Help judging performance of my FE55z, FE35f2.8z horizon/infinity

Started Jul 5, 2016 | Questions thread
l_d_allan
l_d_allan Veteran Member • Posts: 5,087
Re: Full sized images

JimKasson wrote:

These are full frame. Sorry for the earlier error. Comments?

Non-IQ comments (as I have negligible experience with using "tilted near-infinity horizons" (TNIH) for "good copy vs bad copy testing" (GCVBCT):

  • Odd that when you click on the image itself, you get use of the Loupe, and can view much closer than when you click on "Original Size". Has DPR always been that way? "Original Size" is not nearly 1:1 pixel peeking, and neither does the Loupe. Any idea what the viewing ratio is with the Loupe with a7Rii captures of 7952 horizontal pixels?
  • Since you don't care whether the sky blows out or not, seems like you could use a longer exposure ... the EXIF shows EC of -1.3 EV. Do recall if you used "A" mode with EC, or "M" exposure with EC ignored?
  • However, "Sunny 16" with ISO 100 would be 1/3200s at f/2.8, so you clearly didn't use "Sunny 16" (if I did the reciprocity correctly). 1/2000s is actually about +0.7 EV, so perhaps the EXIF value of -1.3 EV reflects where the EC dial was?
  • Do you recall if you used UniWB with Zebras to decide on exposure? If so, what Zebra setting ... I use 100+? Was the sky blinking or not? Or did you back off a click or so from the tree leaves blinking?
  • ...
  • I don' t have that lens, so have no basis of comparison on what the center, near edges at the APS-C off-axis, and extreme corners should look like.
  • I also don't enough experience with TNIH to comment on perceived IQ.
  • We apparently differ on whether validly done TNIH captures tends to be better, worse, or about the same as a validly done brick wall IQ test for GCVBCT.
  • How far away would you estimate the tree line is at the horizon? Half mile? Full mile? Less? More? Ever actually stepped it off, if that would be feasible?
  • What magnification of focal length would your estimate work out to be? 1000X or greater? Much greater?
  • It wouldn't surprise me if you have a laser range estimator with at least a high degree of accuracy.
  • If so, have you checked out how far trees at the "left horizon" are vs the "middle horizon" vs "right horizon"? My experience is there is a definite "learning curve" to estimating distances, but with practice you can get pretty good at it ... such as golfers and hunters.
  • Are those distances within +/- [fill-in-the-blank]?
  • ....
  • OT?
    I've been pondering how much "field curvature" and "focus shift when stopping down" (which this example doesn't do) really matter with the relatively large DOF of a f/2.8 lens and relatively wide 35mm FL. Even with a very small CoC, I doubt even a large print or the DPR Loupe would have these issues be noticeable ... if you print full frame.
  • However, those issues seems maybe relevant for non-IQ test images if you need to crop the image for a print or upload ... then the effective CoC can be truly minuscule.
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