rfsIII: There must be an professor of imaging science out there somewhere who can be hired by DPR to write a nice counterpoint article that will untangle this topic and bring sanity to what is essentially a holy war between two under-informed camps. I would start at http://www.rit.edu/cos/optics-rit and work westward from there.
yes you have; and that is the sensor performance at different ISO,that is how the sensor behaves with more amplification of the signal from each pixel. It was not so long ago that most sensors would not be used over ISO 400 as the sensor noise would become very noticeable. So perhaps now with the extremely good performance of sensors at low and medium ISO, your suggestion might seem to be a reasonable test, strictly it is not.
lumigraphics: Sorry but you guys botched a bunch of this. :sigh:
"Total light" is completely unimportant. Yes, there is less light hitting a smaller sensor, but it doesn't matter because its a smaller total area. Light PER SENSEL is the same.
And lenses don't matter at all. Given a frame-filling grey card (as an example) a 50mm f/4 and 100mm f/4 will give exactly the same 18% grey image on any sensor size. If lenses didn't work that way, you couldn't have external light meters.
Larger digital formats aren't less noisy because they are larger so they collect more light, its because they can have a lower sensel density. In the film days, it was because you didn't have to enlarge so much with a bigger negative.
smdh...and I'm only on page 2.
You actually do mention pixels by implication.The moment you introduce the word image there is an implication that pixels are involved. The only useful measure, Equivalency or otherwise, of Total Light is when normalized by the pixel area, otherwise Total Light captured as a standalone metric without the inclusion of number of pixels is irrelevant to the quality of an image with respect to the lens' F-number or sensor size. There is one scenario where Total Light becomes a useful metric and that is where you wish to decide maximum printing size, with equivalent noise and resolution, but this still includes the need to consider pixels.
the problem with your comparison is that now you have introduced a non-optical variable - that is the sensor characteristics.It still remains interesting as a comparison, but not for noise or resolution, unless you wish to compare characteristic between two sensors.
SouthElginDad: I don't understand why "total light hitting the sensor" matters. The image is captured by pixels, not by the entire sensor. It seems to me that total light -- per pixel -- is roughly the same, whether or not there are more total pixels on a larger sensor. (Granted, a smaller sensor may have smaller pixels in order to maintain resolution, but that's not what this article is saying -- it's saying that the total light hitting the entire sensor, regardless of how many pixels are on that sensor, is what matters.)
I get the part about the DoF, that makes sense. But I don't understand why total light on the entire sensor makes any difference.
Well, I still do not understand, or i do but feel there is one missing point.Indeed a larger sensor that uses a lens with the same f-number will capture more total light and true, if you divide that sensor into a high resolution 4-pixel camera each pixel will capture more light, but only by virtue of the pixels being bigger.If the larger sensor has 16 pixels compared to the ½ size sensor having 4, then the light capturing equivalency is the same.
I think the article is confusing when it discusses this as for the photographer is is irrelevant how much the total light the sensor captures, but that for noise considerations it is really the light per pixel that determines the performance.It still comes out that in general a larger sensors has better noise characteristics as, for example the pixel numbers for a 35mm sensor is about 24 - 36 million, while a 4/3 sensor is 16 million, so in real life you do get better performance from the larger sensors as their pixels are bigger.
Timmbits: I'm not on MFT, but MFT sure gets a nice lens.
Bring out a 20mm f1.2 (40mm equivalent) and I might just take a look at the MFTs.
If your equivalency statements are referring to the light gathering performance then you are incorrect. f/1.4 is equal to f/1.4 on any systemIf you are referring to depth of focus then you have a mild argument as a depth of field at f/1.4 or f/0.7 are both very shallow.
Almeida: Is this an editorial change that's here to stay? Will we start to have rumors on DPReview?
I would rather not have DPR cite rumours.I would rather they maintain their tradition of timely newsand early previews.
...soon it might be a two off...as another airframe could possibly be finished