras go from one acceptable spot to five unacceptable spots in a year? If it's an issue that is not even there when shipped but happens over time (I'm not speaking of user removable dust, but rather a leak (not saying this is what it is)) then it's hard to be too philosophical about it.

I guess all we can do is ask those who have the issue to examine again in a month and compare.

[dylansalt]

Is the same issue being found on the D7000 - it has the same sensor?

If it isn't then it's definitely a Pentax QC problem

Bad news spreads like a wild bush fire - hope Pentax has a plan

[macTak]

hope Pentax has a plan

Rename the camera the Spotmatic-D