Now, the next BIG contest is ON!
in [Digital Cameras]
|
Prev: Here Comes the 3-D Camera: Revolutionary Prototype Films Worldin Three Dimensions
Next: Why the Nikon Coolscan V ED is so expensive event on vintage market ?
From: Kyle Abhams on 15 May 2010 13:15 On Sat, 15 May 2010 06:59:27 -0700 (PDT), DanP <dan.petre(a)hotmail.com> ignorantly trolled everyone with the following stupidity: > >No, I do not think of camera design at all. >Instead I think of binoculars and telescopes where the bigger lens >diameter gives a better IQ. To edify the DanP-Troll's learning experience: In telescopes, yes. Because those lenses and mirrors are figured to diffraction-limited quality. You will not gain any image quality with diameter increase unless your optics are figured to diffraction-limited precision. With errors in the total curvature across the whole surface usually less than 1/10th the average wavelength of light. Some even consider that error too much and strive for 1/20th or 1/50th a wavelength of light. Since the objective in telescopes is comprised of only one element (or single group, as in the case of an achromat), this makes having that quality available at a price that is affordable--but still very expensive. In binoculars, no. The extra steps needed to figure lenses and prisms to that quality (where diameter means an increase in resolution, light-grasp yes, resolution no) would put all binoculars outside of the financial reach of every average consumer. The amount of magnification used in binoculars doesn't warrant it--considering that human eyesight resolution is all that will receive the image, with hand-held image shake thrown in for good measure too. (Except for the few that digi-scope with binoculars.) In larger camera lenses for sensors with large photosites, no. Again the price to bring them to the quality where larger diameter will afford more resolution (diffraction-limited) would put them outside of the range of any purchaser. Just one 90mm achromat alone could cost upward of $500 if made to diffraction-limited quality. Now imagine that cost multiplied by how many elements are in most modern DSLR lens designs. With each surface of every individual lens element requiring figuring to that precision. Any figuring errors away from absolute perfection also being multiplicative. Errors in one lens surface exacerbated by errors of the next. The size of the photosites matters too. Since they are large there's no need for mating them with diffraction-limited glass. Manufacturers will not take the extra expense involved to create a level of precision that you don't require and that you would never be able to detect. DSLR sensors are not like film, where resolutions of 2um (micron) were often the goal (the size of the silver grains). When all your sensors have 2um, or lesser, size photosites then you'll be able to tell if your lenses are of higher quality or not. This is why diffraction-limited quality lenses are made regularly for P&S cameras. That much resolution is required or they wouldn't be able to resolve details down to their ~2um size photosite levels. Their small lens diameters needed makes that an affordable fabrication option. The amount of manufacturing effort to hold a surface to a precision of 1/10th, or better, the wavelength of light across 30mm is relatively easy compared to trying to hold to that level of precision across a distance of 90mm. The effort (reflected in financial cost) is exponential to diameter. This is why it required $450,000,000 in manufacturing costs to create just *ONE* diffraction-limited surface across a 2.4 meter diameter area on the Hubble Telescope mirror.
From: R Davis on 15 May 2010 13:40 On Sat, 15 May 2010 09:55:43 -0700, Paul Furman <paul-@-edgehill.net> wrote: > >The only advantage is smaller size and cost. The DSLR can always stop >down for the same DOF. No it can't. Unless you can increase the ISO enough or use longer shutter speeds. The 2-3 stop noise-free advantage of ISO in a DSLR doesn't equal the 4-5 stop aperture advantage of a P&S lens at long focal lengths. For macro-photography, tele-macro methods on a P&S camera can't be beat. Longer shutter speeds might require a tripod, whereas a P&S camera can be used hand-held under the very same light conditions due to the larger apertures available at long focal lengths. Stopping down your lens will also increase diffraction artifacts. A P&S lens can do the same DOF with the lens wide open. You really don't have much experience with any of this, do you. That fact has been adequately reflected in every image you've ever posted.
From: nospam on 15 May 2010 13:46 In article <jkmtu5t6rjim2jvu44uc7c67d5rct7m2d0(a)4ax.com>, R Davis <spamless(a)anon.com> wrote: > > > >The only advantage is smaller size and cost. The DSLR can always stop > >down for the same DOF. > > No it can't. yes it can > Unless you can increase the ISO enough or use longer shutter speeds. which it can > The > 2-3 stop noise-free advantage of ISO in a DSLR doesn't equal the 4-5 stop > aperture advantage of a P&S lens at long focal lengths. there is no 4-5 stop advantage in a p&s lens > For > macro-photography, tele-macro methods on a P&S camera can't be beat. Longer > shutter speeds might require a tripod, whereas a P&S camera can be used > hand-held under the very same light conditions due to the larger apertures > available at long focal lengths. increase the iso, keep the shutter speed the same. > > Stopping down your lens will also increase diffraction artifacts. A P&S > lens can do the same DOF with the lens wide open. bigger pixels on the bigger sensor nullifies that one. > > You really don't have much experience with any of this, do you. That fact > has been adequately reflected in every image you've ever posted. nor do you
From: DanP on 15 May 2010 13:53 On 15 May, 16:34, Bruce <docnews2...(a)gmail.com> wrote: > On Sat, 15 May 2010 06:59:27 -0700 (PDT), DanP <dan.pe...(a)hotmail.com> > wrote: > >No, I do not think of camera design at all. > >Instead I think of binoculars and telescopes where the bigger lens > >diameter gives a better IQ. > > Does it really? Do binoculars and telescopes really offer better IQ > than camera lenses? I am not saying that. I said the bigger the lens diameter the better IQ is. > Can you recommend a reference where I can look at like-for-like > comparisons? Hard to do that since IQ in photography is a result of many factors. But I notice that larger aperture lenses have bigger optics. A picture is worth a thousand words so I made this sketch http://www.flickr.com/x/t/0097009/gp/danpetre/4zwQ1r Same focal length, same sensor size, more surface area for bigger lens increases the amount of light directed onto the sensor. Plus an imperfection of the same size would have a worse effect on the small lens > >> Don't you mean a D3X? The D3s is only 12 MP. D3X has 24 MP. > > >My Canon 500D has 15 MP but I use it at 8 most of the time. > > Why? File size gets smaller and I don't zoom in to notice the difference. I would use 15 MP if lens zoom was not enough and crop later. The price of a D3X is almost double of a D3s. I am sure the people who buy the D3X have serious reasons to prefer it. Some people actually buy a Phase One and some people settle for a compact even if they have the money for a DSLR. Personal preference. > >http://www.dxomark.com/index.php/eng/Image-Quality-Database/Compare-c... > > An interesting comparison, thanks for the link. DanP
From: R Davis on 15 May 2010 13:55
On Sat, 15 May 2010 13:46:00 -0400, nospam THE TROLL <nospam(a)nospam.invalid> wrote: >In article <jkmtu5t6rjim2jvu44uc7c67d5rct7m2d0(a)4ax.com>, R Davis ><spamless(a)anon.com> wrote: > >> > >> >The only advantage is smaller size and cost. The DSLR can always stop >> >down for the same DOF. >> >> No it can't. > >yes it can > >> Unless you can increase the ISO enough or use longer shutter speeds. > >which it can > >> The >> 2-3 stop noise-free advantage of ISO in a DSLR doesn't equal the 4-5 stop >> aperture advantage of a P&S lens at long focal lengths. > >there is no 4-5 stop advantage in a p&s lens > >> For >> macro-photography, tele-macro methods on a P&S camera can't be beat. Longer >> shutter speeds might require a tripod, whereas a P&S camera can be used >> hand-held under the very same light conditions due to the larger apertures >> available at long focal lengths. > >increase the iso, keep the shutter speed the same. >> >> Stopping down your lens will also increase diffraction artifacts. A P&S >> lens can do the same DOF with the lens wide open. > >bigger pixels on the bigger sensor nullifies that one. >> >> You really don't have much experience with any of this, do you. That fact >> has been adequately reflected in every image you've ever posted. > >nor do you Nospam, it's already been proved time and time again that you've never even held one camera in your whole lifetime. You only parrot what you read from other equally ignorant trolls like yourself. Your comment about bigger pixels and diffraction only confirms this, yet again. |