witticism
Posts: 35
Joined: Wed Jan 02, 2008 3:40 am

Help Pls. Dust Spots @ 1/30sec But Not 1/400th Why

Thu Feb 14, 2008 3:24 am

These are some awesome photos and some of my favs on A.net.

http://www.airliners.net/open.file/1309212/M/

http://www.airliners.net/open.file/1303911/M/

http://www.airliners.net/photo/Bulga...ocopter-AS-532AL-Cougar/1326104/M/

When I've tried to do something similar (admittedly I'm only very novice and I have not managed to be able to shoot a stationary plane) my images sometimes are covered in dust spots when taken at 1/30th See below.

Big version: Width: 1000 Height: 666 File size: 108kb
Dust, dust everywhere!


The very next pic at 1/400th is virtually spotless.
Big version: Width: 1000 Height: 666 File size: 148kb


[Yes I know obviously the shutter speed time difference results in more dust being visible.]

Though sometimes I don't get that much dust;
Big version: Width: 946 Height: 612 File size: 187kb


Big version: Width: 1200 Height: 700 File size: 278kb


What I would pls like to know is;
1. Is the dust in the first image external or internal?
2. How do I maintain my camera so as to minimize dust
3. Any other tips or advice you can provide to get results like the Pilatus shot would be greatly appreciate.

Thanks heaps.
Cheers
"A person who never made a mistake never tried anything new." - Albert Einstein
 
waketurbulence
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RE: Help Pls. Dust Spots @ 1/30sec But Not 1/400th Why

Thu Feb 14, 2008 5:49 am

If you have a DSLR dust might be a part of life you have to get used to. The slower the shutter speed you use in bright light the higher the aperture value needs to be, the higher the aperture the more likely dust will be present. Dust can be internal (camera sensor) or external (on the lens). It is usually on the sensor though. To minimize dust, change lenses in a clean, calm area. You can also clean your sensor with swabs and solution.
-Matt
PS To get good prop blur focus on an aircraft that isn't moving and use a tripod for a longer exposure.
 
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Moose135
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RE: Help Pls. Dust Spots @ 1/30sec But Not 1/400th Why

Thu Feb 14, 2008 6:00 am



Quoting Witticism (Thread starter):
[Yes I know obviously the shutter speed time difference results in more dust being visible.]

Actually, no - aperture has more of an effect on visible dust spots - a very small aperture will allow you to see them more clearly. That's why a handy way to check for dust spots is to shoot a clear sky with an aperture around f/22. It could be that in your first photo, with a slow shutter speed (assuming shutter priority) the camera chose a small aperture, giving more visible dust spots.

Quoting Witticism (Thread starter):
What I would pls like to know is;
1. Is the dust in the first image external or internal?
2. How do I maintain my camera so as to minimize dust
3. Any other tips or advice you can provide to get results like the Pilatus shot would be greatly appreciate.

What kind of camera do you have? If it's a DSLR, you probably have dust on your sensor. Don't worry, most DSLRs come with dust as standard equipment from the factory  Smile

There are many ways of cleaning sensor dust - for me, I only use a rocket blower, but many people use one of the liquid or brush methods (I'm still not ready to go poking around in there). You can be cautious when changing lenses, avoid swapping them outdoors in dusty conditions, but really, there is no way to totally avoid dust spots.

That Pilatus shot is sweet! I'm sure Tino could tell you his technique, but if I was trying to shoot something like that, I'd certainly use a tripod with a long shutter speed for the dark conditions. I can't tell if the reflections on the spinner and exhaust is just from ramp lights, or if he fired a flash to help fill some highlights and pick up the prop tip markings. That would probably annoy the pilots if you didn't plan it with them beforehand, but that might be something I might experiment with.
KC-135 - Passing gas and taking names!
 
eadster
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Joined: Tue Jan 25, 2005 7:31 pm

RE: Help Pls. Dust Spots @ 1/30sec But Not 1/400th Why

Thu Feb 14, 2008 9:08 am

The reason why it shows in some shots and not others, could be exposure. I get them, and mine only show in some shots.
 
witticism
Posts: 35
Joined: Wed Jan 02, 2008 3:40 am

RE: Help Pls. Dust Spots @ 1/30sec But Not 1/400th

Thu Feb 14, 2008 1:25 pm

Thanks guys for your help and advice.

I pretty much expected it was the dust on my sensor  Sad [annoying considering I only got it cleaned a couple of weeks previously]... yes funny how they come factory fitted with dust!  Wink

I've got a Canon EOS 300D DSLR.

I've just been out with it and my tripod practicing and getting some (hopefully) great time-lapse photos of AC taking off and landing.

>"or if he fired a flash to help fill some highlights and pick up the prop tip markings. ">

Thats interesting. Apparently this technic was done for this photo;
http://www.airliners.net/open.file?id=1147166&size=M

A pretty powerful flash ... I can imagine security getting their nickers in a twist if you were letting off powerful flashes as an AC passed over head.

Thanks again for all your help.
Cheers
"A person who never made a mistake never tried anything new." - Albert Einstein
 
chris78cpr
Posts: 2733
Joined: Tue Feb 03, 2004 7:44 am

RE: Help Pls. Dust Spots @ 1/30sec But Not 1/400th Why

Thu Feb 14, 2008 3:06 pm

Basically the smaller your aperture the more that is in focus which means the more it can focus and show up dust spots.

Try shooting a blue sky @ F2.8 and also @ F22. A lot more dust will be visible in the F22 shot than the F2.8 shot.

Chris
5D2/7D/1D2(soon to be a 1Dx) 17-40L/24-105L/70-200F2.8L/100-400L/24F1.4LII/50F1.2L/85F1.2LII
 
sulman
Posts: 1963
Joined: Wed Mar 03, 2004 5:09 am

RE: Help Pls. Dust Spots @ 1/30sec But Not 1/400th Why

Thu Feb 14, 2008 3:33 pm

Don't worry too much about dust. It's part of having a DSLR. Around mid-2005 my 300D was filthy. Cleaning it is not difficult; just be delicate and you'll have no problems. Google sensorswab or pec pads and you can order kits.

What will amaze you is how much they charge for them. It's still cheaper and more convenient (no downtime) than sending the body away though.

J
It takes a big man to admit they are wrong, and I am not a big man.
 
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cpd
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RE: Help Pls. Dust Spots @ 1/30sec But Not 1/400th

Fri Feb 15, 2008 11:14 am

Quoting WakeTurbulence (Reply 1):
You can also clean your sensor with swabs and solution.

That's something I won't do. It's too easy to fall victim to dodgy stuff that doesn't work. Some sensor swabs do more harm than good. That's also part of the reason my camera is out of action and it is still stuck waiting for parts. Yes, I was careful as well.

Even though it costs to get it cleaned by the official dealers, they also have responsibility if they mess things up.

The first image probably has dust on the camera lens.

Regards,
Chris.

[Edited 2008-02-15 03:17:35]
 
timz
Posts: 6121
Joined: Fri Sep 17, 1999 7:43 am

RE: Help Pls. Dust Spots @ 1/30sec But Not 1/400th Why

Fri Feb 15, 2008 10:20 pm



Quoting Witticism (Thread starter):
Is the dust in the first image external or internal?



Quoting WakeTurbulence (Reply 1):
Dust can be internal (camera sensor) or external (on the lens).



Quoting Cpd (Reply 7):
The first image probably has dust on the camera lens.

C'mon, guys-- how could dust on the lens show up on the image like that? Maybe if he's shooting at f/4096, but not otherwise. Try stretching a thread across the front of your lens, a millimeter in front of the front element. Does a line show on the image?

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