is this dust or stain

kamisu · 03-26-2012, 01:02 PM

Hi,
Just received Tamron 17-50.. it is cloudy so can not take a shot of blue sky, but i noticed this dark spot in all photos.
Is it dust on sensor os stain ?

Attached Images

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kamisu · 03-26-2012, 01:11 PM

Indeed I can see it through viewfinder.

Adam · 03-26-2012, 01:11 PM

Dust.

pezmaker · 03-26-2012, 01:19 PM

If you can see it through the viewfinder, it sounds like it's on the rear lens element.

kamisu · 03-26-2012, 01:25 PM

I am not sure if these are the cause or not, but these two small dust particles are inside the lens. Should I return the lens ?

pezmaker · 03-26-2012, 01:27 PM

I don't think i'd be too worried about the front element, I've not had problems with stuff on the front lens, I just notice spots when I have stuff on the rear element.

cbope · 03-26-2012, 01:36 PM

Originally posted by pezmaker

I don't think i'd be too worried about the front element, I've not had problems with stuff on the front lens, I just notice spots when I have stuff on the rear element.

What pezmaker said. Generally, stuff on the front element will have to be very large to be visible in images. A tiny dust speck (or two) will be so blurred, it will not be seen.

kamisu · 03-26-2012, 01:39 PM

Rear of Tamron 17-50, brand new, and these are inside.

SpecialK · 03-26-2012, 02:53 PM

A) that is dust.

B) dust on the front element of a lens is unnoticeable in images unless there is flare in the lens.

kamisu · 03-26-2012, 02:56 PM

As shown in last image, dust is on rear element and inside. So, I should return the lens, correct ? If so, does the seller pay the shipping for exchange ?

Adam · 03-26-2012, 03:22 PM

Originally posted by kamisu

As shown in last image, dust is on rear element and inside. So, I should return the lens, correct ? If so, does the seller pay the shipping for exchange ?

That dust inside the lens won't affect your pictures- are you sure you just don't have dust on the focusing screen and on the sensor? Shoot a photo with another lens to confirm (and stop it all the way down while you're at it).

If you can get the lens exchanged for free you might as well, but then again you always risk that the other copy might have FF/BF issues, so if this one doesn't, I'd verify that it's not the lens and hang on to it.

kamisu · 03-26-2012, 03:47 PM

Unfortunately this is my only lens. The camera has dust on focusing screen too, and that is a sharp contrasty black tiny point that I see in viewfinder, even without lens attached, but others said it is not important and will happen all the time, and I better ignore it.

Dust on the sensor, I am not sure, how make sure it is on sensor or it is because of dust inside the lens ?

Since it is my first dslr, still can not say about BF/FF, should read and test more.

BTW, should I turn the camera off every time I wanna connect or disconnect the USB cable ?

Thanks.

rfortson · 03-26-2012, 03:50 PM

You won't see dust on the lens, either front or rear element. It will need to be much bigger to even be noticable.

As someone else said, you might see flare on rare occasions, but usually dust on or in the lens isn't a problem until you get a lot of it.

JinDesu · 03-26-2012, 03:54 PM

Originally posted by kamisu

Unfortunately this is my only lens. The camera has dust on focusing screen too, and that is a sharp contrasty black tiny point that I see in viewfinder, even without lens attached, but others said it is not important and will happen all the time, and I better ignore it.

Dust on the sensor, I am not sure, how make sure it is on sensor or it is because of dust inside the lens ?

Since it is my first dslr, still can not say about BF/FF, should read and test more.

BTW, should I turn the camera off every time I wanna connect or disconnect the USB cable ?

Thanks.

With regards to dust on the sensor vs dust on the lens - I would bet very heavily that any dust in your lens will not show up unless you got a pebble in there. You can search the internet for people discussing dust in lenses, but the general consensus is that it will not affect IQ unless it's massive:

What To Do With Dust Inside Lens

Dust on the sensor, however, can show up on your images (especially when you stop down). In your image, it seemed pretty undefined at F16, if you stop down to F22 it may become quite a bit more defined. There are several ways to get rid of dust - some people like the Rocket Blower (point your camera down, mirror up sensor cleaning mode), some people like Wet Swabs (Eclipse Wet cleaning system), and some people like very fine brushes. That can be a separate topic entirely.

You can try dislodging the dust by facing the camera downwards when you use the "dust removal" program in the camera. That may work also.

I never bother with a set method of plugging in my k-x. Sometimes, I'll turn it on, then plug it in (because I forget my plug isn't in), sometimes I'll pull the plug out while the camera is on, sometimes I'll turn off the camera, etc. I do not believe there is any harm in it.

kamisu · 03-26-2012, 04:22 PM

Camera dust removal did not help. This pic is after dust removal, they are at least three. I think the white dot in red square is a hot pixel which should be removed by camera.

03-26-2012, 01:11 PM	#3
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,608	Dust. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

03-26-2012, 03:22 PM	#11
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,608	Originally posted by kamisu As shown in last image, dust is on rear element and inside. So, I should return the lens, correct ? If so, does the seller pay the shipping for exchange ? That dust inside the lens won't affect your pictures- are you sure you just don't have dust on the focusing screen and on the sensor? Shoot a photo with another lens to confirm (and stop it all the way down while you're at it). If you can get the lens exchanged for free you might as well, but then again you always risk that the other copy might have FF/BF issues, so if this one doesn't, I'd verify that it's not the lens and hang on to it. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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03-26-2012, 01:11 PM	#2
kamisu Senior Member Join Date: Feb 2012 Location: Iowa Posts: 130 Original Poster	Indeed I can see it through viewfinder.

03-26-2012, 01:19 PM	#4
pezmaker Senior Member Join Date: Jul 2011 Location: Madison, WI Photos: Gallery \| Albums Posts: 276	If you can see it through the viewfinder, it sounds like it's on the rear lens element.

03-26-2012, 01:27 PM	#6
pezmaker Senior Member Join Date: Jul 2011 Location: Madison, WI Photos: Gallery \| Albums Posts: 276	I don't think i'd be too worried about the front element, I've not had problems with stuff on the front lens, I just notice spots when I have stuff on the rear element.

03-26-2012, 01:36 PM	#7
cbope Veteran Member Join Date: Dec 2011 Location: Helsinki Posts: 664	Originally posted by pezmaker I don't think i'd be too worried about the front element, I've not had problems with stuff on the front lens, I just notice spots when I have stuff on the rear element. What pezmaker said. Generally, stuff on the front element will have to be very large to be visible in images. A tiny dust speck (or two) will be so blurred, it will not be seen.

03-26-2012, 02:53 PM	#9
SpecialK Pentaxian Join Date: Dec 2006 Location: So California Photos: Gallery Posts: 16,481	A) that is dust. B) dust on the front element of a lens is unnoticeable in images unless there is flare in the lens.

03-26-2012, 02:56 PM	#10
kamisu Senior Member Join Date: Feb 2012 Location: Iowa Posts: 130 Original Poster	As shown in last image, dust is on rear element and inside. So, I should return the lens, correct ? If so, does the seller pay the shipping for exchange ?

03-26-2012, 03:47 PM	#12
kamisu Senior Member Join Date: Feb 2012 Location: Iowa Posts: 130 Original Poster	Unfortunately this is my only lens. The camera has dust on focusing screen too, and that is a sharp contrasty black tiny point that I see in viewfinder, even without lens attached, but others said it is not important and will happen all the time, and I better ignore it. Dust on the sensor, I am not sure, how make sure it is on sensor or it is because of dust inside the lens ? Since it is my first dslr, still can not say about BF/FF, should read and test more. BTW, should I turn the camera off every time I wanna connect or disconnect the USB cable ? Thanks.

03-26-2012, 03:50 PM	#13
rfortson Veteran Member Join Date: Sep 2006 Location: Houston TX Photos: Gallery Posts: 2,129	You won't see dust on the lens, either front or rear element. It will need to be much bigger to even be noticable. As someone else said, you might see flare on rare occasions, but usually dust on or in the lens isn't a problem until you get a lot of it.

03-26-2012, 03:54 PM	#14
JinDesu Veteran Member Join Date: Jun 2011 Location: New York City Photos: Gallery Posts: 5,638	Originally posted by kamisu Unfortunately this is my only lens. The camera has dust on focusing screen too, and that is a sharp contrasty black tiny point that I see in viewfinder, even without lens attached, but others said it is not important and will happen all the time, and I better ignore it. Dust on the sensor, I am not sure, how make sure it is on sensor or it is because of dust inside the lens ? Since it is my first dslr, still can not say about BF/FF, should read and test more. BTW, should I turn the camera off every time I wanna connect or disconnect the USB cable ? Thanks. With regards to dust on the sensor vs dust on the lens - I would bet very heavily that any dust in your lens will not show up unless you got a pebble in there. You can search the internet for people discussing dust in lenses, but the general consensus is that it will not affect IQ unless it's massive: What To Do With Dust Inside Lens Dust on the sensor, however, can show up on your images (especially when you stop down). In your image, it seemed pretty undefined at F16, if you stop down to F22 it may become quite a bit more defined. There are several ways to get rid of dust - some people like the Rocket Blower (point your camera down, mirror up sensor cleaning mode), some people like Wet Swabs (Eclipse Wet cleaning system), and some people like very fine brushes. That can be a separate topic entirely. You can try dislodging the dust by facing the camera downwards when you use the "dust removal" program in the camera. That may work also. I never bother with a set method of plugging in my k-x. Sometimes, I'll turn it on, then plug it in (because I forget my plug isn't in), sometimes I'll pull the plug out while the camera is on, sometimes I'll turn off the camera, etc. I do not believe there is any harm in it.