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06-07-2019, 12:25 AM   #16
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A rectilinear 16mm on APS-C should give the same field of view as a 24mm on full frame. But my Zenitar 16mm on APS-C gives a field of view significantly wider than my 24mm on full frame and closer to my 20mm. I think of it as roughly equivalent to a 14mm rectilinear on APS-C.

The Zenitar defishes extremely well using the PT lens plugin, and I've often used mine as if it was effectively a rectilinear. But for astrophotography I expect defishing would produce a slight smearing effect on stars towards the corners, although it should work fine if you don't intend to defish.

Note: The quality of the results from defishing is very dependent on the software used for the job. The only plugin I've tried that really works for me is PT Lens.

Last edited by Dartmoor Dave; 06-07-2019 at 12:38 AM.
06-07-2019, 05:48 AM   #17
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QuoteOriginally posted by kypfer Quote
You've done your arithmetic incorrectly. On your K-5ii, with it's APSC sensor, the 14mm will be a "21mm-equivalent" and the 16mm will be a "24mm-equivalent", assuming comparison to a full-frame 35mm camera.
This is true except that the fisheye has a much wider FOV (180 diagonal on 24x36mm FF) for its focal length than a rectilinear 16mm (~ 107 diagonal on FF). The 1.5 crop factor equivalence does not work well in this case.

06-10-2019, 01:29 PM   #18
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The 14mm is great in my experience but I ended up returning mine because of decentering problems. I haven't heard of such issues with the Zenitar.

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