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Old Apr 27, 2007, 11:13 AM   #1
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Thanks in advance for any help that you astute photogs are able to provide for me.

I recently saw or read something that was talking about how people are often duped in thinking that # of megapixels is the biggest determinant that you should consider in terms of the camera's quality. They mentioned some other specification metric that was more important and I can't remember now what it is! Does this ring a bell?

Thanks again.

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Old Apr 27, 2007, 11:20 AM   #2
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The answer is THERE IS NO SINGLE METRIC. Sorry - there just isn't a single metric.

The fact is there is no single best camera - period.

The key is to find the right camera for YOU. This is done by determining what types of photography you want to do. Then forums & research can help educate you on what specific features are important for those types of photography. Add to that REQUIRED FEATURE list any preferencial features - cost, size, weight, ergonomics and other features you may want just because you like them. The key is to then find a camera that best matches those features.

It's not unlike buying a car. There's no single spec that is the end-all-be-all for determining which car to buy. Same with cameras. The right camera for my needs isn't necessarily the right camera for your needs. Unfortunately many people don't want to take the time to do all of the above, so they look for some quick-hit metric they can see on a spec sheet.
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Old Apr 27, 2007, 11:28 AM   #3
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Thanks John.

I wasn't looking for a single metric to make my decision, but instead was looking for the "better" metric denoting picture quality. My recollection was that the article I read (or show I watched) said that people often mis-use megapixels as the PQ determinant, where this other metric is really the better one to look at. Cost, size, weight, and ergonomics were not what I was talking about here.

Thanks.
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Old Apr 27, 2007, 12:21 PM   #4
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Even for picture quality there is no single or better metric. Things done to improve one particular measurable aspect of performance may degrade another measurable aspect. Equally, enhancements to improve pictures under one set of condition may degrade performance in a set of conditions.
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Old Apr 27, 2007, 12:25 PM   #5
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From a technical standpoint, what makes a good photograph is the same for film cameras as it is for digital cameras: 1. the medium that is used to record the image (the film, or the image sensor), and 2. the lens. From the standpoint of the photograph, every other piece of the camera is just along for the ride.

Just as different Kodak, Ilford and Fuji films record the same image slightly differently, different image sensors record the same image slightly differently.And more megapixels in an image sensor, and finer grain in the film, create more detailed photographs that may be cropped and enlarged more that photographs recorded with fewer megapixels in an image sensor, or courser grains in film.

Also, ahigh quality lens from Canon, Nikon, Leica, or Zeiss willcreatea more detailed photograph than a low quality lens from, say,V*v*t*r or C*s*n*.

No other piece of the camera directly affects the quality of the image.

Now, as with film, an image sensor can be pushed beyond it's limits (too high an ISO setting)and will produce an unacceptable image, but happily, most sins can be corrected in post processing. But post processing cannot create detail where it doesn't exist; it may make some intelligent guesses to produce a result that is acceptable, but there are limits to this magic. And some people don't have the patience to do post processing, and most don't have the skills. (Not the people in these forums, you understand. But most people.)

What makes a digital camera a "quality" digital camera? The image sensor and the lens. And while megapixels alone do not make a "quality" image sensor, practically speaking, everything else is a distant second.

So the answer is Megapixels AND Modulation Transfer Function (MTF).
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Old Apr 27, 2007, 1:41 PM   #6
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TCav wrote:
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So the answer is Megapixels AND Modulation Transfer Function (MTF).
Any thoughts on how we, as consumers, get the manufactures cough up the MTF data in a meaningful way?
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Old Apr 27, 2007, 2:37 PM   #7
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ac.smith wrote:
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TCav wrote:
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So the answer is Megapixels AND Modulation Transfer Function (MTF).
Any thoughts on how we, as consumers, get the manufactures cough up the MTF data in a meaningful way?
Well, we could ask for it. And if enough of us do, maybe we'll get it.

But, while Canonand Sigma already do (for their SLR lenses),it is possible that most manufacturers don't know the MTF of their lenses.

And maybe if enough of us subscribe to Popular Photography, they'll be able to test more lenses and P&S cameras. Then we'll have an objective measure of the quality of many more lenses.

But, please, let's not get Consumer Reports involved. They scare me sometimes.
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Old Apr 27, 2007, 3:18 PM   #8
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As you say Canon and Sigma publish their MTF figures. And Nikon do too on their Japanese website. But their figures aren't really comparable between the other manufacturers though they do a decent job of allowing you to compare the different lenses in their own lineups.

Also don't forget there's http://www.photozone.de and my new favourite http://www.slrgear.com

And Steve does reviews of the cameras.

I suppose if you must have a single factor it's how good the print looks. But of course there are a lot of variables in that chain.
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Old Apr 27, 2007, 3:24 PM   #9
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But if we're talking digicam and not DSLR I don't think anyone has mtf data on digicam lenses. Which brings me back to my and ac.smith's point - there is no single metric that you can look at for digicams to tell you which camera has the best IQ.
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Old Apr 27, 2007, 3:28 PM   #10
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One thing you could look at that generally has an impact is sensor size or pixel pitch. Like any other one number though, it's not always that meaningful.

But in general, a 1/2.5" sensor is better than a 1/3", and a 1/1.8" is better than a 1/2.5". But you have to be comparing contemporary models, and image processing plays a large role as well and varies between manufacturers. It used to be some of the highest quality digicams had a 2/3" (same as 1/1.5") sensor, but nowadasy the largest seem to be in the 1/1.8-1/1.6" range. And there aren't many.

There are also many smaller sensors which produce excellent image quality, especially at lower ISO. But this is at least one specification that is available and probably more meaningful than megapixels.

But best bet for image quality is still to pay more attention to reviews, reputation, and samples than specs. And the lens often plays a bigger role than the sensor, but there's no simple way to measure lens quality either. There's alot more to a good lens than resolution.

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