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  • Dustspots and general questions

    I have some questions regarding 2 photos that got rejected. The F-16 was rejected because it was underexposed, because of CMOS dust spots, the 747 only because of dust spots.
    I have no trouble finding one big spot, but as I use Olympus hardware that has a tendency to produce more noise and as sharpening can do weird things with that, I was wondering if that was the one dust spot I needed to remedy or if the noise was creating all sorts of dustspot-like artefacts.




    Thanks for the input

  • #2
    Hi Konrad,

    To be honest I can't believe your camera inherently produces noise to a level that would make sharpening difficult, at least not in standard conditions like we see here. I've seen countless images from Olympus gear that have been pretty much perfect in terms of quality so I think the problem may be more fundamental in how you're shooting and processing, it's very unlikely to be your equipment.

    What kind of settings were you using for these two images? Can you maybe post a screenshot of the EXIF data for them?
    Seeing the world with a 3:2 aspect ratio...

    My images on Flickr

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    • #3
      I used ISO100, F9 and 1/1250th on the F-16 and ISO100, F9 and 1/1000th on the Atlas 747

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      • #4
        In what mode? That doesn't sound quite right for the F-16 and may explain why it's underexposed by around 2 stops.
        Last edited by PMN; 2011-03-20, 19:39.
        Seeing the world with a 3:2 aspect ratio...

        My images on Flickr

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        • #5
          By mode you mean M, A, S or P? If so, I shoot in M for manual.
          I have an e-510 and I used the 70-300mm 4-5,6 lens

          The original picture was underexposed but I changed the exposure levels and I think it's ok like that. I tend to underexpose my pictures because you can always correct the exposure of an underexposed photo, but a blurred photo is practically useless.
          Of course that increases noise, but you can correct that, too. Maybe 1/1250th was a bit much but what can you do
          It's a learning experience

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          • #6
            I had a feeling you'd say M, that's the root of your problem I think. The way you're shooting is technically quite wrong and you're not making the most of what your camera can do.

            If you brightened the F-16 then it must have been really, really underexposed because it still needs brightening by around another 2 stops to make it roughly correctly exposed. There's something that's very important to learn about digital cameras; digital is quite a limiting format and you have to treat it a certain way to get the best out of it. You shouldn't be aiming to underexpose when shooting only to brighten afterwards, you need to be nailing the exposure as accurately as you possibly can when you press the shutter release. This isn't an opinion either, it's how you technically get the highest quality results from the format you're using because you're not trying to push anything too far.

            The first few stages of what happens in a digital camera are entirely analogue. Light hits the sensor which generates tiny electrical signals, these signals are fed into an amplifier to boost them and make them useable and when we boost the ISO we boost the gain of these amplifiers. As with any analogue amplifier (like a guitar amp or a mic preamp on a mixing desk), the more gain we have the more noise we get. This is why high ISO images have more noise than low ISO images. What many people aren't aware of is you get almost exactly the same effect when you brighten images with editing software. If you take an image at ISO 200 and then brighten it by three stops in editing, you'll add roughly the same amount of noise as you'd get had you taken it at ISO 1600. This is almost certainly where your noise problems are coming from; you're assuming you can do whatever you like in editing whereas actually you can't, you'd have the same problem shooting like this with any camera.

            I'd very strongly advise not using Manual for aviation. It just doesn't make sense for general aviation shooting. I know many photographers think there's almost a prestige attached to shooting full manual all the time and it makes them feel like they really know what they're doing, but for the most part that's all nonsense. Manual is great when you have steady light and time to set your shot up; it enables you to tell the camera exactly what you want to do, but that's only really of any use in un-dynamic situations. Shooting aviation you're pointing your lens all over the place and the light often changes quite dramatically and very quickly. When you're tracking an aircraft there generally just isn't time to constantly meter the light and adjust your settings, so why try? Semi-automatic modes are there for a reason, so if they make your life easier then it just makes sense to use them.

            Again, to get the best out of digital it's extremely important to nail your exposure when you take the image rather than wrongly assume you can make huge corrections when editing, so my advice would be forget Manual and try Aperture Priority, learn how to read the histogram because that will tell you exactly how your camera is exposing, and adjust your exposure compensation as you shoot to keep the information in the histogram as far to the right of the graph as possible without overexposing. All of this sounds like way too much to take in, I know, but if a muppet like me can learn it then anyone can.

            Here's a tutorial about the histogram and how to read it. Have a look through and maybe even print it out so you can use it as a reference when you're out shooting:

            Have a question about Photo Editing software (Photoshop, Paint Shop Pro, etc.), improving your photos, etc.? Our crew of Photo Screeners is here to help you out!


            Hope that kind of made sense, and if you need anything else clarifying then just give us a shout.

            Oh, and watch out for dust spots!



            P.S. With regard to your comment on blurry photos, there's a very handy guide you can use to avoid it. Basically try aim for your shutter speed to be at least equal to or greater than your focal length. I usually try be at least a third of a stop over that, so for example:

            50mm would have a shutter speed of 1/60th or greater
            100mm would have a shutter speed of 1/125th or greater
            160mm would have a shutter speed of 1/200th or greater
            400mm would have a shutter speed of 1/500th or greater.

            If you try using this guide then you can avoid a lot of blur but still use your camera in a reasonable way. In saying you underexpose using a high shutter speed to avoid blur you're trying to avoid one problem but in doing so you're creating another in the noise, which as you say you can treat but that's the wrong way of looking at it. With a little more knowledge and practice, using more sensible settings you can actually avoid both problems and have nothing to correct.
            Last edited by PMN; 2011-03-20, 20:35.
            Seeing the world with a 3:2 aspect ratio...

            My images on Flickr

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            • #7
              Thank you for your lengthy reply!
              I actually know how to correct a histogram and that doing so has the same effect as increasing ISO. I just figured that using the histogram, I could set to "my own level" of ISO instead of being forced into ISO200.

              What you say about the automatic modes makes a lot of sense, I'll have to try and see how smartly my camera actually meters and if I like the results more than my own. I actually thought that the exposure was correct back when I took the photo, I guess it was more lack of experience than lack of technical knowledge

              Using automatic settings I have 2 problems, if I set the aperture to F8 (where I found my lens performs best), Im afraid the shutter speed will be too slow, if I set the exposure time to 1/500th, the aperture might move into areas where my lens performs worse.. so in both cases Id be left with similar problems.
              Of the three cases, I think I prefer a sharp, underexposed picture that I correct at the expense of noise. But who knows, maybe my camera is smarter than I thought. I'll follow your advice and maybe you'll have converted another from M to A

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              • #8
                Originally posted by Taliesin View Post
                I just figured that using the histogram, I could set to "my own level" of ISO instead of being forced into ISO200.
                I know what you're trying to get at, but it's actually quite wrong. The two images you've posted here were taken in absolute perfect light and there's absolutely no excuse for them not being perfectly exposed beyond getting your exposure wrong. Photography and exposure are governed by the laws of physics, it's not something where opinions count and to get the best out of your camera you have to understand that there's an optimal way to use it. You can't just invent your own rules, it doesn't work like that.

                When shooting in Av if your shutter speed drops too low then simply increase the ISO a bit. The people who try and tell you shooting above ISO 100 is a really bad thing to do are talking nonsense; it won't destroy your images so if you need to use ISO 200 then do so. As I explained, increasing ISO gives roughly the same amount of noise as brightening an image in editing software, so it makes sense to get it right when you actually take the shot. It also makes sense for another reason, and that's the fact that half the tones your digital camera is able to record lie in the single brightest stop of its range. If you drastically underexpose then you're trying to record information in far less steps of brightness than you would if you exposed correctly, and whatever you do that lost information can't be recovered. It's technically very wrong to try do that and will generally give fairly terrible results, so it really does make sense to just do things in a more technically correct way.

                Again, this isn't me speaking from opinion, it's technical fact. You will get better results by learning to control your camera better and learning a little more about how exposure actually works. I say will with such emphasis because the technique you're using at the moment is just about the worse way possible to go about exposing a photo. All I can do is advise though, it's entirely up to you whether you continue as you are or try what I'm suggesting.

                P.S. Just noticed you said you'd try A. You should find it considerably easier.
                Last edited by PMN; 2011-03-20, 21:54.
                Seeing the world with a 3:2 aspect ratio...

                My images on Flickr

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                • #9
                  Originally posted by PMN View Post
                  You can't just invent your own rules, it doesn't work like that.
                  I didnt say I was inventing my own rules. What I meant was that instead of using ISO200 to avoid blur, I wanted to underexpose a little and later correct it with the histogram. As you said, correcting an image via the histogram gives the same effect as a higher ISO number, but correcting it a little would have the effect of ISO120 or maybe ISO150. At the time I didnt realise I was underexposing my pictures so much.

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                  • #10
                    Originally posted by Taliesin View Post
                    I didnt say I was inventing my own rules.
                    I more intended that to mean the way you're thinking about it isn't quite right, and in fact it's almost the exact opposite of what actually is right.

                    Also if you'd have used the hisogram you'd have seen exactly how much you were underexposing by. Sorry, I'm a sarcastic git, I couldn't resist that!
                    Seeing the world with a 3:2 aspect ratio...

                    My images on Flickr

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                    • #11
                      Originally posted by Taliesin View Post
                      I didnt say I was inventing my own rules. What I meant was that instead of using ISO200 to avoid blur, I wanted to underexpose a little and later correct it with the histogram. As you said, correcting an image via the histogram gives the same effect as a higher ISO number, but correcting it a little would have the effect of ISO120 or maybe ISO150. At the time I didnt realise I was underexposing my pictures so much.
                      Most DSLR's are capable of shooting fairly well quality in high ISO's, with minimal levels of noise.

                      I used share the same mentality as you, figuring ISO had to be as low as possible to produce crisp images and I would later adjust levels in post-processing.

                      As Paul said, adjusting levels in post-processing just introduces the same level of undesired noise, if not more. In the digital world, any unused information is discarded and irretrievable and that is why it's so crucial to come as close to nailing the exposure as possible.

                      Just an example of one of my better shots on a high ISO:

                      "Gander/Halifax" FC heading out on a setting sun. Thanks to the screener's for approving this one!. D-AIFC. Airbus A340-313X. JetPhotos.com is the biggest database of aviation photographs with over 5 million screened photos online!


                      Using a 70-300mm lens with NO stabilization at dusk, camera set to Aperture priority, 86mm, ISO400, f4.5, 1/400. The photo itself has very little noise, is sharp and needed little post-processing.

                      Hope you find a good medium to work in

                      flickr

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                      • #12
                        Originally posted by PMN View Post
                        I more intended that to mean the way you're thinking about it isn't quite right, and in fact it's almost the exact opposite of what actually is right.
                        In the past I had some trouble with blurred pictures and even though my way of exposing the picture was wrong and I wouldnt expose it that way again (knowing what I know now), it still yielded a presentable picture. Exposing correctly will make best use of my camera's capabilities, but if you expose the image correctly and blur it, it will yield a less presentable image than an underexposed one. That was my mindset back when I took the picture which led me to drastically underexpose it.
                        Knowing what I know now, I'd expose the image with 1/400th - 1/500th at F7,1 or set aperture to F7,1 and live with what the camera would set as shutter speed. I dont think I'll use A, I just meant I'd give the programs a try.

                        I'm going back to LGG or BRU sometime soon and I'll use the experience at the Paris Air Show.

                        I think you have the impression that I disagree or that I refuse the advice you give. I'm grateful for your input and I see your point, I'll try to correctly expose my photos and use automatic programs and if your advice helps me to take better photos at the Paris Air Show I'll be doubly grateful

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                        • #13
                          Originally posted by Taliesin View Post
                          I think you have the impression that I disagree or that I refuse the advice you give.
                          I did kind of get a slight hint of that impression but my apologies if I misinterpreted.

                          Naturally a blurry image is less useable than a slightly noisy one, but that's why you develop your shooting technique to avoid both. Both the images you've shown here were taken in perfect weather, and with a well set up camera blur shouldn't even cross your mind.
                          Seeing the world with a 3:2 aspect ratio...

                          My images on Flickr

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                          • #14
                            Just dropping in to say I'm following your advice and trying out the automatic programs of my camera. I havent tried it on airplanes yet, but I attached 2 photos of a little Robin I took using the A program.
                            I didnt know you could tell your camera to over- or underexpose the photos on top of choosing an aperture, that makes it a lot more useful!
                            I usually set it to -0,3 or -0,7 (I cant help it )

                            I think the results speak for themselves. Thanks a lot!

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