Re: Canon Rebel T4i/650D on June 8, 2012? [CR2.5]
Chewngum said:
paul13walnut5 said:
@Chewngum
the current 18MP sensor is terrible. Not event my best resolving lens produces sharp photos on my 7d, whether it is the AA filter or the sensor itself,
Either your best resolving lenses aren't as sharp as you think, or you haven't set the camera up properly, or you can't use DPP or photoshop. 99% of 7D IQ moans are from people who would have been better sticking to rebels. The 7D is a camera that needs set up. Full stop. Set it up. Learn it. Tweak it. Much like the 1D users have been doing for years, and you'll get further. Expect it to behave like a rebel or x0D and you really have wasted your cash.
Nikon users have enjoyed, and enjoy to this day, better JPEGS out the body, price for price point.
Canon users have benefitted more from proper RAW processing, particularly sharpening and luma channel NR.
The 7D gets a poor rep on some forums. I think users who buy a camera designed to give you choices and to be set up and who fail excercise those choices or to spend time setting it up are the real problem.
My sharpness testing was done using macro lenses, far outresolving the sensor, MF, tripod mounted etc... I have tweaked every single setting of the camera to my specifications. Took 2 years to get the settings right. Don't get me wrong its a great camera for everything other than sharpness and contrast. Just imagine the 7d with the 16MP Sony sensor thats in the d7000, that'd be a killer camera. I defended the 7d for a while because i owned one but now i accept that if I'm going to need 100% crops then I won't use it, my 50d and 40d produce more detail than it despite the MP drop. Its just a half done camera, even if they put the 40d sensor in it I'd of been happy, but the 7d sensor does not wow in any way...its adequate but could have easily been so much better. Sharpness is achievable with the 7d, but only when you downsize.
I think its funny that you 100% assume user error, God forbid a person doesn't have the same standards as you and actually isn't happy with what you're happy with. I sold my 7d because i gave it enough time but i can repeatedly get better results with much cheaper options.
You don't understand spatial resolution, or what it means to "resolve". A macro lens
MAGNIFIES...but that does
NOT mean it
outresolves a sensor. The 7D is a very high spatial resolution sensor, about 116lp/mm. That is not the highest resolution ever...there are 24mp APS-C sensors that reach around 128lp/mm, and some rare films have reached a few hundred lp/mm. Assuming an MTF @ 50% contrast (pretty standard for evaluating photographic IQ), you would only be able to resolve 116lp/mm at apertures wider than about f/6, and then, you would have to assume your lens was
diffraction limited at that aperture (i.e. a "perfect" lens at that aperture.) Most lenses are aberration limited at very wide apertures, such as f/2.8 and wider (even if they are extremely sharp lenses, its very rare to find a near-perfect diffraction-limited f/2.8 lens, and when you do, they are extremely expensive.) Some lenses are aberration limited past f/4, and many consumer-grade lenses are aberration limited down to around f/8! Optical aberrations tend to degrade IQ much more than diffraction, and by f/8, diffraction is going to explicitly limit your resolution to around 86lp/mm.
The problem is not the 7D...outside of a rather narrow band of apertures between around f/4 to at most f/6.3 your resolution is limited (depends on the lens...ultra high end superteles will often be near-perfect close to their maximum aperture, although you certainly PAY for that quality). Within that narrow band of aperture settings is the ONLY time you will be able to fully realize the potential of the 7D's sensor. At any apertures outside of that narrow band, and the 7D sensor is going to be outresolving the lens, and at 1:1/100% crop things are going to look soft. That is NOT a bad thing, though...it actually makes it easier to clean up noise and sharpen, as such artifacts are sub-detail level at that point!
That isn't all, though. The more dense the sensor, the more sensitive it is going to be to camera shake. Even on a tripod, slight vibration from wind, or the very slight tug of a cable release that you might be holding in your hand, can introduce enough camera shake to slightly blur your photos. As camera sensors like the 7D's continue to get more and more sense, lens functionality like IS will become more and more important, at shorter and shorter focal lengths, to help ensure camera shake does not blur fine detail.
Neither the 40D nor the 50D produce more detail...it is simply that the detail they are capable of recording is intrinsically sharper as a consequence of lower spatial resolution. That would be one of the benefits of LOW resolution and LARGE pixels...less detail, but that detail is PERCIEVED as sharper "strait out of the camera". Its a matter of perception...but all things being equal, the 7D will
trounce them on an actual "fine detail" level as it
does offer significantly more spatial resolution than either of those two cameras. A moderate amount of post-process sharpening will usually enhance a 7D photograph significantly, enhancing those finer details more, producing a photograph that is superior on a detail level to anything the 40/50D could produce.
So to be frank @Chewngum, as a satisfied 7D owner myself, you need to educate yourself before you make wild claims about how "crappy" something like the 7D's sensor really is. For your own sake, you should make sure you fully understand what it means to "resolve", what spatial resolution is and what magnification is, how those two differ, how lens and sensor resolution combine to produce the actual spatial resolution of a photograph, and what the benefits and tradeoffs of higher density sensors are relative to lower density sensors.
Resolution and detail are not the issues. The 7D excels in that area. The issue is, quite simply, electronic noise. The only real edge SoNikon have over Canon is Exmor, and its extremely low electronic noise across the board. That is ONLY an issue in the bottom two stops of ISO settings...at any other setting, Canon and Nikon are equivalent, as noise at that level is really a matter of physics.
