[CeeBee]

Using K5 (bought Nov.2011) and have just started getting 4 differing sized rings (with centre dark marks) on my images.
Dust test indicates sensor is clean. The rings are in the rough shape of a parallelogram and are in the same position on each image and with every lens used. Camera has not been dropped or had any other damaging experience.
Is it just a case of getting the sensor cleaned or something else?

[SpecialK]

The rings are in the rough shape of a parallelogram and are in the same position on each image and with every lens used.

You're going to show us a sample?

[CeeBee]

You're going to show us a sample?

OK, here is one I took today.

[stevebrot]

OK, here is one I took today.

Cool! Obviously alien life forms! Just kidding.

I vote for stuff on the sensor and lots of it. Do you have a "rocket" blower? I have found that to work best for removing dust, dander, and what not from the sensor.


Steve

[ismaelg]

Hi,

Getting the sensor cleaned should be the first step, and probably the only one required. The smaller dark sports are most likely dust in the sensor. The larger ones could be dried up condensation droplets or something. Whatever they are, they are definitely in the sensor. At this stage I recomend having it professionally cleaned as a wet cleaning may be required.
Best of luck!

[jatrax]

That is a lot of dust spots (in addition to the bigger blobs your are concerned about). Are you using the k-5 dust removal system at startup? Menu>tools>Dust Removal>startup action

That should get rid of most of the smaller spots. The bigger ones I agree look more droplets than dust. Has the camera been open in rain/mist or anything? Regardless, I agree with the above, they are on the sensor.

Dust removal procedure in order:

1. Use the camera dust removal system (shaker) There is a menu setting to turn on/off. If you have dust run this several times in a row and then check for dust again. I leave mine on "run on startup" and think that is best so you don't have to worry about it. The k-5 system is excellent and I rarely see dust spots anymore.
2. Use a 'rocket blower' or equivalent to blow off anything the shaker will not get rid of. Do not use compressed air or canned air. Some folks report it is OK to use canned air if you are careful, but personally I'm not taking any chances.
3. Another suggestion from a poster on PF was to use a fine art brush and spray it with canned air (the brush) this causes a static charge on the brush and helps to pick up difficult dust.
4. Use a wet cleaning kit. This is the last resort, and on two cameras with over 25,000 actuations in all kinds of environments I've never had to use one yet. Get this if all else fails but don't go there unless you are sure you need it.
5. Send in for professional cleaning. Pentax extended warranty (in the US) includes one 'free' cleaning. Not sure about anywhere else.

[JohnX]

Johnsons Photopia are the official UK Pentax repairers, but Harrow Technical and Asahi Photo are also well known and well regarded repairers of things Pentax. That said, your dealer may have a recommendation.

I'm surprised your dust check passed 'ok', though, given the amount of crud visible on your sample shot.

[Stone G.]

Well, I don't want to scare the OP unnecessarily, but my first impression was 'Newton Rings' when I saw the image. That would indicate that something has either de-bonded within or stained onto the sensor. I am not at all sure that dust check would discover that and I would certainly send my own camera to a pro service centre in a situation like this.

SCI - U MUST KNOW: NEWTON'S RING

[stevebrot]

my first impression was 'Newton Rings'

My first impression was roundworm eggs, though that is highly unlikely. I have never seen Newton rings that look like roundworm eggs and think that we are seeing the product of a misdirected sneeze. They look a lot dried bits of viscous liquid.


Steve

[Schraubstock]

Hi

Put your blower away, it won't work !

You obviously have not cleaned your sensor for a long time. This means that some of the organic dust which has settled on the sensor had plenty of time to bloom with humidity. Pollen like to do this. I bet you have pollen and I am almost certain this is exactly what has happened.

The pollen is the centre and the outer rings are what grows from it.

A wet clean is probably the only way to get rid of it and because it is organic the best way to do this is with distilled water.

Look here:
https://www.pentaxforums.com/forums/pentax-k-5/176442-stubborn-dust.html

Posts No. 6, 10 and 13

Greetings