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08-10-2014, 07:37 AM   #1
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Help! Dust inside zoom lens

Hi folks

i bought recently Pentax-F 70-210mm, very happy with image quality produced with this lens but i found something on latest photos. I thought that its dust on sensor, but after sensor cleaning problem remains and i think its dust inside lens

could someone help?



08-10-2014, 07:58 AM   #2
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Looks like sensor dust, ive never known lens dust show up.


Sensor cleaning often leaves some dust on the sensor. Clean it again, there are several kinds of sensor cleaning, and some dust clings like glue even after several cleaning attempts.
08-10-2014, 08:19 AM   #3
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QuoteOriginally posted by Imageman Quote
Looks like sensor dust, ive never known lens dust show up.


Sensor cleaning often leaves some dust on the sensor. Clean it again, there are several kinds of sensor cleaning, and some dust clings like glue even after several cleaning attempts.
THX,but it is not sensor dust.its showing only with this lens
08-10-2014, 08:26 AM   #4
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QuoteOriginally posted by romansolar Quote
THX,but it is not sensor dust.its showing only with this lens
It must be a big piece of dust. Do you see anything on visual inspection of the lens? This is best done with the lens off-camera in a dim room, iris wide open, and looking through the lens while shining a small flashlight (torch) obliquely through the other end. Do this looking through both the front and the rear. If there is dust, goop, or fungus in the lens, this method will reveal it.


Steve

08-10-2014, 08:38 AM   #5
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pls use contact lens cleaning soln and the process as required by that soln to clean contact lens

---------- Post added 08-10-2014 at 09:10 PM ----------

use a chamois fabric which does not leave behind lint (does not leave behind lint is important) and pray that its in the front of the protective glassfilter of the sensor
08-10-2014, 10:04 AM   #6
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That really does look like dust on the sensor: it could be more easily visible with this lens because of slower aperture, for instance.

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08-10-2014, 11:19 AM   #7
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thx people

i will check it again, but for now i am sure it is dust within lens. I also notice something which could be this dust by inspecting lens glass

what do you mean with "pls use contact lens cleaning soln and the process as required by that soln to clean contact lens" i dont understand
08-10-2014, 02:33 PM   #8
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I believe "soln" means solution.

08-10-2014, 06:36 PM   #9
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QuoteOriginally posted by romansolar Quote
i dont understand
He was giving you instructions on how to wet clean the sensor using commonly available stuff.


Steve
08-10-2014, 08:37 PM   #10
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i will try to find more info about contact lens cleaning
08-11-2014, 06:37 AM   #11
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Find the dust first.


I cannot accept this is in the lens without something more than opinion.


The reason is, if you stick a chunk of debris onto a lens it doesn't appear in the images.


Look at a mirror lens, theres a half inch or bigger lump of plastic glued to the lens, and it cannot be seen in any of the images.


If you glue a huge blob to the lens it affects the sharpness of the image it doesn't appear in any image as a blob.


You've got a blob on the image.


Examine the lens. If you don't see a lump of crud the size of a silver dollar, theres a good chance the spot is on the sensor not the lens. It really has to be immense if its on the lens to show up as a blob on the image.


Check out where this blob is.


Is it a tiny speck you can hardly see on the sensor, or a carbuncle the size of a cockroach on the lens.
08-11-2014, 07:33 AM   #12
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QuoteOriginally posted by romansolar Quote
i will try to find more info about contact lens cleaning
I would suggest that using contact lens cleaner and a microfiber cloth is an absolute last resort for sensor cleaning. In other words, don't do it. I don't know what you meant in the original post when you said you had done a sensor clean, but here is the generally accepted action sequence for removing stuff from the sensor:
  • Use the in-camera dust removal
  • Dust still there? Do next step
  • Put the camera in sensor cleaning mode and use a Rocket Blower (or similar) on the exposed sensor
  • Dust still there? Do next step
  • Take the camera in for professional cleaning
    -- or --
    use one of the commercially available sensor cleaning kits. Most of these use some sort of cleaning solution.


Steve
08-11-2014, 07:49 AM - 1 Like   #13
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Hi
Even if it was crap the size of an Australian Dollar coin anywhere inside or outside the lens (and it would have to be this size to show up in the first place) it would not show up the way it does in your image. No way. I bet my bottom dollar it is schmutz on the sensor. It just looks typical. It does not mean anything if it does not show up with other lenses. Buy a sensor loupe (like this one: P4PM GGS CCD SLR Sensor Cleaning Cleaner Magnifier Loupe 5X 2X Sensor Loupe | eBay ) and you will be amazed what you will see. They are a good investment,

Greetings

Last edited by Schraubstock; 08-11-2014 at 07:50 AM. Reason: typo
08-12-2014, 12:20 AM   #14
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thanks so much for helping posts. I will check sensor again for dust
08-12-2014, 01:44 AM   #15
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A little dust in lenses is not uncommon, especially in older glass so don't panic, I've never known it shown in images.

I agree with others here, this still looks like dust on the sensor to me, good luck with the cleaning.
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