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Old Feb 21, 2010, 5:55 PM   #1
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Default ISO and quality in lo light

Hi,

To get a better camera to use in lo light conditions we usually look for high ISO specs. There are cameras with ISO 12800 available...

BUT, how can we trust in these numbers? How can we know the quality of the image in each ISO setting?

The quality can be affected by the size of the sensor, the tecnology, the power source, the lens quality, quantity and size, and zoom available, aperture, etc... All these factors can provide better image in details and NOISE, that is the most problem in higher ISO.

I have a compact camera that can shot in lo light - but it or too noisy, or due Noise Reducing image processing it becomes too blury, loosing all details in the attempt to reduce noise (looking far the image seems better, but in a close look it becomes worse than the original).

There are cameras that have reported high noise in ISO 800 - so we may consider the larger ISO settings unuseful. And there are others that are usable in higher ISO.

How can we define if a camera is good for lo light photos? Is there an way to evaluate it from the specifications, or the only way is to check reviews and opinions?

Thanks!
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Old Feb 21, 2010, 6:05 PM   #2
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Pretty much if you want low light performance. You will want a high iso, with a larger sensor. That is why you only see 12800 iso on dslr only. In the "entry level market" the pentax k-x has the best low light imagine follow by the canon t1i.

Even though allot of CCD sensor has 1600 iso, they really do not preform pass 800iso.
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Old Feb 21, 2010, 6:49 PM   #3
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I will add that, for available light shooting, nothing beats a large aperture, and Tamron and Sigma both make good reasonably priced (relatively speaking) large aperture standard zooms that are excellent substitutes for the kit lenses. And they'd be stabilized on the Pentax K-x, but not on the Canon T1i.
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Old Feb 22, 2010, 8:36 AM   #4
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Let me also add - image quality is a very subjective thing. What is considered acceptable to one person may be completely unacceptable to another. For example, the Nikon D3s is the current king of the hill in high ISO performance. Some pros routinely use ISO 12,800 on it while others won't go above 3200 - all based on their subjective opinions of what is "good enough".

The best way to judge performance is to view actual photos from the cameras. BUT, you have to be very, very careful about the images you view and how they compare to the type of shooting you will do.
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Old Feb 22, 2010, 8:55 PM   #5
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For a long time, and I think it is still true, you should view the top one or two ISO steps that any camera advertises as wishful thinking. Or in common language, bogus.
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Old Feb 24, 2010, 10:44 AM   #6
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There are alot of factors when condisering high iso shots and it can change from scene to scene depending on the lighting of the scene. The image I attached is obviously noisy but for 12,800 ISO I find it acceptable for online sharing and even small print. Of course not really something you would want a print of. Also this was taken in EXTREME low light conditions. Definitely less lighting that you would have at your average indoor or outdoor night sports event. With more processing work the results could be better.

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Old Mar 5, 2010, 1:33 AM   #7
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Thats a good point - WHAT IS a good image?

The picture above is a great picture, considering the conditions it was taken, and as Widowmaker said is proper to a llot of things. But it is not a good photo, if we want cleaness... So it's not a photo to be framed, as an example...

Personally I don't like noise - it borrows me. There are lot of situations that I must accept it, but a noiseless camera is a target. That's why one criteria to choose is good performance in this topic, and also this is why I do not consider that just having 12800 ISO can be a reason to rate a camera as better at low light.

So a solution is to get a good flash, as the only way to solve it... I'm considering it too.

And about lens light, it seems that the options of light lenses are to few for these APS-C zoom lenses. There are only f/1.8 or f/1.4 in fixed lenses, but none in wide angle (~18mm). All zoom lenses are f/2.8 or f/3.5, including the kits (f/3.5) - the reason that I'll choose a super-zoom, that provides the zoom advantage and the SAME light (not mentioning other disadvantages, but that are not priority in this case)...
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Old Mar 5, 2010, 1:51 AM   #8
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You are forgetting you still can chose to go to only 6400iso with all the camera's that have 12800iso as an option. At 1/2 the iso speed, the noise is greatly reduced. And both example you have seen have been with canon at 12800iso. And they are acceptable. The pentax is about 3% less noise at 12800iso. But at 6400iso Both the canon and Pentax are about the same as the all camera's that can do 6400iso. IMHO all within 2% in noise. So with camera's in this price range, it is more about feature then IQ because they are all about the same. It is just what I can tell with an loupe looking at 8x10 prints.

If you want best noise control in low light conditions, you will need to go to full frame, like the Canon 5DMKII. And excellent low light camera that is very big with wedding photog. As mention by many, wedding photographer live in the low light environment, and need a camera to perform in these conditions. Or if action is an important aspect and need a higher burst rate, you would need to go to a nikon D700 full frame camera.

You will not even find in the really high end lenses of up to 4000+ dollars to have wider aperture of 2.8 in long zooms. It is really hard and not cost effective to find a 1.2-1.8 zoom lens. It is so hard to make a big aperture telephoto lens, that not even 12000 dollars lenses can open that wide in the 400-800mm range. And 2.8 is very bright for a lens with 200mm of reach.
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Old Mar 5, 2010, 2:24 AM   #9
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Here is an example of 6400iso, the photo is actually brighter then the actually lighting conditions. My eye could not make out the details of this painting which is only 10 feet away, that was how dark it is. Taken at 1/8 sec, f2.8 range at 100mm. Hand held no IS. WB set for incandescent light.
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Old Mar 5, 2010, 3:10 AM   #10
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There are two ways of looking at this:

Subjectively - which is to say look at pictures and see what is okay for you and the conditions under which you will be viewing. If you want 800x600 web output then most cameras, even at very high ISO will probably be fine. If you want a 20"x30" fine-art print then you are going to need to be much more careful. If you want to pixel peep at 100% magnification or more in photoshop well then (apart from needing a life quite badly) you may need a different type of camera again.

Objectively - at the moment there is only one place that publishes scientific measurements of camera sensors. DXOMark.com. They are scientific in the true sense: they publish their methodology, explain what they think their measurements mean, and anyone who has the means and desire can replicate their results. The benefit they gain from their DXOMark site is that it raises the profile for their DXOOptics image processing software.

The problem with subjective measurements is that they are unreliable, prone to bias and vary widely - not only between people, but between the same person at different times. So even if you do find someone who feels exactly the same way that you do, you still can't put too much trust in their opinions.

So for me it's DXOMark when I want the facts and review sites like Luminous-Landscape, Steve Huff, Sean Read or Michael Johnson (or even Ken Rockwell if I'm feeling seedy) for entertainment. Steves and DPReview fall somewhere in the middle.
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