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Thread: Too much contrast at low ISO speeds?

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    Too much contrast at low ISO speeds?

    Hi All
    just a quick one. Just been told that for run of the mill photo's (ok I know you lot dont take run of the mill stuff). To set the ISO on my camera at 800? Reason being 100/200 adds to much contrast? and above 800 to much grain/noise? What do you reckon
    rob

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    Re: Iso

    Quote Originally Posted by bucketman View Post
    Hi All
    just a quick one. Just been told that for run of the mill photo's (ok I know you lot dont take run of the mill stuff). To set the ISO on my camera at 800? Reason being 100/200 adds to much contrast? and above 800 to much grain/noise? What do you reckon
    rob
    Total load of "cobblers" - don't believe a word of it. 1st of April stuff. To make it worse, on a sunny day you wouldn't even be able to take a shot outside at F2.8 - or F4!
    Last edited by Colin Southern; 30th September 2009 at 09:50 PM.

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    Re: Iso

    Too much contrast? ive never herd/had that happen with low ISO. For a start most P+S cameras are incredibly noisy by ISO800, even 400 is pushing it for some, so to have 800 as the default sounds rediculous. In General keep iso as low as you can for the conditions. Tweak shutter and aperture first if your shot can take it, then ISO last if you need a greater DOF or faster shutter.

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    Re: Iso

    The person who told me said the press use it all the time. But I have always been told to keep it low. He works for the press. My dlsr goes down to 200 then a few L stops too L1 so where should i set mine. At the top end it goes 3200 then a few H stops up to H1
    thanks again
    rob

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    Re: Iso

    H Rob,

    As a generalisation, I feel it is a pretty silly bit of advice without the context now provided. The reasoning IS still utter rubbish though, in my view.

    However, now we know where it came from and who it applies to, it does have some merit as long as you consider the following:
    1) Press will be using mid to top end DSLRs - so noise won't be an issue, and as Colin says (in another thread), it is better to have the shot with noise, than not have the shot, and that motto certainly applies to press 'tog's!
    2) Press will inevitably be using long zooms with about an f4 max aperture and wanting a relatively high shutter speed

    And the reason I now say it has some merit?;
    In my experience, even on a bright day, trying to shoot wildlife at the f5.6 end of my 18-200 lens (at 200mm obviously), I end up using ISO between 400 and 1000! (on my D5000) and the results are acceptable noise-wise, especially if I 'Neat Image' the shot - not that I always need to. Only if I shoot at wider angles AND not need to worry about shutter speed, OR want a wide aperture on a sunny day, does my ISO ever get down to 200 (our ISO ranges are identical btw)

    Cheers,

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    Re: Iso

    Quote Originally Posted by bucketman View Post
    The person who told me said the press use it all the time. But I have always been told to keep it low. He works for the press. My dlsr goes down to 200 then a few L stops too L1 so where should i set mine. At the top end it goes 3200 then a few H stops up to H1
    thanks again
    rob
    Hi Rob,

    Keeping in mind also that the press don't need high-resolution masterpieces. If many DO use high ISO settings then it won't be anything to do with contrast (which would be pretty much the same at ISO 800) - it's more likely to give them higher shutter speeds shooting indoors, and to reduce the amount of fill flash required.

    The biggest issue Ihave with higher ISO settings isn't the noise, the the decrease in dynamic range that the sensor can handle.

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    Re: Iso

    Thank again
    now i think about it he did say it was standard for the press. So little old me thinks there pro's copy them.
    So basically you reckon iI should move the ISO round just as much as F stops.
    thanks again
    One more little prob at the end of each repy is a little thumbs up I think all your replys are helpfull so I have to tick the lot.
    Thanks again
    rob

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    Re: Too much contrast at low ISO speeds?

    Hi Rob,

    My personal philosophy is to use as low a standard ISO as is needed (100 for Canon). If I need more then I have no hesitation in going higher (eg I won't risk camera shake) but (eg) general day-to-day shooting it would be set to 100.

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    Re: Too much contrast at low ISO speeds?

    That advice probably depends on what you mean by gentlemen of the 'press'. I know that photographers for local papers who come around to photograph 100th birthdays or a newly refurbished scout hut, etc, are mostly excellent photographers who vary all their camera settings to suit each scene.

    However, the situation would be different for the paparazzi who might get one quick shot of a celebrity behaving badly and don't have time to make any adjustments. So using ISO 800 would give you the option of being ready for almost any light level.

    I sometimes do the same with flying birds when it is a case of 'look at that' and snap.

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    Re: Too much contrast at low ISO speeds?

    Quote Originally Posted by Geoff F View Post
    That advice probably depends on what you mean by gentlemen of the 'press'. I know that photographers for local papers who come around to photograph 100th birthdays or a newly refurbished scout hut, etc, are mostly excellent photographers who vary all their camera settings to suit each scene.

    However, the situation would be different for the paparazzi who might get one quick shot of a celebrity behaving badly and don't have time to make any adjustments. So using ISO 800 would give you the option of being ready for almost any light level.

    I sometimes do the same with flying birds when it is a case of 'look at that' and snap.
    Which is better; To under expose by two ev to achieve a reasonble speed, or bump the iso up? I don't know I tried the under expose bit and still got a lot of noise.
    Last edited by arith; 1st October 2009 at 04:47 PM. Reason: image too big

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    Re: Too much contrast at low ISO speeds?

    With modern digital cameras and a reasonable lens, I would always (well nearly always) increase ISO to get the correct shutter speed, or aperture, than excessively underexpose.

    With some subjects, like a bird against the sky for example, you have to overexpose a dark bird and underexpose a white one unless you know that your settings are correct for your main subject.

    Usually my chief cause of total failures is camera shake due to insufficient shutter speed for hand holding, and sometimes not allowing for subject movement when using a tripod.

    Total failures due solely to high ISO isn't common for me; and in most cases something can be saved. Which, I think, is what the press photographer meant.

    But if you have a static subject, particularly with a tripod, and have time to think things through, use as low an ISO as possible.

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    Re: Too much contrast at low ISO speeds?

    Yes but I don't normally photograph birds, and it was a particularly dull day and I had to test my lens and use AI servo for the first time.

    I normally use 200 iso and since 800 I'm told excessively increases noise, and I can bump up exposure because I always shoot raw, I thought underexpose was possibly best.

    But it is all swings and roundabouts, I don't know if it is better and probably somebody here has tried both and knows.

    This is superfluous but I'm exposed 2 ev under for the swans and they didn't move as much as this fella.

    Too much contrast at low ISO speeds?

    Most the noise has been removed.

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    Re: Too much contrast at low ISO speeds?

    A rule of thumb I was taught and still see being applied (keep in mind that everybody's "thumb" is different."

    If you under expose a stop or so, your highlights are in the picture and can be brought out later in the "darkroom." Very little, if anything else, is lost, generally.

    If you over expose, you highlights can blow out and you cannot get them back, as they become just blotches of light, without detail.

    I generally under expose by about 2/3 to a full stop outdoors. Of course, I'm shooting in a very bright, desert sunny locale. If up in the forrests, I will under expose only 1/3 stop, unless I'm trying to get sunlight shafts in the picture, when I under expose a bit more. If there are no highlights to capture, I might actually go to +1/3 ev. That is my camera and my eye and my preferance. The way YOU shoud run your camera is dependant on YOUR eye and YOUR camera.

    Most of today's cameras and films will not throw noticable grain and noise on a full frame photograph. If you are cropping to retain only a tiny protion of the photograph, then it can become a major problem.

    Pops

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    Re: Too much contrast at low ISO speeds?

    Cheers, I think I might get it some day with luck. I now generally underexpose if something is white, like a swan, or water especially a waterfall because of sparkling bits, and overexpose for mainly black subjects if it is important to get some detail.

    If I get both together I get confused. lol

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    Re: Too much contrast at low ISO speeds?

    Quote Originally Posted by arith View Post
    Which is better; To under expose by two ev to achieve a reasonble speed, or bump the iso up? I don't know I tried the under expose bit and still got a lot of noise.
    If you under-expose by 2 stops then your throwing away a full 3/4 of the information that you could have captured

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    Re: Too much contrast at low ISO speeds?

    Quote Originally Posted by PopsPhotos View Post
    If you under expose a stop or so, your highlights are in the picture and can be brought out later in the "darkroom." Very little, if anything else, is lost, generally.

    If you over expose, you highlights can blow out and you cannot get them back, as they become just blotches of light, without detail.
    With Digital there's a bit of "theory -v- practice" in this area. Because sensors are (for all intents and purposes) linear, if you halve the light hitting the sensor (by underexposing - from a "perfect exposure" by 1 stop) then you reduce the maximum number of levels from 4096 to 2048 (for a 12 bit A/D conversion).

    1 Stop is hardly noticeable to the naked eye, and in post processing everything gets "rearranged". In a relatively "normal" scene (ie no backlighting, no specular highlights, and largely only reflected light) this one stop correction doesn't cause any issues because the sensor is capturing around 12 stops and we're only using around 6 (max) with a normal displayed (4 printed) image having to compensate for the -1EV EC takes you one stop closer to the noise floor, but your still so far above it anyway that it doesn't make a lot of difference.

    Where it can bite you in the bum though is when you need the full dynamic range of the sensor because your shootig into the light, and need to recover shadow detail in the foreground; in these situations under-exposing can visably add more noise.

    So - one might think that it's a good idea not to under-expose when shooting into the light (eg sunset shots), but in practice, because the sensor can get a little non-linear when pushed to the limits, you can often end up losing a bit of highlight detail, so it becomes a choice between risking highlight detail (even though the image isn't technically over-exposed), or risking shadow noise.

    The ideal answer for these situations is to use a GND filter, and under-expose slightly

    Hopefully not too much information!

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