Please help! Is this dust on my sensor?

Hello guys, <br> <br>

 

I'm calling for your help as you're 100 times more experienced that I

am. I have a 2 weeks old Nikon D70s and two lenses: the 18-70mm kit

lens and the 50mm f1.8. I think I've changed lenses less than 10

times, always indoors, always keeping the lens mount down. <br> <br>

 

Yesterday night, I was shooting outdoors and one of the shots came up

with two strange "stains" on it. I'm attaching a 752 x 500 reduced

version of the shot, and then I'll attach two 100% crops of the

"stains". <br> <br>

 

Please help: what is this? <br>

Dust on the sensor? <br>

A tiny bit of some liquid?(saliva? I once looked "inside" the body

while changing lenses for 5 seconds, maybe I should've held my

breath...) <br>

Or, the best of all, just lens flare because of some light source?

<br> <br>

 

The "stains" don't seem to be visible in the 5-10 shots taken before

this one or in the 5-10 shots taken afterwards. But in these other

shots, the background was very dark where the "stains" are (only the

center part of the photo had some light), so maybe this is no proof.

<br> <br>

 

How could I test this? How can I take a shot that would best reveal

dust/ stains on the sensor? <br> <br>

 

Please tell me if what I'm attaching is proof of dust/saliva/etc on

the sensor or just lens flare. And please tell me how could I perform

a test to check for dust/saliva/etc. <br> <br>

 

Shot's details: ISO 400, F 11.0, 30 secs, 44mm. <br> <br>

 

Thanks and looking forward to hearing your expert answers, <br>

--Bogdan<div></div>

This is a 100% crop of the stain on the right. <br> <br>

Thanks, <br>

--Bogdan

This is a 100% crop of the stain on the left.<br> <br>

 

Please help! Thanks, <br>

--Bogdan

Looks like normal flare to me. (otherwise it's a pretty big dust particle ;))

 

Try using a lenshood and no filter when shooting at night, that should solve most flare problems, unless in extreme situations.

Good news. That's not dust. That's flare from a bright light source reflecting around inside your lens. Notice that the curved sides of that bright spot match the aperture blades inside your lens.

 

Dust spots will generally be tiny on the sensor (invisible to the eye) and show up as dark dots on images. Mine are typically a few pixels wide. They are easy to clean with one the available kits online however. No worries.

Lens flare! not a problem at all. Photoshop even added an effect to create it while editing shots :-)

But unfortunately, sooner or later you'll get dust on your sensor. dont take too long to change lenses (dont panic either or you'll drop and break something). Aviod changing lenses under very dusty conditions. Try holding the camera towards the ground while changing lenses. DONT breath on the sensor, AND NEVER touch the sensor unless you know exactly what you're doing. I never touched it so far (nearly 1 year in my hands and i live in a very dusty country). good luck shooting ... ah ... get a lense hood! :-)

If you have debris on your sensor, you will be able to reproduce the problem on every photo. A good way to test is to shoot a clean, clean, white wall. Any junky stuff should show on your monitor/photo.

Thanks a lot, guys! <br> <br>

 

I should've imagined it's lens flare. The size was too big; on the few cleaning-your-sensor forums I've read, they were talking about small spots, not 10% wide and 10% long of the photo :-) Secondly, the shape is the aperture blades' shape. So it should've been a huge dust particle, nicely shaped :-) <br> <br>

 

Thanks for the advice on the lens hood. My lens came w/ the hood, but I somehow assumed it's flare-proof. Apparently light directed at a certain angle can produce flare. Thanks! <br> <br>

 

And Al: yeah, I'm worried sick about dust. I changed lenses a few times just for the fun of it and for "testing" the lenses -- I just got my first DSLR a couple of weeks ago. Now I'll change them only when need be, avoid dusty environments, keep the lens mount down, no breathing into the sensor chamber. <br> <br>

 

Tito: thanks for your advice! I've just read somewhere that shooting a clean wall (like you say) or the sky, preferably at F22.0 or some super-small aperture will reveal dust spots. I just did it and looked the "negative" of the photo (<a href="http://www.irfanview.com/">IrfanView</a> has a "Create negative" option). There are a couple very minor dark spots, like 2 pixels wide on a 3000 x 2000 photo. That's gotta be dust. No problem as of now, but I think that in a year or so the sensor will need cleaning. Damn digital... :-) <br> <br>

 

Thanks a lot, guys! As always, lots of help here on PN! <br>

--Bogdan

Two important considerations when determining if something is dust on the sensor are that it will always be black or very dark and that it will be out of focus with very soft edges. Hope that helps. Oh and be sure to turn the camera off when changing lenses. With it on, the charge in the sensor attracts dust to it.

Andrew

That's definitely iris shaped flare, often called "ghosting." But I'm surprised because I've never seen any flare in photos taken with my 18-70 DX. It's not my favorite lens but it's been among the most flare resistant of any I've used.

Is it the PPG building in Pittsburgh?

Andrew: thanks a lot. It does help. I took a few photos of a clear sky at F22.0 (18mm), and I've noticed a couple very minor dust particles. They're indeed out of focus. Approx. 2-3 pixels wide on a 3,008 x 2,000 photo. No big deal for now... <br> <br>

 

Lex: yeah I was kinda surprised, too. I don't know a whole lot about DSLR's as you do, but I've been doing a few hours of research daily (internet + in-store camera testing) for 3 months before getting the D70s with the 18-70mm and I've learned enough to realize that the 18-70mm has no right to be as good as it is for the price. I think it's more like a $500-$600 lens. Somehow a ray of light must've squeezed in at a funny angle?... It was a F11.0, 30secs exposure. <br> <br>

 

Obi: I don't know if its name is the PGH building, but it's indeed in my town, Pittsburgh, in the downtown. I liked its design and I wanted to get an abstract photo about its lines and shapes. So I desaturated and darkened it a bit in

<a href="http://picasa.google.com/">Picasa</a> (the D70s has no B/W mode), then I repaired the flare by copy-pasting a "good" rectangle over the flare and cropped a bit in

<a href="http://www.irfanview.com/">IrfanView</a> (the only manipulations I apply, I do not want to do any PS on my photos, they're photos and not digital art... but that's another discussion). Anyway, here's

<a href="http://www.photo.net/photo/4280388&size=lg">the final result</a>. Feel free to rate and critique :-)

 

<br> <br>

Everybody: a big thanks for being so helpful. I continue to be amazed at the quality of this community. <br>

--Bogdan