[Grey Area]

I'm very new to DSLRs...sould someone examine the "blob" at about 10 o'clock in these two pics? Is the fact that it's more visible when focussed at infinity than nearer anyd indication of where it may be? I've cleaned the lense several times but the blob persists!

Thanks!

[jatrax]

Dust spot on your sensor.

Do you have dust removal turned on? If not it should be.

In order of complexity:
1) Camera dust removal system
2) Use a rocket blower to clean
3) Use a sensor wet clean system
4) Send in for professional cleaning work

What camera do you have?

[ohaya]

It's probably dust on the sensor. I had this with my K-r and finally got rid of it using a sensor brush, but you should try one of the blowers like the "Giottos" blowers first. FYI, I got the small one, but then got the large one, because the small one was kind of not very powerful:

https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/313001-s...mages-k-r.html

[Davidparis]

I'm very new to DSLRs...sould someone examine the "blob" at about 10 o'clock in these two pics? Is the fact that it's more visible when focussed at infinity than nearer anyd indication of where it may be? I've cleaned the lense several times but the blob persists!

Thanks!

Definitely just a speck of dust or other impurity on the sensor. Mirror up and clean it yourself with wet-clean swabs available at cameras stores, eBay, Amazon, etc. Works like a charm for me everytime. Shooting in Africa, you need to master this quickly. Alternatively, PP in LR / PS will make that disappear in 2 seconds like magic.

[DeadJohn]

Yes, dust on the sensor.

I'm very new to DSLRs...

Dust is a normal occurrence and nothing to worry about. When dust is on the sensor it shows because that's near where the image comes to focus. Dust on a lens will be invisible. Don't worry about having perfectly clean lenses.

Sensor dust is most visible against bright, single color backgrounds like a blue sky or a painted wall.

Sensor dust is more visible as your stop the aperture down. f/22 shows more dust than f/4.

Post-processing software can erase dust spots from photos.

[Grey Area]

Thanks all for the advice. The camera is the K3-II. I'll put some of the suggestions into practice and see what happens. Will report back here.

---------- Post added 03-14-16 at 01:28 AM ----------

Thanks to DeadJohn for the advice about aperture - F40 showed it up better than anything else (will post a pic later). I was also able to confirm its presence with two separate lenses.
Secondly thanks to jatrax - it was a simple as turning on the dust removal at startup and shutdown!

Fixed! Will post some pictures later but I have to get to work now.

[Grey Area]

At F40 I could probably tell if the dust was male or female...thanks DeadJohn



Also visible on my 50mm lens, so obviously not a lens problem...



And lastly, removed completely by the simple step of turning on the self-cleaning process;



Thanks jatrax!

Question about self-clean though - I have "on startup" and "on shutdown" options. Currently turned both on. Is it safe to leave them on or does it reduce the life of the sensor?

Thanks all for help! The blob is gone!

[ohaya]

At F40 I could probably tell if the dust was male or female...thanks DeadJohn



Also visible on my 50mm lens, so obviously not a lens problem...



And lastly, removed completely by the simple step of turning on the self-cleaning process;



Thanks jatrax!

Question about self-clean though - I have "on startup" and "on shutdown" options. Currently turned both on. Is it safe to leave them on or does it reduce the life of the sensor?

Thanks all for help! The blob is gone!

You're fortunate that it worked for you !! In my case, blower didn't do the job and ended up needing to use a sensor brush, which finally worked. Next step would've been like a wet solution, which I was a little worried about.

[jatrax]

Question about self-clean though - I have "on startup" and "on shutdown" options. Currently turned both on. Is it safe to leave them on or does it reduce the life of the sensor?

I have mine set to run on startup. I have done that on all cameras since the k-x with no issues. Why they do not have it set as on being the default I have no idea. You are certainly not the first (or the 100th) person to post here with the same issue. On older models the dust removal was not as good (or non-existent) so we often struggled with physically cleaning the sensor. But since the k-5 the system has gotten really good. So good that I have never done a physical cleaning of any camera since the k-5.

However, due caution is always advised, try to change lenses with the camera pointed down. Don't change lenses in adverse environments. Dust is easy to clean either with the camera DR system or with a rocket blower, but sticky pollen and other stuff is not so easy and requires a wet cleaning.

In short, take as much care as you can, leave the DR system on at startup, and if the worst happens understand how to physically clean the sensor.

[Des]

Sooner or later you are going to need something more than the inbuilt dust shaker. Here is a recent summary of the options: https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/315880-c...-dot-dust.html

The K-3 has a very nice feature for checking whether there is dust on the sensor. It's called Dust Alert. You need a Pentax autofocus lens mounted to the camera, aperture on A (if it has an aperture ring), and the camera focus set to AF. Go to Menu | Setup menu 4 | Scroll down to Dust alert | right arrow. The camera produces an image of the sensor, with a white background. Any dust spots are clearly visible. (The image is saved in a folder called Dust or something like that.) This is easier and clearer than the traditional method of taking a photo of the sky or a white wall at a high aperture.