[civiletti]

"The highest used f stop is usually f11"

That may be your practice. It is not mine.

[falconeye]

This is certainly a possibility, which raises an interesting question: If everyone tested their other cameras in the same way as they are now testing their K-5s, how many would find similar artifacts? The answer might be surprisingly high. I am not saying that there is not a genuine "stain" problem with some K-5s, but the actual prevalence may be far less than we are led to believe by threads such as this one.

Rob

I already did and commented. IMHO, almost every camera has a few isolated such spots. Certainly, my K-7 does.

What is distinct to the K-5 is the string of stains. Or cluster if there are parallel strings.

I highly recommend people seeing a few stains but no string of stains report "no". Otherwise, we'll never see a pattern in the serial numbers.

It often looks like a splash on pics posted. Is is possible than it's a transparent liquid on the top of the sensor, or maybe between the AA & glasses layers. Could the liquid, be "cooked" by the heat of the sensor, then turn harsh and opaque ?

What looks like a splash, cell, bacteria or oil drop most likely is a solid obstruction of about dust particle size. I explained in Stainology why the image looks as it does.

It certainly appears that there are two distinct types of stains. 1) the long string of (typically) horizontal dots and 2) the single or small grouping of darker circles with a lighter outer ring (the ones that almost look like biological cells). I wonder if they are from the same contamination-source or if it's possible there were actually two different types of contamination.

The string is what is of interest here. Mine is 45 degrees.

The isolated ones is "normal" contamination probably seen in every second camera, if there only are very few and unclustered.

All stains have the dark center if the f-stop and particle are large enough to produce an umbra shadow. The lighter outer ring is penumbra shadow.

[dgaies]

This is such a BS. Sorry guys.
First, all the sensors of all the existing cameras have stains/dust/whatever.
The highest used f stop is usually f11, nothing seen there.
And most of all, please show me those amazing photos affected by that colossal
issue because all I can see right now here is complains and BS, no pictures
what so ever. If your photography is so amazing and your absolutely perfect photos
suffer because of a few darker spots seen only at f22, please show us all
those great pictures, we'd love to see them.

While I understand what you're getting at, that's not really the point of this thread. I don't think most people are complaining that the stains are destroying the camera's ability to take excellent photos. I think people are upset because they spent $1500+ on a camera body with a defect that is different from dust in the sense that it can't be cleaned and therefore will always be present on the sensor. It will be a potential issue if they choose to sell their K-5 down the line, specifically if they don't bother to have it repaired by Pentax during the warranty period. Doing this, however, requires sending your camera away for several weeks, which is also something most people aren't too excited about.

Also, FWIW, depending on the size/type of the strain on your sensor, you can certainly see the spot as far down as f/4-5.6, depending on the conditions. Is it the end of the world? No, of course not. But again, I don't think it's unreasonable for people to expect their sensors to be free of this type of defect.

[dgaies]

The string is what is of interest here. Mine is 45 degrees.

The isolated ones is "normal" contamination probably seen in every second camera, if there only are very few and unclustered.

All stains have the dark center if the f-stop and particle are large enough to produce an umbra shadow. The lighter outer ring is penumbra shadow.

Do you think the "normal" contamination spots are also just below the AA filter, thus making them impossible to remove?

[falconeye]

This is such a BS. Sorry guys.
First, all the sensors of all the existing cameras have stains/dust/whatever.
The highest used f stop is usually f11, nothing seen there.
And most of all, please show me those amazing photos affected by that colossal
issue because all I can see right now here is complains and BS, no pictures
what so ever. If your photography is so amazing and your absolutely perfect photos
suffer because of a few darker spots seen only at f22, please show us all
those great pictures, we'd love to see them.

andi, I would normally agree with you. I am the most vocal one saying that other cameras often have stains too at such high f-stop.

However and this is why the problem is real, the stains in the K-5 typically come in dozens confined in a small region. What we call string of stains.

And this must be considered a serviceable defect in many cases. It is avoidable too.

[Matt Miller]

SN 3894707, no stains.

[falconeye]

Do you think the "normal" contamination spots are also just below the AA filter, thus making them impossible to remove?

Yes. For my K-7, I would say they are mostly at the same place. Maybe underside of AA rather than topside of cover. I even have one which looks to be sharp enough to be under the cover glass. And I see a very soft one which may be a small dirt particle which may be cleanable actually. Dust on the cleanable outer side is invisible at f/32.

I suppose the number of dust particles between AA filter and sensor could be around half a dozen in an average camera. I mean, dust is everywhere, hard to eliminate entirely. I doubt a camera is assembled in a class whatever clean room like the chips are. It would cost a fortune. Vietnam is humid at least

I should add that I boosted the contrast to see all stains. Some stains are from particles too small to be easily spotted. Which is another reason I recommend to report the string of stains only.

---

Last edited by falconeye; 12-06-2010 at 06:40 PM.

[dgaies]

Yes. For my K-7, I would say they are mostly at the same place. Maybe underside of AA rather than topside of cover. I even have one which looks to be sharp enough to be under the cover glass. And I see a very soft one which may be a small dirt particle which may be cleanable actually. Dust on the cleanable outer side is invisible at f/32.

I suppose the number of dust particles between AA filter and sensor could be around half a dozen in an average camera. I mean, dust is everywhere, hard to eliminate entirely. I doubt a camera is assembled in a class whatever clean room like the chips are. It would cost a fortune.

Makes sense. I no longer have my K-7 to directly compare to, but I saw your comparison and I would tend to agree that it would not be unexpected to find several of these types of spots on any given sensor (Pentax or otherwise). I also agree that the strings are more "interesting" (for lack of a better word) and not typical for most DSLR sensors.

As you said, dust is everywhere and is impossible to completely eliminate without spending a fortune. Off topic, I spend the first month I owned my original home theater projector chasing "dust blobs" (dust on the LCD panels) which manifest themselves as faint rings in very dark scenes on the projected image. You could open the unit up and try to clean it, but it was a crap shoot whether you'd end up with more dust after cleaning it, because as you said, dust is everywhere

[ve2vfd]

This is such a BS. Sorry guys.

It may be BS to you, but to many of us who bought a brand new body it's unacceptable. This is the same as buying a nice brand new car and the dealer delivering one with a torn seat or a huge paint scratch. It still works "ok" but thats not what you payed for right?

And FIY on a bright background (like the sky), I see the spots all the way down to f8. You may not mind cloning out spots, I do.

Pat

[falconeye]

Looking at SN, it looks like we covered 3,820,000 to 3,900,000 now. Which are 80,000 units. Congrats to Pentax!

As far as stains and SN correlation is concerned: I cannot see a pattern. It may really depend on a few individual workers ...

[m8o]

Interesting poll & moreso results. I would have suggested two more options.

3) Yes there were stains but not on my replacement body
4) Yes there were stains and they are still there on my replacement body

I voted for #1 but would have voted for #3 if available.

BTW, everyone, don't forget to log your serial # on Adam's serial # tracking page, and make note of this or any other problems if they exist (in addition to your rave reviews & other gushing's regardless of any imperfections ).

[m8o]

This is such a BS. Sorry guys.
First, all the sensors of all the existing cameras have stains/dust/whatever.
The highest used f stop is usually f11, nothing seen there.
And most of all, please show me those amazing photos affected by that colossal
issue because all I can see right now here is complains and BS, no pictures
what so ever. If your photography is so amazing and your absolutely perfect photos
suffer because of a few darker spots seen only at f22, please show us all
those great pictures, we'd love to see them.

I call BS on your call of BS. Go look in the 1st page of my "ISO 80 Light-fill" thread to see how dramatically visible my schmear/splotch was at the very commonly used f/8 and wider aperture. So much so someone made a cropped screen-cap and asked me about it. Every photo I made in landscape mode with the errant blob in the sky required time-consuming spot removal.

[Thesorus]

Also, are those blobs "stable" or will they impact the longevity and durability of the sensor ?

I will be shooting in the cold and snow for the next couple of months, I don't want something that will go worse.

Anyway...

[dgaies]

Also, are those blobs "stable" or will they impact the longevity and durability of the sensor ?

I will be shooting in the cold and snow for the next couple of months, I don't want something that will go worse.

Anyway...

As far as I understand, whatever the "blobs" are, they don't actually touch the sensor itself. So in terms of impacting the longevity and durability of the sensor I wouldn't worry too much there. In terms of getting worse (as in bigger or new ones appearing) I don't know if anyone can answer that question with 100% certainty. I think it's unlikely to get worse over time if these are actually defects that occurred during manufacturing - but I certainly don't know for sure.

[dadipentak]

If your photography is so amazing and your absolutely perfect photos
suffer because of a few darker spots seen only at f22, please show us all
those great pictures, we'd love to see them.

Well, I did post photos in the "no more tests" thread and, make no mistake, I love my K-5. But, while the "issue" is pretty mild in my case, those extended strings some others have discovered certainly are really problematic.

I'm not in a snit or funk about this but, then again, I did plunk down a hefty pile of change for this camera and want as much value as possible.