Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-26-2011, 08:56 PM   #1
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 4,989
Sensor stains

I was just about to post asking what these spots were, then I found something about the K-5 sensor stain issue. I guess it is fairly rare on the K-7, or maybe people just don't notice them (I didn't for over a year), but my sensor is actually covered with them (at least a dozen or so spots). My K10D also has a few.

A few months ago I got a pinhole body cap, which is an excellent way to see to see all the dirt on your sensor. I used it on the K10D and got a few of those weird spots in every shot. (With the pinhole shots, they are easily differentiated from normal hair or dirt on the sensor which you can blow off and will go away.) Didn't think much of it since I could never see them with a real lens on the camera and figured I could clone them out on the pinhole shots. I had not tried the pinhole cap on the K-7 though. Then this week since I recently bought several new (or old, actually) lenses and was testing out the sharpness, etc, I noticed some spots showing with smaller apertures (f22 & up) on one of the lenses. Then I tried f45 on my 18-250mm, an aperture I never use in practice as it eats too much light, and you can see them pretty clearly. Then tried the pinhole cap and oh, the horror -- there are a ton of these little spots.

Now, even though I've never noticed them before in an actual picture it is going to drive me crazy knowing they are there. (Looks like that 2-year extended warranty I got for free on a special from Abe's of Maine will come in handy.)

So, apparently not just a K-5 problem as I've got them on both my K10D and K-7.

10-26-2011, 09:09 PM   #2
Inactive Account




Join Date: Dec 2008
Location: North Carolina
Photos: Albums
Posts: 1,720
The sensor stain issue with the K-5 was permanent spots. Are you sure the spots you see on your bodies are permanent? How have you tried to clean them?

Every interchangeable lens camera can get a dirty sensor, that is why they sell products to clean them.
10-26-2011, 09:18 PM   #3
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 4,989
Original Poster
I've never cleaned the K-7 sensor. I did clean the K10D actually just before I tried the pinhole cap as it had gotten a splotch of something on it (which cleaned off). With the K-7, up until this week, the lens has only been off the camera a few times --and usually for only seconds -- so tough to see how it could get dirty. I have blown dust off it (with a blower).

The spots in question look exactly like the example Pentax provided for the K-5 -- tiny circles. I will try to clean it before I initiate any warranty issue (and make some before and after shots so I can see if any of the spots go away), but the sensor looks perfectly clean to the naked eye.
10-26-2011, 10:17 PM   #4
Veteran Member
Jasvox's Avatar

Join Date: Oct 2007
Location: Melbourne, Australia
Posts: 3,110
Post photos of the alleged stains and see what the consensus here is.

Jason

10-26-2011, 10:25 PM   #5
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 4,989
Original Poster
Will do tomorrow when I can make a pinhole picture in daylight. Now that I think about it I believe I cleaned the K10D sensor twice (wet cleaning with "sensor swab" from Eclipse) -- once before I saw the spots (hadn't used pinhole yet) cause I knew there had been a splotch on there for some time, and then again after I saw them -- thought maybe they were actually caused by the cleaning fluid residue or something. I don't think it had an effect, but I didn't do a careful check to see if the spots were exactly the same before & after. Will definitely shoot some "before" shots of a blank wall so I can easily see them. The K-7 actually has a dust detection feature -- nothing shows on that. (I have used that before and it successfully detects actual dust.) Pretty sure it is not dust in any case -- looks more like someone sneezed on the sensor, but it looks absolutely perfect just eyeballing it.
10-26-2011, 10:41 PM   #6
Ole
Administrator
Ole's Avatar

Join Date: Sep 2006
Location: Copenhagen, Denmark
Photos: Gallery | Albums
Posts: 3,785
Sensor stains typically show as a string of spots, not randomly distributed like dust would be. Is that what you see?
10-26-2011, 10:55 PM   #7
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 4,989
Original Poster
QuoteOriginally posted by Ole Quote
Sensor stains typically show as a string of spots, not randomly distributed like dust would be. Is that what you see?
Some individual, some strings. The K10D definitely has strings.

Last edited by vonBaloney; 10-26-2011 at 11:34 PM.
10-27-2011, 08:30 AM   #8
Veteran Member
Jasvox's Avatar

Join Date: Oct 2007
Location: Melbourne, Australia
Posts: 3,110
To get the best results, stop down to f/20 and shoot against a clear blue sky. focus to infinity. The string of pearls or sensor stains show as an... oblong cluster or "string of pearls"

Jason

10-27-2011, 10:03 AM   #9
Veteran Member




Join Date: May 2009
Location: Twin Cities, MN
Posts: 2,869
Definitely sounds like dust to me. You have to be realistic about using a pinhole cap, the F stop is likely astronomical (triple digits maybe?), not to mention you're letting dust get to your sensor through the hole...it is a charged electronic surface, and will naturally attract dust - turn it on while exposed (even to a pinhole) and that will only be worse. I'm 99.9999% sure your photos will show dust, not stains - there has never been any evidence of this on other bodies, it was a manufacturing defect and would have come to light shortly after release just as the K-5 did.
10-27-2011, 10:08 AM   #10
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 4,989
Original Poster
QuoteOriginally posted by pxpaulx Quote
Definitely sounds like dust to me. You have to be realistic about using a pinhole cap, the F stop is likely astronomical (triple digits maybe?), not to mention you're letting dust get to your sensor through the hole...it is a charged electronic surface, and will naturally attract dust - turn it on while exposed (even to a pinhole) and that will only be worse. I'm 99.9999% sure your photos will show dust, not stains - there has never been any evidence of this on other bodies, it was a manufacturing defect and would have come to light shortly after release just as the K-5 did.
Hopefully, but I've seen dust before and it doesn't look like dust. (And dust shows up on the K-7 dust checker -- these don't.) It looks exactly like the sensor stain pictures that Pentax put out for the K-5. I will do tests shortly and try a cleaning.
10-27-2011, 10:30 AM   #11
Pentaxian
kh1234567890's Avatar

Join Date: Sep 2010
Location: Manchester, UK
Photos: Gallery
Posts: 2,327
QuoteOriginally posted by pxpaulx Quote
not to mention you're letting dust get to your sensor through the hole...it is a charged electronic surface, and will naturally attract dust - turn it on while exposed (even to a pinhole) and that will only be worse
This is of course an internet myth - the outer surface of the low pass filter is not charged in any way, the sensor is not actually exposed, the voltages used there are too low for any electrostatic effect and much of the sensor surface is actually conductive.
10-27-2011, 10:39 AM   #12
Pentaxian
aleonx3's Avatar

Join Date: Jul 2007
Location: Brampton, Ontario
Photos: Gallery | Albums
Posts: 3,873
I have owned the k10D and k-7 for years. I am not sure if what you are referring to is stains. Dust, maybe, but not stains.
10-27-2011, 10:54 AM   #13
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 4,989
Original Poster
QuoteOriginally posted by aleonx3 Quote
I have owned the k10D and k-7 for years. I am not sure if what you are referring to is stains. Dust, maybe, but not stains.
Dust I should be able to get rid of, and dust looks like dust. These are slightly unfocused (even with the pinhole, where normal dust shows up razor sharp) little circles.

Regarding dust and the pinhole -- it IS hard to keep dust off the sensor when using it, but it does generally blow right off. I'll post examples shortly.
10-27-2011, 11:02 AM   #14
Pentaxian
aleonx3's Avatar

Join Date: Jul 2007
Location: Brampton, Ontario
Photos: Gallery | Albums
Posts: 3,873
The stains as most referred to appears beneath the AA filter; and in which case, can not be cleaned by DIY methods. The situation you are referring to (can not be cleaned by jet blower) may be something stuck to the sensor not easily cleaned by ordinary method except by using a sensor swap (wet or dry).
10-27-2011, 11:05 AM   #15
Pentaxian




Join Date: Oct 2011
Location: Savannah, GA
Posts: 4,989
Original Poster
Yes, naturally stuff can get on the sensor that isn't dust, but will still come off with cleaning (one hopes). Which is the reason I got some sensor swabs in the first place -- there was a splotchy thing on my K10D sensor -- some sort of residue or a water drop or something. Came right off with cleaning.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, cap, dirt, dslr, k-5, k-7, k10d, lenses, photography, pinhole, sensor, shots, spots
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Stains on K-x Sensor? tbirdas Pentax DSLR Discussion 15 09-18-2011 12:02 PM
Sensor stains Paschalis Pentax K-5 4 09-14-2011 02:45 PM
Sorry to ask: Are these sensor stains? yoon395 Pentax K-5 11 05-27-2011 10:46 PM
Some K-5s shipped with stains on the sensor/AA filter? Peter Fang Pentax K-5 292 03-06-2011 01:57 PM
% of k5 showing stains on sensor? stormcloud Pentax K-5 2 12-05-2010 08:41 PM



All times are GMT -7. The time now is 10:40 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top