nbaronzzi wrote: freaklikeme wrote:
Here's a great resource for patent information that gives actual tested focal lengths and, in some cases, you can see the lens as tested both at infinity and MFD.
...is a 72-194 f/2.88 at infinity. If you advance through the scenarios using the buttons in the top right corner, you'll see it's a 66.71mm f/2.9-126mm f/3.0 at close working distance. You can also see the distortion and SA graphs by pushing those buttons in the middle-right of the options.
It's not a comprehensive list, but it does take the guesswork out of the venture. Plus, it's fun to see all the optical drawings.
Wow, visualizing the position & movement of the element groups and their effect on transmitting light is super cool. The 'Optics Primer' page is also very thorough. Bookmarked for future reference; thanks for this!
Happy to share the find. If you pano at all, you can use it a reference to help find the no parallax point on which the lens should rotate. It'll show you the entrance and exit pupils and the point will be very close to the exit pupil. It can be helpful if the lens is on there.
Jun 26, 2025 at 06:53 PM
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