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Martin P Wilson

Dust, Smudges Something to watch with mirrorless cameras

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Watch out for this gotcha! It caught me out - so a warning, just something to bear in mind. I was using a Fuji X-E1 and 18-55mm lens but it will probably be a risk with any mirrorless camera especially with wide-angle lenses that have a rear element that comes close to the sensor.

 

I took some photographs on a misty morning and when I processed them I discovered large shadowy smudges down one side easily visible with the large areas of flat light grey. I thought it was dust (but looked a bit odd) or a mark on the sensor but I could not see it with magnification and cleaning achieved nothing. The smudges could even be seen through the viewfinder at f22 against a hazy sky.

 

Turned out to be a greasy mark on the rear element (actually it looks more like a cover glass to keep dust out) of the 18-55mm lens. With the small back element to sensor distance on mirrorless compact system cameras it was only just out of focus on small f-stops and therefore visible in the image. With a dslr I suspect it would not have been visible.

 

So check the rear element before cleaning your sensor! And keep the back element clean, I must have just caught it when changing lenses.

 

See the effect here, just to left of watermark.

Edited by Martin P Wilson
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That's dramatic and untoward . . . but you didn't mention what camera that is???

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Good point Ed, I updated my post but I was using a Fuji X-E1 with 18-55mm lens. I believe it will be the same for all mirrorless esp with wide-angle lens that have rear elements that get close to the sensor and have a deep depth of focus. It shouldn't happen with my 55-200 as the rear element is well recessed.

 

I will make sure I carry a microfibre lens cloth with me in future although I did not notice it until I started to process the raw files. I will just have to check before I mount the lens.

Edited by Martin P Wilson

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Good that you updated your post, Martin.  I thought Ed had dropped his glasses on the floor.  ;)

 

Also good to know since I am considering the Fuji X-T1 and one of the 18 to whatever lenses.  Shoot. Nothing's perfect, is it?

 

Betty

Edited by Betty LaRue

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Good that you updated your post, Martin.  I thought Ed had dropped his glasses on the floor.   ;)

 

Also good to know since I am considering the Fuji X-T1 and one of the 18 to whatever lenses.  Shoot. Nothing's perfect, is it?

 

Betty

 

I don't regard it as a problem once you realise; It is inherent consequence of the slimmer body which I believe gives significant advantages for the design of lenses, especially wide angles. I am sure it will be the same for all mirrorless system cameras, even full frame. So nothing to worry about.

 

After all we should keep our lenses clean anyway.

Edited by Martin P Wilson

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Thanks for the heads up, something to check for when things go strange. 

 

I'd rather clean the rear end of a lens than a sensor any time.  Especially a sensor with anti-shake and ultrasonic cleaning.  My wife knew to steer clear of me for a while when I'd decided that the Canon 5d needed a cleaning.  It was always a long and somewhat frustrating experience for me.  No problems so far with my Olympus mirrorless although I have seen a few artifacts that were probably dust that just didn't stick for long.  Also with micro 4/3rds and great panasonic and olympus lenses I don't tend to use small aperatures much.

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With wide-angle zooms dirt on the rear element and even on the front element can be imaged sharply - and it's not just mirrorless cameras either, though because of the way their lenses are designed to avoid sensor shading, the rear group may have a large diameter meaning that a fingerprint is 'projected' through the element by the main lens group (in the centre of the zoom). I've found this with the Sigma 19mm f/2.8 as an example - you have to keep this lens perfectly clean if you want to use it at f/16 and not see any dust/grease front or back cause a shadow on the image.

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I don't like to shoot even as high as f11 on my fuji as diffraction starts to affect the IQ, in my experience it stars somewhere between f8 and 11. However, if I have to go small aperture for depth of field it's something I'll have to live with. I'd still expect the files to get through Alamy's QC though.
On an aside , I'm finding that Camera Raw 8.4 for CS6 release candidate is an improvement on previous versions and is moving me away from Capture One, as I prefer the workflow. You can get it here   http://labs.adobe.com/downloads/cameraraw8-4.html

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I don't like to shoot even as high as f11 on my fuji as diffraction starts to affect the IQ, in my experience it stars somewhere between f8 and 11. However, if I have to go small aperture for depth of field it's something I'll have to live with. I'd still expect the files to get through Alamy's QC though.

On an aside , I'm finding that Camera Raw 8.4 for CS6 release candidate is an improvement on previous versions and is moving me away from Capture One, as I prefer the workflow. You can get it here   http://labs.adobe.com/downloads/cameraraw8-4.html

 

I had a bit play with 8.4 and it does seem to work quite well (currently a Capture One user). For those with the X-E2 or T1, Lens Modulation Optimiser helps resolve diffraction quite a bit. I'm still waiting for C1 to update and include the XT1 so I can check ifit is applied to raws or jpgs only! 

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Duncan, I don't understand your comment about waiting for C1 to update. I use Capture 1 Pro 7.2.1 and it recognises the X-T1 OK, am I missing something about full X-T1 functionality in C1?

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Re dust, I have been living in dust free heaven since moving from full frame Canon to mirrorless Sony NEX, it's as good as the transition from scanned negatives to digital.

 

Don't know why this should be, but not complaining!

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Duncan, I don't understand your comment about waiting for C1 to update. I use Capture 1 Pro 7.2.1 and it recognises the X-T1 OK, am I missing something about full X-T1 functionality in C1?

 

Duncans post was done before the C1pro update came out for the X-T1

 

Allan

Edited by Allan Bell
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Duncan, I don't understand your comment about waiting for C1 to update. I use Capture 1 Pro 7.2.1 and it recognises the X-T1 OK, am I missing something about full X-T1 functionality in C1?

 

Duncans post was done before the C1pro update came out for the X-T1

 

Allan

 

 

Oops, missed that!

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Dust - the problem was, always, and is, the Canon CMOS sensor. It just attracts dust constantly. The Sony sensors don't and the Olympus ones are legendary - if you ever get a dust spot on an Olympus, it's because you left the camera open in a dust storm. Canons on the other only need to be switched on to activate the dust-capturing system!

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Duncan, I don't understand your comment about waiting for C1 to update. I use Capture 1 Pro 7.2.1 and it recognises the X-T1 OK, am I missing something about full X-T1 functionality in C1?

 

Duncans post was done before the C1pro update came out for the X-T1

 

Allan

 

 

Oops, missed that!

 

 

Oh that was so yesterday man..... we're now on 7.2.2 now  ;)

 

Just installed and seems ok.... it'll get a proper test tomorrow!

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Dust - the problem was, always, and is, the Canon CMOS sensor. It just attracts dust constantly. The Sony sensors don't and the Olympus ones are legendary - if you ever get a dust spot on an Olympus, it's because you left the camera open in a dust storm. Canons on the other only need to be switched on to activate the dust-capturing system!

 

So true.... I was permanently cleaning Canon sensors! It was like painting the Tyne Bridge, never ending.

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Dust - the problem was, always, and is, the Canon CMOS sensor. It just attracts dust constantly. The Sony sensors don't and the Olympus ones are legendary - if you ever get a dust spot on an Olympus, it's because you left the camera open in a dust storm. Canons on the other only need to be switched on to activate the dust-capturing system!

 

So true.... I was permanently cleaning Canon sensors! It was like painting the Tyne Bridge, never ending.

 

 

Me too, I find the Fuji much less of a dust magnet than my Canons.

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Dust - the problem was, always, and is, the Canon CMOS sensor. It just attracts dust constantly. The Sony sensors don't and the Olympus ones are legendary - if you ever get a dust spot on an Olympus, it's because you left the camera open in a dust storm. Canons on the other only need to be switched on to activate the dust-capturing system!

 

So true.... I was permanently cleaning Canon sensors! It was like painting the Tyne Bridge, never ending.

 

 

Me too, I find the Fuji much less of a dust magnet than my Canons.

 

 

Oh yeah.... and i change lenses a lot. As long as you turn the camera so the lens is pointing to the floor when swapping lenses it doesn't seem to be an issue. 

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Duncan, I don't understand your comment about waiting for C1 to update. I use Capture 1 Pro 7.2.1 and it recognises the X-T1 OK, am I missing something about full X-T1 functionality in C1?

 

Duncans post was done before the C1pro update came out for the X-T1

 

Allan

 

 

Oops, missed that!

 

 

Oh that was so yesterday man..... we're now on 7.2.2 now  ;)

 

Just installed and seems ok.... it'll get a proper test tomorrow!

 

 

Ta Duncan. I missed that one.

 

Allan

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