Image & Focus stacking

[DanK]

Interesting. At this magnification, it does look like color noise.

Yossarian (can you please add your real name in your profile?), can you tell us whether you did anything to brighten the image after importing it, and perhaps show the original histogram? I'm wondering whether even the sky was badly underexposed.

[YossarianXXI]

It looks like there are some discrete entities here and there, either Dan's dirt somewhere or possibly out-of-focus distance birds. Rings around the arrowed blotches do imply bokeh which in turn implies out-of-focus objects in the scene ...

Yeah, I knew there was sensor dust when I posted. I haven't gone through with the removal tool and correct for it, yet . It is possible that in the image i didn't focus on the sky, and did my focus elsewhere. At that point i was just playing with the HDR tool to see how to use it and see what i got with it, knowing that, if i was going to make this an image i wanted to share, i'd have to go back and do all the other processing touch-ups i typically do.

Yossarian (can you please add your real name in your profile?), can you tell us whether you did anything to brighten the image after importing it, and perhaps show the original histogram? I'm wondering whether even the sky was badly underexposed.

• Real name is now in profile (Colin)
• The two jpegs i posted are both just a conversion from raw --> jpeg, no other adjustments for this. Histogram will have to be later this evening.

[DanK]

Focus is irrelevant to how much noise there is anyway. It's relevant only in that focused detail may make it harder to see the noise.

The reason I asked about processing and the histogram is that color noise is commonly more visible with a combination of underexposure and high ISO. YOu shot at ISO 320, which shouldn't be too noisy on that camera. The sky in the brighter exposure is much cleaner, which fits with this. It still has the larger blotches, however, which brings me back to dust, even though this is a LOT of dust bunnies.

I think the way to resolve this is to shoot a blank surface, as I suggested, but making sure that the image is well exposed. Then see if you find blotches in the same part of the frame.

[YossarianXXI]

I think I figured it out.

I've also been trying to learn how to clean my own sensor of my camera (because $60/pop for cleaning is something i'm also trying to learn to mitigate)

I think last time i did it i got streaks on the sensor glass, which is what we're seeing.

[YossarianXXI]

Yeah. I think i got my cleaning swab too moist when i tried cleaning the sensor, and got some streaks on the glass. I just did it again and I think I can maybe notice a difference (screenshots of LR's visualize spots mode)

Before
clean_1 by Yossarian_XXI, on Flickr

After
after clean by Yossarian_XXI, on Flickr

[DanK]

Well, the "before" shot solves the mystery of what was going wrong with the images you posted. However, the "after" shot still seems very dirty by my standards. I would confirm that these remaining spots are sensor dust by using the method I described above. If they are, you need a good cleaning.

There are lots of posts about cleaning. However, I never use a swab to start. The goal is to remove as much dirt as possible before touching the sensor/filter with a swab. Step 1 is to use a rocket blower or the equivalent (not canned air) on the sensor, holding the camera with the sensor pointing down. If that doesn't suffice, I use a static brush. Only if that too doesn't suffice do I take out the swab. The swab should be damp, not wet.

Doing things this way, I would guess (I haven't kept track) that I have had to use a swab on average once a year or less.

[Manfred M]

Colin - I echo Dan's comments with two minor additions:

1. My first approach is to cycle the camera's sensor cleaning cycle about 5 or 6 times. That does get rid of a lot of the sensor dust and usually suffices.

2. I also use a bulb type blower and that is usually all it takes.

3. If that doesn't work, I use an Arctic Butterfly brush.

4. I have only once ever had to go to a moistened cleaning pad. The smears that you see are excess liquid dissolving the sensor dust particles and smearing them over the sensor. In my experience, the only sensor dust that has to be removed that way is pollen in the spring time. Pollen is super sticky and moist cleaning is often the only solution.

[DanK]

He has a D80, if I recall. Does that have automatic sensor cleaning?


Sent from my iPhone using Tapatalk

[Manfred M]

He has a D80, if I recall. Does that have automatic sensor cleaning?


Sent from my iPhone using Tapatalk

No the D80 did not have that self-cleaning functionality. That also explains the noise in the sky. This is the last generation where Nikon used CCD sensor technology. That camera came out in 2006.

[YossarianXXI]

When cleaning, I've tried everything you both have suggested (except the Arctic Butterfly brush, which i don't have.)

I use a rocket blower first, then use a damp (pre-packaged) specialty swab for sensor cleaning (the D80 doesn't have a self-clean), as Manfred said. I've only done this a few times (as I got a sensor cleaning kit for Xmas). The result, so far, has been more or less equivalent to the second "after" I posted. Now, I'm new and learning at this so I'm sure there is a technique & skill to it that I haven't acquired yet. I expect i'll improve at removing dust as I practice. Part of the reason I put more cleaner on it was because i thought maybe the swab didn't have any on it and so was completely dry to start with, so lesson learned.

However, Even when I've gotten it cleaned at a shop, I've found that my sensor gets dusty as soon as i change the lens for the first time. Now, again, I've been practicing this and looking up tips & techniques to change lenses to keep sensor dust to a minimum but so far sensor dust (probably equivalent to what's in that second screenshot) is more or less present except the shoot directly after a full shop cleaning.

I'm not really sure what to do about it, other than practice & clean, practice & clean, preactice & clean. I'm sure i can do a better job of changing lenses so that dust doesn't accumulate. I was making basic mistakes at first and i've cut those, so i like to think i'm learning. Part of it may be because I live & shoot in Colorado where it tends to be incredibly dry & dusty (making dust particles more static charged & likely to adhere).

So, I've become more or less resigned to the fact that I will have to clean my sensor somewhat regularly & use a heavy dose of the spot removal tool. As far as I can tell the best way for me to have less a less dusty sensor will be a combination of:

• Improving my techniques to keep dust out when changing lenses
• Get a second camera so I don't change lenses in the field
• Improving my cleaning techniques & skill
• Improving my sensor cleaning tools & locations (Arctic Butterfly Brush, maybe run an air filter while i'm cleaning to remove air dust)

The second bullet was basically what an instructor told me was the best way to keep dust off my sensor. I only have the D80, though, so it's not possible until i get another one. But all those require practice, or purchases.

[Manfred M]

Part of your problem appears to be that camera model / generation. Newer cameras (like my old D90) has built-in sensor cleaning technology that would vibrate the sensor for a few seconds as the camera powers up to knock the dust off the sensor and onto a sticky material designed to trap any loose sensor dust.

Part of the problem is what you have identified; dust can get in when changing lenses, but any time the lens focus or a lens zooms in and out, dust can be introduced into the mirror chamber by that action.

[YossarianXXI]

Part of the problem is what you have identified; dust can get in when changing lenses, but any time the lens focus or a lens zooms in and out, dust can be introduced into the mirror chamber by that action.

So my far & away most commonly used lens is a Nikkor 18.0-135.0 mm f/3.5-5.6, and the only other lens i own is a Nikkor 80-200mm zoom lens. If i understand you correctly - using the zoom on these (and I adjust this a lot) will introduce dust to the chamber?

[Manfred M]

So my far & away most commonly used lens is a Nikkor 18.0-135.0 mm f/3.5-5.6, and the only other lens i own is a Nikkor 80-200mm zoom lens. If i understand you correctly - using the zoom on these (and I adjust this a lot) will introduce dust to the chamber?

That is correct. When you zoom and to a lesser extent focus, the internal elements in the lens move forward and backwards. The air that is displaced has to go somewhere, so air is pushed into and pulled out of the mirror chamber by this action.

[DanK]

you may already do all of this, but there are steps one can take to lessen the problem of dust acquired when changing lenses.

1. Don't change them in dusty conditions. If conditions are really bad, look for some shelter, e.g., change them in the car.
2. Change the lens with the opening pointing down or away from the wind.
3. Have the new lens ready, rear cap off, before removing the old lens, and attach the new one before taking the time to cap the old one.
4. Keep a lens brush or blower with you, and clean the back element if it's dirty before you use a lens.

If I'm not mistaken, the problem of zooms inhaling dust is primarily an issue with externally focusing lenses, that is, lenses that extend and retract when focusing. Some zooms are internally focusing, with a sealed exterior.

[Manfred M]

If I'm not mistaken, the problem of zooms inhaling dust is primarily an issue with externally focusing lenses, that is, lenses that extend and retract when focusing. Some zooms are internally focusing, with a sealed exterior.

That is true to some extent, but not for the reason most people believe it is.

Internally focusing lenses are generally higher end "pro" glass which generally have very limited zoom ratios; somewhere around 3:1. This shorter zoom ratio means that the elements don't move as far as and hence move less air. Both my f/2.8 70-200mm and my f/2.8 24-70mm have a rear element that moves in and out, albeit not that far. Both have rear gaskets to help keep contaminants out of the mirror box.

[YossarianXXI]

you may already do all of this, but there are steps one can take to lessen the problem of dust acquired when changing lenses.

1. Don't change them in dusty conditions. If conditions are really bad, look for some shelter, e.g., change them in the car.
2. Change the lens with the opening pointing down or away from the wind.
3. Have the new lens ready, rear cap off, before removing the old lens, and attach the new one before taking the time to cap the old one.
4. Keep a lens brush or blower with you, and clean the back element if it's dirty before you use a lens.

If I'm not mistaken, the problem of zooms inhaling dust is primarily an issue with externally focusing lenses, that is, lenses that extend and retract when focusing. Some zooms are internally focusing, with a sealed exterior.

I wasn't doing all that previously, but I did my research and had started doing that over the last 6-9 months or so.

"Dear, the experts on the photography forums said it's hopeless and the only solution is to buy a new camera"

[Manfred M]

I wasn't doing all that previously, but I did my research and had started doing that over the last 6-9 months or so.

"Dear, the experts on the photography forums said it's hopeless and the only solution is to buy a new camera"

Given the age of the camera and the limitations of the technology with cameras of that era, I tend to agree with the experts.
The sensor technology (mostly digital noise and some other limitations of CCD technology), the lack of decent in camera dust management in camera are going to severely limit getting images that are up to par with more modern hardware. Most recent camera phones are going to blow its performance out of the water...

It came out when I was looking at getting a DSLR and at the time, film cameras gave me far better (albeit, with processing costs) more expensive results. My first DSLR was its replacement, the D90.

[YossarianXXI]

Given the age of the camera and the limitations of the technology with cameras of that era, I tend to agree with the experts.
The sensor technology (mostly digital noise and some other limitations of CCD technology), the lack of decent in camera dust management in camera are going to severely limit getting images that are up to par with more modern hardware. Most recent camera phones are going to blow its performance out of the water...

It came out when I was looking at getting a DSLR and at the time, film cameras gave me far better (albeit, with processing costs) more expensive results. My first DSLR was its replacement, the D90.

You were one of the experts I was referencing with my tongue-in-cheek response.

That said, ~2 years ago I was looking for a new hobby, had $300 in my pocket & was drinking whiskey with a friend who is an excellent photographer. She convinced me to give it try (it didn't take her much) and she found a used D80 with the Nikor 18.0-135.0 mm f/3.5-5.6 lens for $250. She said it was the camera she learned on and she always loved it.

So that's what I've been learning on. I wanted to invest enough in it to learn and create good images. In general I'm not really a gear hound, I very rarely go out and by the latest & greatest for any hobby or gear in my home, however I keep thinking it may be time to upgrade my camera body. I've also been thinking about a wide angle lens, too.

So, My eyeballs have wandered to the Nikon D7200, and there's a used (nearly mint condition) for ~$580 on eBay.

[DanK]

Used gear can be a good way to go. IMHO, eBay is a complete crap shoot, but there are places that offer honest evaluations of used equipment and guarantees.

[YossarianXXI]

Used gear can be a good way to go. IMHO, eBay is a complete crap shoot, but there are places that offer honest evaluations of used equipment and guarantees.

Yeah. I don't buy off eBay often, but when i do I always look at seller ratings & do some research on them. Especially something expensive like this.