« on: October 22, 2012, 04:59:01 PM »
You still have a very skewed idea, or simply bad terminology, in describing what you are actually experiencing with a TC, though, Lee Jay. Your previous argument in that other thread, that the virtual image of the sensor shrinks when it is observed by looking through the lens into the camera is not indicative of what is really occurring. A teleconverter does not change how many megapixels you have, nor does it change the resolution of the lens.
No, but it has the same effect as doing either one.
As we discussed in our last debate, the spatial resolution of whatever is projected by the lens, as well as the spatial resolution of the sensor, are pretty limited. If you use a TC or multiple TC's that reduce your aperture to f/8, then according to the laws of physics spatial resolution becomes limited (specifically to around 86lp/mm), which is WELL below the fixed luminance spatial resolution of pretty much any APS-C sensor these days.[/quote]
f=1/(0.00055* = 227lp/mm at MTF = 0. Using MTF=50, as you did above, is arbitrary and of little value in this context.
Spatial resolution is not increasing, magnification is increasing.
Same thing, since the optics (the lens) didn't change.
I think what you are doing is accounting for the "entire" size of your subject. If you magnify a part of the moon such that only that one part fits on an 18mp sensor, the "effective size of the whole moon if it were to be measured in megapixels would require a 184mp FF sensor to image in it's entirety." You could look at it that way, but it is extremely confusing, and running about stating "It's like having a 369MP FF sensor" is not really true, and I WILL argue that point whenever you bring it up.
That's fine, and you'll be wrong each time. This is the way people do it in astrophotography, where resolution is what you are after. "Image scale" is determined by arc-second per pixel, and the lens is measured by aperture diameter. TCs leave the aperture unchanged and decrease arc-seconds per pixel. More pixels leave the aperture unchanged and decrease arc-seconds per pixel. Same thing.