Quote:
Originally Posted by PeterEde
If you understand this already please ignore. Just seen a lot of people get caught in this myth.
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Sorry, but I'm one of those who do
not understand this. Could be because I'm not a reputable camera dealer cause I'm not a camera dealer
Quote:
Originally Posted by PeterEde
Crop factor magnification is a furphy. It's an illusion. Nothing can increase the focal length of a lens.
What crop does is actually reduce the FOV of your lens compared with fullframe.
So you are actually getting less use of your EF lens.
It's what some less reputable camera people use to sell crop frame cameras.
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Looking at the magnification issue alone, isn't that a bit like saying "by using a 24mm eyepiece you are getting less use of your scope than with a 32mm EP"? I think when comparing full frame with smaller sensors, a change in magnification in the final image is anything but an illusion in the vast majority of cases. In fact, only when the number of pixels per area unit - the pixel density - on both sensors is exactly the same does the "illusion" argument apply. Good luck finding a FF camera with the 7d's pixel density. You'd be looking for a body pushing 30MP. Hardly a practical comparison.
APSC (or "crop") sensors tend to have smaller pixels than full frame sensors. Smaller pixels resolve finer detail (provided the lens used is sufficiently sharp, and that can be a real bottleneck
). So if the optics are good AND there is sufficient light reaching the sensor, I'm not convinced that the 7d will not resolve finer detail than most FF cameras available to mortals today - at the same focal length. I call that higher magnification of a given feature because of the crop sensor. Not because crop sensors are smaller, but because they have a higher pixel density. For an eclipse specifically, it stands to reason a crop sensor is actually the better choice over full frame plus x1.4 extender using the same lens. The extender slows the lens down & introduces extra glass, the smaller sensor may introduce more image noise at the same ISO setting, but doesn't need the same setting because of the faster f ratio.
However, I do agree that saying the magnification factor of APSC sensors is at x1.6 is a bit misleading and only applies when looking at the photo as a whole, not the features in the photo. Most of the time, the factor is something other than 1.6. For instance comparing the 7d with, say, the 6d, it would be around x1.5 I expect. That's the ratio of the respective pixel sizes (6.54µm:4.3µm). I also agree that crop sensors aren't always desirable in the field due to higher image noise in low light and, yes,
magnified lens aberrations.
Bottom line: Go for it Duniac, the 7d does magnify
, it will not disappoint, and it's certainly no worse for this purpose than most full frame cameras.
Other thoughts appreciated.
, and Australian observers should send their reports to me at
