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04-11-2011, 08:54 AM   #1
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HDR towards sun artifacts

Hi
I was taking shots at a church steeple with the sun directly behind it, in HDR. The photos all show specks or artifcats that have to be dirt or dust.
However...all my regular shots don't seem to show the dirt/dust. They are not birds or any other moving thing that would show up in the three HDR exposures...Any ideas ?

Posted pictures below...steeple is the HDR shot with artifacts; the other photo was shot AFTER the HDR picture and I cannot see any dirt at all. I clean the sensor with the shaker daily. I live in a very very dusty part of San Francisco..it's terrible. A never ending battle.

thanks for any help

Gene

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04-11-2011, 09:04 AM   #2
REM
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I believe dust spots will show up easier when your aperture is stopped down fully( i.e. around f/22). Your HDR picture's exif shows the aperture to be f/22 and you can see dust marks. Your second picture was at f/6.3. You didn't specify which lens(es) were used but if you used a variable aperture telephoto zoom such as 50-200mm or 55-300mm, F/6.3 is close to being open towards the end of the zoom range. Also white or close to white backgrounds (sunny skies) will also help show dust marks.

You may need to use a rocket blower to knock off some dust. If it is still really dusty, then perhaps using the Pentax sticky tool to clean the sensor or other commercial sensor cleaners should be used.
04-11-2011, 09:05 AM   #3
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they do look like they may be dust Gene, but they could also be something that was moving in one of the shots comprising of the hdr. I had a bird the other day in an ir shot that looked like a dust blobby much like these.
The 2 shots aren't a direct comparison it looks like the hdr was f22 and the non hdr was f6.3. blobbies show up on small aperatures that don't on larger ones
If you want to test for certain point at a clear blue sky stop right down (f22 or more) and take a shot then analyze it on your monitor. the dust shake thing works but not for everything all the time. next step would be try cleaning with a rocket blower. if they are still there than a cleaning kit like the Pentax one is the next step. I'd be really surprised if these steps didn't deal with it.
or you could just clone it out of course, but if it is dust better to deal with it before it welds itself to the sensor
there are numerous threads on how to clean a sensor. Jeffjs wrote one of the best instructions i've seen

edit, i see REM posted essentially the same while i answered a call
04-11-2011, 04:18 PM   #4
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HDR shows up dust, f22 shows up dust, put together you have a great dust detection photo.

Try a blower, I find that works for most of the time. I'd strongly recommend the next step after a blower to be the Pentax Sensor lollipop. I recently had a bit of a nightmare cleaning my sensor and found through much trial end error that the pentax lollipop is both safe and effective.

04-12-2011, 03:37 AM   #5
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HDR dust

As always..many thanks for the replies.

I tried a 'blower' but its a cheapie I had in my EOS kit. I think it blew more dust onto my camera than it blew out.

I need to get a rocket and a lollipop...i did the dust sensor picture thing and it only showed 2 specs...chances of moving objects, i don't know but pointing into the sun..at that aperture...maybe. Although I took alternate shots...a couple...and they all have artifacts except one that is not quite into the sun.

God..I hate dust. Where i live on the main street in Frisco--it is dust hell.

thank you..appreciate everything.

Lens is DA L 55-300...and I LOVE that lens. it is very crisp and clear. A little stiff on the twist...but I am happy with the pictures.
04-12-2011, 04:47 AM   #6
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QuoteOriginally posted by smilinpig Quote
As always..many thanks for the replies.

I tried a 'blower' but its a cheapie I had in my EOS kit. I think it blew more dust onto my camera than it blew out.

I need to get a rocket and a lollipop...i did the dust sensor picture thing and it only showed 2 specs...chances of moving objects, i don't know but pointing into the sun..at that aperture...maybe. Although I took alternate shots...a couple...and they all have artifacts except one that is not quite into the sun.

God..I hate dust. Where i live on the main street in Frisco--it is dust hell.

thank you..appreciate everything.

Lens is DA L 55-300...and I LOVE that lens. it is very crisp and clear. A little stiff on the twist...but I am happy with the pictures.
Instead of getting a rocket blower or other sort of hand bulb blower, get one of those bellows foot pumps. like this one They are much more...er...robust in getting a good stream of air onto the sensor. Instead of the gentle puff puff of a bulb blower, I get a very satisfactory wooossshh wooossshh. The foot pumps usually come with a variety of nozzles, I find the smallest gives the best air pressure and precision. I got the foot pump idea from a professional camera repair tech here in NYC, it's what they use.

NaCl(works very well for me)H2O

Last edited by NaClH2O; 04-12-2011 at 04:53 AM. Reason: typo in inserting the link
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