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Lens / sensor dust

PostPosted: Sun Apr 08, 2018 4:00 pm
by Grarea
Can you help me out?

I am dire need of having a good clean.
Nothing I own was new.

I can see a couple of spots on my sensor, so I guess it needs a clean anyway.
I suspect dust on lenses and sensor.

While looking into it, I was hunting for how to tell if you have sensor dust.
From what I gather, you need a plain screen / sky / bit of paper, and a small aperture.

Then I got a bit lost.
I have done it focussing at infinity and as close as it will go.
I see dust when I do that on one lens, but then not anything with my 50mm.
But I can see dust by eye.
Then my 200mm seems to show some of it.

Do different lenses show the sensor dust differently?


Is there a definitive way of checking if it is sensor dust without confusing it with different lenses?

Lens / sensor dust

PostPosted: Sun Apr 08, 2018 7:53 pm
by petrochemist
It's unlikely any dark spots you see in images will be from muck on your lenses - this would typically give reduced contrast and can be spotted in the Bokeh but will effect all points on the image so not be visible as a dust spot.

For viewing sensor muck a small aperture is best while shooting something with no detail (indeed a long exposure moved around to even out detail helps), focus is not needed. Any sensor muck will give the same shadow whatever the subject with it being sharper at smaller apertures as the light is more direct.

Lens / sensor dust

PostPosted: Mon Apr 09, 2018 12:46 pm
by Grarea
OK, thanks.
I am a bit confused as it seems to show up different on different lenses.
Not at all on my 50mm, which is why I was wondering if it shows different from lens to lens.
But it is VERY apparent on a zoom at 70mm.

Short answer is, yes, I have dust on my sensor.

I saw a youtube with Mr Northrup using a swab type affair.
Do you agree that is the best way to go?

Is there a make I should get or are they all much of a muchness?
(getting a bit nervous here :D )

Lens / sensor dust

PostPosted: Mon Apr 09, 2018 7:25 pm
by Smeggypants
Yes, get some proper fluid and swabs. It's a bit daunting wiping something over your sensor the first time, but it won't harm it and the fluid will evaporate and leave your sensor clean. :)

Lens / sensor dust

PostPosted: Tue Apr 10, 2018 7:24 am
by petrochemist
I suspect the differences you're seeing with your lenses is down to their apertures.

A wet clean is most effective, but has the most potential to cause other issues. I would try non contact methods like a rocket blower, or artic butterfly first.

I work in a lab & have access to high grade chemicals so I've never brought any photography wet clean kits. I'm sure there are good and bad brands, but couldn't tell you which brands fit in which band.

Lens / sensor dust

PostPosted: Tue Apr 10, 2018 10:47 am
by Burnhole
Let me know how you get on with your clean. I have sensor spots and I'm trying to decide if I buy some fluids and swabs or book a while you wait sensor clean at SRS (it's only 30 mins away) - has anyone tried SRS for a clean?

Lens / sensor dust

PostPosted: Tue Apr 10, 2018 11:03 am
by LennyBloke
I've read in the past that the Pentax Image Sensor Cleaning Kit (O-ICK1) is very good. I can't personally recommend it as I haven't used it, and you will of course need to do your research for suitability with your sensor.
It's mentioned on this thread over on the US site:
https://www.pentaxforums.com/forums/58- ... or-k1.html
and there are reviews of it:
https://www.pentaxforums.com/accessoryr ... -ick1.html
Price varies a lot (£26 to £49 I've seen - Bristol Cameras is one of the cheapest I think) :thumb:

BUT - As has been said already, try non-contact cleaning first.

And... If it's a Pentax you may have the option to let the camera take an image that shows you where the dust/mark is.
Take a photo of a white surface at a small aperture (but ensure you don't get camera shake) - this should give you an idea of where the problem is!

Lens / sensor dust

PostPosted: Tue Apr 10, 2018 11:37 am
by Grarea
Thank you for this.
It is my K3.

Image17-70mm @ 70mm by chuffedas, on Flickr

This shows them up the best.

I shall get on to it.
Well, once I have worked out my bike fuel leak that turned up last night.
I was hoping to play lenses today.

Lens / sensor dust

PostPosted: Tue Apr 10, 2018 1:05 pm
by Grarea
Whilst avoiding my petrol leak issue, I discovered the dust alert function.
(I also did a firmware update)

Lens / sensor dust

PostPosted: Wed Apr 11, 2018 10:37 am
by Burnhole
Thanks LennyBloke - I've ordered the Pentax Image Sensor Cleaning Kit (O-ICK1). I'll do some before and after images and let this forum know how I get on.

Re: Lens / sensor dust

PostPosted: Mon Apr 16, 2018 2:09 pm
by Burnhole
As promised here's how I got on with the sensor cleaning. After a few passes with the Cleaning Kit - many of the sensor spots had been removed but 3 stubborn ones remained. These were still visible at my 'regular' f-stops of 8 or 9. So I decided to try SRS and their while-you-wait cleaning service - after their clean I can still see a single spot in the test shot but this is not visible at the f9 test. In summary I think that the cleaning kit can certainly remove some of the sensor spots but the stubborn ones required a different treatment.

14mm/f22 - Before
1563

After self-clean - (switched to 21mm ltd @ f22)
21mm/f22
1564

After SRS - (switched to 21mm ltd @ f22)
21mm/f22
1565

Lens / sensor dust

PostPosted: Mon Apr 16, 2018 2:30 pm
by Smeggypants
I must clean my monitor :D - I had to scroll the image up and down to determine which was muck on my monitor and which was muck on your sensor :)

Re: Lens / sensor dust

PostPosted: Mon Apr 16, 2018 9:34 pm
by petrochemist
Smeggypants wrote:I must clean my monitor :D - I had to scroll the image up and down to determine which was muck on my monitor and which was muck on your sensor :)



That's a familiar situation. There have been several times when I've opened up the clone tool on a laptop, only to find the muck was on the screen not the sensor.

Lens / sensor dust

PostPosted: Tue Apr 17, 2018 9:13 am
by Grarea
I got one of these and had similar results.
Boy, is it sticky.

I had a pretty good go at it.
I found it a bit tricky to get into the corners.
It is great at picking off the dust.
I suspect that is its role.
You avoid liquid when all you need is to lift a few specs of dust.

But I think I have more stubborn marks perhaps.
I had one that I could see by eye and went over the same spot about six times and it gradually removed it.

I shall have another go when I get a chance.

Lens / sensor dust

PostPosted: Tue Apr 17, 2018 12:55 pm
by Arbalist
I want a new compact for holiday and have been somewhat put off of buying a zoom model as apparently they can suck in dust?
Having a fixed lens means it’s obviously not something a user can remedy if you get dust on the sensor. I’m now considering a M4/3 mirrorless. Am I being over cautious?
Not sure if it’s a rumour but I read somewhere that some Canon zooms are particularly good at sucking in dust? :hyenas: