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Old Jul 28, 2003, 12:40 PM   #1
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Default 4/3 system vs the world

...Seeing the continuous discusions on the new olympus 4/3 digital system, I just thought of this question yesterday: why is the 1.6 magnification of the existing format SLRs so bad really? If you think about it, the fault of all lenses of all sizes and quality is seen in the outer edges via CA, BD etc. With the ccd only using the central area of these lenses, the images should benefit from it. Also, if the 4/3 format is designed for today's CCD's, what will happen to it when we reach CCDs the size of 35mm film? At that point, the standard lens format comes back to relevance. Is this train of thought correct? What do you guys and girls think?
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Old Jul 28, 2003, 2:23 PM   #2
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There are a variety of things in your post.

1) If you are like me, and photograph things far away, the 1.6x (or 1.5x for nikon) is the next best thing to sliced bread. I get more reach out of the same lenses. But if you take pictures of: portrates, interior shots, pictures of groups of people, arcatecture then you need wide angle. And really wide angle (lenses that stay "wide" even when lengthened by 1.6x) are really expensive. We're talking 17mm lenses and the like.

2) If you have done photography for a long time, you know the field of view a given lens gives. And you pick a lens partially based on this. Well, the 1.6x crop factor ruins all of this. Completely. I believe this also works for DOF, but I'm not sure.

3) You are right, the smaller sensor only uses the best part of the lens. That is very nice.

4) I believe the 4/3 system has projected that it will only grow to about 13mp or so. Not bad, IMHO, but full frame sensors are already at this mark.

5) I don't think its fair to say "Also, if the 4/3 format is designed for today's CCD's, what will happen to it when we reach CCDs the size of 35mm film?" for two reasons. First, we already have a full frame 35-mm SLR. The Canon 1Ds. Very expensive, very nice. The 4/3 system is designed to keep the price down by using a smaller sensor. Second they are already planning for future CCDs. They expect this system to die eventually, but it should alllow for cheaper camera design and cheaper lens design right now. Nikon is doing a similar thing with the DX lens line. Smaller lenses which work at wide angles for less cost because they are made to fit their 1.5x crop factor.

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Old Jul 28, 2003, 2:24 PM   #3
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I think we're putting the cart before the horse. Just because edge distortion is an issue with lenses, doesn't mean the aspect of current digicams is right. If this was the case we never would have had Panavision and cinemas that show pictures closer to the way the world really looks through our eyes.

A lot depends on whether you want pictures as records, or a more enjoyable visual experience and some immersion. The optimum aspect to design your camera ccd for is circular - remember those first TV sets that used radar display tubes, because it was difficult to make tubes with straight sides?

I'd rather have a better visual experience - and have been listening to Stereo for many years now! VOX
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Old Jul 28, 2003, 11:47 PM   #4
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On all this talk about senosr size and edge distortion, I feel like the hobo in court who, when the judge announced "I aquit the defendant of the charge of grand larceny" he replied "Does that mean I can keep the watch?" :shock: Speaka-da-English, please, I'm just a simple picture-taker. What does all this mean, I really want to know! :? Can someone explain on an 8th grade level? THX........... ops:
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Old Jul 29, 2003, 1:17 AM   #5
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Lenses aren't as perfect as you may think. Resolving power, chromatic aberration (when all the colors don't focus at the same place giving color fringing) and rectilinear distortion (when straight lines aren't straight) are all a reality of lenses in the real world. When designers correct them in the center they sometimes can't correct as well at the edges. Using a sensor smaller than the original film frame often crops away the less than optimum part of the image.

CCDs themselves also present optical challenges not found in film. The surface is three dimensional and actually has little pits rather than being perfectly smooth like film. At the corners the light strikes the surface at an angle and not all of it gets into the pits. CCDs with microlenses over each photosite can actually make this worse. So even if you have a full size CCD it may not perform very well with lenses made for film.

Olympus is trying to get around some of these limitations with the new CCD size and lenses made specifically for digital use. Nikon is also doing the same with digital only DX series lenses with a smaller image circle.
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Old Jul 29, 2003, 9:23 AM   #6
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Quote:
Originally Posted by padeye
CCDs with microlenses over each photosite can actually make this worse.
This is the solution to the problem you described. It's part of the reason the 1Ds costs so much (raises the cost of the sensor even higher.) So maybe it can make it worse, but it doesn't have to. It can also solve the problem.

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Old Jul 29, 2003, 12:43 PM   #7
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...it seems that we all, sort of, kinda agree that this is a finite system. I just thought it was a heck of a lot of money for a system that will some day reach a peak, in comparison to the prices for other SLR lenses that are progressively re-usable with newer technology. I think this is the uphill in the 4/3's battle.

Of course, e genius lens designer may see merit in creating a floater, a glass element that allows the lens to be mounted further from the CCD focal plane, allowing for a larger field of view w/out loss of near and far focusing limits; but thats another story. I think tend to overanalyze these things. I will think about this very carefuly though, if (hopefuly when) some day I can afford to go to a DSLR system.
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Old Jul 29, 2003, 4:51 PM   #8
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THX for the explanation, it was very helpful. Best - john
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Old Jul 29, 2003, 7:15 PM   #9
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Perhaps a new type of sensor made specifically for a certain mount system, where photosites around the the edges are actually leaning inwards to avoid the use of microlenses. maybe it'd cost too much, but who knows what the future holds for digital camera sensors?
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Old Jul 30, 2003, 7:45 AM   #10
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I'm surprised no one brought up the DOF with the 4/3 system with a smaller image circle... Theoretically there should be an increased in DOF, and shouldn't it be the same with the DX lenses as well, albeit to a lesser degree?

... It seems like there's a trade-off/compromise in every design (or the photographers can settle for the format(s) that fit his need)! :lol:
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