SEL1670Z samples on the tripod

Started 7 months ago | Discussions thread
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stoppingdown
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SEL1670Z samples on the tripod
7 months ago

I have to anticipate that I wasn't able to test everything I wanted to do, for three reasons: 1) today I was supposed to enjoy a copious and long dinner with my family 2) when I went out and got to the place I had choosen, I wasted quite a long time to find a park for the car (lots of people around) and 3) in spite of being small gear, my NEX-6 attracted quite a few attention and people asked about it (and to look in the EVF), so I had to restart from scratch the test sequence many times... In the end there wasn't time for doing everything.

My intention was to test the same subject on the tripod, hand-held with OSS, hand-held without OSS and compare with my Nikon gear. I was able only to test on the tripod (and, as I said, I wasn't in the proper relaxed conditions). Sorry for that. I'll try to redo it as soon as possible.

Anyway, if you don't mind, I'd like to share at least what I did, so I can collect some feedback (and eventually use it at the next iteration).

First, test procedure:

  • tripod
  • OSS off
  • auto-focus on the subject (the large green window) at the centre of the frame
  • take one shot
  • switch to manual focusing, without touching the focusing ring further
  • since the NEX-6 doesn't guarantee that it doesn't refocus while you're switching to manual focus (the operation is not a single button pressure), re-take another shot at the center to confirm that nothing changed
  • turn the camera to place the subject at both borders and shoot
  • each shot is indeed a burst of 3/4 shots, from which I picked the best one

I know that some people think that focus-and-recompose could not achieve optimal focus, but in this case we're looking always at the same target, whose distance of course didn't change.

My evaluation from the samples I took today:

  • my lens sounds good enough (I can see decentering, but I think it's reasonable - with the exception of 24mm, where I see a strange thing, but I suppose I've done something wrong)
  • in all cases at least one border is decently sharp (of course, it would be nice to have the other border as sharp...;-) ) - let me know what you think
  • so far, my evaluation of the lens is good for what concerns sharpness - but there's something that makes me curious (see below)
  • hell for the fact that I wasn't able to test hand-held in the same session: compared with my previous tests these on the tripod looks sharper - so, perhaps the OSS is really the responsible for the softer borders that people are complaining (plus some copy variation, of course)

These are the results per focal:

  • 16mm: right border softer
  • 24mm: right border much softer (hmmm possible error of mine here)
  • 35mm: right border softer
  • 50mm: right border slightly softer
  • 70mm: left border softer

This is consistent with my previous round of tests: the decentered border is the right at shorter focals, they tend to equate at 50mm and beyond that the softness goes to the left border.

What does make me curious? Look at the sample @70mm, for instance. If I look at the green window, they look almost the same. If I look at the merlons on the roof, there's some more difference, but not so much. If you look at the tree branches and foliage at the lower border, the difference is quite obvious. So, it looks as the softness at the border looks less or more evident in function of the subject. I have an idea for to explain this, but I've posted too much for now and I'd like to hear from you. I'll give more details at the next round.

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Fabrizio Giudici

 stoppingdown's gear list:stoppingdown's gear list
Nikon D7000 Nikon D5100 Sony Alpha NEX-6 Nikon AF-S DX Nikkor 35mm f/1.8G Nikon AF-S DX Nikkor 18-70mm f/3.5-4.5G ED-IF +14 more
Sony Alpha NEX-6 Sony Vario-Tessar T* E 16-70mm F4 ZA OSS
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