Sensor marks

I recently bought a pretty recent K5 II second hand and have been getting used to it and I am really enjoying it. But recently I have noticed, particularly on portrait format pictures rather than landscape, dirty smudges on the pictures. See below a full sensor picture and a cropped area.







Initially I thought it was on the filters or the lens but by taking photos with different lenses with no filters I have come to the conclusion it is on the sensor.

With my K-r I have managed to keep the sensor clean with a big blower and the shaking built into the camera and this was all I was going to do with this one. However, this looks to me like I need to wet clean it as it looks like some residue left from a previous wet clean.

Can anyone give me some expert advice as to what it might be and how to get rid of these marks please. And even whether it is something I can/should be dealing with or that I would need to send the camera away for?

Many thanks,

Hi Andy

I would give it a wet clean, I think you are right in that someone has previously tried to clean and probably used too much solution. The pad you use to clean the sensor should be only very slightly damp, not wet, otherwise it will leave smears.

I have successfully used 'Pec Pad' lens tissues wrapped around the end of a lollipop stick cut exactly square at one end, this then dampened in a very small amount of isopropyl alcohol. It costs very little to try a clean this way as Pec Pads and the alcohol are cheap and the lollipop sticks cost nothing. Carefully wipe the sensor surface in a single direction, applying very light pressure. Make sure the whole surface is wiped, into all edges and corners and also make sure there is no residue being left by the swab, if there is any residue it is likely the swab is too wet, if so, let the alcohol evaporate a little, then try again.

Before doing the wet clean make sure you blast the sensor with a rocket blower or similar to get rid of any dust particles, this will avoid the risk of any scratching occurring.

I know there are proprietory solutions and swabs available for sensor cleaning, but I've successfully used this method several times with no damage caused. It's a fairly straightforward process as long as you take your time and do it carefully.

I hope this helps.

Regards
David

Thank you David. I will give this a, very careful, try. And, yes it has helped.

Many thanks,

Just one more thing to add to David's advice is to ensure your battery is fully charged before you start

Yes, I understand.

Thanks Ken