Camera setup
1) Camera placed on camera back (Pretty stable)
2) Using Canon 28 - 135mm "IS" on
MY QUESTION:
Given no camera shake, why are all the lights not sharp but looked foamy? :dunno:
Without getting into the technicality of camera shake since a tripod is not used. I can think of a few reasons for your remark of "sharp but looked foamy"
1) Have you ever shot a picture in day time...say a shot in a room without any lamp. Just the stray light coming in through the window. Now say you take the meter reading and expose it more bias to illuminate the room wall so it does not appear very dark. Now doing so, the light streaming in from the window will be really OVER exposure. And you notice that the light ray shining in has blurry edges or even foamy if you want to call it that. Not only blurry but it looses all details in the brightest areas right?
Okay now imagine shooting at night. All those pin spot light or lit windows of a building, can become like that too. This is usually due to over exposure. As the light from the ray coming in from the window in the room or all those bright little spots on a building in a night scene...well the longer you keep the exposure going, the most light keep hitting your image sensor or film. This can cause a burn-in effect and this gets worst if there is camer shake going on. No lens is 100% sharp and there are for sure stray light distortion as it passes through the lens( made up of multi layers of glass elements) to the sensor and film. Thus you can get those foamy unclear definition of a lit object for example. If the exposure is just right you might avoid seeing too clearly that ghostly foamy aura at all the light spots.
2) You can limit this futher by closing down your apertune. f5.6 is not one of the aperture I like to use for night shoot. I tend to use f8 or even f16 as most lens sharpest f-stop tend to be around those numbers. This is becasue lens elements are made up of many layer of glass that is concave or convex. Typically therefore most lens has what I call the sweetspot range. Anything less or more...quality will deteriorate....quite badly at times too! So if you have a few lens, take the time to go give them all what I call an "apeture test" Trying to work out all the "sweet spots" of all your lens.
3) Walking out from a cold aircon room into a normal room temperture or outdoor can cause some fogging. Sometime it is so light that it does not fully fog up your shot but just enough to cause some foamy or foggy auro to certain bright edges? Changing lens can cause foggy glass if that lens was in a cold room and you took it out and change it with another in the outdoor. Doing so, now not only will the front glass be foggy but the rear one too and now that you seal it on the inside of your camera body, it can take abit longer for the foggy coating to evaporate.
4) Some blurry edges can be due to a dirty front lens or filter you need to clean as smudges might have compromise the quality of the image passing through it on it's way to the sensor or film.
5) Sometime...quality of the lens you bought also play a part in the quality of the type of shot you can capture too.
6) This is the worst scenario. A damage sensor heheheh...
Apart from all this yes it could be camera shake due to hand holding, not using a tripod and even with a tripod..was it securely place on solid groung or like on a bridge where heavy vehicles can shake the bridge enough that shot taken at speed like 1 second can still register in your shot.
There are many variables at play here. And yes a bigger picture would help some of us here to better establish what really was the cause of it or maybe looking at it, we can go mimic it to see if we can reproduce the effect to confirm what caused it.
Just my two bits...