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Old Feb 7, 2008, 10:29 PM   #11
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BillDrew wrote:
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the text refers to the change from 6 to 12 Mp while the illustration shows an increase in pixel count by a factor of four.
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--I guess because you need to multiply by 4 not by 2 to get a photo twice the size.
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They also neglect to note that a bunch (if not all) of the increased noise can be eliminated by downsizing to the smaller pixel count.
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--Are you saying we need to go down to 4mp on a 6mp to get lower noise photos?
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Another point they neglect to mention is that higher pixel counts typically come along with an improvement in the basic sensor. They assume that everything is constant except the pixel count - that may or may not be true.
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--I was confused on this point as well. Are they saying 4mp cameras of 4 years ago had better quality photos than 8mp of today? Certainly technology has improved and the quality, if not the size of the sensor, has increased.
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Old Feb 9, 2008, 11:35 AM   #12
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being a total amateur to digital, i am notyet in a position to challenge anyone,I can only learn. But what hope for newcomers like myself when experienced photographers and experienced technicans cannot agree ?

[glow=red]Keep in mind that this post is aimed at digicam(p&s) cameras[/glow]

[suB]One example is the illustration of the division in the sensor to get more pixels: the text refers to the change from 6 to 12 Mp while the illustration shows an increase in pixel count by a factor of four[/suB]

I think that [glow=yellow]romphotog[/glow] has explained away that misunderstanding.

[line]
Maybe I am being a little simple minded, but as their claim is that pixels have to reduce in size to incease the amount on a given sensor,this worsens the noise factor and(despite various efforts to counteract it)can only really be dealt with by reducing to a given maximum for any given sensor, based on a 3micron pixel.



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Old Feb 9, 2008, 4:57 PM   #13
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glent wrote:
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... Maybe I am being a little simple minded, but as their claim is that pixels have to reduce in size to incease the amount on a given sensor,this worsens the noise factor and(despite various efforts to counteract it)can only really be dealt with by reducing to a given maximum for any given sensor, based on a 3micron pixel.
The web site you reference says:
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if one pixel has a size of 3 µm which we believe to be a minimum size for good image quality at higher sensitivity levels (>ISO 400).
The key words are "we believe". They offer no evidence of any kind that a 3 micron pixel size is a minimum. Probably not a bad guess since it is a single digit multiple of the wavelengths of visable light (400–700 nm), but they could easily be off by a factor of two or three - which would change the maximum pixel count by a factor of four to nine. Even a 50% difference would make more than a factor of two in "allowed" pixel count.

I don't think what they are saying is absolutely wrong, but it is overstated and lacks evidence. Their basic point that increasing pixel count will increase noise is right, however, their specific numbers lack justification.

In addition they neglect the fact that photography is a long series of trade-offs. In this case ISO vs noise. Much the same as ISO vs grain in chemical photography. Perhaps someone wants higher resoution and is willing to give up high ISO to get it.
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Old Feb 9, 2008, 5:33 PM   #14
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Another thing to consider is that even when cameras had lower megapixels, high iso performance was still quite poor, and in many cases even worse than today's current crop of higher megapixel cameras. I had 2 and 4 megapixel cameras that couldn't produce usable images at any iso except the lowest available. At least 400 is usable now, and with more megapixels available, you have more cropping latitude and the ability to print larger, if only slightly.

Also as Bill mentioned, photography has always been about tradeoffs. In my opinion, 800 or 1600 film was never very usable, and only in the 90's did 400 film become truly usable to make larger prints. High ISO's have always been a tradeoff...grain (and now noise) as opposed to not being able to get the image.

Although I agree, megapixels don't tell the whole story, typically if it's available, I'd rather have the extra resolution than a small incremental gain in noise handling.
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Old Feb 9, 2008, 7:43 PM   #15
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okay guys, Thanks for all the practical help. Some,no, most of this technical stuff is well over my head, so theres nothing more that i can add to this post except to say that Fuji's 800asa film was just superb! :-) thanks again.
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Old Feb 9, 2008, 10:50 PM   #16
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I recall using Kodachrome ASA10 slide film and rejoicing when ASA25 became available. I think digital sensors still have a way to go in the efficiency of converting photons to electricity in much the same way chemical photon detection has improved.

It is also likely true that there is a lower limit for the size of a "pixel" in a digital camera. Likely some small multiple of the wavelength of visible light, but that still could leave room to get smaller than 3 microns.
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Old Feb 10, 2008, 2:41 PM   #17
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thanks
billdrew
for your last comment. Will be keeping an eye on this forum/post.

I have input with one other forum totally unrelated to photgraphy. The one thing that these two forums have in common,which may be shared by other forums,is just how few people participate. Plenty of hits,but so few people willing to reply and give advice. Has anyone ever tried to psychoanalyse this one way traffic. I wonder if its simply a case of total novices (apart from you fewexperts)desperate foradvice who bump into these sites.I find it odd that,despite the anonymity these forums give them, (unlike an open classroom) that they are so reticent to participate.
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Old Feb 10, 2008, 3:18 PM   #18
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I often lurk in forums for subjects I am only marginally interested in, or at least have no interest at all in discussing. Looking at the current posts at a forum gives an idea of the quality and a search will most often find an answer without asking anything.

There just isn't enough time to spend a lot of it on every subject.
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Old Feb 21, 2008, 10:13 PM   #19
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Hi
1. Advice: There are few P&S with 28mmm lens so rest is up to you. Price and design will determine choice.
2. You are very strange amateur with lot of pro questions. What is the catch?
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Old Feb 22, 2008, 1:32 AM   #20
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glent wrote:
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Fuji's 800asa film was just superb!
ISO sensitivity is the one point where so-called 'point & shoot' (I prefer the term 'small sensor') digicams remain well behind film. I generally used ISO400 colour negative film in my film SLR and 35mm compact camera until I got my first digicam 6 years ago. In nearly every aspect of my photography the technology has caught up with film-like quality since then.

But when I have to turn up the sensitivity in poor lighting, to achieve a satisfactory shutter speed, the quality is perceptibly worse, when I compare my currentdigicam results to my negatives and filmscans from a few years ago. To achieve equivalent quality I'd have to go to a dSLR plus lenses, at much greater cost, weight & inconvenience.

However, image stabilisation regains some of the ground by allowing much slower hand-held shutter speeds. The convenience in having such things as a huge zoom range in a small light 'superzoom hybrid' and an excellent electronic viewfinder with 'live preview' means that I haven't regretted selling my little-used film SLR when I got my newest digicam 10 months and many thousands of shots ago.

No doubt a new generation of small sensors with less noise at high sensitivity will appear before long.
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