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Thread: VR/IS/OIS Vs ISO

  1. #61

    Default Re: VR/IS/OIS Vs ISO

    Quote Originally Posted by yanyewkay
    it's because the IS/VR/AS (hereafter ref as IS for simplicity sake) works on the modelling of a camera shake. It will "anticipate" (or predict if you want to see it this way) the camera shake movement direction and input from the 3D accelerometer to form the final axis of compensation.

    So if we only have 1 input, "the prediction" and no input from the accelerometer, because it's mounted on the tripod, then the IS will react according to the "prediction" model which will result in the errorneous and unexpected behaviour of the IS.

    Different brands have different preception of camera shake and model this "prediction" differently.

    Why not get rid of the 'prediction' part and based compensation purely on the sensor? this will rid the problem on tripod right? well.. this is another field in control systems altogether. I'm no pro in control systems but just happen to know this tiny bit.
    Thanks for your explanation.

  2. #62

    Default Re: VR/IS/OIS Vs ISO

    Quote Originally Posted by yanyewkay
    I think "opinions, guesses or deductions" should be left to 'uncharted' areas of a subject. For example "I guess that if I turned on IS and rotated the camera along the axis parallel to the lens would render IS useless" No one or very little ppl has done it and i cannot find any details on this.

    However, if I posted "I guess battery life of the IS on tripod would last longer becos the lens auto turns IS off while on tripod and thus would not consume any battery" is wrong becos on the manual section entitled Tips on Using the Image Stabilizer.

    I don't own any IS lenses as well. But just 'happened' to 'stumble' on the above info from Yahoo!

    Although I have also "guessed" in the 2nd part. The truth is out there only if I bothered to research before posting.

    There was also another forumer that used his own deductions and guesses and got into a lot of trouble however, he quickly learnt his lessons.

    I guess it would be more responsible for us to do our research before posting out our deductions.
    I actually did some researches previously about Image Stabilisers and have a rough idea of how the different brands (Canon, Nikon, Panasonic, KM) implement it.

    Then I also recalled reading that Panasonic FZ5 cannot do panning with OIS turned on and therefore deduced that Image stabilisers wouldn't work with panning. It's not something which I've plucked from thin air.

    I always hold the view that in a forum, it's ok to express guesses, deductions and opinions as long as the person indicates where he is coming from ..... by using "I think", "I guess", "I deduce" or clearly stating something to that effect if they're not stating facts so that they are viewed in the correct light and people won't mistake that he is stating them as facts. That was also the reason why I declare that it was my deduction and I didn't own any camera or lens with image stabiliser. I thought by doing so, anyone who reads it would know where I'm coming from and anyone with any facts, opinions, guesses and deductions can come to throw more light into the discussion. If I had not mentioned "panning", this discussion wouldn't have revealed so much more info about Image Stabiliser to the benefit of everyone.

  3. #63

    Default Re: VR/IS/OIS Vs ISO

    Quote Originally Posted by binbeto
    Good info so far, even though temperature has raised a bit.

    Clockunder, you have raised a few good point in your post that I find beneficial.. Please continue to contribute as I can see you have spend time to write all these.. At 3am+?!!

    Wai, you have pointed out some grey/discrepancy in other info. Very useful for people like me who know nuts. To have someone in the know to correct some misinfo is good.

    Still wanna emphasize that this is just a discussion and all info shared is good.
    Hope this kind of discussion will go on..
    After having some thoughts over it, I think no one can please everybody. As long as my conscience is clear and that, from the expressions I use, most people know where I'm coming from (whether stating facts, guesses, deductions or opinions), I shouldn't behave just to please the dissenting ones to the detriment of the discussion.

    By the way, back to the subject of this thread.

    A lot more info have surfaced and this thread is now not only ISO vs Image Stabiliser but also the technical implementation of Image Stabilisers and whether they work in certain situations.

    Just in case someone misunderstand, I have to state clearly that when I use the term "Image Stabiliser", I refer to the term in general and not specifically to Canon IS.

    After reading most (if not all) the info above and also doing a little more research on Image Stabilisers, this is my understanding (may or may not be correct) :

    1) May or may not work with panning, depending on the camera model and brand and how it's implemented. Some work with only panning horizontally but not vertically; some work regardless of panning directions. In general, they do work with panning.

    2) May or may not work with tripod, depending on the Lens (how it's implemented. Old vs new), the stability of the tripod and the shake experienced (vibration on roads/bridge or wind). In some forums which I came across, opinions differed mainly because of the differences cited above. For some lenses (new?), the image stabiliser works even when mounted on tripod because the manufacturers have improved the implementation. Actually, the issue is NOT the tripod but the magnitude of the shake the camera experiences, be it handheld or on a tripod. If the camera is rock steady (by rock steady hands (if that is possible), or mounted on a tripod which is a very firm one and there is little vibration from the floor or wind), then the Image Stabiliser (in older lenses or (some brands still haven't improved?) tends to over-compensate the shake and caused the image to be blur. So the issue is "shake/vibration" instead of "tripod". For some (newer?) lenses, over-compensation of the Image stabiliser in " too steady "conditions have been reduced (not sure if it has been eliminated) and therefore there is no problem even when mounted on a sold tripod without any wind/virbation when the Image Stabiliser is turned on.

    3) Image stabiliser is helpful not only in low light conditions but also when long zoom is used and there is a presence of some kind of shake (e.g. vibration from car, on helicopter, on a bridge with fast moving vehicles, strong winds etc.) even in strong light conditions (as long as it's within 2 stops or so. The FZ7 compensates up to 3 stops if I didn't read wrongly ). As long as the shutter speed used is lower than the focal length and it's within 2 (to 3) stops, Image Stabiliser has a role to play. Moreover, this is regardless of the light conditions. For e.g. shooting on a windy morning and focal length used is 400mm while the shutter speed used is 1/200. So Image stabilisers are not restricted to use only in low light conditions and slow shutter speed.

    And now back to the main issue of high ISO vs Image Stabilisers.

    ISO is about light while Image Stabilisers are about image blur due to camera shake.

    In one of my previous posts, I categorised into 2 situations in which Image Stabilisers might be useful.

    In the first situation, high ISO with noise levels as low as low ISO would solve the problem and Image Stabilisers would be redundant.

    In the 2nd situations where shutter speed is the priority, high ISO doesn't help and Image Stabilisers has a role to play and the use of Image Stabilisers in this shutter priority shooting is not limited to only low light conditions. E.g. if you want to propeller of planes or blades of the helicopter to give a "rotating" effect in your picture, your shutter speed used may have to be slower than 1/focal length when you're using very long lenses (e.g 300mm, 400mm or 500mm). From what I read in one website, someone said that the shutter speed to have this effect is 1/200 or slower. If shot at 1/400, the propellers and blades may be freezed still and the plane/helicopter appears "dead" (i.e. stationery) in the picture. So this is where Image stabiliser comes in : shutter speed 1/200 at focal length 400mm in bright day light condition. Low noise high ISO is not useful in this situation. Of course, the actual shutter speed to be used depends on the rotating speeds of the propellers and blades and the preference of the photographer (just in case someone mistakes that I'm saying that die die must use 1/200 shutter speed and 400mm lens.) I think there are many other situations both in low light as well as day light that we encounter situations where we want to shoot with shutter priority but it happens to be within 2 stops slower than 1/focal length. Therefore Image Stabilisers may be useful in panning in which the shutter used is slower than the focal length (racing circuits, F1 powerboat, Wakeboard etc.) even though this is not a low light condition. I have previously tried 1/125 and 1/500 for panning on F1 powerboat and found that 1/125 gives a much better result as the background is blurred. I could't go any slower shutter speed with my camera because I had already used lowest ISO and smallest aperture in my camera and over-exposure would occur if I set it to 1/60. I've seen some very nice panning pictures of the F1 powerboat taken at 1/60 or 1/80 with very long zoom (200mm or more) and I suppose Image Stabiliser would help.

    The key here is "shutter priority" where higher ISO would be of no use.

    So in my opinion, low noise high ISO and Image stabilisers have a place to co-exist.

    After doing a bit more reading, I discover that most of the postings here are not 100% correct (because they're only part of the whole story) and could also be misleading if they not viewed in the right frame of mind, especially when it's not expressly qualifed.

    Anyway, thanks for starting the thread. Your question about Image Stabilisers vs low noise high ISO has triggered some thinking about the difference between them.

    The above may not be 100% or even 50% correct and is just my own understanding.
    Last edited by Clockunder; 23rd January 2006 at 10:20 PM.

  4. #64

    Default Re: VR/IS/OIS Vs ISO

    To switch off IS or not, it really is dependant of the IS technology of your lens. If you had bought these expensive lenses, then learn about the lens characteristics and technology and make full use of it.

    Now, My question to you then..... think of it from another perspective, does it means that if you can take picture in noiseless 6400 ISO, Would IS be less important as you can maintain a cleaner picture due to less handshaking when the exposure time required is very short ? (That is if you don't require the image blurr effect ) (Another side question to all the PS experts in here - Can image blurr(to accentuate speed) be acheive in photoshop???? ).

  5. #65

    Default Re: VR/IS/OIS Vs ISO

    Quote Originally Posted by AhSeng
    To switch off IS or not, it really is dependant of the IS technology of your lens. If you had bought these expensive lenses, then learn about the lens characteristics and technology and make full use of it.

    Now, My question to you then..... think of it from another perspective, does it means that if you can take picture in noiseless 6400 ISO, Would IS be less important as you can maintain a cleaner picture due to less handshaking when the exposure time required is very short ? (That is if you don't require the image blurr effect ) (Another side question to all the PS experts in here - Can image blurr(to accentuate speed) be acheive in photoshop???? ).
    My guess :

    If shutter speed is not a priority, then use a shutter speed which is above 1/focal length and Image stabiliser would be less important. (assuming that a faster shutter speed and/or a smaller aperture has not negative impact on what you want to capture).

    I'm a newbie in photoshop of about 3 months although I've been taking picture much longer and so I declare that I'm no PS expert (just in case someone mistakes that I'm pretending to be one). In photoshop CS2, there are many different kinds of blur you can apply in the filter function and some of them are intended to accentuate speed blur although the effect is not as realistic as a true motion blur captured by the camera. Specifically, the motion blur filter simulates the kind of blur you're talking about if I catch you correctly :

    Blur filters

    The Blur filters soften a selection or an entire image, and are useful for retouching. They smooth transitions by averaging the pixels next to the hard edges of defined lines and shaded areas in an image.

    Before (left) and after (right) using the Lens Blur filter; the background is blurred but foreground stays sharp

    Note: To apply a Blur filter to the edges of a layer, deselect the Preserve Transparency option in the Layers palette.

    [Average] Finds the average color of an image or selection, and then fills the image or selection with the color to create a smooth look. For example, if you select an area of grass, the filter changes the area into a homogeneous patch of green.

    [Blur and Blur More] Eliminate noise where significant color transitions occur in an image. Blur filters smooth transitions by averaging the pixels next to the hard edges of defined lines and shaded areas. The effect of the Blur More filter is three or four times stronger than that of the Blur filter.

    [Box Blur] (Photoshop only) Blurs an image based on the average color value of neighboring pixels. This filter is useful for creating special effects. You can adjust the size of the area used to calculate the average value for a given pixel; a larger radius results in greater blurring.

    [Gaussian Blur] Quickly blurs a selection by an adjustable amount. Gaussian refers to the bell-shaped curve that is generated when Photoshop applies a weighted average to the pixels. The Gaussian Blur filter adds low-frequency detail and can produce a hazy effect.

    [Lens Blur] (Photoshop only) Adds blur to an image to give the effect of a narrower depth of field so that some objects in the image stay in focus and others areas are blurred. You can use a simple selection to determine which areas are blurred, or you can provide a separate alpha channel depth map to describe exactly how you want the blur added.

    The Lens Blur filter uses the depth map to determine the position of pixels in an image. With a depth map selected, you can also use the cross-hair cursor to set the starting point of a given blur. You can use alpha channels and layer masks to create depth maps; black areas in an alpha channel are treated as though they’re at the front of the photo, and white areas are treated as if they’re far in the distance.

    To create a gradual blurring (none at the bottom to maximum at the top), create a new alpha channel and apply a gradient so that the channel is white at the top of the image and black at the bottom. Then select the Lens Blur filter and choose the alpha channel from the Source pop‑up menu. To change the direction of the gradient, select the Invert check box.

    The way the blur appears depends on the iris shape you choose. Iris shapes are determined by the number of blades they contain. You can change blades of an iris by curving them (making them more circular) or rotating them. You can also reduce or magnify the preview by clicking the minus button or the plus button. See also To use the Lens Blur filter.

    [Motion Blur] Blurs in the specified direction (from –360 to +360) and at a specified intensity (from 1 to 999). The filter’s effect is analogous to taking a picture of a moving object with a fixed exposure time.

    [Radial Blur] Simulates the blur of a zooming or rotating camera to produce a soft blur. Choose Spin to blur along concentric circular lines, and then specify a degree of rotation. Choose Zoom to blur along radial lines, as if zooming into or out of the image, and specify a value from 1 to 100. Blur quality ranges from Draft (for fast but grainy results) or Good and Best for smoother results, which are indistinguishable from each other except on a large selection. Specify the origin of the blur by dragging the pattern in the Blur Center box.

    [Shape Blur] (Photoshop only) Uses the specified kernel to create the blur. Choose a kernel from the list of custom shape presets, and use the radius slider to adjust its size. You can load different shape libraries by clicking the triangle and choosing from the list. Radius determines the size of the kernel; the larger the kernel, the greater the blur.
    Smart Blur Blurs an image with precision. You can specify a radius, a threshold, and a blur quality. The Radius value determines the size of the area searched for dissimilar pixels. The Threshold value determines how dissimilar the pixels must be before they are affected. You also can set a mode for the entire selection (Normal) or for the edges of color transitions (Edge Only and Overlay). Where significant contrast occurs, Edge Only applies black-and-white edges, and Overlay Edge applies white.

    [Surface] (Photoshop only) Blurs an image while preserving edges. This filter is useful for creating special effects and for removing noise or graininess. The Radius option specifies the size of the area sampled for the blur. The Threshold option controls how much the tonal values of neighboring pixels must diverge from the center pixel value before being part of the blur. Pixels with tonal value differences less than the Threshold value are excluded from the blur.

    Hope this helps.
    Last edited by Clockunder; 24th January 2006 at 12:32 AM.

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