Chris S.
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 p.1 #10 · Report: Megadap vs. Viltrox Sony E to Nikon Z adapters On Sigma 14mm f/1.4 lens/Nikon Z8 | |
DWOfPaul wrote:
Have you gotten a chance to try the FotodioX adapter?
The Fotodiox looks and feels first rate. I have "tried" it, but can't yet claim to have "tested" it. Rather, I've discovered a couple of test regimes that don't work very well for me. Two attempts at using landscapes placed the small details I care about in pixelation territory, which told me very little. Possibly, with another attempt or two, I could place fine details to be rendered just a bit larger than where pixelation occurs, which might tell me something about the two adapters. But would this predict what stars will look like, when they are pinpoint-or near-pinpoint light? I'm doubting it. At very least, pinpoints of light would help in recognizing what sort of aberration we're trying to correct for.
So I tried with the artificial star--this one 50 micrometer diameter, placed at 65-70 feet away from lens. Found two problems with this. A big one is that at this distance, the lens is still not focused out to infinity, so I don't know if such testing will predict infinity behavior of the lens. A friend has showed me how to contrive a setup that puts the artificial star at optical infinity (with the help of another lens, arranged backward) without being all that far away, so that is the next job on my list.
Another problem is an effect of Bayer filtration, and how cameras and raw development software--having only red, green, or blue information for a given photosite--"guess" at what colors to fill in. With the (white) artificial star arranged to be very small in my test, this color guessing was disastrous and gave me a useless mess of false color smeared across a number of pixels with no clear "star." So after I cobble together an infinite arrangement for the artificial star, I'll need to test different star diameters (one pixel, 2x2 pixels, 3x3 pixels, etc.) to see what is most illustrative.
Perhaps then I can test more systematically.
Remembering that I want to eventually test different thicknesses/indices of refraction of glass between lens and sensor, I really want a repeatable and robust testing approach. So, as frustrating as the "pilot runs" have been, they have likely been helpful in moving slowly forward.
Thanks for the interest and help. Stay tuned!
Pomanferrari wrote:
I use the Megadap with a Z9 and Sony 200-600 for videos (8K50 raw video). It's about 80-90% of the focusing speed and accuracy compared to my A1. Having bad experiences with adapters going back 20 years, I'm happy with the MegaDap.
I suspect lenses such as your 200-600, which likely has its light cone much more narrowly entering the camera, create far fewer problems for optics-free mechanical adapters, than do very fast, very wide lenses, where the light cone is much wider. Lenses such as my wide angle probably send a lot of low-angle, "glancing" light, especially to the corners of the frame, which much pass through more of the camera's sensor stack. This is perhaps why sensor stack differences between cameras tend to cause more problems with very wide angle lenses, especially fast aperture ones. At least that's my current thinking.
Cheers,
--Chris
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