azemon Loc: Saint Charles, MO, USA

Dust has become the bane of my existence. I have been a serious photographer "since the middle of the last century" but have never been plagued by dust spots as I am now. It all started when I bought my Nikon Z 50 with the delightfully tiny Nikkor Z 16-50 kit lens. The camera with lens weighs next to nothing; my shoulder loves this combo.

For the first time in my life, I keep having dust ruin the skies in my photos. I think it is because the front element of this lens is so small. It takes a 46mm filter and the front element is only about 25mm in diameter. The only thing that I can think of is that a spec of dust which would be well nigh invisible on the front of a larger lens appears HUGE because it is so large relative to the size of the front element. Does that make sense?

Any other ideas? Do I need to go back to a normal size lens? There is a new Nikkor Z DX 18-140 with a 62mm filter, or perhaps the Nikkor Z 24-50?

-- Art Z.

CHG_CANON Loc: the Windy City

The cause is more likely that lack of seals within the camera and lens, where neither are sealed / weather proofed internally, and especially not where they meet. It's not frequency of changing lenses, size of the lens, nor a lack of being careful, and so forth. I get dust inside a Sony a7II when the lens is never taken off.

Get yourself a Giotto Rocket Air, or a few, since they're cheap and come in various sizes. You can have one in a camera bag and one on your desk, etc, anywhere you might need one to have handy and blow-off your sensor.

Here's an example of their effectiveness: https://www.uglyhedgehog.com/t-551677-1.html

mwsilvers Loc: Central New Jersey

I use that same lens on my Nikon Z fc which basically has the same sensor as your camera. I've been using that combination since mid August and so far I have not noticed any dust spots on my images. Are you actually seeing them on the images or just through the viewfinder? Don't know how often you've taken the lens off your camera, but perhaps dust has gotten on to the sensor. The sensor on both your camera and mine does not have vibration dust removal built in.

CHG_CANON Loc: the Windy City

You might too consider your apertures when shooting. Are your images with the dust spots from smaller than f/11; and therefore, more likely to show / find those dust bunnies on the sensor? If yes, do you really need such a small aperture for a cropped sensor size in a digital camera?

therwol Loc: USA

A spec of dust on the front of your lens would not show up as a discreet spot in the sky on a picture. It wouldn't be in focus and would have little effect on the sensor. You probably have dust on your sensor.

azemon Loc: Saint Charles, MO, USA

I should have included a sample shot along with my original post. Sorry about that. Here is one that bugged me on Monday. If you "download" you will see dust spots all over the sky. This was shot at f/25, so I think you are onto something CHG_CANON.

I found all of this dust on the front of the UV filter when I got home.

My sensor and the back of the lens are clean. I have checked those *very* carefully.

CHG_CANON Loc: the Windy City

We get into debates about small apertures and diffraction on a regular based, 'we' being the UHH community. Let me take a different tack and assume the distance to the Stihl sign is 30 yards. Say the lens was 35mm. The near focus is about 4 yards into the image and the rest of the image thru infinity should be in focus.

But, if we change the aperture to f/11, the near limit is 6 yards and the depth of field is also infinity. There really isn't a need to use such a small aperture to capture this exact same view in the exact same focus. But, that aperture might help with sensor dust in the sky.

If you research diffraction, you may find the f/11 image is more likely to be in sharper focus than f/25. Or, you can take the exact same digital image at every 1/3-stop from say f/8 through as small as you want to go. Then, look at the images on your computer at home at the 1:1 pixel-level details and judge for yourself. If performing such a test, maybe even tilt the camera by one-quarter so the horizon passes through two corners of the frame instead of the sides. This approach gives you 'details' in the corners to consider rather than a sky at infinity with no real details. See if you can identify an aperture setting for the specific lens that is the point of diminished returns where the aperture getting smaller adds nothing to the image overall sharpness.

azemon Loc: Saint Charles, MO, USA

You're absolutely right about diffraction and small apertures. The image above was part of a self-learning exercise that I did. I discovered (new to me, not a new discovery for the world, of course) that the images I got at f/8 were razor sharp while images at f/25 and f/32 were terribly soft.

Thank you for so patiently explaining.

-- Art Z.

therwol Loc: USA

Excellent advice. The Z50 does not have a sensor cleaner. Dust on the sensor is inevitable. The OP feels that the dark spots on the picture come from dust on the lens/filter. I would suggest the following. Duplicate the picture, same lens, sky aperture, exposure, clean the lens front and back, and take the picture. If I could bet money on the outcome, I'd bet on the spots being there in the same places. The second thing to try would be to duplicate the picture with a different lens. I'd bet on the same spots in the same places. The third thing to try would be to blow off the sensor with the Rocket Blower and examine the results. (Never blow off a sensor with a canned air product unless you want an oily residue on it.) If the OP is still there, please keep the dialogue going with anything you try that pinpoints the problem. This is how we help one another.

azemon Loc: Saint Charles, MO, USA

I went home, found the spots, and screamed in agony. Well, not really, because the photo was just part of a learning exercise so, in this one case, the spots didn't matter.

Then I carefully checked the font of the filter and found the dust. I cleaned it off. The next day, I went back and re-shot the same photos (same time of day and same lighting). Guess what: no spots. :-)
You can see the clean results from the second day here https://gallery.wonderart.us/Other/Architectural-Photography/

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

If the spots are light and fuzzy, it could be dust on the lens. But it will not be visible in most cases. You WILL see it as flare if you have a light source in the image. If the spots are dark or black, then it is sensor dust. Lens size will not make a difference. But lens build will - a lens that is well designed will have good dust and moisture sealing. Another often overlooked culprit is the rear lens cap. These are often filthy with dust and debris since most people don't clean them. Dust gathers on plastic, then it can transfer to the rear element and lens mount, and viola! you have dust being deposited on the sensor. As has been suggested, keeping things clean, purchase a blower that has a filter (never ever use compressed air, it is filthy and the particles will scratch the sensor when blown across the sensor), and be careful when you change lenses.

camerapapi Loc: Miami, Fl.

I just wanted to mention that if using a filter it is always good advise to make sure lens and filter are clean before shooting. In regard to Nikon and its sensor cleaning I have never been impressed with it. I do not know about other manufacturers since I use Olympus bodies but in the many years I have had my cameras I never ever had to clean the sensors, so efficient their sensor cleaning is.

kymarto Loc: Portland OR and Milan Italy

That is dust on the sensor. Super easy to eliminate with Photoshop.

ecobin Loc: Paoli, PA

I have found that some filters seem to attract dust. Some of the newer filters have coatings to resist dust. I use the Nikon clear filter on my 500mm pf lens and other than using a rocket blower it’s never required cleaning. It’s available for the z16-50mm lens on Amazon & B&H.
https://www.bhphotovideo.com/c/product/1511312-REG/nikon_2494_46mm_clear_nc_filter.html

azemon Loc: Saint Charles, MO, USA

Yes indeed. I have found that both the front and rear caps attract dust, especially since I am often shooting with just the camera, no bag. That forces me to slip the cap into a pocket between shots and the cap picks up lint and dust when I do that. What weird is that I have been doing this for decades (literally) and it only became a significant problem when I bought the Z 50, in the spring of 2020.



That's a thought, too. I had never used a Promaster filter before but was tempted by their description of the HGX line as "repels dirt."

Of course... maybe the dust bunnies have decided to curse me after I ignored them for so long :-P