All this talk about "equivalence" is silly

Started Jun 10, 2011 | Discussions thread
Great Bustard Forum Pro • Posts: 40,064
Part II

Like I shot wildlife I want the that 1.6 crop and as long of good lens I can buy, at first I got a bigma 50-500mm f6.3 lens, but then added a canon 300mm f4L none IS, and just looking at the math the bigma wins easy.

But in real life the 300mm was super sharp and a AF that nail it every time, that means it could be pushed much more, so I then got a 400mm f5.6L prime, and am very happy with it, I then upgraded from a canon 400D XTi 10 mp.

To a canon 50D 15 mp for even more reach, it's also why most others doing wildlife got a new 7D, on the other hand wedding photog's use mostly FF, as far as how fast of a lens most buy as faster as funds let them.

None of that has anything to do with Equivalence, I hope you know.

Not many people think in terms of what they need in FF then ho to convert it to a crop, their is no need for that anymore like I pointed out before, and my other points was about trying to convert how fast a lens would need to be from a FF.

I believe I said this before:

h ttp:

Equivalence is only relevant when comparing different formats.

If you're not comparing different formats, no need to invoke Equivalence.

To make the same image on a crop digital, and I was trying to point out, it's not really needed because chip sets and software, as well as jumps in hardware, has taken care of that for the most part.


So it's simple a 1.6 crop factor is and was the best way to put it, that is after all why makers like canon called it a crop factor, and not come out with some big theory, to help everyone under stand it all, they are the designs with inside info on all of it.

I guess you missed this as well:

h ttp:

  • Equivalence is a framework for comparing the IQ of different formats on the basis of five parameters (perspective, framing, DOF, shutter speed, and display size), which all directly relate to the visual properties of the final photo, and are independent of the technology. In addition, the same amount of light will fall on the sensor for Equivalent photos, which will result in the same image noise for equally efficient sensors.

  • Consider two cameras with sensors that had the same efficiency and pixel density, but one with a sensor twice the size (four times the area) as the other. If we were to shoot the same scene with each camera from the same position, using the same lens and camera settings, crop the middle 25% of the photo from the camera with the larger sensor, then the resulting photo would look exactly the same as the photo from the smaller sensor camera if displayed at the same size.

  • Alternatively, if the sensors had the same efficiency and same number of pixels, but the larger sensor camera used a perfect 2x TC (teleconverter) with the same lens used on the smaller sensor camera, and shot the same scene from the same position with the twice the f-ratio and two stops higher ISO, then the resulting photos from the two cameras would be exactly the same.

The bottom line is that you criticize Equivalence because you don't understand Equivalence, and the reason you don't understand Equivalence, is because you don't even know what it says.

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