Jack 13088 Loc: Central NY

Amen! The sole purpose of a sensor site (or a clump of silver in film) is to count photons that arrive at the pixel. The bigger (area and thickness) the pixel the more photons it has a crack at catching. Common sense and Physics tells us that! (The only graduate level level quantum mechanics course I was subjected to was exactly 55 years ago this fall so I remember nothing. I can’t reproduce Schrödingers equation let alone conclude anything from it. So let’s go with common sense.) Sensitivity (ISO) and dynamic range improve with pixel area and thickness. Unfortunately, sharpness diminishes with larger pixels. Same with film actually. Pan X is much sharper and finer grain than Tri X.

So an FX sensor has pretty close to twice the area of a DX sensor and for the same millions of of tiny pixels spread over the sensor FX pixels have twice the area hence twice the ISO for the same noise. It also means that if you don’t need or use the increased resolution fewer larger pixels you will be better off with fewer pixels. About ten years ago I did some back of the envelope calculations and proudly announced that 20M pixels was the most you wanted given the widely available optics at the time. The downsampling Gene suggests is fruitful is you are stuck with too many pixels. Actually some of that downsampling or low pass filtering occurs during the de mosiacing processing.

TriX Loc: Raleigh, NC

I’m already “testing” it. Would be irresponsible to turn it over without a proper shakedown 😎

TriX Loc: Raleigh, NC

What are your favorite noise reduction tools Bill? I have the native LR and P/S tools and Nik, but haven’t gone further (haven’t really needed to until now)

amfoto1 Loc: San Jose, Calif. USA

They're already seeing some of the limitations.

Full frame sensors are better able to do high ISOs with less noise because they are less crowded, reducing cross talk between individual pixel sites and better dissipating heat... both of which contribute to noise, especially at "high gain" (i.e., high ISOs).

The individual pixel sites on FF also can be larger and they now often use weaker or no anti-alias filter to better capture very fine detail in images.

Plus, images from FF sensors require less magnification when making a print of any given size, so any flaws in images are also less magnified.

But, as MP count increases, some of these advantages tend to disappear.

For example, the Canon 5DS models are 50MP full frame cameras. Because their individual pixel sites are about the same size and crowded in the same manner as an APS-C camera, Canon chose to limit the 5DS models' high ISO range to 6400 (digitally expandable to 12800). In comparison, the 5D Mark IV with it's much less crowded 30MP full frame sensor offers an ISO range to a high of 32000 (expandable to 51200 and 102400). Or, the APS-C Canon 7D Mark II with is much smaller area, 20MP sensor (that actually has close to the same size individual pixel sites and similar density to 50MP 5DS), has an ISO range with a high of 16000 (expandable to 25600 and 51200).

If you make an 8x12 print from a full frame image, assuming no cropping is done, it will be magnified approx. 8X. In contrast, the same size print, uncropped, from an APS-C camera is magnified about 13X. Any increase in magnification also makes for an increase in the appearance of any flaws in the image for whatever reason... be it digital noise, short-comings of the lens, etc.

There are other things to consider, though...

Full frame sensors are much more expensive to produce. When making either APS-C or FF, they start out with a standard silicon wafer.... which can be used to make 80 APS-C or 20 FF sensors. So in just the most basic raw materials, FF is four times more costly. Further, those wafers used to make the sensors have flaws that cause some loss to quality control. If a wafer has two flaws and that causes two APS-C sensors to be discarded, it's a 2.5% loss. But if the same wafer were used for FF and two sensors don't pass quality control, that's a 10% loss. Some other components of FF DSLRs may also have to be scaled up to accommodate the larger sensor: the reflecting mirror, the AF point array, the pentaprism, the shutter, etc.

Another thing that people often overlook is that FF cameras require FF-capable lenses. APS-C cameras can use both crop-lenses and FF-capable lenses equally. So, in a real sense there's larger lens selection for the crop cameras. Plus, crop lenses don't need to produce as large an image circle as FF lenses, so the crop lenses can be smaller, lighter and less expensive. Even when using a FF-capable lens on a crop camera, there can advantages.... For example, I often use a FF-capable 300mm f/4 lens on my crop cameras. It's comparatively affordable and its size and weight makes it very handholdable. If I were using a FF camera for the same purpose and wanted to be able to frame a distant subject the same way, I'd have to instead use a 500mm f/4 lens that costs 6X as much and weighs more than 3X as much.... so isn't handholdable for more than a few minutes, so also factor in buying and using a good sturdy tripod!

On the other hand, a FF camera has some advantages of its own, besides what's been noted above. Depth of field is different on FF.... Well, actually it doesn't change simply due to the different sensor format. DoF only changes with aperture size, focal length and distance to the object. So long as those all remain the same, there's little difference in DoF. HOWEVER, when you switch from crop to full frame, in order to frame the subject the same way you'll need to either use a longer focal length OR move closer to the subject with the same focal length OR do a little of both.... And this DOES make for shallower DoF effects. So folks often say "full frame has shallower DoF" even if it doesn't really. It's about one stop difference... like using f/2.8 instead of f/4.

There's something similar at the other extreme with small apertures, but once again it's an indirect result of the larger FF sensor. With really small apertures, an optical effect called "diffraction" becomes an issue. This effect robs images of some fine detail. The smaller the aperture, the stronger the effect. But, all other things being equal, FF can "tolerate" about one stop smaller apertures than crop cameras. The reason is the degree of magnification done to the image when making a print of any given size. It's not that there isn't diffraction still occurring, but just that it's less apparent in a less magnified finished product made with a FF camera.

Both FF and crop sensors have progressed and improved a lot over the last 15 or 20 years. Frankly, for most peoples' "real world" uses, an APS-C camera is more than enough and FF is overkill.

burkphoto Loc: High Point, NC

Those are the same things I use. They should be sufficient. Judge sharpness and NR at 100%. Do sharpening last, in your workflow. Amounts of NR and sharpening vary according to ISO, end use, print size, and other factors. They interact... If you need less NR, you can usually sharpen more, and vice-versa.

Bobspez Loc: Southern NJ, USA

Good point. The digital backs for medium format cameras are generally limited to 800 iso, even the newest 80MP models that sell for more than $30,000. I recenty was bidding on ebay on a Mamiya 645D digital body and a Phase One P20 16MP digital back, that eventually sold for just $1600. I dropped out at $700. It suddenly seemed more reasonable to continue to use my Mamiya lenses with an adapter on my 16MP Nikon D7000 which performs decently in low light at iso 1600.

n3eg Loc: West coast USA

Sensor size will always matter as long as people connect it with status.

I feel bad for those people in third world countries who can only afford maybe 12 megapixels...they will never be able to appreciate cat photos blown up to 8 1/2 x 11....feet...

Dennis833 Loc: Australia

I recently purchased a cheap Sony A6000 APS-C camera for a back up when travelling. I tested it against my full frame with a Zeiss 16-35 lens set at the matched focal lengths of 16-24mm. I shot some landscapes with full depth of focus at 100 ISO on a tripod f8 APS & F11 FF. I was surprised when I could not see any difference in the dynamic range. I did another test with a Samyang 12mm shot at F8 and the Zeiss at 18mm F11. I was so impressed by the APS-C files that I increased them in Photoshop 2 x 10% to match the full frame. I would give the edge to the FF but remember the interpolation!

Hal731

As technology improves, sensor size becomes less and less important. Because of my physical condition, I had to start using smaller cameras and lenses. It was no longer fun for me to do photography. I did not like the IQ from point and shoot and bridge cameras. I started using M43 cameras and the IQ was acceptable. After having heart surgery, I have regained much of my strength and endurance. I am still using M43 and the IQ and high iso performance has got much better and is increasingly improving. I certainly do agree that the full frame cameras have much better high iso performance. I have no desire to carry larger cameras with much larger lenses. If I were young and strong, my answer could be different but as sensors get better and better the difference gets smaller.

Hal

moonhawk Loc: Land of Enchantment

lamiaceae Loc: San Luis Obispo County, CA

I rather came up with the same conclusion of 20MP as well. Possibly by different means and a different reason. Seems to me above 20MP on a APS-C Sensor or 46MP on a FF Sensor, Diffraction Limitations become noticeable and annoying. Even now with my 16MP and 24MP APS-C cameras I try to shoot with apertures no smaller than f/8 to f/5.6. In my youth and with film many decades ago I'd shoot at f/16 and f/22 (My Macro Lenses go to f/32). Actually I found somehow that films are equivalent to about 12MP.

burkphoto Loc: High Point, NC

All right on point...

scaltony

There are more than just 2 sensor sizes. The 1" sensor in the high end travel compacts can produce stunning photos. The 2/3 sensor in the compact zooms provide a needed niche for those who want 1200 mm without lugging around a dslr and heavy long lenses. Then there is the 1/3 sensor in the IPhone 5/6/7.