Dark spots in pics

explr1 · 10-16-2008, 09:38 AM

I was taking some pics yesterday trying to get to know my K10d better. I up loaded the pics to the PC and noticed that they all have a dark spot in the same place, upper left corner. I cropped the pics a little to show the spot. By the way, I've been thinking about getting a Pentax 18-250mm lens, will it take better pictures than the Sigma 24-135mm that I used to take these pics? Thanks, Chris

MRRiley · 10-16-2008, 09:45 AM

That a piece of dust on the sensor. Run your K10 thru a sensor cleaning cycle (in the menus) and take some more shots to see if it's still there. If it is you may have to contact clean it. Lots of threads here on how to do that... just seach "cleaning sensor".

mrpackerguy · 10-16-2008, 09:58 AM

Originally Posted by MRRiley

That a piece of dust on the sensor. Run your K10 thru a sensor cleaning cycle (in the menus) and take some more shots to see if it's still there. If it is you may have to contact clean it. Lots of threads here on how to do that... just seach "cleaning sensor".

Try this thread. I have the same issue. Ended up buying the Rocket blaster from Ebay on recommendation from posters in the thread. t hasn't arrived yet. Is this dust on my K200D sensor?

Class A · 10-16-2008, 07:07 PM

Your spot definitely looks like dust on the sensor.
I recommend the following actions:

Make a test shot into the sky or a white wall, out of focus, with the lowest aperture possible. Check this image on a monitor. Some image processing, e.g., increasing the contrast, will make all spots very visible.

Try the following steps one at a time, making the test shot again. Stop when you are happy with your dust level. Note that it is difficult and not necessary to achieve 100% cleanliness.

Try the built-in sensor cleaning.
Try a blower (avoid canned air, Giottos Rocket Air Blower Review).
Try a sensor brush (I suggest to follow this article The Pixel Sweeper)
Try wet cleaning.

Originally Posted by explr1

I've been thinking about getting a Pentax 18-250mm lens, will it take better pictures than the Sigma 24-135mm that I used to take these pics?

If they aren't crops they look a bit soft to me.
Check Flickr: The Tamron-based 18-250 zoom for lots of shots with the Pentax/Tamron 18-250. There are some close up shots on my flickr page as well. The flower shot isn't as sharp as it should be but I still like it.

Note that you'll probably won't get any more magnification factor out of the 18-250mm, perhaps less. It is "just" 1:3.5. Bob Atkins reckons the 18-250mm has about 125mm effective focal length when focusing at the close focusing distance of 45cm. See his full findings in his Tamron 18-250mm F/3.5-6.3 AF Di-II LD Aspherical (IF) Macro Review.

explr1 · 10-16-2008, 07:55 PM

Originally Posted by Class A

If they aren't crops they look a bit soft to me

Yes there cropped to show the spot better. The Sigma I'm using seems to be soft, I shot the bee pics in apeture priority mode using f11.

tomtor · 10-17-2008, 01:00 AM

Originally Posted by explr1

By the way, I've been thinking about getting a Pentax 18-250mm lens, will it take better pictures than the Sigma 24-135mm that I used to take these pics? Thanks, Chris

In the dpreview forum a guy who owns both the 24-135 and 18-250 said that they are comparable in the overlapping range. So unless you want a bigger range in a single lens, investing in a 55-300 or 12-24 might be better.