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Could someone help me understand this technology better? If you attach, say, a full-frame 35 1.4 to it:
- I assume it will have the field of view and Dof as if you had attached it to a full frame camera?
Yes! You will get use of the full image circle, that gets diminished to only cover APS-C.
- Does using the Speed Booster actually result in more photons of light striking the NEX APS-C sensor than without the SpeedBooster? i.e, is it actually "faster" (from a light gathering perspective) than using that lens on NEX without an adapter?
Yes! The converter shortens the focal length while the entrance pupil stays the same.
- Is that number of photons essentially the same amount that would strike the sensor if you attached the lens to a full-frame camera? So from a light-gathering perspective, it's not "faster" than a full-frame f1.4, it's the same?
Yes! You will get as many photons in total as if you used the lens on FF. Which means about one stop more on APS-C than usual with the same lens.
What you get is a device that makes up for the smaller sensor, but at the cost of some optical aberrations, I presume. Could be very well worth it since there are no FF alternatives to a NEX with manual focus lenses for example.
Edit: A tele converter works the same but in the other direction. Instead of using a smaller sensor, the image circle is enlarged by extending the focal length, and thus the aperture gets smaller since the entrance pupil stays the same. This thing does the opposite.
Edited on Jan 14, 2013 at 05:43 PM · View previous versions