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Author Topic: the so called minuature formats  (Read 20539 times)
BJL
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« on: September 28, 2005, 06:04:45 PM »
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It is interesting that Michael wraps up his recent essay with a reference to the introduction and eventual dominance of the "so called miniature format", the 24x36mm of 35mm film cameras. Interesting because he otherwise rejects the idea that smaller formats have virtues for professional and enthusiastic amateur photographers. His predictions turn largely on two ideas
a) expectations of the FF price penalty getting below US$1,000
 the claim that cost is the only advantage of a smaller format (as if the downsizing progression from LF to MF to 35mm film format was solely for cost reasons.)

His strange weight comparions of the very robustly built and three year old E-1 to the new unsealed body of the 5D is a bit strange; for a different spin, compare the new lightest Four Thirds body (the new Olympus E-500, at 479g) to the new lightest FF body (the 5D at 895g): about one pound difference.


But the big missing point is lenses, and how they will increase the size and weight of the larger format kit needed to realize most of the claimed advantages, if suitable lenses exist at all.

1) You get absolutely no advantage from a larger sensor unless you also use a longer focal length, to spread the image over more sensor area. Using the same focal length as with a smaller sensor and then cropping more means that you use only a portion of the larger sensor of the same size as the smaller sensor. (Meanwhile you have to compose for a heavy crop in the viewfinder.)

2) Using a longer focal length but the same effective aperture diameter (f-stop increased in proportion to focal length) helps only with image quality at close to minimum ISO speed, requiring a lower shutter speed than with the smaller format due to the higher f-stop. When instead the larger format uses ISO speed a stop or more above minimum, the smaller format with its lower f-stop can use a lower ISO and yet the same shutter speed, and this lower ISO balances out the noise/DR advantages of the larger sensor when sensors are compared at equal ISO.


3) That leaves only using larger focal lengths and larger aperture diameters: for example, using equal f-stop despite the longer focal length. This only applies when the larger format can use a larger aperture diameter than the fastest lens available for the smaller format at the equivalent focal length, because if the smaller format can match aperture diameter, we are back in case (2).

Simple optics and physics says that this high speed advantage requires bigger front elements and lenses that are heavier and probably more expensive, and also leads to very shallow DOF (often a disadvantage, believe ot or not!)

What will sports/action/wildlife users choose? Probably telephotos are the main realm where high speed is of great importance, and beyond about 85mm for primes and 200mm for any lenses for 35mm format, the speed advantage only exists for only a very few heavy, expensive lenses, like a 400/2.8. Shorter but brighter telephoto lenses for use wit hteh smaller formats, like the new Nikon 200mm f/2, can probably eliminate most or all of this high speed/low light/low DOF performance difference. As to price and weight, comparing that Nikon 200/2 to a 300/2.8, or a 400/2.8 to a 600/4 suggests that there is no significant price or weight penalty to this "shorter but brighter" telephoto lens strategy,and in fact probably  abit of a size and weight advantage. Any performance difference that remains will continue to cost and weigh a lot.

Only wide to short telephoto focal lengths have a likely long-term advantage from larger apertures in 35m format; a realm where I expect most photographers will find few problems with the speed of the smaller DSLR formats.



To me, case (2) always has been and probably always will be the main larger format advantage: more dynamic range, finer tonal gradations, and maybe more resolution, by using low ISO for optimal quality and generally higher f-stops and lower shutter speeds than with smaller formats.


P. S. I do not see the existing lens pool holding back smaler DSLR formats much. For focal lengths beyond about 60mm, 35mm format lenses work equally well (though differently) with smaller formats, since such lens designs naturally throw an image circle big enough for the 35mm frame size. So the transition to smaller formats does not obsolete many lenses. It typically require getting one or two new shorter ones, and in exchange, the longest one or two lenses might become dispensable.

Anyway, a majority of DSLR buyers have never previously owned a 35mm format SLR, and so have no legacy lenses.
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John Camp
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« Reply #1 on: September 28, 2005, 07:13:23 PM »
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I've noticed on a number of forums that people are using the phrase "legacy formats," and to me that signals a critical shift in thinking (if that shift might also reflect on the way camera manufacturers may be thinking.) I see little advantage to "full-frame" sensors, and quite a few for the smaller sensors. (I will grant that there are some definite advantages to legacy size cameras for people who need to strongly manipulate depth of field; but this will eventually be rendered less important by Photoshop.) It would be a curious reversal if Canon someday found itself to be the "new medium format" camera: much more expensive both as a camera body and a system, and carrying much more weight, and often relegated to specialist photo applications -- fashion and landscape -- while cameras with non-legacy sensors (perhaps not only APS-C, but possibly even with a 6x7 or 5x4 ratios) become the "new 35s" used for all photo journalism/action/street shooting, and even fashion and landscape where huge print sizes are not required. The Sony P&S zoom cameras will never have the flexibility of a fully exhangeable-lens system, attractive as they may be -- and if they were smaller, I would find them very attractive indeed. They will eventually wind up like the film point-and-shoots; there were, in that category, some extremely able cameras, if you can remember back that far...

I will have to say that I've always found Michael Reichmann's specific loyalty to the legacy-sized sensors to be odd, given that much of his most critical shooting is with a different format (and he's always seemed fair-minded enough that I would NOT attribute this to any connection with Canon.) Well, I suspect we will see, and really, rather quickly. By 2008, who knows...?

JC
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Ray
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« Reply #2 on: September 28, 2005, 10:40:24 PM »
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But the big missing point is lenses, and how they will increase the size and weight of the larger format kit needed to realize most of the claimed advantages, if suitable lenses exist at all.

BJL,
Look! The bottom line is this. The smaller format will always have the advantage of being lighter, but always at the cost of a sacrifice in image quality. If someone can design a smaller format that is significantly lighter than a larger, heavier format but offers equal (or close to equal) image quality at a similar price, then such a camera will have a huge competitive advantage in the market.

The D2X almost fell into that category. Image quality is almost on a par with the heavier 1Ds2 and the savings in weight (as well as price) can justify, for many, that slight loss in image quality and increased noise at high ISOs. That's fine. I'm all in favour of the consumer having a choice, but ultimately, with equal technological development amongst formats, comparing the latest with the latest, the larger format will always retain an inherent image quality advantage.

The issue therefore revolves around the size of the various trade-offs. Is the weight advantage significant but the image quality loss only marginal, or vice versa?

It seems to me, the Olympus 4/3rds format is really a competitor to the APS-C format. Affordable FF 35mm could well knock it out of the market, as Michael predicts.

You argument that lenses longer than 60mm have a sufficiently large image circle for a larger format, even though they might have been designed for a smaller format, is working against your main premise here. Again you are shooting yourself in the foot.

To make this clear, I'll give a concrete example. Let's say I'm mainly interesting in shooting wildlife and sporting events where the smaller format such as the 4/3rds and APS-C supposedly have an advantage. I consider 300mm to be my most used focal length and I look around for systems that support an excellent 300mm lens.

I'm impressed with the Zuiko 300/2.8 for the 4/3rds system, but I'm concerned that the FoV might be too narrow (effectively that of a 600mm lens on FF 35mm), however a 300mm lens is a 300mm lens. The size of the sensor cannot change that fact.

I consider the Canon 300/2.8, also a very fine lens, up there with the best that Canon produce, if not the best. I'm torn between the Canon 1Ds2 with 300/2.8 prime lens, and the latest 8 megapixel Olympus 4/3rds with Zuiko 300/2.8 lens.

I compare the specs. What do I find? Lo and behold, the Zuiko 300/2.8 is actually heavier than the Canon 300/2.8; 3.3KG as opposed to 2.55KG for the Canon. I don't know what the street prices for these 2 lenses are, but the RRP prices are about the same, with the Canon perhaps being marginally cheaper.

Now I'm not going to quibble about a few grams. A 1Ds2 plus 300/2.8 lens is going to be insignificantly heavier or lighter than an Olympus/Zuiko 300/2.8 combination and therefore not a factor in my deliberations.

The point has been made many times in this forum; it makes no difference if the camera's sensor does the cropping or the image editing program. Cropping is cropping.

The difference between these two systems is one of cropping choice. With the olympus/Zuiko 4/3rds system, I've got less choice. The sensor crops the image circle to a far greater degree than does the FF Canon/300mm combination. I would therefore much prefer to use the 1Ds2/300mm combination, unless, of course, the cropped 1Ds2 image is inferior to the Olympus 4/3rds image  Huh .

And here's the rub. I haven't seen any direct comparisons, but I'd be prepared to accept that currently the 8mp Olympus image would be sharper and more detailed than the cropped 4mp 1Ds2 image. If this wasn't the case, there'd really be no reason for the 4/3rds system to exist.

However, this latest article of Michael's is addressing trends and future scenarios. The current advantage of the 4/3rds format in my example above is partially offset by the choice of a wider FoV with the FF format, with any lens. Furthermore, the resolution advantage of the 4/3rds format will continue to be eroded as it becomes economically viable to produce FF sensors with higher pixel densities.
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Willowroot
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« Reply #3 on: September 29, 2005, 09:21:59 AM »
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That makes little sense.  If you wanted a 300mm FOV you'd be looking at a 150mm lens for the Oly, not 300.
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Jason Elias
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« Reply #4 on: September 29, 2005, 09:46:37 AM »
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I've just come fron handling a new Canon 5D at the camera store where I do business. As a current XPan (film) user, I've just been waiting for the right digital camera.  For me, this is a full frame digital camera and Canon appears to have built this model for people like me. Kudos to Canon for giving so many of us-what we have been waiting for-at a price many of us can live with.  Imagine, giving customers what they desire, and are willing to spend their dollars on-what a concept! This is not a question of legacy to me-I'm just thrilled to have this choice at this price point.  Who wouldn't like it to be less expensive, but that also will follow.
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Del
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« Reply #5 on: September 29, 2005, 12:59:55 PM »
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I agree with BJL's initial comments on this topic - even given that the price difference between FF and 1.5x sensors drops, that is not necessarily enough to relegate the 1.5x to the low quality consumer market.

I believe that the 1.5x cameras will provide image quality that is good enough!  That is the key word here - I dont need better, I am confident that within a couple of years, we will have an 11Mpixel 1.5x sensor on the market at the same price as todays 20D/350D, with the same or lower noise.  That is what these cameras gave us over their predecessors - 33% more pixels at the same price and the same noise.
At 11Mpix and the noise of the 20D, I dont need anything else, but I have these advantages over a FF set-up:
  You can cover the same zoom range with cheaper, smaller, lighter lenses - I own a 10-22, 17-85, 28-135 and 100-400. To cover the same range on a FF camera (effective 16mm to 560mm), would cost and weigh lots more.
  The camera is also smaller, cheaper, lighter

I believe that within a few years, people who used to shoot medium format will move to FF (these are the people who really need extreme quality).  People who used to shoot FF will move to 1.5x sensors - Its good enough, and to get better is just not worth the extra cost and weight.
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BobMcCarthy
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« Reply #6 on: September 29, 2005, 02:05:13 PM »
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I have never thought of Michael as being dishonest in any of his analysis. I do feel he assigns a bit of "hero" status to some of his interview subjects. Adobe (Knoll), Phase (Raber?), and Canon (?)has been pulling at his heart strings. He appears to give them the benefit of doubt in any issues regarding them.

I have always approached the subject of FF vs DX as an economic issue. I have no doubt that technology will advance in many ways (hardware and software)where we reach a point of "good enough and then some" with reduced format sensors. It appears the huge installed base of 35mm lenses are a powerful reason for the infrastructure to leverage off of that base.

DX is very good already and will likely continue to get better. The edge to edge sharpness issue is probably the FF archiles heel. I can even see a small amount of differential in the DX world. It approaches unacceptable with FF.

All the above can be solved as new FF lenses, sharp edge to edge, are possibly introduced. Far more important with wide so the entire line doesn't need to be revamped. These babys will cost a pretty penny though.

All this has been discussed endlessly. BJL has provided valuable insight into the optical side. Others have contributed on other issues.

But, in the final analysis, it comes down to money. Sure FF will come down somewhat in cost, but DX/AP-C will always be less expensive and deliver acceptable quality at a lower price to the customer. Technology only makes it better. I can see the day of a 12-15 mpxl camera going for $500 in basic trim and it will be DX long before its FF. The market will flatten when that occurs as high quality becomes universal and improvements will be based on other issues like in the old days.

Maybe Nikon will produce a FF camera but it will be to compete with Canon for the Medium format customer. That customer base can grow well beyond the 'blad days as it shares infrastructure with 35mm systems

Medium format is becoming marginalized and less and less economic. 35FF digital will replace it. I suppose med format can replace large format, but the cost differental is enormous. Large format film is cheaper than 35mm/DX digital at the pro level, just not as versatile. When med format digital unit volume drops below a certain level it will implode in on itself. Just not enough units to fund R&D etc. In the meantime 35mm based digital camera are closing in.

In the end its all about economics, no matter what our heart tells us.

bob
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Ronny Nilsen
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« Reply #7 on: September 29, 2005, 02:53:23 PM »
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In the end its all about economics, no matter what our heart tells us.

It's also about physics. With todays senors we are aproching the diffraction limit, and if you want more pixels you will have to have a larger senors.

So even if we some day in the future can make senors with no noise in any size we wish, the diffraction limit will set a barrier and make it meaningless to make them smaller.

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You can cover the same zoom range with cheaper, smaller, lighter lenses - I own a 10-22, 17-85, 28-135 and 100-400. To cover the same range on a FF camera (effective 16mm to 560mm), would cost and weigh lots more.

In a FF camera with the same pixel density as the smaller sensor, you could cover the same range with 16-400mm lenses and get the same or better image quality. You would only need a 560mm if you want beter quality than the smaller senor can give you. A 400mm on a FF will give the same image after cropping i PS as the smaller sensor. :cool:
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Ben Rubinstein
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« Reply #8 on: September 29, 2005, 03:07:30 PM »
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What will sports/action/wildlife users choose?

As you say, for most everyone else, especially those who don't have huge studios and want to keep their legacy lenses for the purpose that they were bought or don't want to buy a new bunch on DX/AFS lenses - Crop sensors are a serious pain in the tuchus and to heck with them.

If I was going on safari then I would take a 20D no question, for a wedding or portrait session you just try and tear that FF DSLR away from me!
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BobMcCarthy
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« Reply #9 on: September 29, 2005, 03:35:35 PM »
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In the end its all about economics, no matter what our heart tells us.

It's also about physics. With todays senors we are aproching the diffraction limit, and if you want more pixels you will have to have a larger senors.

So even if we some day in the future can make senors with no noise in any size we wish, the diffraction limit will set a barrier and make it meaningless to make them smaller.


At what point is enough, enough?

At 300 dpi, just how big are you going to print. I'll admit my average print has moved up to 13x19 and 18x24 compared to 8x10 and 11-14 in the film days but...

Hardly worth playing with 30-40 meg files, that turn into monster Tiffs, especially with the way some folks just hammer on the shutter release. The amount of processing is out of control. Some digital trained folks shoot more in a month that I did in a decade in the film days. I already spend too much time in processing...

I disagree that DX/APC sensors are approaching the limits...

Maybe some of the P&S but not DX. You're being too theoretical.

Bob
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Ray
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« Reply #10 on: September 29, 2005, 05:55:46 PM »
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That makes little sense. If you wanted a 300mm FOV you'd be looking at a 150mm lens for the Oly, not 300.
The point I'm trying to get across is one that's been misunderstood from the day the first APS-C DSLR hit the market, and it's this. A 150mm lens or a 300mm lens is just that, whatever camera it's attached to. I can never get a field of view greater than the inherent image circle thrown by the lens, whatever the focal length of the lens, but I can reduce the FoV as much as I want by cropping.

Whilst it's true that a 150mm lens on a 4/3rds format produces the same FoV as a 300mm lens on a FF frame 35mm camera without more cropping than has already taken place in-camera, there's nothing to stop me continuing to crop the image in Photoshop. The more I crop, the narrower the FoV becomes. Why stop at the degree of cropping already done by the camera's sensor? Answer: because the more you crop, the lower the image quality.

A cropped image from a 150mm lens ultimately can never have the same quality as an uncropped image from a 300mm lens, if both lenses are of similar quality. As sensors continue to have greater pixel density to a point beyond the resolving capacity of the lenses used, and as the prices of FF 35mm sensors fall, the APS-C camera becomes a less attractive proposition.
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Ronny Nilsen
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« Reply #11 on: September 29, 2005, 06:10:05 PM »
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I disagree that DX/APC sensors are approaching the limits...

Maybe some of the P&S but not DX. You're being too theoretical.

It depends on subjective factors ofcourse, but for me my 20D has small enough pixels. If I stop down to f/22 or smaller the effect is visible.

Take a look at  http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm to see a visualisation of the size of the airy disk.
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BJL
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« Reply #12 on: September 29, 2005, 07:39:18 PM »
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It's also about physics. With todays senors we are aproching the diffraction limit, and if you want more pixels you will have to have a larger senors.
If diffraction got to be a problem at even the largest apertures of lenses (as it possibly is with 8MP 1/1.8" sensors), then there would be a problem. DSLR's are not even close: the D2X is diffraction limited only at about f/11 and beyond.

That leaves diffraction problems only when one stops down to get lots of DOF. Changing to a larger format requires using a higher f-stop to achieve that same DOF, making the diffraction effect equally great.

That is, once again, comparing different formats at equal effective aperture diameter (focal length divided by f-stop) gives equal DOF and equal diffraction effects on equal sized prints; no advantage to either larger or smaller formats.

One difference is that since the larger format is then using a higher f-stop, it must use either a higher ISO speed or a lower shutter speed, vaporising its supposed noise/speed advantage.
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BJL
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« Reply #13 on: September 29, 2005, 08:02:59 PM »
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The bottom line is this. The smaller format will always have the advantage of being lighter, but always at the cost of a sacrifice in image quality.
Exactly: lighter, cheaper, and in some situations less image quality, but in others, no noticable difference.

This is the same trade off that 35mm film offered in comparison to the earlier larger roll film formats, and 4"x5" sheet film in comparison to the older, larger 5"x7" and 8"x10" sheet film formats. In each case, smaler not only survied but evedntualy dominated ove teh older, bigger formats. So clearly the advangtages of small can be sufficient for healthy survival sometimes, contradicting the simplistic "bigger formats give better image quality and so will eventually dominate" argument.

Please explain why 35mm (and 4"x5") did so well despite their "size disadvantage".


Your comparison of Four Thirds and 35mm both with 300/2.8 lenses shows that you have totally missed or ignored one of my main points: a larger format needs to use longer focal lengths, or the extra sensor area is completely wasted.

Another point about cropping and focal length needs: the Canon 35mm format DSLRs have all consistently had distinctly lower sensor resolution (wider pixel spacing) than contemporary far less expensive smaller format DSLRs. For that reason also, they must use longer focal lengths to record about the same amount of detail from a subject.

And why compare to Four Thirds in particular? I used Nikon DX for my main examples, since that is clearly the current pre-eminent "smaller than 35mm" DSLR format. Nikon DX is above all the one that the one that Canon's 35mm format has to vanquish in order to fullfill your apparent desire that photographic enthusiasts be denied DSLR options that are smaller, lighter and less expensive than 35mm format, while also clearly exceeding 35mm film quality overall, as the D2X already does.
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John Camp
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« Reply #14 on: September 29, 2005, 11:11:58 PM »
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A cropped image from a 150mm lens ultimately can never have the same quality as an uncropped image from a 300mm lens, if both lenses are of similar quality.
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I either don't understand this, or don't understand your argument, one or the other. I'm willing to take a further explanation of either.

An APS-C image is NOT cropped. It's the full size of the APS-C. It simply uses less of the lens' circle. So what? The FOV in an APS-C at 200 is the same as in a FF at 300. So what?

The APS-C isn't cropped, nor is it the same thing as a crop, because -- and this is the crux of the question, or the problem -- the sensors are not the same. All of the D2x's pixels are in the APS-C sized sensor; most of the Canon's are outside of that similar area on the Canon's sensor. So a D2X has much more resolution and sharpness over the APS-sized area, does it not?

I really don't understand this focus on "crops," or even what is meant by that. A crop is when you have an image and cut the edges off of it, either on paper or in Photoshop. You simply throw away pixels; the pixel density doesn't change. If the pixel density across a ff sensor were the same as across an APS-C, *then* the APS-C with the same FOV would be the equivalent of a crop.

But they're not the same. Anmd most reviewers would suggest that the quality of a 200 D2x and a 300 1DsII are extremely close -- so close that something other than resolution or sharpness might very well be the deciding factor of which you buy. If you want fast long lenses, lighter weight, less cost (and, for the time being, anyway, better corner sharpness in wide angle lenses) then you go with the D2x. If you want more easily manipulated depth of field, better high-ASA performance, or (according to some reviewers) slightly greater DR, then you might want to go with the 1DsII.

But crop? Not a factor.

JC
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Ronny Nilsen
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« Reply #15 on: September 30, 2005, 01:39:08 AM »
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It's also about physics. With todays senors we are aproching the diffraction limit, and if you want more pixels you will have to have a larger senors.
If diffraction got to be a problem at even the largest apertures of lenses (as it possibly is with 8MP 1/1.8" sensors), then there would be a problem. DSLR's are not even close: the D2X is diffraction limited only at about f/11 and beyond.

That leaves diffraction problems only when one stops down to get lots of DOF. Changing to a larger format requires using a higher f-stop to achieve that same DOF, making the diffraction effect equally great.
There is another reasons for wanting to stop down, and that is to control shutter speed.   ::

So for me (not you or anybody else) I feel that I am aproching (not passing or indicating that it's problem on current DSLR's) the diffraction limit. I am not thinking of a particular camera here, we are talking about cameras in the future and the direction we are headed in.

It's not unlikely that we in, let's say 5 years, have cameras with different size sensors but with about the same pixel size that is close to diffraction limit of say f/5.6.

Then you can chose your image resolution based on sensor size the same way we have up to now done so by choosing different film formats.

And if you have been unlucky and bought a FF camera and want the benefits a redused sensors gives to your images, you can always put som duck tape covering part of your sensors and focusing screen to get the improved image quality.  Cheesy

The paragraph above is ment as humor, but it illustrates that in the long run image quality is tied to sensor size the same way it has been with film. But for most people a redused size sensor will give more quality than they need (and probably does already).
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« Reply #16 on: September 30, 2005, 02:17:48 AM »
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What I did mind in this whole thing, at least watching the Olympus SLR forum on dpreview, is that Michael was again unfairly attacked, as if he insulted a leader of some cult, and now the followers are out for revenge. The similar thing happened to Mike Johnston, and now he stopped writing his columns, which is a great loss for the photographic community. People take cameras way too seriously, it seems.
I, personally, can't tell if it's better to invest in full frame 35mm sensor and lenses, or in 4/3 sensor and lenses. It probably depends on what one finds to be good enough. A couple of years ago Michael said that 3MP Canon D30 equals 35mm film, and that 6MP D60 is actually better than 35mm film. OK. So let's see, Olympus makes an E1 body with 5MP (which I own, BTW), and this body is generally agreed to have picture quality similar to Canon 10D, which should be better than 35mm film. In reality, when I compare A3 prints between E1 and my Minolta film gear, film has less clarity, and the amount of detail is either similar, or E1 is better. That goes hand in hand with Michael's estimate. So what do I have here? I replaced my film gear with equally powerful digital gear, and saved lots of money and time on processing and scanning. Why would I complain about limitations of the 4/3 format? That would be the case only if 135 film wasn't enough, and I wanted to upgrade to medium format.
Technically, Michael is right - bigger sensor will give you better quality of information per pixel, all other things being equal. However, are they? I mean, Canon FF cameras are obviously lens limited. Only the best lenses give optimal results, and that usually means L primes. So if you want to extract all that extra resolution the sensor allows, you have to shoot with primes, like with medium format. Fine, but that is not very convenient. On the other hand, Olympus makes great 4/3 zooms, with excellent resolution. 4/3 is sensor limited, while 35mm is glass limited. Sure, I guess when Canon makes a 24MP 35mm sensor, Olympus will have to stop at 12 - what a major tragedy that would be. However, let say, for argument's sake, that Olympus releases a 12MP sensor camera with resolution and DR better or equal to Nikon D2X. Would anyone have reason to complain about limitations of reduced format? I don't think so, as 12MP Nikon equals 6x6 Velvia scan, from what I've seen. The only way up is through medium format backs, not small format cameras. Michael himself has two systems - Canon and Contax. What's the problem if someone builds one system around 4/3, and another around a 35mm or even a 645 sensor? Why would 4/3 be limiting, if it allows me to pack 28-400mm range in two reasonably compact lenses, and get quality similar or identical to that of Canon L glass and a 10d body? I am very pleased with the results I produce with my E1. Yes, I can hardly wait for them to release a professional grade body with better resolution and noise performance. However, I'm not getting into seizures over it all. I use what I have, and try to improve my photography, as I did with 35mm film. I'm not into insane consumerism. If a 3 MP camera equalled 135 film three years ago, then I guess it still does today. So why would I treat a great 5MP camera as obsolete and outdated, when it actually still does outresolve 35mm film, still makes great pictures, and there always were better, bigger format cameras around? Well, just my two cents, anyway.
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Danijel
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« Reply #17 on: September 30, 2005, 05:58:48 AM »
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Attacking Michael seems to be the national sport on forums after his essays, as if somehow he isn't entitled to his own opinion. MR must have thick skin or more rightly just not care about what people say and say and say..........while he's in an exotic location like China taking photos with the new equipment. I know which side of the ring I'd prefer to be in!  
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dturina
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« Reply #18 on: September 30, 2005, 06:43:10 AM »
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Attacking Michael seems to be the national sport on forums after his essays, as if somehow he isn't entitled to his own opinion. MR must have thick skin or more rightly just not care about what people say and say and say..........while he's in an exotic location like China taking photos with the new equipment. I know which side of the ring I'd prefer to be in!  
I know what you mean, and I know Michael says he has thick skin, but I do feel that unfair criticism really hurts him, which is quite normal. Actually, I would doubt his sanity if he were indifferent to it all, as it is not just criticism, but consists of very malicious personal attacks and slander, most of which would be prosecuted in courts, if Internet weren't such a mess. I stopped writing on dpreview forums because Phil Askey ignored my complaints about venomous personal slander by a user. I just didn't want to be a part of a place maintained by a man who de facto supports such behavior and earns sponsorship money from all the slander generated traffic.

The second part that irritates me are attacks on MR's photography - always and without exception by those who either produce or consume kitsch and cat/dog/child snapshots. I guess photography is subjective, and this leaves room to all kinds of idiotic opinions, but the problem with those people is that they have such immature and primitive taste, that they cannot discern between photography that looks good on 700x500 px resolutions on screen, and stuff that is printed big and hung on a wall, to complement the room atmosphere. I know what kind of stuff they'd call "good" - extreme kitsch, with simplified composition and maxed colors. Well I invite them to hang this stuff in their place, and make it look like Gipsy circus. Whew, I feel better already.
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Danijel
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« Reply #19 on: September 30, 2005, 06:47:19 AM »
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A cropped image from a 150mm lens ultimately can never have the same quality as an uncropped image from a 300mm lens, if both lenses are of similar quality.


I either don't understand this, or don't understand your argument, one or the other. I'm willing to take a further explanation of either.

An APS-C image is NOT cropped. It's the full size of the APS-C. It simply uses less of the lens' circle. So what? The FOV in an APS-C at 200 is the same as in a FF at 300. So what?

The APS-C isn't cropped, nor is it the same thing as a crop, because -- and this is the crux of the question, or the problem -- the sensors are not the same.
John,
Okay! Here's the further explanation. All lenses project a circular image inside the camera. Basically a 50mm lens is a 50mm lens because it projects an image circle 50mm in diameter. A 100mm lens projects an image circle 100mm in diameter, although clearly there are exceptions such as wide-angle lenses. Also lenses can be optimised in the design process for better performance at particular f stops or a specific range of f stops and for better performance closer to the centre than to the edges.

When I use a 50mm lens with a full frame 35mm format camera, the diagonal of the FF sensor (24mmx36mm) is approx 44mm. I'm essentially cropping a circular image 50mm in diameter to get a rectangular field of view with a diameter of 44mm. That's not a sigfnificant crop, but a crop nevertheless.

When I use that same 50mm lens with, say a Canon D60, I'm unavodably cropping the circular image (50mm in diameter) to a much greater degree. The diagonal of the APS-C sensor is approx 29mm. Place a rectangle with diagonal of 29mm against a circle with diameter of 50mm and you should appreciate just how much cropping is taking place.

Now I could keep on cropping that 50mm circle by using an even smaller sensor (such as the Oly 4/3rds sensor), or I could achieve the same effect by cropping the image in Photoshop. There's essentially no limit to the amount of cropping I could do. Want a cheap 1200mm lens? No problem. I'll take a shot with a 1Ds2 with a 50mm lens and crop the 24mmx36mm image to 1mm x 1.5mm in Photoshop. Voila! Same FoV as a 1200mm lens.

I've taken an extreme example, but the principle is sound (unless BJL would care to dispute this  Cheesy ).

However, it sometimes takes an extreme example to clarify a point. I think it should be easy to appreciate that any image so severely cropped to achieve the same FoV as one would get actually using a 1200mm lens is not going to be anywhere near the same quality.

Likewise, one can't expect a 50mm lens on a D60 to produce image quality as good as an 80mm lens on a 1Ds2. Because these two cameras have the same pixel density, there is no image quality advantage for the D60 under any circumstances with any lens that might fit both cameras. There are only image quality disadvantages for the D60.

The notion that a 600mm lens on a D60 is equivalent to a 960mm lens on a 1Ds2 is pure illusion. However, a 600mm lens on a D60 will produce an image of equal quality and FoV after the 1Ds2/600mm image has been cropped in Photoshop to the same size.

Now you might ask, why would one want to crop the 1Ds2 image? Well, if that's your longest lens and you are shooting wildlife there might well be no option. The point here is that nothing would be gained by using a D60 for the same shot. Cropping is cropping, whether it's done by the camera or in Photoshop.
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