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I have a Canon 600D with a Canon 70-200 f/4L (non IS).

Now, when it's sunny and bright the images are splendid, but as soon as it becomes a tad cloudy and gray, noise and grain starts to become visible. (This, on a 27" Thunderbolt display, at 13" its not visible). I am no stranger to my cameras settings in manual mode, so I do not believe that that's the issue here (though tips and tricks are more than welcome).

Will a upgrade to the Canon 5d Mark II help here? I've been thinking about it for a long time and it makes sense. 16% more pixels, higher ISO without noise and, if you can think about it this way, with full frame, the IQ should look better on a large screen due to the larger image(?)

  • 3
    If you're going to ask about image quality, you should show an example image. – Caleb Sep 21 '16 at 13:56
  • What ISO are you using when the issue is visible? – Aganju Sep 21 '16 at 14:00
  • Could be as low as 800. As I said, It looks just fine on a 13" laptop. – Tindra Sep 21 '16 at 14:03
  • Are you viewing the images full screen on the 27" display? – Michael C Sep 21 '16 at 14:52
  • Yes, so they are quite big! – Tindra Sep 22 '16 at 6:01
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Will Full Frame solve this?

Probably not. Nothing can make image quality as good as you'll get in bright sunlight when there's less light. But it will help by about one stop in terms of signal-to-noise ratio.

Ultimately if the scene is two or three stops dimmer then you have to open the aperture or slow the shutter time by the same two or three stops to get the same amount of light on your sensor. Using a FF sensor vs. a 1.6X APS-C sensor buys you one of those stops.

How much that will improve the way your images look on the 27" Thunderbolt Display is hard to say. That's a very high resolution monitor with very precise color differentiation that will show the flaws in a lot of images that lessor displays will not.

If you do decide to make a move to full frame I'd strongly urge you to consider the 6D or even the 5D Mark III. The 6D is every bit as good a camera as the 5DII other than the fastest shutter speed of 1/4000 second vs. 1/8000, a flash sync speed of 1/180 vs. 1/200 second, and no user configurable Custom Exposure modes. The 6D also has a slightly better AF system (11 vs. 9 AF points functional to EV-3 vs EV-1.5), a better exposure meter (63 zone dual layer vs. 35 zone), a DiG!C5+ vs. a DiG!C4 processor, wider EC (+/-5 stops vs. +/-2 stops), more flexible AEB (2, 3, 5, or 7 shots at +/-3EV vs. 3 shots at +/-2EV), Multi Shot Noise Reduction, in-camera CA correction, multiple exposure, in-camera HDR, in-camera resizing and RAW processing, a faster max fps (4.5 vs. 3.9), a deeper buffer (1250 JPEG/17 RAW vs. 310 JPEG/13 RAW), and a shorter shutter lag (<60ms vs. 73ms).

The 5DIII is on an entirely different level in terms of the AF system and also has everything the 5DII has and a lot more. Of course it also costs a little more, but having shot extensively with both the 5DII and the 5DIII I can say the 5DIII has slightly better image quality than the 5DII but is a lot more camera in every other way. With the recent introduction of the 5D Mark IV, now is the time to find a deal on a 5DIII, new or used. Unless you manually focus everything the AF system alone is worth twice the price difference.

  • I have the 6D, and especially the low-light capabilities are outstanding. You can go to ISO 12800 without any noise. – Aganju Sep 21 '16 at 15:38
  • @Aganju Probably not if you're over sharpening and displaying on a very high quality 27" monitor and aren't happy with APS-C images shot at ISO 800. – Michael C Sep 21 '16 at 15:39
  • The 6D seems like a good choice I agree, but its more than twice the price since I can find used 5DII everywhere. Still, would 5DII be a good upgrade from 600D? It does feel like it, both in terms of AF and IQ (?) – Tindra Sep 22 '16 at 6:06
  • Aren't there used 6D and 5DIII models as well? Considering that the price for a new 6D is about $1250 right now the used ones have to be cheaper than that. A new 5DIII is currently $2100! Get them while they last! This will drive the price of used 6D and 5DIII down as well. They're both better enough over the 5DII that I think they are worth the extra unless you will never use autofocus, and I've put more clicks on my 5DII than any other camera ever. – Michael C Sep 22 '16 at 7:36
  • The 5D Mark II is a great camera, but the AF system is slooowww, inconsistent from shot-to-shot, and it has trouble focusing in very dim light - sometimes the same light in which the 6D and 5DIII can focus. Image quality is outstanding, but the 6D and 5DIII are both better in terms of IQ and AF. – Michael C Sep 22 '16 at 7:41
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The digital chip is covered by an array of photosites. During exposure, these are bombarded by photon hits. The number of hits received is proportional to scene brightness. Each hit induces a charge into the photosite. Sequent hits elevate this charge. Nevertheless, at the end of exposure the charge is too feeble to be useful.

The mechanism of imaging hardware and software is to amplify this charge to a suitable level. Signals that are amplified will gain noise. This is analogous to static in an audio system.

In other words, amplification boosts the good signal but it also induces noise. The countermeasures are, lower amplification via elevating scene brightness, or use of a faster lens. The idea is a lowered ISO setting requires less amplification.

A larger imaging chip offers larger photosites. Larger photosites have a larger capture area that naturally accumulate more photon hits. More hits during the exposure translate to a lowered need to amplify, thus lowered noise.

Note: Time marches on and tomorrow's imaging chips will be improved. Future cameras will sport smaller imaging sensors.

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